Wednesday, April 27, 2011

It was bad highs that made bass seem bad

Moving from the near listening position to the "imaging compromise" position merely 6 inches back, now I can't hear much difference, if any, in the quantity bass.  The differences seem to be more in the highs.  The highs go from decidedly dull to bright and open (perhaps a tad too bright).  But that also does seem to have an effect, not on the quantity of bass but the quality of bass instruments.  When the sound is dull from high frequency rolloff, the bass instruments don't seem very distinct.  Everything, including the bass, has a dull quality.

Underlying this, I had forgotten I had also angled the Acoustats for the new compromise position.  So any listening position closer than that would be too far off axis for good response, since the speakers are angled just inwards from where the highs start to roll off abruptly.

It has long been observed by many that good high frequency reproduction is necessary to get the bass right.    There is a rule (can't remember who named it) that even provides a formula.  If you have bass response to 20Hz you must also have treble response to 20kHz.  If you have bass response to 30Hz, you should have treble response to 15khz (and no higher).  And so on.  With the bass response to 15Hz that I achieve, I need corresponding high frequency response to 30kHz (!), according to the rule.

Anyway, ignoring that rule for the present, why should treble response affect the bass sound?  I can think of several possible reasons.

1) It's in the mind, so to speak, a perceptual or psychoacoustic effect.

2) It's in the harmonics.  You need the HF to get the bass harmonics.

3) It's in the sound physics.

4) It's the nature of the actual instruments.

I want to explore (3) a bit.  A steady bass tone such as from an electronic oscillator is just bass.  But any tone that starts and stops is a "transient".  And transients, by their nature, have lots of frequencies.  Assuming a bass tone were to abruptly start, at that very instant you would have the equivalent of a impulse or square wave, containing a range of harmonics up to infinity (depending on how abrupt the start really is).

That's my limited understanding anyway.  Most discussions of frequency response, from a simplistic Fourier Analysis standpoint anyway, make lots of assumptions including waves that continue unchanged forever.  Once you have changes, the steady state analysis no longer applies.  And I'm not exactly sure what applies then.  But I think the argument in the preceding paragraph are somewhat true.  An actual mathematical analysis would be far more complex.  You might consider that the bass tone is "modulated" by an underlying on-step and off-step, and then you have to consider the mathematical effects of that modulation.

And that's not even considering the nature of bass instruments and bass instrument players.  Bass instruments can have "attack" sound (from a pluck, say) which truly is something like a step or impulse or short square wave.  Failing to reproduce that "attack" sound correctly, which requires fully extended frequency response, will also result in dull sounding bass.

I'm not actually sure which of these effects is greater, though I suspect the reproducing (or not) the attack sound is really the most important, and the quasi-impulse character of all tones which start and stop is a less important, but non-negligible factor.

WRT the natural harmonics of steady bass tones from bass instruments, I suspect they trail off pretty quickly.  So if you have a bass tone at 60Hz, by the time you get to 1200Hz (20th harmonic) there isn't much there anymore.

Tuesday, April 26, 2011

New LP's for $7.99

It seems too good to be true, new LP's for $7.99 (plus $5 shipping) on 180g low noise vinyl.

But I decided to take a roll on the Gerry Mulligan LP.  Maybe that will help motivate me to get one of my LP players working again.

Bass? Remember the listening position

Well, it now appears I may have been too hasty in juding the KT-6040/PAD-1 combination as having lousy bass because of lack of gain (it reaches about -12dB maximum).

I was noticing the same lack of bass listening to Supernatural on my BDP-95/AD10.  That can't be, I thought.  Ohya, prior to weekend party (which moves everything temporarily) I had been using the new "compromise" listening position, not the previous more forward position that gives the best imaging.  The compromise position is about 6 inches further back from the speakers.  More importantly, it is about 6 inches back from the center of the room, where there are bass nulls for all major room modes.  Imaging suffers slightly, but bass goes from zero to acceptable.

I've been reading "Get Better Sound" and one of the most important tips is that if bass seems wrong, start with the listening position.

This happens all too easily because I don't yet have tape markings for either new position; I judge from the original tape markings (from last year) which is another foot further back, and by turning my head to see which book I line up with in the bookcase.

