Monday, June 11, 2018

Audiocheck

A friend sent a link to this collection of audio tests:

Audiocheck.net


Tuesday, April 24, 2018

Turntable Peripheral Clamps (aka Rings)

Clamping records at the periphery has seemed to me like a good idea since the first I heard of it in the early 1980's.  I'm surprised it hasn't caught on more than it has.  Center weights and clamps have definitely caught on.  It seems like all serious audiophiles either:

1) Have a center weight or clamp on their turntable

OR

2) Own a Linn or Rega and have bought the non-clamping ideology those two firms promote.


I know relatively few people with Linns or Regas anymore.  And curiously all those people I do know...which includes myself...are fully into clamping nevertheless.  With the one exception of the Linn guru Mark who was once a dealer.

I will say that if you are not listening "seriously," just background listening or dancing, non-clamping is more convenient and even sometimes lends itself to background listening (because more highs) and dancing (more percussive sound from record resonances).

So, I've decided I will not always bother to clamp, even though I believe it sounds Much Better generally speaking.

And I'd like to take it to the next level with peripheral clamps, sometimes called "turntable rings."  From both my intuition, and limited experience (I heard the R.E.A.L. once)  I strongly believe this is the way to go.  While center clamping, it's always bothered me that the edge of the record wasn't getting much if any help, or worse.

There is a VPI stainless steel version, which sells for $999.  VPI advises that you not use this on many VPI models until you upgrade the platter and bearing to the HRx level.

https://www.musicdirect.com/analog-accessories/vpi-periphery-outer-ring-clamp

Wayne's Audio in Pomona California has two "universal" models for $599 and $699 apiece:

https://www.waynesaudio.com/shop

Merrill sells their ring clamp for $850, or part of $1200 set that includes center weight.  It is not clear if these are suitable for other than Merrill turntables.

http://www.osageaudio.com/merrill_williams.html

I'd like to have Merrill's version most of all...as he really seems to understand turntables and resonances and clamping the best from decades of experience.  And I'd like to have a Merrill turntable to go with it, either a R.E.A.L. or one of his previous designs.  But, understandably, his version is the priciest, and the tables aren't cheap either (except relative to performance compared with other tables).


Friday, April 6, 2018

Observations on the LP12

1) Is it the most tuneful turntable I've ever heard?  Yes.  And I appreciate it for that reason, though as one person once said, no turntable is perfect and therefore you can never have too many turntables.  This "tunefulness" is not entirely a matter of superior speed constancy, I believe, but part of kind of pleasant coloration not entirely involving rotational speed but also high and lowpass filtering and/or combination with resonances.  The speed, for it's part, varies as much or more than other premium turntables, but it varies in a peculiarly slow and pleasant way that sounds natural and relaxed.  I'm thinking it might vary around the same speed as the effects of off center wow, possibly sometimes cancelling the off center wow, and otherwise being masked by it.  Other turntables may vary speed in a more abrupt, forced, and mechanical sounding way.  Of course I'm talking about tiny variations that are not easy to hear, especially in the case of the Linn.

2) My LP12 Vallhalla with Ittok LVII (does LVII mean 57 ?  like Heinz ketchup ???) arm, seems to have a slightly over-brightish quality.  I think the largest part of this may come from the quite noticeable metallic resonances of the stainless steel tonearm (with the funny name not coincidentally made to sound like "I Talk" ???).  Those resonances could be damped, and otherwise I think the excellent pitch and bass produced by the arm indicates that it has marvelously tight bearings, which is one of the hardest parts to get right in making a tonearm.  So this is a good tonearm which could be made even better, I believe, by getting past the designer's religious convictions against damping.

3) My belief remains in harmony with a majority of high end audiophiles that in principle records should be clamped (or otherwise held close to) a highly absorptive mat.  The Linn felt mat is only partly absorbtive--but it may or may not be part of some mysterious "synergy" with the rest of the turntable.  Clamping on the Linn is made difficult and less useful by many factors : the loose suspension, which quickly bottoms rubbing the aluminum platter on the stainless plinth top when trying to apply the clamp; the low spindle, requiring round-the-platter checking for level balance if the clamp--like the Michell clamp--has no level and doesn't deal well with low spindles...I suspect most if not all clamps would have a problem with it, and clamping it might not do entirely the right things here with the thin felt mat and undamped platter, reducing much of the felts isolation properties between the platter which is ringing from many things, including the bearing and the vinyl, and the record.

At minimum, clamping should be done with a different kind of mat, or combination of mats.  And it's too much trouble on the Linn except for the most critical listening or transcription.  It is nice how tuneful the turntable sounds without taking such bothersome measures.  It could be regarded as a kind of "convenience" turntable, much the way audiophiles thought of CD's when they were introduced.

