Friday, July 31, 2015

The Great Debate: Amir vs Arny

The Great Debate, Part 1110250, at AVSForum

The Great Debate, Part 1110251, at What is Best Forum (where Amir is a moderator).  Amir starts it by saying this thread was inspired by a thread at AVSForum, although he didn't link to it.*  The previous thread seemed to be the one…but I'm not sure because there were many others!  And, note that the threads I have linked are a hundred pages or more.  Are audiophiles obsessed with their arguments or what?  We are (yes me included) apparently argumentophiles also.

(*Sadly, typical of how Amir argues, without linking back to demonstrations of crucial points.  In contrast Arny's arguments are almost always backed up with a plethora of links, though not always of the highest quality and many are now dead, including his sadly long gone website pcabx.  For the service he has rendered to society, yes simply by being a gadfly and contrarian to the mainstream high end audio industry, I think Arny should have the resources of a titan of industry himself, but I fear it's not like that at all...)

Technically these debates are about whether the potential improvements from "high resolution digital audio" (meaning it has greater than 16 bit resolution and/or greater sampling rate than 44.1kHz).  But it's also a debate about methods, results, and personalities in all aspects of The Great Debate between White Hats and Black Hats (the terms coined by Peter Aczel, a self declared White Hat who believes that most decent amplifiers sound the same, the classic White Hat position going back to the 1970's).  We've apparently even superseded the always shaky term "Audio Objectivist" (having nothing to do with, say, Ayn Rand) and "Audio Subjectivist" with Amir calling himself the Objectivist--so where does that put Arny?  The object/subject difference hardly gets at it either, since Black Hats (and especially Grey Hats, like John Atkinson--I respect him and his self identification, and myself) may be quite into certain kinds of measurements, or at least technical phenomena, real things happening, that just don't happen to tickle the White Hat sense of importance.  And a hidden argument which is never even touched is absolutely fundamental--must everything pass DBT immediately, and what if not?  Should technical criteria (say, Jitter) be ignored simply because there is no current DBT proof of their importance?  I strongly think not, however any person not an Amir or higher titan of industry has to prioritize, and I've been shaming myself for spending several years now far more on digital issues even at the fringe of the Grey Hat regime, when I sort of intended to have been working on room acoustic issues instead.  So Jitter should not be ignored, and let's have John Atkinson's and even better jitter tests developed.  But generally, we should probably move on to more important things.  We should be skeptical of all existing Black Hat claims, but not necessarily at the existence of to-be-found issues discovered by Black Hats, even as White Hats do, though the White Hats always often end up with the more minimal explanation.  So the world needs everyone, even as it needs everyone's mind to evolve.

Amir Majidimehr (principal of Madrona, formerly VP of Windows Digital Media at Microsoft) and Arny Kruger have been frequently sparring about what equipment differences are actually audible.  And this goes way back.  Though I'm not sure how long Amir has been involved in these debates, Arny has been involved since at least 1976, and he has recounted a history of the development of the ABX test method around that time and the ABX comparator in 1982.  He was one of the principles of the ABX company.  The very creation of the ABX test method over 30 years ago was precisely to answer the question of what equipment differences are audible.  Way back in the mid 1970's as an audio society member Arny was involved in these debates, and he's still at it now on a multitude of websites.

Reading Arny (who I've never met in person) I am very impressed with his arguments and generally the ways he makes them.  I'm also very impressed with his patience and dedication.  I think I take his side, mostly.

Reading Amir, it is clear he is very smart and is a very technically qualified professional audio designer.  I believe he is honest and not a shill.  However I think he makes poor and sometimes ugly arguments (often to authority, and sometimes to his own authority, and often discrediting the authority of others) far more often than Arny does.  He also seems to me much more to be a tireless bully.  Nevertheless, Amir may be right about some things.

Sadly, in these arguments, there isn't really a suitable technical qualification.  Certainly being an electrical engineer, as such, doesn't necessarily make you an audio scientist, and The Great Debate is not engineering it is Science.  Within Science "Audio Science" is too small to be particularly tractable.

The Audio Engineering Society (AES) is really an engineering organization, not a scientific one, but it does strive mightily (and perhaps too mightily) to retain respectability.  Therefore it is not surprising it cleaves tightly to Double Blind Testing results in its papers which are often written by academic scientists and not engineers.  Meanwhile, many audio engineers don't bother with DBT's.  Many have never done DBT's and never will, but nevertheless often are believed to speak with authority about such matters.

The truth is, right now, there is no authority.  And it is difficult to establish one given all the possible economic conflicts of interest, not to mention egos, etc.

Amir starts the second thread with a post showing a DBT result which confirms his ability to hear the benefit of high resolution.  At the beginning, Arny was not posting (and in fact Amir said that Arny had permanently retired from posting after Amir had posted some brilliant refutation--another unfortunate Amirism).  I have been unable to confirm that Arny ever quit posting anywhere, and in fact Arny posted to this exact thread some time later, as well as continuing to post at AVSForum and HydrogenAudio).

It happens I have seen at least one of Arny's argument which has has often made with regards to some DBT results.  He has argued that high frequency nonlinearity in amplifiers, speakers, or headphones can produce differences at audible frequencies, and that is what people are hearing.

As it turns out, at least in the first page or so of the second thread, Amir did not reveal the particular equipment he had gotten his positive test results with.  I had read up to the first point and which that question was asked an an answer still was not provided.

Now quite often subjectivist reviewers are quite clear about what equipment they have used to perform some test, and when they do so they go into great detail about every last cable involved, because of course they believe it is all of importance.

So it is more than a bit suspicious actually that Amir left out this detail.

I have not read all of either thread, though it looks somewhat worthwhile for someone like me who remains very interested in The Debate, despite going on for hundreds of pages.

One of the high points of the second thread is where Amir presents a very respectable paper published by AES (Convention Paper 9174 presented at the 137th convention of AES in 2014, by Helen Jackson, Michael Capp, and J. Robert Stuart) recently proving the audible differences of different kinds of digital filters.  That result does cleave very much away from the "all digital sounds perfect" position of the White Hats, including Arny.

(Similar experiments in the past with positive results have been shot down on the basis of sampling artifacts caused by equipment configuration.  In a earlier blog discussing that, Arny nails the best way of preparing test material.  It should start from the High Res material then be down sampled to the lower rate.  THEN it should be up sampled to the high rate again so as to avoid playback differences caused by switching sampling rates.)

Now one wouldn't think J. Robert Stuart (a Fellow of the Audio Engineering Society) would make such mistakes.  But it seems he may have padded this test in various ways, according to Arny and others at Hyrdogen audio.  It's clear from information available that Stuart used defective Rectangular Dither in this test.  He tries to justify this on the basis that "it is often used."  He knows it is not the best because he makes products that use the better method (some kind of triangular).  The question being addressed is not Rectangular dither.  The correct approach is to use the best reasonably available technology except for the item being tested.  So, sadly, this positive looking result is not acceptable and the Convention Paper now looks more like slanted advertising for Meridian.  AJ at Hydrogen Audio writes:

The BS test is a complete farce and fabrication of results in a desperate attempt to justify $$$ales of "Hi Rez" which of course nosed dived once people realized the scam, confirmed by M&Ms AES peer reviewed tests of actual audiophools, their hardware and purported "Hi Rez" media, the EXACT conditions they and the scam industry claimed to be able to "hear" differences.
The scam industry does not require the audiophool be "trained", the "Hi Rez" equipment/system to be certified, the room to have a specific noise floor, or the music content be cherry picked and doctored as in the BS test.
And he goes on…  But I believe he meant to say "the music content must be NOT be cherry picked and doctored."  That may be required for some official standards.  But if we are talking about the limits of audibility, cherry picking sample music that best illustrates the differences between system is fine, and even doctoring that music is fine (so long as this is described).  To say that we must prove limits of audible differences only on average hifi systems with average music is ludicrous.  I am fine with parts of the Meridian test methodology.  But the whole experiment sucks because it seems the control condition uses outdated technology that was not supposed to be under test.  It is that particular part that blew it.

I will say emphatically that a person's achievements in audio engineering do not necessarily qualify that person or any person to make an authoritative statement about The Great Debate.  Even very qualified, experienced, and successful audio engineers are not necessarily up to speed on this.  It requires a skeptical stance toward many things, which is not engendered in our society, and a broad view rather than a focused specialist one.  Such skepticism is not about making money, and these days the incentive exists to show that everything is audible, because that sells more stuff.  Nor is it about "proving" anything except to the fickle and superstitious marketplace.  Successful audio engineers can therefore not be expected to have explored finding The Truth very deeply as part of being successful.  They only have their personal truths, which work for their game.

So even what some experienced engineer says is not evidence.  The only admissible evidence is from actual double blind testing done to the highest standard, and every aspect of that testing is open to deep criticism.  Will progress be made?  Who knows!  Heat death of the Sun or the collapse of human civilization may well occur first.

My position remains that the audible differences that Black Hats obsess about and White Hats dismiss are likely very small, if they exist at all.  That idea is tangentially supported by a very sophisticated exploration of the meaning of p values in testing I have been reading:
Getting a big p-value is not, by itself, very informative; even getting a small p-value has uncomfortable ambiguity. My advice would be to always supplement a p-value with a confidence set, which would help you tell apart "I can measure this parameter very precisely, and if it's not exactly 0 then it's at least very small" from "I have no idea what this parameter might be".
OK, this doesn't appear to apply to the Great Debate at all, because it's concerning the situation even when you have small P values, whereas the problem with most DBT's in The Great Debate is the continuing lack of small P values generally.  But turn it around, and you see even if we were getting small P values consistently it still wouldn be The Proof many people want.  The fact that p values are related to effect size and sample size means it's not easy to tease these things apart.  The safest thing to assume when an effect that is expected isn't verified in DBT is that the effect is small, not that it does not exist.