The more forward position lines up with the book "The Perennial Philosophy."  That gives best imaging based on ear angle and stuff like that.  It varies from person to person.  The basic strategy is that you move as close to the speakers as you can until the image collapses and all you hear is left and right.  Slightly back from that is the maximum stereo separation that still forms a coherent image, and thus, the best imaging.

The compromise position, now about 6 inches back, lines up with "Justice as Fairness".

But one extra variable is the speaker angle.  The change ALSO has a huge effect on the highs.  Now, with the speakers directed slightly away from listening position, moving back increases highs.  Perhaps, though counterintuitively, the increased highs make the bass seem more defined.

This listing position thing clearly needs a lot more work wrt speaker angle.  That's why I haven't put down new tape, I'm still experimenting.

One way or another, I do get tingles listening to various parts of Supernatural.  I also sometimes miss the room corrected bass I was trying last year, though correction at the listening position increased bass elsewhere so much room was really shaking...enough to be uncomfortable often.  And if you were a guest on the sofa, well you wouldn't want to be there.  That's why now I'm trying to see what I can do without EQ.

Though I'm thinking about getting one of those active-mode-cancelling gizmos from Bag End.  I'm thinking that be easier to fit into my room that the equivalent in passive bass traps.

Monday, April 25, 2011

Kenwood KT-6040 through MSB PAD-1 w/o gain lacks bass muscle

Somehow, I'm not finding the current tuner setup with Kenwood KT-6040 being fed straight (1 foot solid core coax from Blue Jeans cable) into MSB PAD-1 to sound as solid as it did when I fed Kenwood through Lavry AD10 (in one of various less-straight configurations).  It has a distinct thinness now.

I'm wondering if this is just coincidence (the music KPAC has been playing most recently perhaps?) or quasi-psychological (the gain is 12dB lower, so although in principle I could boost gain exactly to match, perhaps I just don't because the numbers look too high) or something technical.

One ready technical explanation is that while I could boost the gain on the Lavry (and did so, about 10dB) I cannot do so on the PAD-1 as it has no gain adjustment.  As described earlier, I ONLY use the balanced input on the PAD-1 (since the other inputs are very inferior) which means I have to use a RCA-to-XLR adapter and either boost the gain with external preamp or not.  (Currently, I am not boosting the gain, though it appears my Aragon 28k is still working after all, so I could use that, except there's no room for it in the current physical configuration.)

By not boosting the gain, I am loosing about 12dB gain (peak output is at -12db), and comparable S/N and dynamic range.  That's equivalent to two bits, so I don't really have much better than 16 bits actual S/N in my digital encoding.  My previous argument was that should be sufficient for a tuner anyway.  But perhaps I was wrong.

It would be nice if there were a tiny stereo lineamp based on OPA-2604 or other high end opamp (IMO 5534 might be good also).  Such a thing could be built in a small hammond box with external DC supply.

But nobody seems to make anything like that.  You can find various gain boxes intended for musicians of non-high-end quality, or fancy and incredibly expensive preamps which have features I don't need.  But not a the combination of stripped-down-features and high-end-quality and low-price.

The PAD-1 used through balanced inputs seems about as good as I am able to measure, distortion about 0.001% or less, and it seemed perfectly adequate for Denon 5900 when used with Aragon 28k to boost gain.

Better improvement might come from better antenna than buying high end preamp.

Other option might be routing all analog inputs through Lavry.  In that case, I need a balanced selector, and made with premium components those can be as high as $375.

Saturday, April 23, 2011

Santana Abraxas SACD (updated, fixed by supertweeters)

Update: Just discovered that supertweeter amplifier was turned off in earlier testing on this disc.  Turned it back on, and voila Abraxas is now a fairly listenable disc.  Still might hesitate to play for friends, and a MoFi might sound better, but it now has the liquidity that makes the full package work for me.  Still has a sharp edge, but much less harshness.  Another proof how supertweeters make music sweeter and less harsh (strange but commonly reported).  This disc puts out considerable energy in the supertweeter range, I'm getting 1 LED for the supertweets vs 3 for the midrange amp.  My supertweeter is lowpassed at 18.4kHz BU24, but there is still some output below 16kHz (though not much). [end Update]

I intended to check out Supernatural SACD now that my system has no boom enhancing EQ.  Actually I think I have already done that before in the last two months, but wanted to hear it again now with the state of the art Oppo/Lavry/balanced front end combination.