Update:  With NO metal washer, and a 180g pressing of Blood on the Tracks, the clamped version was clearly better.  I did the claming in one careful press, not needing to verify the flatness until afterwards, by releasing and spinning, which was much more convenient than the previos pressing down at each slight rotation.  Both ways it was flat around the edge, in fact the claming didn't seem to have much direct isolation at that point, but much more isolation through the rest of the record.  (A Merrill-Williams type perimeter clamp...Merrill's innovation since the 70's...would be ideal but impossible on most tables, except those designed for clamping or vacuum...I'm now thinking perimeter plus central weights as Merrill does may be better than vacuum--quieter.)

Unclamped it was harsh and edgy, clamped it was cool but highly transient.  Clamping was the clear winner in realism, pleasantness, spaciousness, musical interaction.

Unclamped was that old "tuneful" simplification, as Arthur Salvatore says.  He doesn't say it comes from clamplessness but I'm thinking the clamplessness, even with old Linn mat being used with the clamp, must account for 80% of the familiar tuneful (de-complexifiying) coloration goes away.

Now at least one would think it wouldn't have much impact on timing.  Though, BTW, the Linn and most belt drives are host to a myriad time issues.  For the Linn, setting the speed is a final setup step.  It stays as good or bad as that...at least under indentical conditions and the belt hasn't passed some aging threshold.  But if that were not done, it would be hopeless, as the timing depends on the precise angle of the chassis and subchassis, which in turn is determined by the mass on the platter and armboard, for starters.  But then in actual use...all these things are still somewhat varying.

It seems to me the LP12, just becuase of the suspended belt and pully and subchassis design, is doomed to a sort of slow varying imprecision.  It's only "tuneful" however because it's so slow as to not actually be objectional, just slightly making everything different each time.  Other systems like ider and direct drive are more "locked in" by high torque control systems, belt drive is constantly resonating the drive frequency of the platter at the fundamental frequency of the belt system, and possibly others.  Imperfect perhaps, but the choice of so many phonograph users for so long...it can't be that bad...and may have some advantages.  Which is why I want one, and choice units of other kinds.


4) Now I'm thinking, much as I have before, that a vacuum hold down system is the best of all, and it can be had, though at higher prices than I paid for the Linn, but that's an unfair comparison because I did not buy the Linn Valhalla with Ittok brand new either.  On similar terms, the Linn and Sota turntables with vacuum are priced fairly competitively in the USA.  On these terms the highest end Sota Millenium is far less expensive the most fully loaded Linn Radikal ($10k vs $20k), with similar differences down the line.  This matters if you consider them comparable, which you may not.  I'd last heard of Sota in the 1980's and was thinking they were long out of business but no, they are still selling and servicing servicing older turntables too.  That's a path I'm still somewhat interested in, as other vacuum clamping turntables are much more expensive.

I might try to trade my SP 10 for a Sota, but the ultimate ultmate would be a fully refurbed SP10 with vacuum holddown added.


4) Anyway, the special characteristic the Linn imparts as a result of drive operation, foremost is non-correlation, where no radial part of the platter has a tendency to raise or lower pitch even slighlty.  The pitch may be wavering, for sure there is wow and flutter just as in other premium turntables, but it is non-corrlated.  Direct drives have wow correlated with platter position, as shown by graphs published by a Linn lover (who conveniently didn't disclose the scales on the platter rotation dependent wow, making you think if the scales were equal, the better direct drives might be so low anyway the platter dependency shown was a small issue).

As well the Linn has olympian isolation from the environment, mostly.

Direct drives are somewhere in-between, with finer grained platter rotation dependency mostly.

Does this matter?  I am beginning to think the rotational constancy IS the most important factor, and it's not perfect in any turntable, the Linn just hides the imperfection better than most.

With regards to the initial transients, it all comes down to effective platter inertia.  It's follow through that is determined by the drive system.  The belt drive takes it's time to correct, ultimately averaging out.  The idler whell corrects immediately and perhaps too abruptly.  Direct drives may vary with implementation, but in principle can respond faster than belt drive, but perhaps not as fast as idler wheels.

So, if there is a superiority of idler wheels in the attacks of music, it's all in the follow through, in microscopic terms, though you might not hear it this way, the "follow through" begins microseconds after the initial transient, for which the platter inertia is everything, and the failure to correct begins appearing within the minimum audible time interval.



Wednesday, April 4, 2018

MQA unmasked and denounced

I was shocked to read the findings of Archimago (a trustworthy and reasonably open minded objectivist audiophile) about MQA.

It looks like if there is a difference in the sound with MQA, it's largely produced by an increase in aliasing artifacts.

As Archimago argues, we don't need MQA.  We have MP3 for those who don't care about quality, standard resolution formats, and high resolution formats for those who want the highest possible quality, and they are all open formats.

