Tuesday, August 25, 2015

Two Too Noisy

Unfortunately my newest DVR, the Magnavox MDR-557 doesn't have a quieter chassis than the older MDR-537 I just started using recently.  It seems slightly noisier, and more importantly, slightly more irritatingly noisier.  While the MDR-537 does produce a slightly tonal operating noise, a midrange whine, the 557 produces a tonal noise that warbles slightly, making it significantly more irritating despite being barely louder.  This was with just the HDD operating, as it would often be overnight while I'm sleeping mostly.  There is also a random clicking as the HDD stores the previous 6 hours of video.  I'd like to be able to turn that on and off, but it does not appear to be a user-controllable feature.

It's very hard to measure most chassis noise.  It's clearly audible in my bedroom at night, but isn't above the self-noise of the SPL meter built into my Android phone, as I quickly determined.  Even with purpose made SPL meters, in my previous experience, chassis noise is still hard to measure.  The noise itself may be only 15dBA or so but still stand out irritatingly in a quiet room because of the tonality.

WRT measuring, or at least more objective comparison, the best thing to do is make low noise recordings.  I have a studio quality 1" condenser microphone which has 5dBA self noise.  It would make a fine recording, which could be measured afterwards, or analyzed with a post processing RTA such as a program I once wrote called GFFT.  I had been thinking about measuring chassis noise for many years when I bought my R0DE NT2000, so I knew to look for a microphone with low self noise, and that is good for general recording purposes also.  About the only lower noise microphones are from Neumann.  Cheap SPL meters have microphones 1/4" or smaller and these have many times more self noise.  Small microphones are good for high frequency response but bad for low self noise.

You may think it's curious to be concerned about chassis noise.  But it's a far more objectively important thing to be concerned about than whether source material is 16 bit or 24 bit.  The noise level in a 16 bit recording is 96dB.  At a recurring peak level of about 85dB which is a typical "loud" listening level (louder than most non-audiophiles listen at) that puts the noise floor -11dBA in the environment.  Meanwhile, if you have a disc player producing noise at 20dBA, it is 31dB, or 35 times louder.  And 20dBA would be a relatively average one, I think…the Magnavox could be higher (of course this depends a lot on how measured), my guesstimate is about 25dBA (537) with just HDD operating, as it always done when the unit is on.

Another thing I think is almost always overlooked is the fact that most equipment has internal resonances that react to ambient noise.  I'm less concerned about the effect this has on the signal path through transistorized electronics (which is minimal) than on direct radiation of the resonances into the acoustic environment.  Even with tube electronics, except for phono preamplifiers, the effect on the signal path is probably the smaller part of the story.  Direct resonances are one thing good about having "overbuilt" equipment in heavier gauge metal boxes than is absolutely necessary.  Of course the Magnavox players were built according to a different set of criteria, namely to be as low priced as possible.  This means they use thin gauge metal which is not helpful to keeping the noise level down, in fact it may increase the noise level as compared with having no metal casing at all.

My comparison so far is further corrupted by the fact that I have the 537 sitting on top of the 557.  Even when only operating one unit at a time, the other unit serves as a resonating chamber for the operating one.  Further, the position is slightly different in the cabinet, and might matter which unit sits directly on top of the shelf.  Obviously a fair measurement would only measure one unit at a time, sitting directly on the shelf and with nothing on top of it.

While some people might worry about the heat of having one unit on top of the other, that hasn't been a problem for me.  I've never noticed the case of either unit to get above ambient temperature, they have no vent holes on top, and are constantly fan cooled.  Also my house is continuously climate controlled to have ambient temperature no higher than 79F.

I plan to do the fair comparison, each unit on the shelf by itself.  Then I will compare the better unit operating by itself with having the other unit above or below it.  If it does really help to have only one unit sitting on the shelf, I will put the noisier unit somewhere else.  I will operate it less either way.  I will only operate both units at the same time if I need to, but mostly just the quieter one.  And I will use acoustical foam wedges and other measures external to the chassis to reduce the noise as much as I can easily do that way.  I have already carved a large piece of 6" thick Sonex foam that fills up the shelf space above the top unit, and blocks some or most of the fan noise coming from the back.

That's just the short run.  In the long run, I intend to make the 537 first, and later the 557, into the quietest unit I can.  I think the hard drive is the largest source of noise in the chassis, and the hard drive can be replaced, I hope, with a quieter one or even an SSD.  The fan can be externalized into a larger fan that runs slower.  I have done that sort of business with computer fans before, and it is not a walk in the park.  It took years to perfect the semi-external fan system I ultimately used with my Amiga 2000.  It featured a circuit to break the fan-sensor line in the computer when/if for any reason the external fan wasn't running.  It never failed in the two or so years I used it, in fact the nature of such "ultimate" tweaks is that shortly after you have finally reached the summit of a new invention, it becomes absolutely necessary to switch to a different unit, such as my subsequent Amiga 3000, for which all the old interventions are useless.