But instead I reached for the Santana Abraxas SACD.  In the right mood, as I was about 2-4am Saturday morning, it was awesome rhythm in space.  But come the morning light, it's clear this is a troubled recording.  Others have said far worse in online reviews.  It was one of the first SACD's, released by Sony during the introduction of SACD.  Rumor has it that Sony used a low rez PCM master for this one, rather than tracking down the original 1970 analog master tapes.  Whatever, it mostly has an annoying glare that makes the artfully used distortion (in the music itself, I especially dig that raspy B3) just awful.  Well, in the right mood, I can take it, but I wouldn't play it for friends.

Oye Como Va fares better than most tracks.  At slightly reduced level, I could play this for friends. The first track is also OK if played at very low level.  The rest of the hard driving music demands you to crank it up, but when you it sounds like crushed styrofoam.

It will be interesting to pull out the Denon 5900 sometime, this disc might be good for comparison.  Certainly on CD's, with it's AL24, I recall the 5900 has an incredibly sweet sound.  A friend said so too, unprompted.  Sweeter than real.  That might salvage this recording.  OTOH, the Oppo seems straight up, what's there is exactly what you get, total transparency, good or bad, and I've never heard such transparency in any source, though sometimes I might prefer a more pleasant sound than was actually there.

The Mobile Fidelity version is supposed to be good.  Last year, the MoFi Gold version of Pink Floyd Meddle blew me away, totally wonderful, and very different from the grungy standard release.  And, BTW, it had nothing to do with the gold backing.  I've played it mostly through my server.  I think one of the main glories of the MoFi Meddle is the lack of compression.  It sounds like (and is alleged to be) a straight up encoding of the original mastertape.  So background tinkles are not converted into hashy clangs.

Thursday, April 21, 2011

Kenwood KT-6040 back online in left side pile

The new re-arrangement of equipment is coming together.  (The inspiration, from a few posts back, was that no stack of equipment should be higher than seated lap level, to avoid interfering with the dipolar sound field of the Acoustats.)

The left side pile has these items:

Kenwood KT-6040 tuner, my current favorite for all-around musicality with reasonable quietness.

MSB PAD-1 Analog-to-Digital converter converts Kenwood output to 24/96 PCM which is sent to my Tact digital preamp.

Sony 507 ESD CD player, a classic from 1989, but mainly used for guest CD's because I don't like putting potentially dirty discs into my premium universal disc players.  I will use the coax digital output (not connected yet).  This player has excellent error correction, better than some universal disc players, as I discovered last year.  I dug out the 507, and sure enough it played a terribly scratched disc flawlessly.

The setup includes:

1 foot interconnects (Kenwood to MSB) from Blue Jeans cable (can't remember which version, probably LC-1).  Not teflon, but foamed polyethylene, and unbeatable shielding.

220V stepdown transformer for Kenwood, nicely made from Hammond transformer.

Power adapter for MSB.

Wirewound 6 green dot outlet strip in white aluminum box (wonderful!).  This grips plugs very tightly!

Used a nice looking premium Radio Shack 75ohm video for the digital connection.

9 foot RG-6 for connecting to twinlead dipole antenna on other side of room.  F-to-Euro adapter.

Used nylon tie wraps to coil up AC cords for neatness and to avoid proximity problems.

Just the wiring part of the setup took about 2 hours and lots of kneeling gymnastics.  non-Audiophiles will probably never appreciate what hard work this is.

When first hooked up, I was amazed by the transparency.  Perhaps PAD-1 digitizer is as good or better than Lavry AD10, I initially thought.  Then I noticed the lack of bass.  I hadn't re-powered subs or supertweeters.  Re-powering them robbed a slight bit of the unreal transparency but gave much more warmth and reality.  My ultimate guess was that the Lavry is still slightly better, but the PAD-1 is very close.

Unfortunately, the music on my 3 favorite stations was a bit lame at 4am.

I'm glad I can now switch over to Oppo disk player using remote control, because Oppo uses a separate digitizer (the Lavry) and they both feed digital to the Tact.