But this is never what the blackest of Black Hats say.  They always trumpet their unproven differences as very important, because otherwise why would anyone spend the megabucks necessary for Black Hat tweaks such as cryogenically treated cables?

We cannot trust the most successful audio designers or retailers any more than we can the most successful lawyers.   We can have much more trust in the White Hats who have gained little and have nothing to sell.  Things are not proven until they agree also.  The whole history of high end audio is full of flimflam, lies, and half-truths.  Progress has been made, but more slowly because of that.

Monday, July 27, 2015

James's Charlie and SAE

The low serial Sumo Charlie with rack handles (indicating final alignment by James Bongiorno) is a remarkably nice sounding tuner.  As with the non-handled Charlie, there is reduction of ambience, but not nearly as much.  The quieting is just as good or better.  It is able to hold the weakest of my favorite stations, KSYM, in wide stereo.  That was just the trick, I thought.  Then I brought back the other Charlie and unlike the week before, it was now holding KSYM in wide stereo also.  Shows the need for quick A/B switching when testing tuners.  Even if you can remember the sound or reception objectively, it can differ from time to time.

If Charlie can't hold KSYM in wide, it has to be switched to the inferior narrow.  Actually I had no need to use the Narrow IF in my one day testing of the handled Charlie, and I forgot to do so, but it would be interesting to see if it sounded better too.

The handled Charlie has the punchy bass and clear highs that I associate with the Marantz 20B, which I think Bongiorno may have worked with when he was at Marantz in the mid 1960's.  I suspect that is where he learned the best way to align an IF, or at least the Marantz 10 and 20 way, and he carried this knowledge with him to SAE and Sumo.

And speaking of the Bongiorno sound, I unpacked the SAE MkVIII to check it out, and it had, fuzzily, a similar sound.  This was the first tuner whose design could be more or less fully credited to Bongiorno.  He had been hired to save the MkVI tuners, but he had to work with what SAE had already done.  On the MkVIII, he was given a free hand to make a cost-reduced tuner nearly as good (and it could actually be better).

Despite my belief that air capacitor front ends are better, I actually though the Charlie to have better sound than the SAE MkVIII.  The SAE was slightly noisier, though, and the punchy bass and clear highs were a tad less punchy and clear, respectively.  Perhaps it needs a front end alignment, which would be possible I think, or a refurb.  An IF alignment isn't possible because it uses potted IF modules.

Both these tuners have issues not revealed by the eBay sellers.  The Charlie has the thing I fear the most.  It has a serious smell problem, like the Marantz 2130 I now have in storage because I couldn't bear the smell inside my house.  A previous owner must have been a heavy cigarette smoker.  In all the equipment I've bought on eBay, I've only seen this problem with 2 different FM tuners.  I will not be able to keep this Charlie permanently in my house, though it seems OK now in the garage room which has the best ventilation.  But it sounds so good, I can't just return it or toss it either.  I have to continue with my Investigation of the Bongiorno-sound tuners!  My ultimate goal would be not just to determine how they differ among themselves and compared with other tuners, but why.  Just how exactly was the Charlie aligned by Bongiorno, and how did that differ from what Sumo did after Bongiorno left?  What did Bongiorno know about the IF alignment of the Marantz 10/20 and are they different fundamentally from other tuners?

The SAE has a problem with its numeric readout.  Not just the broken segment claimed by the seller, but an additional and far more bothersome problem right now.  It doesn't show the station frequencies accurately at all.  It is way, way, way off.  When tuned to 90.1 it shows 80.5, which isn't even a valid FM frequency.  When tuned to 88.3 it shows a number in the 70's.  But then once and awhile the number displayed will briefly snap to the correct number, and then back.

The numeric display on the SAE is utterly unlike that on the Charlie.  The SAE only shows the correct number (or whatever it shows) when you are actually tuned in to a station.  Until you are actually tuned into a new station, it shows the number of the station last tuned in.  So it's not as helpful as you might think.

Sadly the motorized Kenwood KT-413 isn't very good at all, and just as FMTunerInfo says.  But I'll add more.  The motor is very fast, even when switched to the "slow" position, and I think that is part of the problem.  Sometimes it actually skips over stations going one way, but finds it in the other.  One wonders how accurate the tuning is.  Anyway, the sound is noisy and wimpy and utterly unlike the Charlie.

Sunday, July 26, 2015

DAC output level measurements

Since this blog is my notebook, here are the measurements of my various DACs, with 10M DMM loading (sorry didn't bother with different), at about -26dB (whatever level, it was consistent):

Denon DVD-5000:
L: 41.6 mV
R: 41.5 mV

Onkyo RDV-1:
L: 48.8 mV
R: 48.0 mV

Audio GD DAC 19
L: 63.0 mV
R: 63.3 mV

The Onkyo does show the most inter channel difference at 0.14dB, which is just above the usual 0.1dB matching requirement.  The Denon is the most tightly matched at 0.02dB.

I suspect the Denon has comparatively low output because it is saving output range (which may actually peak above 3V) for HDCD boost, but this is just a guess.

This shocked me to calculate, but the Audio GD is 2.2dB (left) and 2.4dB (right) louder than the Onkyo.  I would expect the measurements with actual amplifier loading (22k ohms) to be 0.2dB or less different at most and probably below 0.1dB different.

While ABX testing sets a condition at 0.1dB matching, typical matching isn't that good.  Some preamps with steps won't let you set balance closer than 1dB, though 0.5dB is common on digitally controlled preamps.  Old fashioned potentiometer volume controls might have +/-3dB inter channel mismatching (a 6dB total range)--so you really needed to use the companion balance control.  (I was glad to dump those in my then-main bedroom system in 2005 or so with a Classe CDP-35 preamp with digital volume control in no small part for the sake of being rid of potentiometer balance variation, which I barely remember but when I do it is with great dread.  Even my Aragon 28k preamp had considerable channel variation at the very low position I had to use on it.

Friday, July 24, 2015

Audio Nirvana Speakers…Slam!

I listened to these at a friend's house, Audio Nirvana speakers (12 or 15) in large and tall cabinets, with the speakers just above ear level IIRC.

It was in many ways very impressive sound, dynamic, full of slam, powerful and deep bass, clear midrange and highs, excellent left to right imaging, stable but not too much pinpoint.  He said he was unimpressed by other speakers he had heard, often very expensive, in audiophile's homes.  I sympathized with that, and in some parameters (dynamics and slam, especially) I have only heard megabuck systems at audiophile shows, like the largest MBL demonstration, that actually bettered what he could do.  Even with all my complicated and intentially overwideband system, I actually can't quite do slam as well, maybe, except perhaps if you are sitting in a corner instead of the sweet spot...

But I wouldn't say it was the least colored sound, it had clear colorations, a slightly exaggerated mid bass, elevated mid highs, obviously absent highest highs.  They always say things like "most people can't hear above 15,000 Hz anyway" but it seems to me, if it's missing, I can sense that somehow.  Though I couldn't name any instrument or anything that was obviously missing except for possibly noise anyway.  The other colorations seemed apparent but not particularly annoying either.  Possibly the worst aspects of this speaker could be fixed with digital EQ, making it truly reference, save for the supra 15 kHz…And there, supra 15kHz super tweeters might do the trick, without much messing the actual imaging.  Though once we get into all these further approximations of the needed changes, we would likely end up with…less slam.  The apparent missing high frequencies could also probably be adjusted with speaker aiming (beam that center right at the ears) and replacing damping used in the room with dispersion.  Much of what I was hearing as missing highs might not have actually been the speaker limitations.

Distortion, I don't know, he was playing pretty loudly in a small room, and there didn't appear to be anything like rising distortion near clipping.

But there was not much depth, and I think that was the ultimate sign of a cone speaker distortion type*…which should be expected!  The dynamic speaker is driven from the near center, and the propagation of sound through the speaker cone is dependent on frequency.  And the propagation through the speaker cone creates delayed radiation of that frequency for as long as it takes to travel through the speaker cone to it's ultimate point.  It's very fast in a relatively stiff cone (compared to air, say) but not instantaneous.  So there is an irreducible amount of time-smearing, and there may be some distortion from traveling through the cone also.

(*other explanations are possible, say related to room acoustics and speaker placement.)

There is one single cone (or mostly single cone) speaker which gets around these issues, and that's the Walsh driver, where the contour of the cone exactly matches the delay for time alignment.  And it also does it with omnidirectionality.

Actually, a relatively flat and stiff but still contoured cone like the Audio Nirvana may already do that same sort of thing to a considerable extent.  If we want to understand just this angle, we have to do the kinds of measurements few people bother to publish.  The sound suggests good but not quite perfect.

Anyway, electrostatics have their limitations too, which may be more bothersome to many who like slam.  These can be overcome in a reference system, like the one I'm still working on, with additional time aligned drivers for deep base, super highs, and so on.  Without those complicated fixes, whether one prefers electrostatics or single cone Audio Nirvana is a matter of choice, neither is perfect really.

So the Audio Nirvana approach makes a truly excellent Value system (by Audiophile standards of Value…non-audiophiles would think you were already spending enough for Reference).  But it may not offer as much potential for improvement as a system based on electrostatic panels plus additional drivers like mine.  I imagine that Electrostat loving friends of mine might be horrified at the idea their speakers are lacking anything, but I think it's a mainstream perception anyway that you get maximum slam with a dynamic loudspeaker system.  People like me try to get the best of both, by mixing both.