Then for all it's unsolved (though heavily tweaked, even fan replaced) noisiness, my Amiga 3000 is now unused, though it could be fired up again if I ever excavate the junk in the computer room back where I can set up the video distribution amplifier and hook it to the new home networking panels, bringing Amiga Vision back to life.

But for the last two years, I've been busy with other matters, now an all new bedroom video server, which suddenly became necessary because the last one, a Sony DVP-995C 400 disc carousel from 2006, quit working last month and nobody makes those for reasonable prices anymore.  Besides, a system based on hard drive like the Magnavox is far neater to operate.  You can switch between titles quickly and it even shows previews beforehand, all without doing any metadata editing.  But a constant whine is a big drawback, and the Sony was quieter, especially when there was no disc playing.

Saturday, August 22, 2015

Video Recording has not vanished

It almost  seems like conspiracy.  Pretty much the only video recording done anymore is through cable, satellite, or service fee type boxes like Tivo.  Standalone video recorders that let you freely record unprotected video content over the air or re-record or compile or even display earlier recordings of which you may already have a large collection, a staple of consumer electronics 1980-2009, have almost completely disappeared from stores.  Computers can also do recordings, but that takes more work than most people can imagine.  (I spent 40 hours with Nero before I made my first working DVD.  And now I can't get Roxio to do things the way Nero did, no matter how much time I spend with it.)

Back in the 1980's, it seemed like most Americans had a video recorder, a video cassette recorder.  Those haven't been visible in stores for a decade or more.  Interestingly the Movie industry made a turnaround making more profit from recorded video sales than theaters for the first time, only after the consumer right to record certain kinds of video (not copy protected the way movies usually are, but most broadcast programming) for personal and "fair use."

DVD recorders were hot in the 2000's.  This time there was little evidence of a movie industry conspiracy to shut down video recording.  The history of recording capability and pre-recorded video sales going hand-in-hand was remembered, it seemed.  Then, right around 2009, when the new ATSC video standards kicked in, and recent changes to US laws, and new corporate monopolies (notably Blu Ray) and agreements, DVD recorders vanished from stores as well.

Now the leading electronics manufacturers Sony, Panasonic, Pioneer (a resurrected Pioneer btw) do not manufacture video recorders for sale in the USA.

This is (or would be) hideous for collectors now archivists of old video recordings.

As it turns out, the situation could be better, but it isn't the end of time.

For one thing, if you are willing to take a gamble, virtually every piece of gear ever made is still being sold on eBay, much of it claimed to be in mint condition.  Right now, for example, there's the ultimate star of consumer DVD video recorders, the Pioneer DVR-650, for a buy-it-now of $999.  That's actually better in key ways than another very high end Pioneer you can buy brand new today (new old stock) for world import dealers for around $750, the region-free Pioneer LX-70, which lacks the playlist combine feature, but may otherwise be one of the best machines Pioneer ever made.

Sony makes consumer Blu Ray recorders, for reasonable prices, but only for the Japanese market, with Japanese tuners, lower voltage, and other aspects that are sufficiently infuriating to Americans that they aren't much recommended, so forget them.  Sony doesn't make DVD recorders anymore, and it turns out that when they did, they were having Pioneer make them, and Pioneer seemed to make their own machines slightly better.

Panasonic makes DVD recorders sold as nearby as Canada, which also lack American ATSC tuners but are great for recording from video streams and re-editing existing discs.  They have some of the best disc editing features.  These machines can be bought Brand New from video specialty dealers.  No US warranty.  I bought a Panasonic EH69 from B&H and added the 4 year extended warranty for $60.  This is up there with the best machines sold in the USA ever, so why whine?

So we can actually buy some of the best machines ever made brand new in stores, just not around the corner at your local Circuit City.

But around the corner at your local Wal-Mart or Sears you can get a Magnavox 557 DVD recorder with 1Tb hard drive for $299.  Actually they are not in stores, but you can order them online and pick up at your local store, as I plan to do today.  You can get 3 year extended warranty which I also did.  These feature ATSC digital tuner so they can record OTA broadcasting for time-shifting and archiving just like the old days with VCR's.  These machines are not made to have the luxury feel that Pioneer and Sony, especially, were famous for.  But that so-called "build quality" actually may mean quite little in performance or reliability.  Especially reliability.  Heavy users were reporting failures with their Sony DVD recorders in three years or less.  Mine went 6 years until the hard drive died (which I easily replaced), but only 8 years until the DVD drive failed (which is extremely difficult to replace and no service center will do it now that the official $300 part is no longer available).  So called "build quality" is often done to please the techie owner who pops the top off, or hefts the unit, or reads the specs, but may mean little in actual performance, especially using HDMI instead of analog outputs.  We'll see how it seems to me.  At least the 557 is brand new with warranty unlike most of what you get on ebay.  And it is said that Funai sells replacement parts for reasonable prices and repair is not as expensive or difficult as with Sony.