One problem with this setup is that the PAD-1 only works well through it's balanced inputs.  (Through balanced inputs, the distortion measures 0.001%, almost at my residual, but through the single ended inputs, distortion measures 0.01%.)  The balanced inputs are set up for 10V RMS input.  So by using the balanced inputs, but without a preamp, I may be loosing as much as 12dB of potential dynamic range.  But I don't see anywhere in the existing setup I can place of my Acurus L10 or Aragon 28k preamps to boost the level 6dB or so.  Perhaps I could build new line amplifier inside the MSB itself (replacing whatever junk they have in there now), or in a smallish box.  Or find something small but high quality.

Using the Lavry elides this problem because the Lavry has a 13dB gain adjustment range with handy peak holding LED meters.

Anyway, the loss of dynamic range is probably not much to worry about for FM.  Even with 12dB loss, I still have 100dB or so in the digitizer, whereas FM stations are more in the range of 50-60dB with my current antenna.  I need to improve antenna!  Actually, you can't push FM level too close to the max anyway, you need lots of headroom to avoid clipping while tuning in stations.

Wednesday, April 20, 2011

Mouser delivered in One Day (standard shipping)

I got my new high quality Wiremold 6 green-dot-outlet strip.  I ordered online Monday afternoon, and it arrived on Tuesday.  Now that's FAST!  I've always enjoyed good service from Mouser.  Back when I lived in San Diego, there was a Mouser warehouse in nearby Santee.  Now I usually get items shipped from the Mouser warehouse in Dallas.  One "downside" is that I have to pay sales tax.  Actually, that's an upside.  "Every purchase supports services provided to working people in Texas."

I'm re-arranging the Belkin power conditioner connections so that the 2 high current outlets both connect to subwoofers (they need it, and the subs have interference-immune and interference-causing switching power supplies anyway, I believe).  The Acurus A250 could use comparable power, but since it is only powering tweeters at expected levels well below 20 watts, it is now on the "audio" filter bank.  The satellite line powers only low power gizmos like the MSB PAD-1 and the Kenwood KT-6040, so it is being connected to the "audio" filter bank (as it has been in past).  I think it's important that this line get fully conditioned rather than "high current" AC power.  I'm not totally sure about this, but it seems like the Belkin might not have the PI filter (two caps and one choke) on the high current line.  It's not clear if the high current line gets much more than surge suppression.

While messing with the tangle of cords behind the Belkin (how come it seems I spend most of my life untangling something or other) I noticed that the Belkin itself has a low pitched hum, possibly resulting from scads of inductor-based filters.  That contributed a small, but probably unmeasureable proportion to my measurements of the Oppo fan noise.

It seems like every audio system I've put together in the last 30 years quickly uses up all available outlets.  This makes non-audiophiles nervous, but the combined draw of all the low power gizmos (and often endless AC adapters) usually adds up to less than one ampere.  It's the power amplifiers (like the Parasound HCA-1500A which currently powers my acoustats) that *can* have an actual high current draw on musical peaks, but even they (except for the Krell) typically draw less than one ampere.  An electric heater continuously draws 15A while operating.  BIG DIFFERENCE.

(Now the Krell can have draws comparable to electric heater.  That is one reason the Krell is always plugged straight into the wall socket for my dedicated audio circuit, never into any kind of conditioner or outlet strip.  Currently, the Krell is waiting for disassembly, analysis, and shipping back to Krell for repair, see earlier posts.  Hopefully now that I have whole house surge protection, I'll have fewer failures like this.)

This is verifiable, all three of my main systems have current readout.  Currently bedroom and kitchen systems use Monster Power 2000A which give voltage and current readout.  The living room has Belkin with same information on a cool looking blue screen.

Now, in principle, any one of these gizmos could have an electrical short.  If so, the 13A breaker on the Belkin will trip (and if not, ultimately the 20A breaker on the outside panel).  To make this possible, all cords connected to the Belkin should be at least 16gauge, even if they are only connected to power adapters.  The Belkin's cord is 12 gauge.

If there is an electrical short in one gizmo, the fact that so many other gizmos are connected is in some way irrelevant, *that* item would have shorted anyway even if it had been the only thing connected, and the same outcome should occur.  There is a minor problem that as more things are connected, the possibility of failure rises.  But the same would be true if I simply had a larger home, with all the gizmos more spread out into different rooms and each plugged into wall outlets.