Thursday, March 22, 2018

Linn Sondek LP12

Thanks to the very nice Mark of Austin Hifi, the Linn specialist (but no longer a Linn dealer) who originally sold it to me in the first place in 1998, my Linn Sondek LP12 Valhalla is now fully operational again with a brand new Dynavector 17D3 cartridge (my house standard) mounted and playing beautifully in my living room.  Mark himself repaired my Valhalla board, replacing capacitors, installed my new cartridge, and set the turntable up in my living room, all for a very reasonable charge.

Immediately I enjoyed it more than my Mitsubishi LT-30.

Thinking "the pitch is now more stable" I went back to the problem record, Dance of the Universe with Peter Sprague, which was the very first LP I played on the Mitsubishi and led me to worry about the speed constancy of that turntable.  (The Mitsubishi was greatly improved after that by damping and mass loading the tonearm, counteracting the arm-cartridge resonance which was the key issue causing the underwatery sound with this record, but perhaps not the only issue.)

On the Linn, the pitch of most of the band seemed perfect, with the exception of the greatly out-of-tune (to my ears) bass line, which is exactly the way I remembered the band in a live concert around 1981.  This contrasted greatly with my first playing on the Mitsubishi, in which the out-of-tuneness of the bass seemed to permeate the entire band, making it sound underwater.  The Mitsubishi has gotten better than that now, though from memory (I didn't do an A/B test) I think the Linn is still better.

I shouldn't be asking this question, but here I am.  What is the next thing to upgrade???

According to Linn, and many Linnies, the best thing to upgrade is the bearing, which should be upgraded to the Cirkus bearing (which requires a bunch of other parts in the Cirkus upgrade kit).

That rubs me a bit the wrong way, and did in the 1980's when this upgrade first came out.  The Linn was supposed to have this super superior "mirror polished" bearing in the first place.  IMO still the turntable design has many other faults, why upgrade the best part of it first???

IIRC, it was the bearing that was most bragged about in the mid 1970's.  For a considerably lower price than the Linn Sondek, one could buy the Ariston, which seemed pretty similar, but lacked the highly praised Linn bearing.

Apparently that exclusive bearing wasn't so fine after all.  In this Linn authorized blog, it is explained how the Cirkus bearing was required before the subchassis could be beefed up as most peopled claimed to want.  The original Sondek subchassis was deliberately designed to be lossy, a "mechanical filter" of sorts, to absorb the fault (very low frequency vibration?) of the original bearing.  It is claimed that when people beefed up the subchassis with the old bearing, the sound simply got worse.

(Maybe this was it.  It wasn't so much the Linn had a better bearing, as that the Linn had the deliberately lossy subchassis to absorb bearing noise.  In fact, I do remember that the Ariston subchassis was more substantial than the Linn subchassis, and at the time I wondered why the more expensive and highly touted table came with such a flimsy subchassis when the cheaper unit had a more substantial one.)

Nowadays the Cirkus upgrade kit does not include the required less-lossy subchassis because there are even better less-lossy subchassis models available (Kore and Keel) which the Linnie might choose to upgrade to, or they can get a traded-in subchassis from the Linn dealer (who has been collecting them from those who do upgrade to Kore and Keel).  I might also note that Cirkus-suitable subchassis are also available on eBay at prices less than the difference between the original Cirkus kit and the later one.

Personally, the thing that bugs me the most, is the ridiculous belt repositioning required to play 45 RPM records, many of which are my favorites.   I have always refused to do that.  But this problem is not so easily or inexpensively fixed, Especially if you already have the Valhalla board, and a 60 Hz motor.

Here's a discussion about the origins of the Linn Sondek LP12.

Linn disputes this sort of story, saying instead that the Ariston RD11 was an OEM turntable that Hamish Robertson "ordered."  They have tried to correct the story at Wikipedia, though it seems about the same now.

A friend of mine insists the design of the AR turntable, in 1960, was better.  But they were not made for universal arm mounting, and the arm of the AR turntable was far inferior to my Ittok LVII.

Here is the list of lists of Linn upgrades and serial numbers.

In my initial test of using clamp, it does change the sound to blacker and better imaging, which I think is good.  It may however sour the intonation slightly.  I think the felt mat performs both damping (on either side, platter and vinyl, separately) and also isolation, and compressing it with clamp reduces the beneficial isolation from platter ringing.

Because of the suspension, it is a big pain to clamp correctly.  The record must be turned when you are clamping to be sure that the clamping is good all around at the periphery.  At each spot you then must press the platter down to the top of the plinth.  I'm not sure if this is safe (though I think it is), but it is awful and time consuming.

Clearly, however, the Ittok arm speaks louder than the surface of vinyl.  I think in my system it is the arm which requires damping more than the vinyl.  The felt does a pretty good job at damping the vinyl without a clamp, and because of the difficulty of clamping, I'm inclined to leave that alone and focus on modifying the tonearm.