It's kind of a miracle that they've made single dynamic drivers these good now.  Most people would not think it possible.  I didn't.

Wednesday, July 22, 2015

Updating the SACD player

In sorting out my junk for sale, I also retested my Sony DVP-NS500V dvd player.  This was in the second generation of SACD playing products (after the SCD-1/777ES), and it was the lowest priced single disc SACD player.  It was also a DVD player of pretty low credentials now.

It was a cult player, and favorite of modifiers because you could buy this player new for as little as $149 and then fill it up with $1000 or more of mods, and people would say it challenged the big dogs.  My audio-nut brother-in-law liked it pure stock as the best sounding SACD player, I think for the few days that he even considered SACD's worth listening to.  He had suggested that the second generation of SACD decoders from Sony was better than the first.

In scientifically useless sighted testing I preferred it in some ways to the Denon 5900, my living room player.  It had a more dynamic and expressive sound on SACD's.  The Denon sounded quieter, cleaner, as though it wasn't taking any chances.   On CD's I preferred the Denon 5900 and even the Denon 2900.

Now I don't take SACD or the equivalent (and I stress equivalent) digital file format DSD as the ultimate of anything other than hype.  In no way are these formats superior to PCM formats using the same amount of data, and my personal feeling remains that SACD's or PCM files are even inferior to Redbook CD….although it may be fooling at times since the SACD does have better midrange dynamic range.

So I don't obsess about SACD's or pure DSD signal paths.  But I feel it's worth having the best SACD playback, at least, as I can, for music that is only or best available that way.

I couldn't have pure DSD anyway because  the backbone of my system, from selection to level control and crossover and EQ are all done in PCM, and cannot be done in anything like DSD anyway.  I read SACD's by resampling them to 24/96 digital using a Lavry AD10.

I strongly reject the concept that DSD files have the potential to sound better than optical disc transports.  Highly tuned optical disc transports have the possibility of not only having the lowest jitter, but of having a particular kind of forward-motion timing much like idler wheel turntables.  Lack of motion is not a possible state, given the rotational inertia and forward drive force.  Whatever variation exists is forward running and not fed back into itself.  This is going to sound free as in freedom.  Meanwhile, most asynchronous digital systems like USB and Sonos operate on the principles of handshaking and full duplex communication.  This is going to have a different kind of time signature, one of deliberate action, give and take, action and reaction.  I know this sounds like magical thinking, and may be, but it seems to me that at the very finest of levels, these correlations (or something similar to what I'm describing) are what actually exists…whether we can detect them or not.  Clocks are never exactly perfect, etc., and furthermore in real systems all the imperfections have ample force to be correlated through sharing space, grounding, and connections.  When you have multiple stages of time varying devices which are intended to reject the incoming time variations, they can never do it perfectly.  Basically, everything is awash in tiny variations, with relationships that produce actual if not statistically verifiable correlations.  The mere fact that you have "buffering" or whatever doesn't mean the problem is completely solved…at least at the level of the tiniest actual particles and wavelengths, variations continue to go on at the tiniest of levels, and everything within an electromagnetic sphere of influence has some contribution to the proceedings.  Best is to make everything, at every level and every way, as stable, simple, uncorrelated (free), forward running, and close to the next amplifier as possible (distance is loss too), that's the best linear system for music.  That's what you get with a very high end packaged SACD player, as compared with a network of interacting devices which ultimately decodes DSD files.  And timing is more critical to DSD.

(Audibility?  There is no reason to believe such effects would be remotely audible (DSD 1x files vs SACD players).  Jitter becomes audible many orders of magnitude better than the worst but correctly performing digital equipment, according to published research.  But remember, proven audibility is not what I am concerned about.  What I am concerned about is not the verifiable, but the potential for difference, a difference that ultimately might make a difference within the infinite possibilities of the future.  Anyway nobody who claims an audible difference can back that up with scientifically respectable research at this point.  It's all just hand waving.  So if I can point to what actually has better potential, not just someone's current opinion based on biases, I win.)

So I believe it's worth having an SACD optical player, and maybe even play CD's this way too, by resampling them to digital rather than using the digital output or digital files.  I am thinking now that this  works precisely because both the player and the ultimate digital signal are decoupled in time.  Digital sampling is measurably so close to perfect as to be as good as any analog preamp, so there is no penalty for using it in this way, and anything can be resampled to anything else with nearly perfect dithering.

And now I find out that generally the first generation DAC chips Sony used in its statement SACD players, the SCD-1 and SCD-777es and also the cheaper DVP-9000ES, the "V24" series, is considered superior to the second generation chipset in my NS500V player…which was intended for AV products and not audiophile products.

I'd always lusted over the cool looking SCD-1 with a top loading drive with weight, which I think in general is a superior configuration (though the specific unit in the SCD-1 may not be as good as transports in other units such as Esoteric and Accuphase which are conventional drawer loading--or even possibly the transport in the DVP-9000ES).  Now I find out I can get almost the same thing in the 777ES, but all the players after that, including the current 5400ES, look cheaply built in comparison, lacking the heavy build and heavy transport.

(When a CD plays in a cheap front loading player, it may be vibrating like hell.  You wonder how the system works, but it works just up to a breaking point.  But this is further time variation at the beginning of the whole process, messing everything up downstream, no matter how much buffering, etc., there is a chain of causality and correlation is created.  And with higher speed media such as SACD, it's 10 times worse, or maybe 20 times worse, on top of the timing itself being 64x more critical.  Now the vibration may not always be so bad, I'm talking worst case here.  But you simply can't imagine this happening with a SACD clamped or weighted down onto a heavy metal platform.  So this is why I like the idea of a top loading player, because it makes sure you are going to have a flat spinning disc without too much vibration.)

So the kind of thing I'd like to get would be SCD-1, SCD-777ES, DVP-9000ES.  Also it looks like the Marantz units are especially good, and may honor the SACD/DSD signal better than Denon.  Something like an SA11.  I'm not sure whether the Esoteric DV-50, now available not too far out of my price range, would honor SACD as well but it could be far better with CD's, and looks to have a transport that may be among the best among these alternatives.

I actually don't see any reason why having the laser fixed as in the SCD-1 is a good idea.  The usual method of fixing the spindle sounds much easier, and possibly better.  Might as well have the rotating element fixed--it's certainly the harder thing to move.  A simpler top loading drive would be a good idea, for reasons I have explained, but neither Sony nor Esoteric nor Accuphase nor Marantz offer that. I do have the feeling now that of the mechanisms available, the top of the line Esoteric is the best.  But that's not something I can imagine affording soon.  At this point I can only imagine the DV50 and that is really way beyond my need for SACD, and I think it might not be the better choice for SACD among these options anyway, though it could make up for any inferiorities with a better mechanism too perhaps.

Timing is very very important for one bit formats.  In a way, all of the information is just timing.  So an especially good transport is a must.  Sadly many of the old classics like the CEC belt drive transport were made for CD not SACD.

Saturday, July 18, 2015

Rethinking the Sumo Charlie Tuner

The Sumo Charlie tuner produces good sounds: very quiet, and yet also very dynamic and tuneful, even on weak college radio stations.  In comparison, a Yamaha T-80 (the penultimate model just below the famed super tuner T-85) has more noticeable noise on just-above-stereo-threshold signals, and even without the high filter (which I cannot bear at all because of how dull it makes everything) seems slightly dull and tuneless but has more real 3D ambience if you listen for it.  The Charlie seems to bring the musicians into my living room, stripped of their original ambient environment, but close up so you see them better, as part of achieving the low noise yet dynamic (passionate!) sound.  It isn't really what I want, I want to be transported in my imagination to the musical venue, but it's an interesting trick, since not much else seems to be lost.  In particular the Charlie does not sound "filtered" (as in held back) in any way, indeed the dynamic sound seems exactly the opposite, full of life, moxie, and musicality.  It is not especially lacking highs, though the bass does seem a bit bumped up and loose from everything else, and you might wonder if the highs aren't slightly reduced, but there's no pervasive dullness.  I like the Yang sound more than Yin sounding tuners like the T-80 (the T-85 is a Yang sounding tuner like the Charlie, actually not quite as much as the Charlie, but not an ambience minimizer).  You only notice the missing ambience if you have previous experience with good hifi and good tuners, as I do.  (Interestingly, just as this tuner was being made James Bongiorno left the hifi business and started talking about how he enjoyed his own grand piano better.)

I noticed this lack of ambience in the Charlie output, and then noticed that others have made the exact same observations at FMtunerinfo, that the Charlie sound falls down from lack of ambience and depth.  It is said to sound "flat" (meaning lack of depth and 3D).  It is said to have bumped up sounding bass (which actually measures flat).

It's also doing extremely well for a 35 year old tuner that has never had any kind of refurb.

I do not observe a general lack of sensitivity and weak stations come in remarkably quietly (if not the actual quietest).   However the muting is very fussy about actual quieting and will mute even the strongest of stations if there is an interfering signal nearby.  The best solution is to enable the narrow IF when this happens. Unfortunately the narrow IF does have a negative effect on the sound, but many stations require the narrow IF anyway.  If instead you disable the muting, then you get the problem of stereo intermittently dropping out, and there is a temporary muting when stereo goes in and out, which is annoying.  Furthermore, neither the muting nor stereo thresholds are adjustable externally.