One affect of yesterday's rewiring is that *all* audio components, including subwoofer, are on the dedicated Audio circuit (which is very quiet compared with normal circuits in my house which are VERY noisy).

Happened to notice that the copyright date on the MSB PAD-1 board is 1998.  That's funny, I thought it was much later generation technology.  MSB provides an interesting white paper on Jitter written in 2007 featuring the PAD-1.  Based on the results shown there (the PAD-1 technically trashes a professional ADC), I think the PAD-1 is sufficiently good for digitizing most single-ended sources like the Kenwood KT6040.  Only if I need to do exacting comparison (like Denon 5900 vs Oppo BDP-95) would I need to use my best ADC, the Lavry AD10, on both.

Tuesday, April 19, 2011

Ordered new outlet strip

New satellite power strip, extending extra outlets for Kenwood tuner, spare CD player for guests, and MSB digitizer for tuner.  And will add subwoofer and Kurzweil lines to that (to be powered by "high current" output from Belkin power conditioner).

Perfect item found on Mouser, Wiremold 15A 6 outlet strip with aluminum case, green dot outlets (real outlets, hospital grade), and 15 foot 14/3 SJT cord (ULBH6-15 is the mfg part number).

No surge or filtering (should not connect those to power fact those can be very bad).

Price $71 plus tax and shipping.  Shipped today.  I use an identical unit in bedroom for powering turntable and phone preamp.

Similar audiophile products start around $199, PS Juice Bar.  The Wiremold looks better to me, more bone and less flash, though for audio purposes, it has a breaker/switch which is considered undesirable, and it's hard to imagine when it would be needed.  I once purchased special limited production Wiremold strip without switch or breaker of any kind.  But it did not feature "real" outlets (like you could put in the wall) like this one, but rather the "thin" outlets that are intermediate between the real outlets and built-in-the-box plastic strips.

Monday, April 18, 2011

King Crimson on Oppo

Last year I was delighted to find the DVD-Audio 40th anniversary edition of King Crimson's Court of the Crimson King.  It sounded fantastic on my Denon 5900 re-digitized to 24/96 with my MSB PAD-1, then on to living room system.

This year I have been even more delighted to play back Court of the Crimson King on my Oppo BDP-95 and Lavry AD10, with 1 foot balanced interconnect in between.

Unfortunately, DVD-Audio discs must be navigated with a video screen.  That a pain, IMO.  I normally don't like to hook my universal music disk players to a video display because that often introduces ground loops.  On this disc, somewhat count-intuitively, you must press "down" and then "right" to get to the audio menu, from which you can select two stereo modes, MLP lossless stereo at 192kHz/24 bit, and LPCM at 96kHz/24bit.  I greatly prefer the MLP version and immediately figured that it was a different mastering.  Indeed, the LPCM version is a 2004 remastering of Court, and the MLP version is a 2009 multitrack remastering for which they went back to the original pre-mixdown tapes and did a 24 bit digital remix, thereby bypassing all the previous technical limitations.  The MLP version is far sweeter, less harsh, and yet quieter and more detailed, all at the same time, a timeless recording done to the best of modern standards.

This is one of those recordings which is so essential you nearly must own a DVD-Audio player just for this one disc!

I had started by connecting my small battery powered TV display (bought for navigating DVD-Audio discs last year) to the Oppo, but not connecting the AC supply.  That lasted about a day or so with very little usage, then the internal rechargeable battery was dead.  So then I connected the plain old composite video output of the Oppo through a Jensen Isomax video isolation transformer, to the Olevia TV.  That should have been about enough isolation, but anyway I also chose to re-connect the Olevia TV to the dedicated 20A audio power circuit through the Belkin power conditioner.  That took some rearrangement including the removal of a new nearly functionless outlet strip connected to the non-dedicated circuit.  That circuit now powers only two things: the light (on X10 timer) and the remote control extender.  Anyway, now not only is the video isolated, the TV is on the same circuit and power conditioner anyway (which normally would make video isolation unnecessary).