I do find my Magnavox 537 to be noisier than I would like and am hoping the 557 will be better.

Anyway, if you look, you see we have some of the best stuff still available, it's just not as visible as it was in the 2000's.

WRT high definition recorders, we have those too.  Forget the Sony's, as I said, sadly because they are reasonably priced, but you can get Blu Ray recorders from JVC and Tascam at B&H.  The problem is the steep price and limited capabilities.  The cheapest has a regular price of $1400 and they go up to $3000 or more.  I once saw a special on the cheapest JVC for $999--that's not bad considering the superiority of high definition recording.  I am not sure how fully useful these are for US consumers.  I think people buy these for recording from high definition cameras.  They do record standard definition through analog inputs up through S-Video, but only permit high definition digital input from cameras and the like.

So the limited high definition recording options are one valid reason to whine.  The movie industry got the copyright law it wanted, and that's the fallout.  Also, another thing I haven't mentioned, no video recorders permit any kind of digital unit-to-unit connection, which would be very handy in many dubbing and editing situations.  Digital input is only allowed from cameras, or from discs themselves if not copyright protected.

There is some loss in dubbing through the analog connection because digital video must be converted to analog and back.  But when you adjust things just right, it can be extremely good.  I'm doing that right now, offloading the videos on my Sony DVDR-HX900 (which has dead DVD drive) onto my Pioneer LX-70.  I discovered that to really get the direct output of the Sony and the Pioneer to match, I needed to set the Pioneer Black Level to IRE 7.5.  Before that, the Pioneer looked washed out, even through HDMI at 1080i (which shouldn't require the "step up" black level that was standardized in the USA during the early analog era).  After the adjustment--WOW!--the Pioneer really looks good, and it seems as though nothing is lost recording from one unit to the other through S-Video.  The key test was a "black screen" test.  The the IRE 7.5 artificial black background in the 4:3 picture exactly matches the black bars.  This also suggests, contrary to some reports, that the S-Video output of the Sony RDR-HX900 does have IRE 7.5 black step up, which is the NTSC standard.

Standard definition NTSC, 480i, isn't bad at all.  It was the best you could get until not long ago.  I often say that DVD's are standard definition, and this is mostly true.  Commercial DVD's can use a progressive scan rate 480p, and that is just beyond anything a standalone DVD recorder will let you record.

As was said going way back, you may need reasonably good attention and a large retinal distance (big screen or close screen) to see the difference between 480i and 480p on the best material and with the best up conversion to your display (though it has seemed many devices just don't do well with 480i inputs anymore--aha another conspiracy!).  Not long ago, a high end video system would be built for $30,000 with video projector, screen, and Farudja deinterlacer just to display 480i content because that was basically all that was available.

Now let me whine some more.  One of the worst things about Commercial DVD's are the endless Copyright messages and often now Previews which go on and on.  And they go on and on no matter how many times you have watched the disc.  And if you haven't pre-stored the position, if that's even possible, when you pick up viewing you have to go through all the crap all over again.

The Kitchen System has a Sony RDR-HX900 which has a dead DVD drive and is being retired.  It will be replaced with a new Panasonic EH69.  The other recorder is a Pioneer LX-70, which is great for dubbing from PAL or World Region discs.  For dubbing PAL discs, I have a video format converter.  So this makes the Kitchen remain the A/V production center it has always been since 2005 when I first got the HX900.

The Bedroom System had a Sony DVP-CX995V DVD/SACD/CD carousel.  It's being replaced by a pair of Magnavox DVR's with 1Tb drives, a 537 and a 557.  So this continues the tradition of having a vast array of videos online at the push of a button in the bedroom.

Here's an interesting discussion about the video recorders still available today (well, 2012, but things are about the same).

Tuesday, August 11, 2015


My Audio GD Dac 19 was highly praised at the River City Audio Society meeting on August 8, decoding digital from a Rega transport and driving a Rogue amplifier.  After listing to a number of old vinyl records, they played a CD track from my collection, The Tango Boy played by sax player Jessie J.  There was jaw dropping silence lasting for a few seconds after it was over.  I was told it sounded open and analog from an audio engineer who said those were exactly the qualities he liked.

But actually I hadn't been playing it for several weeks.  I had hooked up the Audio GD to drive the Krell amplifier, and the Onkyo RDV-1 to drive the Aragon amplifier.  Because of summer heat, I've been using only the Aragon, so I hadn't been enjoying the Audio GD, though it was still running.

But the plan to hook up both amplifiers to the Audio GD was quickly started after I brought the DAC back home.  I had already obtained a custom set of BJC-1 cables from Blue Jeans Cable specifically for this wiring, along with barrel and Y adapters from Audioquest.