Many Yamahas and many other Japanese tuners would automatically engage the Narrow IF in situations like this, or at least have an "auto" mode which would.  Bongiorno leaves all controls fully manual, and not even retained in the station memory, so you have to remember which stations need Narrow and which work even better in Wide, and you must manually engage the correct IF even when using the 5 presets.

This might not have turned out exactly the way Bongiorno wanted.  Full manual and presets would have been OK if the stereo could come in and out without much effect.

I think the muting may have been less fussy when I first bought this tuner in 2000.  But maybe I was also less observant and more inclined to just use Narrow (which I didn't hear any difference from then, either).

I'm now thinking the fussy IF and the in-your-room sound are two sides of the same coin (design).

The development of this tuner was a life's work for Bongiorno, given his history of working as an assistant on legendary tuners including the Marantz 10B, the SAE MkIV, and as a primary designer of the SAE Mk VIII (aka 8000).  He joked about the Charlie tuner when I first met him at the first GAS company in 1976, and a GAS prototype was built, but it was not until the Sumo stint that Bongiorno finally got to do things the way he wanted…or maybe not quite (and perhaps it's no coincidence that Bongiorno's association with Sumo ended just before the last batch of Charlie's could be personally adjusted by Bongiorno himself).

I know Bongiorno was interested in tuner IF stages because…he got me interested in them!  In one of the most memorable experiences in my life, Bongiorno was the presenter at a San Diego Audio Society meeting (sometime before I became President of SDAS) around 1981.  He talked about tuners and different kinds of IF's, and I'm sure I asked him a question or two that suggested to him a deep ability to misunderstand what he said.

I don't even necessarily remember him pushing The Charlie.  At that meeting he praised recent Kenwood tuners as much as Marantz, etc., and singled out the L-01t and L-02t.  Well he was always a windbag and mostly a self-promoter, but he nailed that one, way back then, as it took me years to discover.

I imagine the development of The Charlie to have been a battle between Bongiorno and the manufacturer, and even the very thing that led him to leaving the company and the hifi business.  It is not a fully successful realization of what Bongiorno had imagined it could be.  And I chalk this off to the lack of awareness at the time (and even through the marketing of the designs Bongiorno had previously been associated with) of the importance of tuner front ends and the pervasive weaknesses of varactor based front ends.

So it's not the most wonderful tuner ever.  But it is relatively unique in the singularity toward which the IF was designed.  It uniquely suppresses hiss despite the weak front end.  Unlike the Pioneer F-93 and similar tuners which used very complex processing to achieve a similar effect, and I should also mention Carver who long did similar things, Bongirno was able to achieve similar effects merely by the way he tuned the IF.

As people have said regarding the F-93, though it has weaknesses, there may be stations it renders more listenable and enjoyable than other tuners, despite limitations.

Though right now it seems I enjoy the presentation of other tuners, especially my F-26 and L-1000t better, on the stations I actually listen to.

One of the things that blew my mind regarding Frequency Modulation a few years ago was learning that FM produces not just 200 kHz of modulations…but an infinite spectrum of modulation.  To really decode FM properly would require unlimited wideband…with open airwaves at all other frequencies.

With a fully continuous signal, such as a 880 kHz sine wave, all these sidebands are going to basically contain the same information.  But with a constantly changing signal, they are going to represent small differences in time.

So having a very high Q filter in the IF, which restricts these sidebands severely, the effect is going to be that things that are more changing are going to be discarded.  That nicely suppresses noise, but it simultaneously suppresses correlations only seen in the very wide IF--the ambience!

My mysticism tells me the Charlie should not have needed that 280 Mhz ceramic, which is messing the whole can.  But that would suggest I have the Q thing backward, or perhaps if you're going high Q you have to high Q all the way.

But perhaps it had to have the 280 Mhz ceramic because of the weak front end.  A nice air capacitor front end could have done wonders.


It lacks remote, which I need in my setup.  But it looks cool, the 100 kHz steps are cool in some ways (you don't feel a need to mess with fine tuning--since you can't anyway), it is far simpler (and easier to deal with) than the Kenwood KT-6040 I'm now using as my remote tuner  With the Charlie, I tune in the station and press Narrow if needed…done.  On the Kenwood there are scads of different combinations of settings including off tuning that may be helpful, and for some reason I off tune every station now.

It does seem that Bongiorno didn't just buy off-the-shelf front end…he got them to do particular things. And it does seem that it's been quite stable, over time, to work as well as it does now, 34 years or so after having been made.  Bongiorno was a stickler for lack-of-drift in the frequency domain.

I was just about to sell mine, but after listening to it's unique presentation I've decided to keep it for now in my tuner Collection Museum and even get a Bongiorno Tuned unit if I can.  I sometimes joke that I could use it, in a closed FM circuit, as a special effect processor--ambient stripper.  But IF I maintain a collection of 10 or so tuners, which I'm thinking is ok (though many of the ones I have now should go).  The the real angle is the same as the F-93 one.  There might someday be a station it gets better than other tuners in it's unique way.

Regarding the off tuning of the Narrow IF…I think this was a deliberate if partly unsuccessful attempt to utilize the effect of closely tuned--but not exactly tuned--serial filters in making a super filter.  This is rarely attempted.  It has failed to reach objectives I fear, and especially in its sonics.  One can hear a similar effect with off tuned crystals…though the crystals are more inherently effective.

As it turned out, the lousy sounding Narrow IF is worth avoiding if you can, and I can avoid it most stations but not the college radio stations I now use the Kenwood KT-6040 for.  So it can replace neither the F-26 nor the KT-6040 in my setup, but if I had a dozen tuners online it would be an interesting one, especially if I could add remote to it.

**** Update 9 PM

I have won a second Charlie, one with the handles which means it was given the final alignment by Bongiorno himself.  It has an amazingly low serial number too.  Actually my unhanded unit has a serial number in the 1400's…which makes me wonder about production estimates I've seen that put the number of handled units over 2000.

I don't know why it didn't occur to me back when I was blogging daily at the FMTuners group, back when Bongiorno himself was participating, and I complained about not having a handled unit (he made me an offer for tuning AND upgrade which I never followed through on) having the magic adjustment, why I didn't just get a second unit?  Well back then the handled units did command a considerably higher price, and the unhanded ones too, and I had read all the complaints about the tuner and how it's performance was substandard (some of which may be explained by not setting the Narrow switch when needed). And, I didn't believe a Charlie would solve the strange whistle I had been hearing in KPAC, which had been my motivation for trying so many tuners.  I had hoped that a fully (or at least nearly fully) LC type IF would eliminate the problem, and it clearly didn't, or the unhanded Charlie would do it too.

(Many tuners later, and a big experiment, I determined the problem was with the station transmission system.  The Charlie, which attenuates the gaussian, wouldn't help.  The Sony XDR-F1 eliminated it entirely…but falsely, which is the problem of open ended noise elimination systems, they always reduce real information along with the noise.)

Now I'd like to know, among other things, what is the difference?  Is the Narrow tuned to sound better, for example???

Friday, July 17, 2015

Vintage vs Pre-Owned

As it has turned out for many reasons, I purchased relatively few of my audio components brand new through an audio dealer.  I often buy used components precisely because I can (often) get exactly what I want at reasonable prices.  The real high end components I have lusted after, such as the Krell FPB 300 I have now, were just too expensive at their original prices for me to have even contemplated buying (or so I thought) and I had even less spare cash way back through the 70's, 80's, and 90's.  It's really only been during the past 5 or so years I've had the kind of money to imagine buying such things, and since then I've been more preoccupied with making my house into a more livable castle…so I still haven't had the money for truly high end gee gaws (though, through a series of steps last year I ended up spending about $3500 on 6 turntables of which all except for one are still in "project" or "spare" status…and I coulda gotten one pretty nice one for that much cash, much nicer than the actual working one I got and am now using--though still not the kinds of ones I lusted after and what my project-phase tables will represent when and if they are finished or at least brought to a good plateau…the plan is ultimately to have a hot rod Technics in the bedroom and a hot rod Lenco in the living room, and backup tables for each one).

I ok with this general approach, and actually I very much like getting super fancy pre-owned stuff from much richer people who have already taken off the biggest chunk of the original price for me.  I like good sounding stuff but I'm also a sucker for features and and the right kinds of fanciness.  I get no thrill out of finding the $19 portable CD player that blows away all the heavyweights from Wadia, Theta, and Krell.  My brother-in-law goes about things more that way, and I followed him for several iterations of that search.  By his lights at any given time, I wouldn't have to search, he had already Found the one that blew away every expensive DAC he had ever heard.  But by the time I actually bought the each of the $19 players he was bragging about, he had already moved on to the next one, preamp-of-the-month style.  Not only were his judgements not the ultimate judgements claimed, I myself couldn't really be sure any one was better or not than anything else I had.  Meanwhile, I was stuck with a growing pile of flimsy cheap looking, cheap feeling, and often cheap sounding and marginally reliable stuff* I really didn't care for that much.

And I still lusted after the brushed or anodized metal heavyweights.  I very much like the High End audio magazines (Stereophile, The Absolute Sound) and endless webzines covering the mega expensive equipment few people, including me, can afford.  Because I'm just reading about the stuff I could be buying in 10 years with a zero or two lopped off the price.  Or I can think about how I am achieving the same or better things with my stuff, or perhaps could with a tiny bit of adjustment.  And anyway, it's escapism, the higher the prices the more we can simply ignore any feeling that we MUST buy this, and instead appreciate the vicarious experience, often saying to ourselves we have better for much less.