When doing this, I discovered that I still had one of my subwoofers plugged into the non-audio circuit.  That might not be a bad idea for load sharing, but is not a good idea for isolation and ground loops.  I reconnected it to the Belkin through the line that goes to my Kurzweil keyboard and other equipment.

I need to create a new satellite power center for the pile of components on the right side, which will include Kenwood KT-6040 tuner, MSB PAD-1 (which will digitize the output of the tuner), and Sony 507ESD CD player (for playing guest discs), and subwoofer.  Probably the best configuration for this would be a 6 outlet strip with no surge or filtering and a integral 9 to 12 foot cable.  It will be plugged into the Belkin.  It could also have detachable cord, it may be easier to get the right length that way.

Thursday, April 14, 2011

Sounding better than ever

Last night I listened again to one of my recent favorites: "We want to be loved" by Grouse.

I had been blown away when I first heard this (on Pandora, actually).  I then played on Rhapsody, finally got real CD version.  No advanced resolution version available that I know of.

But a few months ago, and this was one of the reasons why I began seriously re-examinging the listening position, room correction, room acoustics, crossover, and ultimate re-capping one of the acoustats was this: it wasn't sounding good anymore.  Notably, in the second track it sounded like the band was being replayed over a speaker system with speaker foam rot.  Clever, but very annoying sound.

Well now it does sound different and better, and the image I had was wrong.  The closer listening position really makes the imaging here 2 dimensional, if not 3 dimensional.  The way the speakers are now slightly angled away from the listening position, which brings the highs more inline with the midrange.  And the replaced speaker cap helps improve inner detailing (still on one side only though).

Now the band sound is direct.  But there is some other object making a razz noise in time with it.  I still find the razz noise a little unlistenable, but it sounds much better than speaker rot.

Tuesday, April 12, 2011

Equipment piles must not get too high

In the last few days, I had built up a pile of components near the right speaker.  This pile started with the Belkin power conditioning UPS, which was low enough (lower than the Acoustat interface boxes) that I figured I could put it near the speaker.

I had also piled on the Acurus A250 power amp, which drives my ribbon tweeters.  Sitting atop the Belkin, it simply looks like one unit: a big impressive amplifier.  That's been there since I got the Belkin (and was there even before I got the Belkin actually).

Then last week I added these: the Nakamichi RX-505 (sits nicely atop the Acurus, and the Acurus doesn't even get warm in normal use now), the Kenwood KT-6040 tuner, the Oppo BDP-95 disc player, the Lavry AD10 analog to digital converter, and (just yesterday) the Sony 507ESD CD player (so I can play discs from guests, I only put the cleanest or new discs into the BDP-95).

And yesterday or thereabout I determined that I could reduce the fan noise from the Oppo by moving it down in the pile, to just above the Nak.

Well now, looking at this pile that was up to nearly eye level, I was wondering if that was causing the image to shift to the right.  So I took the Kenwood and the Sony off the top, and it seemed to make little difference to the orientation of the image.  I moved the right speaker back about an inch and that fixed it.  I was listening to a friend's CD of Long Black Veil by The Chieftans.   The effect of centering a female vocal by moving the speaker and lowering the equipment pile was truly magical.

Anyway, I think it's not good to have a pile of equipment up to ear level around a dipolar speaker (in this case, just slightly to the side and behind), so I'm keeping the pile low for the time being.  I think it should be no higher than lap level.  I moved the Kenwood and Sony to a new pile near the left speaker, still no higher than the interface box on the back of the Acoustats.

If I need to do a Denon/Oppo comparison, I can put the Denon in the left pile, replacing the Sony CD player temporarily, or put it in the right pile, replacing the Nakamichi temporarily.  The really heavy components need to go near the bottom.  The Nakamichi is fairly heavy.

I thought again of getting a second Lavry ADC for the single ended components.  Note that the Sony 507, however, sends coax digital to my Tact preamp and doesn't need an ADC.  So the only analog components which need switching are: Kenwood tuner, Nakamichi tape deck, Sony tuner.

After lowering the right pile, the Oppo is again on top (from the top: Oppo, Nakamichi, Acurus, Belkin).  Since moving it down in the pile had reduced fan noise, I remeasured the fan noise.  It actually seems slightly improved, from 22.5dB to 22dB (actually stayed at 21dB for a few seconds).  Perhaps the Oppo was causing slight vibration in the Kenwood sheet metal above it.  My previous measurement with Oppo turned off was 20dB, and I did not repeat that measurement.