NB: the barrel adapter allows the male tip of the incoming RCA to plug into the male input of the Y adapter, which has one male and two females.  In my estimation a three female Y adapter is the most useful and with that the barrel would not be necessary in cases like this.  It's most reasonable to feed a Y adapter from cables on every side, plugging the big Audioquest Y adapters with heavy wires into any piece of equipment is going to cause very unreasonable stress on the equipment RCA jacks.  But for some reason the people who make these things haven't thought this out.

NB2: What I call "barrel adapter" is called "RCA coupler" by Audioquest and possibly others.  I learned the "barrel adapter" term from my friend George decades ago.  They were useful then too.  Now they are too removed from the simplicity audiophile magical thinking.  You want the simplest possible cabling.  Well actually, you do.  But hugely more complicated cabling isn't necessarily much worse.  So just a little complexity, to make things work, is just dandy fine.

The output from the Audio GD first flows through an 18 inch BJC-1 which reaches nearly to the ground.  The end of that BJC-1 is attached to the barrel adapter and then the Y adapter, which is almost touching the ground (and completely isolated from ground with a Dark Field elevator on one side, unfortunately I only had one left.  The other side is about half an inch above ground.  The Y adapter feeds a 2 foot cable to the Krell and a 7 foot cable to the  Aragon.  Thus to drive both amplifiers at the same time, the Audio GD is loaded by 10.5 feet of BJC-1, which has a total of about 160 pF.  That's actually less than the previous 4 foot (nominally one meter) cable I had been using, a Straightwire Sonata, which has 284 pF, just to connect to the Krell.  The Aragon had previously been driven through about 400 pF of early 2000's Radio Shack interconnect: 3 and 6 foot lengths tied together with a Radio Shack barrel connector.  I measured an early 2000's 6 foot radio shack interconnect as having 180pF.  I measured 2 feet of BJC-1 as having 31pF.

Closeup of couplers and Y adapters connecting two amps to one DAC

So I'm driving both amplifiers through far less capacitance than either one before.  These BJC-1 cables are marvelous.  Though intended to be entirely non-tweako (Blue Jeans is expressly non-tweako, the point is to sell top professional grade cables at fair prices, not magic cables at astronomical prices) these cables scratch many a tweako itch, featuring solid core bare copper wires (btw, most of my friends prefer pure copper to silver plated) and foamed polyethylene insulator/dielectric--which is next best to PTFE teflon.  The low capacitance and double shielding is great too even if non-tweako.  I should mention that I consider coax the Only acceptable coduit for a single ended voltage signal.  It does only harm to run a single ended signal in balanced configuration with an additional shield.  That's far more complexity and it actually works less well wrt shielding.  Coax has an inherent shielding characteristic, it's sort of like super-twisted.  The Only reason why network wiring switched to twisted pair with complex modems was to reduce cable cost: less copper.  A good coax like the BJC-1 will use a lot of copper in both the center conductor and especially in the braided shield--which is another requirement for decent audio cabling.  BJC-1 famously has two shields, one braided.  Inductance isn't a significant factor in line level cabling because of high load impedance, endless twisted or flat wiring is unnecessary and probably doesn't deliver the shielding or low capacitance as well.

I did at least think about the effect of the capacitance of one amplifier loading the other.  Because the inputs are high impedance, I don't think they express much capacitance.  Even if an amplifier were to have a low pass filter at the input, that would by necessity have to follow an internal resistor, and thus be isolated from the input cable.

Back of Krell with red and white BJC-1 connectors

Before actually measuring the capacitance of the Straightwire Sonata, I had been planning to order a pile of its closest current equivalent, Straightwire Chorus II.  It does the tweako big time but at incredibly low cost.  It features PTFE (which I consider the real Teflon, and not the Teflon FEP commonly used in plenum rated and audiophile cables because it is far easier to tool than PTFE) dielectric and solid core wire, with a good braided shield.  This seems to get the basics right.  It does have that silver plating I consider slightly worse-than-useless, but I'd overlook that and I could be wrong about whether silver is good or not.  It's hard, hard, hard to find real PTFE cables, and Straightwire cables can be ordered in lengths starting from 0.5 meter and increments of 0.5 meter.  Almost as fine as BJC-1, which can be ordered in 1 foot increments.

Aragon 8008 BB with BJC-1 and other cables on right

Living Room System seems to be sounding extra fine now, even though I'm still using the Aragon, I seem to be getting more than 50% of the sound improvement I had been mentally associating with the Krell in the most recent testing.  I did adjust the new level (by raising the subwoofer and super tweeter levels by 2.3dB) of the Audio GD relative to the Onkyo.  It technically does have at least 2.3dB more dynamic capability simply because of the higher output of the Audio GD.  But it sounds far more dynamic, as if the dynamic range has increased 12dB.  Rather than setting levels in the 90's I'm now setting them in the low 80's, and yet it is sounding louder.