(*To be clear, often the anodized heavyweights that look like you could drive a truck over them fall ill at the first chill and must be sent back for repair.  In fact things are all too often precisely this way, the heavyweight equipment is designed for Performance first and reliability isn't something that necessarily comes from overbuilding and most often doesn't, but from having a well tuned design and production process--often making the same boring stuff year after year--which values reliability more than novelty.)

I believe now a person could easily convince themselves quite easily that a $19 CD player is "the best sounding" even when it isn't true.  In fact, I go much farther, and say that almost all of the "listening tests" and comparisons audiophiles do and have done are utterly useless or worse, and that generally speaking, except for speakers or phono cartridge it isn't necessary to do listening tests at all…since good amplifiers, CD players, and the like are likely audibly indistinguishable in DBT, and such differences as there may be between two pieces of equipment (other than speakers and phono systems) can be much more reliably be ascertained with measurements.  So then what do all your listening tests mean?  They are most likely just random events of perceptual self-fooling but tend to lead to false belief and superstition.

But I simultaneously reject the idea that I therefore must buy the cheapest unit that DBT cannot find to be any worse than the best.  Though there is a nagging voice, though, that does tell me I shouldn't be contributing to the general level of bullshit even by playing along with Audiophilia and even creating my own strain of Endless Philosophizing or something like that.  At least other people may believe they are performing useful experimentation, though sighted and not level matched and limited to one or a small number of trials.

Anyway, I maintain that in the long run, a slightly better device whose difference can't easily be discerned in systematic comparisons might (and this is a lack of impossibility) lead to an epiphany that the other doesn't.

Since we can't really be sure which devices is better through either sloppy or even very careful listening tests--the thing to do is use reasoning first, and then measurement to confirm.

One way another, my ultimate standard is Harry Pearson's "The Absolute Sound."  I am seeking perfect recreation of the experience.  But I know I can't really advance much even by exhausting listening tests.  So I do what I do, some of which you can read in these pages.

I'm not interested in going back to a smoother, silkier, rounder, less aggressive, etc., sound simply because it is pleasing.  However it turns out that The Absolute Sound is almost entirely non-irritating anyway, so irritation is not correct.

Some audiophiles, perhaps having also given up on the technical (logical, measurable) aspects of performance to explain their preferences, sometime seek an actual "Vintage" sound, the recreating of earlier sonic performance, through carefully restored Vintage Equipment.  This is not what I do, though it does turn out I don't see that much value in newfangled equipment and especially at the newfangled prices.  I own speakers from the 80's, and amp from the 90's, etc.  But this is a judgement that I can get what I want often better as well as affordable from a slightly earlier era.

One of the most curious of these Vintage obsessions of all to me is the fondness for Japanese made Marantz equipment from about 1970 to 1980.  I myself bought one of these first in 1973, a Marantz 2270, the original Japanese series (insiders called it the "B" line, often as derogatory).  I was not very proud of myself for doing so…in fact I immediately regretted not spending the extra bucks to get the Model 19, which I truly lusted after.

Then I thought the switches noisy, I got a one month non-repair from the dealer but they ultimately fixed themselves through usage.  Then I missed the deeper bass of my Dynaco SCA-35, though I ultimately considered that to be a defect on the part of the Dynaco (which I couldn't stand anymore, the frying noise on that unit was just not getting fixed).  By about the 6th month I had gotten over my regrets, and felt I had the best thing in the dorm, and for a few more months anyway had that uber feeling.

It didn't last more than months, once again I was regretting not having separates, not having a direct drive turntable instead of a Dual 1209 small changer--which several years later I found definitively inferior to the library's Lenco.

So most of the time I was actually using my 2270 in college, and shortly thereafter, I had very mixed feelings about it.  When I started working as an audio technician, it wasn't long before I was measuring it, and ultimately seriously (and with no thought to aesthetics) modifying it beyond repair.

That process began in September 1977 when I joined Audio Directions.  By 1980 I had the Marantz upside down mostly, with the preamp board having been replaced by a simple board of my own construction which let me substitute different op amps.  I hated the original preamp because it couldn't be set flat without measurements.  The detents were fake and the controls really did not track all that well.  The worst of it was that this affected the midrange too because there was a midrange control.  So great flexibility had become a liability.  I cursed myself for not having bought the 2275 model, which I could have at the time for an extra $100 or whatever.  The 2275 had a tone defeat switch.  I had often felt inferior during my college days for not having that feature, but the though was academic.  I never realized that I was listening to significantly non-flat response, with almost 1dB (actually I can't remember how much it was, it could have been as little as 0.1dB)  of variation in the midrange, due to lack of a tone defeat switch.

I never really got around to doing anything about the rest of the 2270, in fact I pretty much thought the rest of it was fine, except for lacking a whole bunch of new things: fully complementary circuitry (as in GAS products), audiophile caps, Class A operation, and more.  But as I didn't expect to be able to have those things, I didn't think they were that important, and it didn't worry me much, I had replaced the capacitors in the line stage anyway (in fact, I may not have been using capacitors, relying on the capacitors in the power amp input).  Except that I gutted the front panel for some reason, filling the tuning dial in with damping material, and used my Kenwood KT-7500 instead.

Anyway, perhaps very sadly I dumped that 2270 around 1992 because I simply had too much stuff and I hated carrying it around because I sometimes cut myself on the exposed chassis edges.  I was making a move at the time.  Though I might have left it at the curb, and maybe somebody got it.  Anyway I had purchased a second 2270 around 1991 just so I could have a nice looking one in my collection (I didn't really plan to use it), and that's the one I still have today.  I don't use it much, but I did use the phono preamp when I was first testing the Lenco last year simply because I didn't have anything else.  It worked fine.  I've sometimes used the amp in a pinch, but never on the Acoustat speakers.  I do find it hard to part with stuff, the 2270 is nicely made if not perfect and if your not too fussy, and it features several usefully separable parts.  But perhaps I shoulda gotten the 2275 if not the Model 19….

Anyway, knowing it's imperfections I wouldn't use it (and I can't anyway) in my main system.  And yet this is what you see on eBay, endless 2270's I think I've seen them as high as $999, more than I paid new in 1973 ($499 if I remember correctly…they were being closed out and replaced with 2275's).

Though in some sense, generally, I don't see much wrong with using vintage equipment from the 1970's.  In fact it was an era, and perhaps the first, when the largely Japanese manufacturers got it right, and were making good (and better and better) and reliable audio equipment, equipment…that is still being used today (and in some cases, without ever having been refurbed, though that is likely necessary for something in actual continuous usage).

And according to DBT produced understand of what is audible and what is not…in many cases you would not be able to tell the difference between a good piece of gear produced in 1975, say, and one produced now.  So if it's not going to make any audible difference, or even much audible difference, why worry, just enjoy that retro feeling, the looks or whatever.

Even wrt my original 2270, even if it's measurable error say at 1kHz were as much as 1dB, how greatly in the negative (if not the positive) is that going to affect my experiences anyway?  Even 3dB might not make much difference to my pleasure.

Well, OK, but I simply try to have the most actually transparent.  I don't care if the difference has been proven to be audible or not, the ultimate traits I am looking for can be determined by other means.  And I don't necessarily enjoy retro, I just get what I can if it does the job and is the most transparent within affordability.


Meanwhile, subjectivist audiophiles and audio magazines at least put on a good show regarding the march of progress brought about through their unsound methods.  They create, exemplify, and harshly criticize those who don't follow the fashions they are promoting, which are ultimately shaped if not intended toward Selling More Expensive Stuff.

So it is by these standards that that the concept that old people are seeking something more of everlasting value through recycled stuff is going to be portrayed as going off the rails, at least slightly.

I tend to see things the other way, that what's basically good doesn't change much, and there hasn't really been much audible advance in amplification electronics since 1970 (despite all the techno wizardry and puffery).

But I get as much as I can from what little advance as their has been by catching the stream a little back from the present in pre-owned equipment.

Saturday, July 11, 2015

Top Tuners

I have a winning bid on a Scott 310D as I am writing this, though I may not win the final contest since usually at least half of the action, if not more, happens in the last 3 seconds.  (Update: I won, and now I'm wondering if I'm nuts in having bought two new tuners in a week, the other one being an analog tuner with motorized control--the Kenwood KT-413.  But anyway here is a great Scott Tuner history to show the 310D as Scott's best ever mono tuner.)

But I've been thinking about the inherent superiority of analog tuning via variable air capacitors, and  it occurs to me that at it's time, the 310D was the best tuner made.  OK, well there was also the REL Precedent, so maybe not quite.  But compared to anything not rare beyond unknowium.

Then after that, I skip the 10B which I consider beautiful tuner with a few technical deficiencies, and zoom up to the Marantz 20B, which I consider the best Marantz tuner.  Interestingly the 20B is a very wideband tuner for a single IF width tuner.  It relies as much on capture ratio as selectivity.  Same was true of the Scott, but I wonder about the 10B.  So I'm thinking the 20 (which became 20B) was Dick Sequerra's 2nd(or 3rd) try for the ring, and he tried a bit differently, more like the Scott had…, and won, in the eyes of revisionist 20b-is-the-best-Marantz/Sequerra'ers like me, with only his 20B on the list of best sounding and performing tuners.

So the next I'd nominate would be the Sansui Tu 9900, a gem, followed by their TuX1.  After that, the Pioneer F-26--a tuner barely appreciated at the time, barely advertised, only available for in instant and then replaced by a series of successively worse F models.