Back on Sunday, I finally got around to setting up the Oppo audio options.  It seems funny to me that HDCD was not turned on by default.  I also changed SACD mode from multichannel to stereo, though I wonder if that makes any difference through the stereo outputs.  When I made that change, I was hoping it would reduce fan noise by turning off the multichannel analog outputs and reducing heat.  Most of the heat generated is most likely due to the multichannel outputs.  But it did not seem to make any change to fan operation.

Some people say that the Oppo fan does not run until it gets warm.  However in my experience, with SACD's and HDCD's, the Oppo fan starts running a minute or two after the player is started, and then never turns off.  My room temperature is below 78 degrees.

Though I've tended to obsess about the Oppo fan noise, I also measured one of my quieter Denon's, a 2900, while playing an SACD.  It has no fan noise, but a very obvious high pitched whine, much more annoying than the Oppo hummm, and it measured 26dB at 1 meter.  I have two 5900's and one of them is quieter than this, and the other is noisier.  So even with its fan, the Oppo is quiter than some high end players.

I'd much rather have the Oppo near the front of my living room system than a player as noisy as my Denon 2900.  And it turns out that I really like having a player near the front.  The player near the back of the room is nearly always inaccessible because of junk piled up near the back of the room.

Monday, April 11, 2011

Getting the Oppo Music up and Fan Noise down

The weekend started out with a continuation of experiments as to how to lower the audible significance of the fan noise of the Oppo BDP-95.  Using my Genrad 1933 SPL meter (which badly needs recalibration), I measured the noise level before modifications at around 25dB (at 250Hz) at a convenient position (ottoman) about 1meter from the 2meter listening position.  I liked making 250Hz octave band measurements at first because they clearly show the fan turning on and off.  Turned off, the noise level drops to 18dB.  (This is assuming A/C and kitchen refrigerator are not running, both of those together raise room noise level to 30dB or so.)  You can also see that for the first minute or so of operation, the Oppo fan is not running.  The actual drive mechanism is virtually silent.  But after a minute or so of playing, the 250Hz rises from 18dB to 25dB.  The fan stays running even when there has been no disc playing in hours, but shuts off quickly after the unit is turned off.

I figured I could reduce this noise by putting 6" thick Sonex pyamid panel (2 ft square) behind the stack of equipment that Oppo is in.  I also lowered Oppo from the top position to the middle position of the stack, so the noise that it originates is more likely to be blocked by other equipment or the Sonex in back.  With those two changes, noise level at 250Hz lowered from 25dB to 22.5dB.  Then I noticed the A weighted noise level is also around 22.5dB, and drops to 20dB when the Oppo is turned off.

Then I found an additional tweek which seemed to have more subjective effect than measured effect.  I cut a felt cloth into 2 inch wide strips and folded them back on themselves and inserted between the Oppo player and equipment above it and below it in the stack.  Subjectively, this seemed to make it impossible to locate the Oppo in space based on sound.  Fearing that the felt might be blocking air inlets on the bottom of the player, I eventually removed all felt from the bottom, but kept it around the front and two sides of the top.  There are no air inlets on the top of the Oppo.  Most players (which lack fans) tend to get rather warm on top anyway.  The Oppo did not seem to get excessively warm on top, even with felt around 3 sides.

It would be nice to have felt block material for this purpose.  It does seem like the gaps between equipment in a stack provides channels for sound to exchange from front to back and resonate with everything in between.  Though the Oppo player feels pretty solid, nothing is perfectly solid.

Trying to get the Oppo fan noise down, I began paying attention to all the other noises.  I discovered that I could reduce my A/C and water heater noise significantly by putting a folded director's chair across the corner where the A/C return vent is.  I did this in such a way to maximize noise reduction but minimize effect on airflow.  That corner should eventually get a full acoustic treatment.