While I was at it, I changed out some other cables.  I have gone from mostly Radio Shack cables in the Living Room system (yes, I don't believe cables are very important, and I believe that most often if audiophile cables sound different it is likely for the worse) to mostly BJC-1.  My ultra high end Denon DVD-9000 was connected through 6 feet of Radio Shack cable having high capacitance (about 200pF), mediocre shielding, and wrapped around lots of digital and power cords.  I used a 4 foot cable (minimum length) having about 80 pF (20pF/ft) of unknown maker for that.  The DVD-5900 I use for SACD was already wired with 17pF/ft mogami cables, but now I'm thinking that might be the perfect spot for the Straightwire with high capacitance  (help reduce the noise) and Teflon (a minimum of smearing relative despite the high capacitance).  Plus it's a high endy cable.  Putting my whitish hat on, the capacitance is not high enough (given the 100 ohm source and 20kohm load) to change the response for the worse audibly.  Only enough to count for audio fool magic.

Monday, August 3, 2015

Calibrating the Super Tweeters

Not in all the 5 years that I have owned the Elac 4pi super tweeters have I set their level by a measurement comparing their output level to that of the Acoustats.  I have set their level by ear (of course) and by overall system response measurements, but those don't give very much detail about the high frequencies where the super tweeter is operating.  I high pass the super tweeters at 20kHz and the Tact RCS spectrum analysis I have most often done has one point at 18kHz and one point at 20kHz and I wonder about how accurate they are since microphone angle has a huge effect on such frequencies and for stereo measurements I point the microphone straight forward.  Also the Tact microphone calibration itself has been called into question.

It is not easy to accurately measure levels at 20kHz and above.  But for the purposes of determining relative levels, it was simple enough to temporarily change the high pass to a lower frequency and test some signal that is easier to hear and/or measure.  I had been thinking about doing just that for several years, and that is what I finally did last Sunday.  I made a 30 minute aiff file with a steady 14080 Hz tone (A9).  I figured this was good to test tweeters: high and away from any low cutoff, and yet still not too high to be dangerous or inaudible to me.

I used Sox to make the file with the command:

sox -n a14k.aiff synth 30:00 sine 14080 sine 14080 gain -20 rate 44100

For some reason that wasn't acceptable to Sonos.  So I ran the file through Triumph, which had no problem re-writing it.  Then it was OK to Sonos.

At 73 dB playback level (6 inches from the Acoustats) it was just barely audible to me.  At about the same distance by eyeball, the Elacs measured about 3dB less, about 70dB, in both speakers, with the DCX crossover set to 10khz.  (The Elacs may also have their own internal high pass at 4kHz.)

It was difficult to do this near field measurement because it is highly dependent on distance, and I don't think right at the surface is valid (though…it might be as good or better than what I did).  I was thinking of attaching a ruler to the Galaxy SPL meter, but then I decided this measurement was good enough.  I was very pleasantly surprised, almost incredulous actually, that I had set the tweeters this close to the level of the Acoustats (and that is a very long story…they've been set all over the place on the DCX and further confounded with the Parasound amp's own attenuator, and a pair of Harrison Labs attenuators that I may have used different versions and sometimes had turned the wrong way).  By this primitive measurent, it seemed likely that I had not been setting the Elacs way too high, as I had been doing at one time and feared I was still doing.

It did occur to me that any near field measurement as I was doing was likely to be unimportant because the Acoustats have far more total radiating area.  By that standard, the Elacs might need to be set not just 3dB higher but 10-20dB higher.  I couldn't really figured that.  I tried measuring from my chair but the it was hard to get a good measurement without cranking the tweeter level much higher and I decided not to do that this time.

For awhile I tried setting the tweeters 4dB higher.  But, just to confound things further, I reset the crossover point down to 18kHz and I'm not quite sure if I had previously used BE24 but somewhere along the line I did that too, now that I was no longer worried that I was overdriving the hell out of the Elacs.

Well this indeed seemed to clarify the Sax in Jesse J's Lovesong, which had been seeming a touch dry on my system as compared with Luther's.  I have often found (or I should say, I though I found in sighted listening tests) that the Supertweeter actually removes harshness and glare, and that seemed to be the case here too, at first.  But then I did find it overbearing, and dialed the super tweeters back to 2 dB higher than the previous level (see below).

Well after this I couldn't stop playing with the adjustments during each thing played because it didn't sound or figure right one way or another.  One thing for sure, with the crossover reduced to 18kHz, the level raised 1-4dB, and the slope changed to BE24 or LR24, the output of the super tweeters has become clearly audible near the speakers themselves, which wasn't necessarily true before.