Kenwood in this accounting is slightly behind at first, finally producing the very well performing KT-8300 following the 9900 but not exceeding it, and not being as good as TuX1, and their pulse count tuners 600T and KT917 being a design mistake…poor signal capture and sound.   But at leas the KT-8300 was a fine tuner, and then the L-02T and L-1000T were Kenwoods winners, with the L-02T being possibly still the best tuner ever, and the L-1000T not far behind for a "digital" tuner (using varactor diodes, sadly, being somewhat behind the ultimate performance of air capacitor analog tuners in principle).  Latter Magnum's I have not heard good things about, but the big Accuphases with far superior pulse-count system might be OK, I'm still suspicious of that as with any delta sigma system.

Of these, I now own 310D, 20B, 9900, F-26, KT-8300, L-1000T, a short list of many one-time neglected best-at-the-time tuners.  (Plus many others perhaps less neglected, but not a 10B or Sequerra.)  Only one on that list, the L-1000T, uses varactors, but in such a high end design that their limitations are finally accommodated.

For the 310D, I have a Fisher MPX-100, considered a better sounding MPX than the ones made by Scott, though I consider all tube MPX to be somewhat limited, and a repurposed analog multiplier from a Yamaha T-85 tuner might do better (Katz does this, connecting his REL to a Yamaha MPX).  With the 310D/MPX-100 I have a potential 10B killer, and certainly with the 310D/T-85.

Along with the 10B, another mistaken effort was the Sequerra, in which Dick failed to recognize the inherent inferiority of varactors.  It seems almost no one did at the time, except perhaps McIntosh which was still doing analog air-capacitor tuning in the 1980's with the MR80.  The benefit is not obvious with test signals, only with real world reception, where the front end noise reduction--air capacitors have about zero noise and infinite overload--becomes enormously important in preserving the integrity of each signal.  Analog tuning had died in the vine primarily to the success of DIGITAL! over all marketing of the 1980's and 90's.  But it had already started a comeback with Magnum Dynalab, and is now in full swing with the unending lives of classic tuners, with guides such as fmtunerinfo (to which even I have contributed a bit).

(The Absolute Sound, in perhaps the first issue I picked up, #5 or #6, reviewed top tuners of the time, including the Sequerra Model One.  They declared the Sequerra the winner.  But here is the catch: they used closed circuit FM transmitter, not real world reception.  Then, interestingly, they published a page of heresay about the 10B, all of it negative, not unlike the negative comments at fmtunerinfo: overload, birdies, noise, bloated bass, softened highs, just not that good.  But those were *not* based on the closed circuit listening test which the Sequerra had won.)

Now one thing I wonder.  Frequent blogger and one time radio station engineer John Byrnes bought a 10B as soon as they came on the market.  He took it home and found overload problems all over the dial, and took it back to Marantz.  They made some changes, he took it home, same problem.  He ended up returning the 10B (or was it 10???).  Meanwhile he never had any problems with his Scott tuners until he finally replaced his 4310 (or was it 310e?) with a McIntosh MR80.

Well, the adjustment of the 10B didn't work for Byrnes, but what if it did work for a few others?  What if Marantz actually upgraded the alignment formula, and/or had different formulas for different problems.  Well in that case, even from the factory, there wasn't just one 10B.  I wonder about that possibility, and also Saul Marantz's claim that it was the development of the 10B which lead to Marantz the company running out of money, and part of the reason behind his decision to sell the company, just after the 10B came to market.  I'm sure Dick Sequerra was well paid, but not THAT well paid.  But what if part of that "Development" cost was the readjustment of tuners, and given that Marantz did sell the company, and if he may have thought of that before, or not, it would be best to be sure everyone was happy one way or another with their 10B, even if that required some extra "service" because of certain touchy aspects of the design, aspects which Dick Sequerra would have been motivated to fix in the next version.  Well the 10B and it's reputation did the job, Saul got his price for the company, but for latter day users, it may not be, and generally is not considered, the solution to common urban reception problems.  If you want the classic Marantz Sound by Sid Smith, then it works, but not as the ultimate tuning machine…according to reports I hear…and I have bid on many 10B's anyway.

It seems like the Sumo Charlie is another attempt, like the Sequerra, the re-create the 10B's greatness (on a signal it is capable of receiving well) with high Q tuned LC filters.  But the high Q tuned filters are much more sensitive than lossy filters to the noise in the varactor front end, the same problem Dick had with the Sequerra tuner, and have reachable overload levels.  Bongiorno said to me once that he also used a single 280 kHz ceramic filter "to get all the crap way out there."  But I see that as not being enough.  I would have expected a Bongiorno-adjusted (rack handled) Charlie to have very low distortion on a good clear channel however.  It just has the usual problems caused by weak front end in the presence of difficult reception.  The 10B had a relatively poor front end actually, the 20B was much improved.  But even the 10B had a weak capacitor front end, which is still better than a midrange varactor front end.

Just this weekend I removed my non-handled Sumo Charlie from the pile, hoping to sell next weekend.  It's a fine tuner, actually.  It sounds perfectly fine on all the stations I normally listen to, including weak college stations.  I have second thoughts about selling it.  But for the same price on eBay nowadays you can get many fine tuners, such as a Pioneer F90 I see tonight.

Meanwhile, my newly acquired 310D is obviously a station puller, but needs a little work.

Sunday, July 5, 2015

A Microscope for Sonos

One of my previous annoyances at Sonos has been the lack of any way to find out how well it is working.  It usually works flawlessly, but then a problem may happen out of the blue.  When that happens you begin to suspect that something isn't quite right, perhaps an ethernet cable is loose or something like that, but you have no way of getting more information.  It either works or it doesn't.  Lots of other devices like mobile phones have indicator that show the signal strength, etc., but not Sonos.  In qualification it must be said that Sonos is far more reliable than cellular connections if you are moving about, so it doesn't need a "quality meter" as much as those other things do.  At least in my experience.

(And it is especially reliable when playing back files as compared with line in sources.  It can do that almost flawlessly over wireless.  But when playing line-in sources over wireless, which is my most frequent mode of usage, I sometimes did get dropouts, so I switched to fully wired, which still sometimes may have dropouts, which have virtually disappeared mostly now that I'm using a 24 port gigabit switch that most things are connected to, and may get still better if I actually connect Everything to the switch.)

Though all my Zoneplayers and Connects are wired, I sometimes worry that they may have decided to use wireless mode and once having made that decision sticking with it.  I have read that Sonos nodes that are wirable determine whether to use the wire when powered on.  But I have seen situations where nodes go wireless when after a power failure the ethernet services were temporarily unavailable.  I don't believe the blinking lights on the back of the Connect as definitive as to whether the node is using wired or wireless.  I wish there was some definitive indicator that told you which mode was being used, as well as things like signal quality, error rates, and so on.

But now, I have found the "back door" to Sonosnet which lets you get all the status information it makes available.

Turns out the Sonos has an admin web interface on port 1400. A URL like brings up a bunch of debug data; substitute the IP address for one of your Sonos devices. It loads slowly. Also appears to be centralized, no need to find the right device first.

This is very interesting.  What I see does seem to suggest the Living Room node, which is connected via Living Room #2, is getting the weakest connection in my system.  I should probably upgrade that to having a direct connection to my switch, which will in turn require me to upgrade the video connection to the living room so it only needs one Cat6a rather than the two it now requires, thereby giving me a spare Cat6a.  Possibly even just unburying the wire from the bottom of the pile of wires it is currently under would even help.  I mean the ethernet wire connecting Living Room and Living Room 2 zone players.

Unfortunately this status interface isn't documented at all.  I am getting the idea that I can also tell that everything is using wired connection however.  Over time I'll figure things out better, I hope, and will hopefully continue being able to use this interface.

I checked out the Python interface to Sonos.  But it doesn't provide anything interesting to me: any new back door information (or control!).

But over here, I found out both how to interpret the Sonos displays, AND, over here, I found out how to shut off the Sonos wifi altogether, which is neat.  With this explanation, I could see that indeed my Turntable and Tape Zoneplayer was communicating with Bedroom Sonos via wifi.  Well I checked the connection, and I had never actually hooked the Cat6a wire between the two!  No wonder I had been getting dropouts, and in retrospect it's also interesting how after awhile the dropouts disappeared even with two-way communication involving the Zoneplayer.  So the "mystery" is now solved.  Also I could see that as soon as I connected the wire, the wifi connection became disused, no need for a reboot.  But it appears there may be some kind of diversity operation involved, which sometimes hits the wifi hard if there is ethernet congestion.  (This also causes ethernet congestion…further retarding the original problem for awhile.)  I have long suspected this, and the discussion seems to confirm this.

I followed the latter instructions and permanently disabled the wifi in all my Zoneplayers with commands like this:

This removed all the colors from the diagnostic mesh display, which apparently is mostly about the wifi.

But it has always seemed to me that the dropouts for line inputs were a cost of having kept the line input latency fairly low--low enough to be tolerable if barely tolerable when working with TV for example.  That appears to have been a design decision.  Well I don't think low latency is a big issue for me, so I'd love a way to crank up the latency to 1 second or so, giving the ethernet an almost perfect ability to prevent dropouts.  I've looked several times in the control menus for a latency control and failed to see it, but the above command gives hope there may be lots of hidden controls.

Explanation A, B, or S ?

I just described how I determined, by process of elimination, that a signal dropout problem I was having in FM playback was not caused by the tuner, but apparently by the twin-lead antenna routing.

That was for my tuner #2, which is slated to be a remote control tuner.  Tuner #1 is the non-remote tuner always tuned to the classical station.  Both tuners play anywhere and sometimes nearly everywhere in my house through Sonos, and playback of sources in other rooms is a key feature which made me choose Sonos over SqueezeBox.  I actually do that as much as or more than playing music files, and mostly now for the tuners (although also LP's and cassette tape).