Is the name "Ittok" mean something like "I talk" meaning it's an undamped and therefore somewhat "loud" tonearm???

It seems excellent quality, but I think it NEEDS damping, contra Linn and Rega myths about damping being bad.

Here's a discussion of one company's modified Ittok, along with a discussion of the different Ittok versions.



Friday, March 16, 2018

Update on the Godar FM DXR 1000 antenna

Extended full length, the antenna has a high SWR at FM radio frequencies.  The manufacturer recommends extending full length for AM and TV frequencies, this has the effect of suppressing FM broadcast stations, which is useful because they are quite strong and can interfere with AM and TV.

The manufacturer suggests reducing length by 5 inches for FM if it needs it.  This creates excellent SWR at FM broadcast frequencies, so I'd suggest always doing this for FM.  I measured the precise length of the second section required for best FM performance: 3 inches.  All other sections are fully extended.

I couldn't see any effect of this change above 120 Mhz, so I left it that way--optimized for FM, though I "intend" to use this antenna for a 140 + 880 Mhz scanner, it might also serve as an extra FM antenna.



Monday, February 19, 2018

FPB vs Trans Nova

The FPB 300 right channel now seems to overheat at low playback levels regardless of input or speaker connected.  One time in January it reached 207F before I shut it down.  That time it had reached 197F during playback, I shut the music off, and the temp kept rising anyway for ten minutes.  Power consumption was about 900W.  This looks like at least one malfunction!  But it could have been noise or DC offset at the input.

After the 207F incident, I reversed input and output channels, put in place a brand new DAC, and connected the RCA instead of XLR inputs, with shorting plugs in place.  So I changed about everything that could be changed.  I resumed playing a test with maximum 2W playback levels as measured by my Keithley meter on sine wave tests (see below).  It seemed fine until after about 30 minutes consumption hit 1000W.  It just kept on rising to 1380W when I shut it down.  So, putting the right amp channel on the left speaker didn't help.  But was it the right speaker that was now causing a problem with the left channel?

For that test I shorted the XLR input of the right channel with a Cardas XLR shorting plug, disconnected the output too, and played the left channel of the amp with the right speaker as before.

That is operating flawlessly for hours now, total consumption around 530W (right on for just one channel playing, the other idling).  Showing that "the problem" didn't move along with the right speaker.  The left channel plays the right speaker just fine, but apparently the right channel goes haywire with either the right or left speakers connected to it playing low level signals, stays cool only with shorted input.

I will be filing a problem report soon.

Meanwhile, while doing this high stakes testing I tested another hypothesis: that the Krell sounds more dynamic and layered because it has higher damping factor, especially at high frequencies.

My actual measurements below show the reverse is true!  The Hafler 9300 has less voltage drop under load at middle frequencies AND even more so at higher frequencies!  In the low power test I performed.

Here is the raw data:

Hafler 9300 connected to right Acoustat
1kHz 1.765V
16kHz 0.213V

(The actual test files apparently are rolled off at higher frequencies deliberately.  Emotiva level is -4dB.)

Hafler 9300 not connected
1kHz 1.802V
16k 0.225V

Krell FPB 300 connected to right Acoustat (left amplifier channel, Emotiva at -1.5dB)
1kHz 1.723V
16k   0.204V

Krell FPB 300 not connected
1kHz 1.779
16k    0.220

There are many ways to compare these few numbers.  Let's compare like with like, at 16kHz (the most stringent test).

The Krell shows 0.656dB loss under load relative to open at 16kHz.

The Acoustat show 0.476dB loss under load relative to open at 16kHz, an almost 0.2dB difference.

At 1kHz, the Krell vs Hafler numbers are 0.28dB and 0.18dB, a 0.1dB difference.

Now, curiously, under no load, the Krell is about 0.2dB flatter, so the effect of the extra 0.2dB loading loss is to make their response curves equal under load!

Because of that, I'd expect the effect of the apparently slightly poorer high frequency damping factor (or output Z if you prefer) of the Krell (as wired, but actually the Hafler has much longer speaker cables of the same gauge...so that doesn't explain this difference either) not to have an audible effect on high frequency response.

So the two parts of the hypothesis are both rejected by these data.

The Krell shows no audible superiority, and since I'd consider better HF damping to be more important the flatter unloaded response, the Hafler looks to be the objective winner here in one tiny way.

Since only one channel is safe to run, I did blind AB test on just the right speaker, Krell vs Hafler.

In about 10 minutes of A/B switching, I hear no consistent difference, with Krell at -1dB and Hafler at -4dB (less than 0.5dB advantage to Krell, with -1.5dB being the other way, as shown by numbers above).