And it seemed like I was hearing huge differences with the slope changes.  BE24 did have a clarifying intensity, but also seemed to add some roughness (possibly boosting the 6kHz region, or causing comb filtering at more audible frequencies).  It was instructive to listen to the tweeters without the Acoustats playing, then the differences in the sounds of each option was far clearer.  The LR crossovers sounded by far the most refined, with LR48 the most refined of all.  I believe I had previously been using LR24, which reduces the super tweeter output to nearly nothing (but what there is is high high high).  But with LR48 at 18kHz, the effect sounded very top heavy.  The BE24 and LR24 seemed to have the least top heavy sound, a natural balance.  I ended up with the LR24 which sounded good by itself and also blended well with the Acoustats giving a very clear yet refined sound without coarseness.  The current adjustments as I am writing this:

19.2 kHz
6dB attenuator

Note that this was -2.3dB by the old standard where I was boosting the DEQ for the panels by 1dB.  That seemed to work weirdly I determined.  With 1dB of boost, an input of -2.5dB caused peak clipping at the digital output.  I dialed back the boost to allow higher levels (and Monday I have been using +3dB on the Tact (96.9) when playing SACD from the Denon which peaks at -4dB).  I have to make sure I'm not loosing any digital gain because I need pretty much full digital level out of my DAC's for a good loudness.

(The difference between the output of the Onkyo which now powers the Aragon, and the DCX which powers the Parasound, is on the order of 12dB.  Oh, and the Acoustat 1+1 are about the most inefficient speaker ever, in the 70's!  Whereas the Elac speakers my tweeters were matched to were in the upper 80's.  So actually a combined attenuation of only 9.3dB seems to small, intuitively I would have expected 24dB or far more, and before these tests I wondered if I wasn't setting the level way too large and causing a huge ultrasonic peak.  Update: now I wonder if the Elac crossover was at 14k, and my measurements off by 6dB or more as a result of that--in which case I now have a slightly larger ultrasonic peak than before, but in which case it must not have been as large as I feared anyway.  I need to retest with higher frequencies.  And I should record amplifier drive levels and push the levels harder now that I know the Elacs can officially handle 400W continuous and 600W peaks, or at least a later one did.  So I should be able to reach above 80dB and make proper listening seat measurements.)

So when dialing back the DEQ boost to 0, I reduced all the DCX settings to compensate, putting the tweeters at -3.3 from -2.3.  When the day had started it had been set to -4.3.  So this was a 2dB rise as seemed conservative from measured levels, with twice that much sounding too much.

This is almost like having super tweeters for the first time.  You would have thought I'd do this kind of calibration the day they arrived.

The 19.2kHz LR24 seems intuitively consistent with the limitations of the Acoustats FWIW, just where a super tweeter should fill in.  20kHz was probably too high.  I suspect the actual rolloff of the Acoustats is close to 24dB/octave also, including 6dB/octave from the resistor in the crossover, the trannies, and the mass of the speakers.

Also contrary to earlier fears about one being bad from ribbon warping, both super tweeters measured the same in level and sounded the same.  (I've seen some ribbons even more warped than my left tweeter.)

Here are the specifications for the Elac 4PI Plus, which I think was a later model.  Mine is more impressive looking, and I think a very similar earlier model, except it did not extend to frequencies higher than 35kHz as later models did, but possibly extended lower, perhaps to 4kHz.  Well according to these specifications, not for my exact model but similar, the maximum power handling is 400W continuous and 600W peak.  They should be safe with the current Parasound HCA-1000A amplifier, but maybe weren't safe the the Acurus A250 amplifier I was using before which can produce 500W or more into 6 ohms rated impedance.  At least once, due to some technical error, I was clipping the A250 into these speakers at peak.

Other specs show sensitivity variable from 84-92dB at 2.83V (this model had sensitivity and crossover controls, I believe mine has fixed crossover but I'm unsure of the frequency).  The crossover is selectable for 10, 12, and 15 kHz.  Frequency range 10-53 kHz.  Impedance >10k ranges from 8-3.5 ohms.  Weight is 4kg (about the same as mine).

Here is an advertisement for what appears to be my exact model, the Elac CL 4Pi Plus.    I had been afraid it was only sold as part of a specific full range speaker, but here it appears to be sold specifically as an add-on module.  The weight is 5.5kg, frequency response 3.5k-35kHz, power handling 400/600W,sensitivity 88-91dB, minimum impedance 7.5 ohms at 25kHz.  It says Crossover Frequency 7,000Hz and I believe that refers to a built-in crossover which is not adjustable in this model.

WRT Bessel "filter" (it's actually a class of filters some say) something like that may form the basis of the crossover for the Spica T-50, which has excellent time response but ripple in the frequency response around the crossover according to some.  Because of ripple, it hasn't generally been recommended for crossovers.  The "bessel high pass" does not retain the perfect linear delay that the theoretical low pass does, it's merely the "maximally flat" case given the amount of phase shift which must occur.  Actually since LR24 has Q of 0.5, and BE24 is actually slightly higher, the LR crossover would have more gradual phase shift I would think, but I'm thinking it might be a more constant phase shift.