After doing those tests and writing that post I switched back to using Tuner #1.  Actually it was almost a day later and I was setting up Tuner #1 to record through a repurposed Zoneplayer now serving my cassette deck and turntable.  So this was new, though I had set up the Sonos box before.  I added an Insteon switch to the cassette deck so it would turn on at 7pm to record the classical station.  I got everything set up just before 7:00, and it started as it was supposed to.

But right away there were dropouts again.  I made sure the Tape/Source switch was set to "Source" and there were still 5 or more dropouts in the first 30 minutes.  Some of the dropouts were extremely messy sounding.

I hadn't heard the dropout problem before with Tuner #1.  Tuner #1 has always sounded perfect.  So what happened?  First I panicked worrying that I had damaged the Pioneer F-26 (which, btw, some people are now selling as an ultimate, as they should, for collectable prices like $36,000, which sounds too high, I paid $1000 for mine, but I'd think they should be priced about the same as TU-X1 if not slightly higher).

Remember than in the previous day's testing I had connected the F-26 to the antenna used by tuner #2, to make sure the problem that the KT-6040 was having hadn't been caused by the antenna.  Then when all the testing was done, the F-26 had been disconnected, so I reconnected it to Antenna #1, which is a twin lead dipole on the southeast side of the living room--best for KPAC.  It is connected via a 10 foot length of coax to the tuner…coax is used specifically to eliminate interference with all the other gazillion wires it must run next to, so it couldn't have the kind of problem that had happened with the twin lead signal being periodically interfered with by the AC in the power cord (or so I thought, anyway).

During that moment of reconnection I almost wondered if I had felt a slight shock as I rehooked the antenna, no I don't think I actually did--but I hadn't done my usual thing of deliberately discharging the hot wire, but then I though to myself at the time I was holding the F connector with my bare fingers and also holding the chassis with the other hand, there couldn't be that much of a built-up potential.  But being obsessive, I alway worry about such things.

So anyway, I dismissed the thought at the time I was reconnecting the antenna, but now that I was hearing dropouts my first worry was that I had damaged the tuner itself when reconnecting the indoor antenna, just as I had momentarily worried when doing the reconnection.

Well that wasn't likely true (and doesn't appear to be true either) but the next thought was that I might not have reconnected the antenna well, I might not have fully tightened it (though I had taken several minutes in tightening and had tried to make sure it was turned as hard as I could by finger).  Another weird concern is that there might have been some kind of conductive dirt on the F-connector of the 6040--and the very thing that had caused it to malfunction perhaps in this case--which in the process of testing had gotten transferred to the F-26, and therefore the F-26 had been "infected" by the disease that the 6040 had previously had, because the cable had been changed from one to the other and back.

As I was hearing these dropouts get recorded on my new but flawed automatic recording system, I had been planning to take a nap, and I found the frequent dropouts disconcerting, so I muted the Sonos volume for the bedroom.   I'm actually having trouble remembering exactly what I did when I got up, and in what order, but I think I probably first tried simply "Pausing" the Living Room (which was playing Tuner #2), to see if Sonos interference hadn't caused the problem.  Well it still seemed to have dropouts, though less frequent.  So then I removed and reconnected the antenna, this time wetting both the conductor and shield thread surfaces, and even a tiny bit on the back of the connector surface, with DeOxit Gold, which makes for better conduction AND is actually an insulator on insulated surfaces.  I inspected the cable and there was no dirt inside the connector that I could see.  I observed this time just as I had before that the reception was perfect from the moment I brought the connectors together and before I even got the threads mated, and remained perfect as long as the connectors were together, even as I was turning and tightening them.  I felt that the tightening was a bit smoother the second time, possibly helped by the deoxit application.  It been a bit tricky the first time, but did not show serious resistance as it would have if it had been cross threaded.

Even before that I pulled the 75 ohm coax from the very bottom of the pile of wires in from of the equipment, and re-routed it loosely above all the other wires, then pulled of the bit of dust and cobwebs the connector picked up from being pulled under all the other wires.  And I think before I tried that, I had simply tried re-inserting the 300 ohm transformer on the other side, and when I was done cleaning, treating, and re-connecting the cable I did that again.

Well despite all this fiddling, I was still hearing dropouts in 2 or more tests I did, though it also seemed they were getting less frequent and severe.  So this is how things go in casual experimentation, nothing seems to fully work, but there may be smaller effects one isn't sampling enough to have any clear ideas which things are helping more than others, but it does seem to be getting better.

I had becoming more concerned, however, that it was the Sonos system that was glitching, because of piping multiple line-in sources to different rooms.  So after having shut things down, and still reach a level of decisive indeterminacy about what was going on, I decided to go back the other way and see if Sonos could handle a full many-to-many with line in.  BTW I had also done this test before, and since I installed the gigabit managed switch at the center of my LAN there have been no problems.

I set up Bedroom #2 to play Tuner #1 (which is the Living Room Sonos Connect).  I set up Living Room to play Tuner #2 (which is Living Room 2 Sonos Connect).  I set up Tape & Turntable to be playing Tuner #1, recording onto the Nakamichi, and using Source Monitor to go to the main Bedroom system.  And then Kitchen was playing Bedoom, which was the Souce output of the Nakamichi.  As I was resting in the Kitchen, I could listen to the end product of several different links in series.

The end result of all of this was--hardly any dropouts at all.  In fact the first dropout that I did hear, I was suspicious that it was just a small bit like 0.5 second of dead air during station switching.  Unlike previous dropouts that tended to occur on peaks, this occurred during a silent interval, so it seemed qualitatively different and perhaps not even the same kind of thing.

As the night went on, it seemingly just got better and better, even with all this Sonosnet activity going on.  After a few hours, I'd say it was close enough to perfect that I might have been ignored it like this before.

So maybe it was Sonos after all, but just running Sonos to the max on blasted all the carbon out of the cylinders (that was a pseudo rationalization a teenage friend of mine gave for flooring his GTO, only for the first time protesting that I didn't necessarily see why it would not be blowing more carbon in than out…but now I feel this sort of strategy is not a bad thing in limited or applicable doses…some things like Halogen lamps even require being operated at full brightness regularly).

Or maybe not.  Maybe the deoxit in the F connector took some time to do all its deoxing.

The point I'm trying to make here is that "results" from trying to fix things are often useless in developing a model of "what was wrong" for use in creating a definitive similar problems (though they can become a set of possible hints).  I believe that many people premature leap to conclusions that might be less than fully explanatory, and even maybe not explanatory at all.  Any kind of real world activity involves many microscopic actions which may not be replicable or reversible.  I pay much more attention to these tiny details than most people, but even I don't and can't pay attention to every detail that might include the most uniquely effective details.

And then too, the goal counts.  My goal was firstly to fix my system, and only secondly to determine exactly what the problem had been.  If it had been the reverse, I might have spent weeks exhaustively trying tiny changes and establishing baselines and doing sampling and so on, with statistical verification, and still not know because some small change might have happened without my notice that caused it all to change.

Given the reality that we will never exactly know how things work, or what we should do when they don't, the best approach is to be flexible and patient and not leap to conclusions.  One other things is that things that are working reasonably well seem to improve over time to working nearly perfectly.  Things that haven't been used for awhile, such as the repurposed Sonos node which had been take offline for awhile, and the Nakamichi, may take awhile to fully "remember" (that's what an engineer once told me) "what they are supposed to do."  And the Sonosnet itself, which is an aggregate of many active players.

That's just the way things are.  Most things that happen are far below our notice, and we only become aware of the aggregate affects of complex systems, and complex systems are weird in many ways.

I often think of how Western Electric had a standard for making 300B amplifier tubes, and the standard was very careful and detailed about how everything should be done, and then, after everything was made by specification and the newly created tubes were meeting specifications, you kept making tubes continuing to meet specifications for another 6 months before you made tubes for field usage.

Following a sensibility like that, keeping the Sonos line inputs running may be a good thing.  The system is prepped to do that, and it seems it irons out irregularities over time.

Sunday night: no confirmed glitches.  Last "glitch" was actually Nakamichi flipping the tape I was listening to, so it wasn't really a glitch.  BTW the Nakamichi is sounding fabulous too, and some of my greatest elation has been hearing a college FM radio recording I made on the Nakamichi RX-505 (can't remember the tuner, possibly Kenwood L-1000t), played on the Nakamichi, through Sonos to the Living Room.  Despite all that processing, still sounded perfect and good enough for bliss.

Wiring all Sonos Connects (and ZP80, ZP90's) straight to my managed gigabit switch would probably be the way to go, and I can do it with a few changes in my video networking.

Saturday, July 4, 2015

A, B, then A again

In a typical sighted listening comparison with more than one person, there are 2 typical outcomes:

The most common is to listen to A, then B, then declare that B is so much incredibly better than A that there is no need to go back and listen to A again.  Your hearing abilities may be criticized if you fail to hear the huge improvement.

In the other typical outcome, for some reason, a decision is made to go back and listen to A after listening to B (perhaps because the audience has an "A" partisan).  Sure enough, the change from A to B was overstated, now A is showing that it does the same things that B did.  In fact it may be a better compromise overall than B.