In my case, given that I am correcting the low pass of my panel speakers, I want a matching time response around crossover to that of my panels.  If the panels roll off like a pair of second order butterworths in cascade, and they probably do something not entirely unlike that because of cascading rolloffs in the transformer primary and secondary circuits, an LR24 or similar high pass on the tweeters would provide the correct inverse time response, and the flatter Bessel filter would be too-flat in the time domain for correct cancellation and cause some comb-like responses.  Perhaps that was the grundge I thought I was hearing.  But I would find it hard to believe I correctly sorted that out by ear, and I still suspect my selection of LR24 was more related to loudness than anything else, it was less loud that the BE24 but more loud that XX48.  Perhaps another crossover function would work better at a different loudness level.  I have not tested that.  But what I am doing seems intuitively correct or close to it, and sounds good.


[This was held up in the draft queue unexpectedly a long time.  Perhaps because all too soon I was fiddling with things again…  And then the re-cabling changed all the levels.  And so on.]

After a long time with LR24 on the super tweeters, I decided that was too hot.  So I rolled it up to BUT48, which is like the next step less rolled up than LR48--the historical setting until a couple months ago.

When I re-cabled to permit use of the Audio GD Dac 19 on both amplifiers, I chose to increase the gain by 2.3dB in the sub and super tweeter crossover rather than decrease the gain for the panels.  Which is all to the good as far as gain structure.  So what was a -3.3dB on the super tweeters is now -1dB, not because the relative level has changed.  Also the subs are now at -11.7dB.

Speaking of subs I felt that the SVS were contributing too much above 80 Hz.  So I made the crossover asymmetric as I often have.  So I've messed up the calibration I did a few months ago, and this probably isn't the right way to do things, but I think I like the sound better, maybe.  Anyway the SVS are crossed with LR48 while the Acoustats are crossed at LR24, both still at 80 Hz.

Fixing the SCD-1, SCD-777ES, or other transports

Advice on fixing SCD-1 or similar transport

General advice on fixing CD players from Lampizator, a celebrated audio modder.  Lampizator has spent more time noodling around with old CD players than anyone, and he says he has only once ever seen a bad laser, and that was caused by his boosting the laser drive signal.  Most of the time, CD problems are caused mechanical failures of various kinds, many due to accumulating grunge or hardening lubricants.   Lamizator curses the professional techs who make bucks by unnecessarily replacing lasers, therefore depleting the precious stock of factory parts.  He says that if you can hear the disc spinning at a controlled speed for 2-3 seconds when the disc is loaded, the laser is fine because in most players the disc won't even start spinning unless the laser detects a reflective surface.

It does now seem that the "fixed laser" transport (FPM) was Sony's most intense, and probably best, effort to remove transport vibration and jitter.  Sony had been making these transports back to the beginning of the CD era with the professional CDA-5000 Compact Disc Analyzer, and a series of high end CD-only models in the 90's also used a fixed laser transport, such as the CDP-XA7ES.  The last go around was for the SCD-1 and SCD-777ES models.

The Vintage Knob says:

FPM was intended to suppress vibrations where there are more in the first place (the spinning CD) rather than try to minimize those which have a much lower magnitude - in the laser pickup itself.
So the disc's spinning motor and rotor become the moving parts (one big moving part), and the laser block remains... fixed on its base.
But TVN also says that FPM was less expensive than Sony's other premium mechanism, the all aluminum BU-1 with magnetic rails.  And lower cost was a key motivation to bring it back in the mid 1990's.

The SCD-1 did achieve a lower jitter measurement in Stereophile than I remember for any other player, FWIW, playing CD's.  However I have not tried doing a systematic comparison and the jitter measurement techniques may have changed over the years.

While the original high end SCD players have many SACD loving fans (the consensus emerged almost right away that there were better Redbook players from Esoteric, Krell, Marantz, and others) many have had a love/hate relationship with the transport.  It is apparently somewhat unreliable, and by 2006 or so many owners were stocking up on lasers, sled motors, and spindle motors.  Sony tends not to offer service or even parts after 10 years or less, and they may have already used up all the spare parts before them in earlier repairs (sometimes unnecessary part replacements, according to Lampizator).

The general consensus now is that Esoteric makes the best mechanisms such as the VRDS which itself comes in several versions.  But if I want a "reference" player specifically for SACD, the SCD-1/SCD-777ES still represent a kind of reference benchmark.

Here are the 3 parts that some people were stocking up on:

1. Spindle motor: P# 1-763-254-11
2. Sled motor: P# X-4952-147-1 
3. Laser Pick up: P# A6062396A

Here's a thread with a guy fixing an SCD-1 which originally had pictures.

A friend has a boom box with cassette and CD player.  The CD player is often not working, though I got it to work a few days ago up to track 7 out of 10.  I think there is possibly something making laser movement difficult.  We agree it is worth fixing this because CD/Cassette boom boxes are basically not being made anymore, thanks to the kind of planned "markets" we have (planned by corporations to extract the maximum from us).

It's a CFD-S26.  Here is a similar model being repaired:


And here's a DIYAudio thread about fixing CD transports that starts (near the end) to discuss the adjustment of the sacred pots "track and gain" and "focus gain" that the service manual advises you not to adjust.  Well apparently lots of people with nothing to loose often try and win, for a few months anyway.  I once saw a friend adjusting those pots…and it looked just crazy.  After watching that you wonder how CD's mostly work at all, if just a hairs breadth of a turn of some pot inside is the difference between Perfect Sound Forever and junk.  But then again, I once calibrated a Sound Technology 1700 analyzer…and that's a similar experience.

And here's a more detained DIYAudio thread on CD player restoration and adjustment.

Sunday, August 2, 2015

Fixing the symptoms first

I heard Jesse J from Oregon in a live concert Saturday, bought the CD, got it signed by Jesse, played it at home, was wonderful.  Though I though a bit more wonderful when I lowered the TacT level (92.9=0dB) to 79.1 on cut three, that may have reduced some critical rattling in my living room.  This CD is no wimp when it comes to deep bass!   The next day, my friend thought it sounded a bit mechanical.  Right at that time, there were several rattles obvious to me, I've set about fixing them, which brings me to the title point.

As a general rule in such situations, it's better to fix the symptoms first.  By symptoms I mean the effects farthest from the original causation.  Why?  Because if you wait until after fixing the primary cause, you might not be able to find the symptoms again.  So I will fix the rattling before fixing the frequency response.  The frequency response doesn't require a non-linear failure like rattling to measure and can be fixed after the rattling is fixed.

But actually the frequency response is not bad.   I went through the test frequencies I have used to make adjustments before.  I have a series of tones recorded at something like -20dB, in Hz:  16,18,20,22,25,28,31.5,36,40,45,50 and up to 160.

Sitting at the Kitchen table listening casually, it seemed like 36Hz and 40Hz seemed a bit low.  But measured at the listing position, 22Hz-45Hz are within 1dB, which is pretty incredible and testimony to my hand-tuning of the EQ's, especially to fight the 10dB room mode at 45 Hz.

Playing the subwoofers alone makes it easy to find the rattles.  The bass is amazing tuneful considering the 80 Hz lowpass and everything.  I did think there was a kind of excessive bounce, excessively electronic sound in the bass, which I think is an unfortunate attribute of my system (I am not faulting the recording, which sounded just fine and natural on the bass on another audiophile's system which doesn't go quite as deep).  So, for that reason, and also because of booming and rattling all over, I dialed back a 20 Hz boost I had in one channel to zero.  Now there is no boosting below 31.5 Hz (at one time I had several boosts below 31.5Hz to enhance the lowest bass) and in fact there was a -3dB Q=1 cut at 20Hz, which I dialed back to -2dB after removing the 1dB Q=5 boost.  I can see the trick I was playing here (high Q boost combined with lower Q cut) but it's precisely that sort of tricky EQ that could add an artificial sound from extended reverberation.  Anyway, it's hardly any different from a 1dB change overall.

I only measured 20Hz after removing the 1dB boost, and it was actually 2-3dB below the 22-45Hz level.  But 20Hz is quite problematic, it causes a lot of wall flexing and rattles the kitchen range, among other things, which I can't fix.

The rattling wall clock was fixed by applying self-stick felt to the back, top and bottom.  Now this had an unintended effect of forcing the bottom of the clock away from the wall because of constraining the space for the wall hook on top.  At first it appeared as though the bottom was entirely away from the wall, but after some time, one side is almost touching the wall, the other side about 1/3 inch away.  I pound on the wall and it doesn't seem to rattle at all, so this is fixed for now, but may need to be monitored.

The rattling china cabinet was investigated, and finally the source of rattling was found: two vessels on the bottom shelf were touching.  That was it!  I was prepared to use felt, whatever, but that wasn't necessary.  Going one step further, I pounded on the shelves with my hand, and found one other potential rattle in the teapot and butter dish, with both have top and bottom parts.  I wedged pieces of paper in between top and bottom pieces and now they seem quiet.

The rattling in the range hood and back plate has eluded me for now.  Nothing I could hold with my hand changed it.  Anyway, this was not the rattle I heard on Jesse J's album, but something else that turned up playing spot frequencies up to 100 Hz.

The "cause" of lack of LF absorption will be a long time in fixing.