I believe most such "testing" is bogus, and the sighted aspect is usually only one of many factors that makes typical audio comparisons by audiophiles unreliable.  The lack of level matching is another huge factor.  Going back to A has usually been, for me, and decent control anyway.  Most often the differences I heard with "B" were mainly because I had just heard "A" and now my senses are primed to listen for something different.  But then whatever I thought I heard anew with B just because of listening experience tend to still be there when I go back to A.  So whatever the other limitations, and A/B/A test is far better than a A/B test, and it tends to moderate the sense of huge differences with people who have at least some degree of ability to change their minds when exposed to evidence.

I was reminded of this when I found how to fix the frequent dropouts in my 2nd FM tuner during this vacation week.  I had been noticing dropouts in my second FM tuner, a Kenwood KT-6040, going back some time.  I'm not sure how long this problem had been present.  I keep the Kenwood tuned to one of two college radio stations mostly.  Tuner #1, the Pioneer F-26, is usually tuned to the classical station I listed to more often.  But this being a vacation and holiday week for me, I'd been noticing the dropouts more and more and it was beginning to drive me crazy.

So first I tuned in the same college radio station on my Pioneer F-26.  It had no dropouts.  Well that was not a good comparison because they use different antennas also.  So I connected the F-26 to the antenna I normally connect the KT-6040 to.  Still no dropouts, and at this point I had to reflect on how good the F-26 was sounding on this station, better than I had remembered, not only more musical than the KT-6040 but about equally quiet.  Because of sophisticated multiplex IC's which became available in the late 70's and appeared in tuners mostly in the 1980's, generally newer tuners are considerably quieter than old ones, but they often don't sound as good.  Older tuners tend to have ganged air capacitors which make far better machinery for tuning than the varactor diodes used in all "digitally tuned" FM tuners.

Anyway, at this point, with the F-26 not having the dropout problem (a dropout about every 10 minutes or so--after an hour of listening there's no need to A/B or A/B/A or ABX to be sure, the difference between a channel with frequent dropouts and one that doesn't is absolutely apparent if you listen to the channel long enough for there to be no doubt) I was beginning to think it was that superiority of tuning capacitor in the F-26.  I was thinking which analog tuned tuner might become my next #2.

But just to be sure I wouldn't be relegated to only using analog tuners, I decided to try a second digital tuner, a Yamaha TX-1000.  Interesting enough, it did not have the dropout problem either.  I didn't like the sound as well as that of the F-26, nor even the KT-6040 when it is not dropping out, but it was good enough to be the new #2, though I do like a lot of things about the KT-6040 better, including especially the ability to scan for new stations using the remote control.  Nevertheless, I continued listening to the Yamaha on both college stations all night, just to be sure it didn't show the dropout problem, and it didn't.

Well now I thought there were two possibilities that the KT-6040 was actually OK after all.  One was that when I was attaching Antenna #2 to the Yamaha, I had found the twinlead caught below a power cord.  I had to fix that just to pull out the twin lead far enough.  So perhaps the fix was not actually changing the tuner but just re-routing the antenna lead.

The second was that I changed the Sonos input level.  I listen to each of the two tuners through Sonos, by connecting the tuner outputs to Sonos Connect inputs.  I find Sonos with uncompressed I/O to be very transparent, so I don't bother bypassing it as I used to do (both tuners are actually in the living room, I could simply hook them up to the Lavry AD10, and in fact I used to do that).  One of the cool things about using Sonos this way is that I can set the level exactly for various kinds of devices.  But I can also set it wrongly, and unfortunately Sonos doesn't provide any feedback like a "clip" light, even in the computer interfaces.

I noticed when I was connecting the Yamaha that the input level for Tuner #2 was 6, which assumes a very low voltage level.  Meanwhile, the Pioneer F-26, which has < 1V output and 0.58V for full modulation, was set only to level 2.  Well I couldn't believe that the Yamaha would have far less output than the Pioneer, in fact I would think the Yamaha being a late 1980's design, and the F-26 a late 1970's design, that the Yamaha would have more output, inspired by the 2.0V output of CD players.  Prior to the introduction of CD players, most line level sources were less than 1.0V, sometimes a lot less.  CD was launched with higher output as to trumpet the high measured dynamic range.  So I changed the level to level #1.

So anyway, both or either of these changes could have been responsible for the drop-outs on the Kenwood, as they were changed when I changed to the Pioneer and Yamaha tuners.  I switched back to the Kenwood, keeping the level at #1 and making sure the route the twin lead far from other cords.  And now, there were no drop-outs with the Kenwood.

I was really glad I had checked, because I do like the sound of and remote control features of the Kenwood better.  But it would still be interesting to distinguish between the antenna change and the Sonos level difference.  But I was thinking I don't need to do this test, I have the Kenwood working now, and I'm sure it should have Sonos set to the highest level, and I'll always be careful about twin lead routing.  Plus I didn't think the antenna cable routing would be responsible for this big a difference, I was sure it had to have been causes by the Sonos level setting.

But it was easy to change the level back to 6 so I did, and now thee were still no dropouts.  So it does appear that it was antenna routing that had caused this problem, and it probably started when I added the new DAC and didn't route the power cord and antenna to avoid each other.

So this shows how it is, to really find out you have to go back and try many additional tests, rather than making assumptions, or just settling with good sound without worrying about how it came about.

And that's probably how it ought to be, but I won't promise to always do more tests because I don't always need to know…I can maintain a "not sure" about any belief so I won't be trapped by it in the future.  I'll find out, if I need to, by doing the extra tests when I need to do them.

I won't commit to either approach, only to doubting a result if it hasn't been fully verified.

Wednesday, July 1, 2015

The Warning Label

Warning!  This product makes explicit or implicit claims regarding auditory performance which have not been verified by published Double Blind Testing.

So we can just slap this label on high end gear, and the DBT evangelicals should shut up.

Just in case you haven't heard the argument.  There are 4 kinds of deficiencies in playback that we can hear: noise, distortion, changes in timing, and changes in frequency response.  Those are the only things that have been established to be audible, and only within certain measurable limits.

My version of the high end pursuit goes beyond the "established audible" and tries to make things as good as reasonably possible, combined with perhaps some additional parameters, my favorite being "information" given that we have lossy systems and systems like DSD and Delta Sigma Dacs that I believe are lossy.

I believe indeed many things have been overplayed, my key one is jitter, whose established audible limits are far beyond the level audiophiles obsess about.  Overobsession with jitter leads to paranoid avoidance of digital signal transmission via SPDIF which is what we have.  I do as much transmission and processing as I can in the digital domain, because it is measurably far superior, and sounds transparent to me.  At the end of the crossover lines, I (will) have nice DACs that drive amplifiers via decent cables and that is pretty much all (I like blue jeans BJC-1 design…it even satisfies my tweako itches with a solid core center conductor and polyethylene dielectric, not to mention the low capacitance and double shielding.)  So that gets to another thing for many audiophiles: cables, often at increasing stratospherically increasing multiples of the cost of a Blue Jeans Cable, and most often inferior in many ways, supposedly sold on "listening" but as much as anything it's all cultism, hero worship, tribal identification, and so on.

I am convinced that PCM is fine, and nothing wrong with high rez PCM.  I also believe that transistors are fine and tubes are most often used as a flavoring device--which may significantly reduce transparency.  I don't find the need for much flavoring, and transparency is the thing to me.

Digital is fine, but analog well done is also fine, and often seems more pleasurable.  I don't understand this though I theorize about it a lot.

Meanwhile, I do see much of the high end audio scene as a circus medicine show.  But I also think it should be patently obvious that it is so.  Need not argue with the clowns.  Pointless anyway and generates bad feelings.  Meanwhile, I follow my own magic practice to which the High End Warning nearly equally applies.

Sadly none of my audiophile friends wants to accept the key finding of DBT, that things are very hard to hear reliably.  Their magic practice depends on the belief that they have discovered many important things, important to them, by (non-DBT) listening tests.

I have rarely even attempted DBT, but I have the additional view that because sighted tests often lead to superstitions that don't hold up to DBT, listening tests beyond the basic may not be worth doing.  I haven't even much "tried to hear the difference between DAC's" except at clubs and friends houses.  I follow my casual listening result, just plugging new things in and assessing sighted difference over time, knowing that it too may be wrong, but not much different than "careful" sighted A/B testing.  But measurements of certain kinds are, in my belief, still useful, so I have them too, and thinking about how things work.

Here's one of the more amusing (and less bitter) confrontations between audio objectivists and subjectivists.

I've been discussing ABX hardware (not so much the Big Debate) just a bit on my computer club blog (which I am nominally "President" of).  I've been taking apart a QSC ABX box.  The account was not renewed by the actual owner and the email list turned defunct.  Conicidence?

I wouldn't think of mentioning anything about the ABX comparator or DBT at the Audiophile club I am a member of.  If it comes up I try not to say much or anything.

It is an in-your-face thing.  To suggest that people are all wrong.  But the sad thing is, most audiophiles are wrong, almost all in fact.  Even very smart people, Especially perhaps very smart people.  But best not to make a big deal about this.  The minimum one's conscience will let one get away with will do.  Let the rich sheep get slaughtered by the fraud.

I'm only "right" because I have a very nuanced leopard spotted view.  (I like leopard spotted better than grey hat, what John Atkinson claimed to be when confronted with Peter Aczel's White Hat (Objectivist) vs Black Hat (Subjectivist) dichotomy.

No actually I don't claim to be uniquely right, but I think overall I'm on a better track, and I do work constantly on improving mistakes, updating my views.

Having one's own ABX facilities is a bit like having one's own casino.  Want to try your luck?  I think it's a very cool feature for an audio system to have.  And it does actually require greater precision in fine level adjustment than most people are used to.