The fan sound is distinctly measureable at 250Hz, but may actually be greater at 60Hz or so, it's just hard to measure there because the self-noise of my 1933 SPL meter begins to interfere.  It is interesting how well the sound level at 250Hz tracks the A weighted noise level, while the level at 60Hz is actually much higher, maybe 35dB or so.  But probably the higher frequency components of the noise are the most noticeable and distracting.  That's why little tweaks like putting felt dams between pieces of equipment seemed to help.  Those tweaks probably have relatively little effect at lower frequencies, but may interfere with higher frequencies.

Mind you I wouldn't be going to all this trouble if it weren't worth the effort.  The Oppo is the most amazing audio source I have ever had.  Listening to some classic RCA living stereo recordings on SACD, such as HiFi Pops conducted by Arthur Fiedler, it is astonishing to hear so much detail and life.

(Hifi pops also has some serious subsonics, not sure if they were intended.  Some of these are a bit too much.  The balanced connection seemed to give better control of the subsonics, making them actually musical.)

I'm now seriously planning to get a second BDP-95, for actually playing blu ray discs.  I need a second one of these amazing machines just for audio discs in my main audio system.

To get the most out of the Oppo, I reconnected it to the Lavry AD10 ADC with a new 1 foot balanced wire (Belden 1800F) from Blue Jeans Cable.  I moved the Lavry on top of the new equipment stack, and connected it to the Tact digital preamp with a new 5 foot 1800F AES/EBU cable.

As expected, this raised level by 6dB without adding any noise, making the Oppo performances even more magical.

Saturday, April 2, 2011

Maybe I'll just let Oppo whirr

It does sound wonderful, despite the whirring sound of the fan.  I continue to believe the Oppo mechanism is one of the quietest, with the package only marred by an audible (if not terribly so) fan.

I put a sound absorbing 6" pyramid Sonex panel behind the Oppo, since nearly all of the noise seems directed toward the rear (nice way to go, if you must go) and it did seem to make it quieter.

I then noticed how loud the computer sounds were coming from the second bedroom Computer (and Electronic Tech) Room.  I put the panel in front of the old caseless Amiga computer in that room, and voila it made more audible difference than anything I did behind the Oppo.  So now the total noiselevel drops, and once again the Oppo is audible.  It does seem like the Oppo is *less loud* in some sense than before, apparently the additional noise was partly parceled out from the Amiga sound to the Oppo sound by my perceptual system.  But, on the other hand, now the Oppo more dominates the noise landscape from the listening position (when all else like A/C and refrigerator are not running) much more than before because all else is so quiet.  So it goes with trying to make rooms quieter.

I then worked on putting a case on the Amiga, making it quieter still.  (It has been one of the sore points of my castle that one old computer makes so much noise).  The measurement in-room ultimately dropped from about 45dB to 36dBA, and at the door from 40 to 33, if I remember correctly.

Part of the change to Amiga 3000 involved turning off an external whirring CDRom drive (still haven't figured out how to get it to work on Amiga, maybe it can't) and removing one of two harddrives from the chassis (putting one into safe retirement) before putting on the case.

Listening to Weather Report SACD, I was really thinking I could just live with the Oppo and its fan noise in front of the room.  But when the music was over for awhile, I again decided I couldn't.

A friend thinks, possibly wisely, that I should deal with the noise at the source somehow, rather than trying to move player to back of room.

I think it must be possible to have a quieter fan.  I measure 40dBA at 6 inches from the rear opening (background level is only 38.5 however, so this is higher than accurate) rising to 70dB right at the case (perhaps that kind of measurement, picking up vibration, is inaccurate, the SPL is not a proper vibration meter).

It seems that sooner or later someone ought to work out a mod for this.  I'm not sure I want to void my warranty just yet, though perhaps just opening the box and checking out the fan wouldn't do that.

I also wonder how the Denon 5900 would sound in front of room plugged into the Lavry.

Friday, April 1, 2011

Fan Noise on the Oppo BDP-95

Just as I was strongly leaning to buying a second one...

The fan noise of the Oppo BDP-95 is a serious issue.  While not very noticeable from a distance, in the quietest living room condition (no AC or refrigerator running) it is noticeable, just barely noticeable, from the listening position, which is about 6 and a half feet from the new equipment stack currently having the Oppo on top.

It is just barely noticeable in the quietest room condition, at about the same level as the barely audible whine from the computers in the second bedroom down the hall (I'm still working on that) and particularly noisy trucks on the freeway 2 miles away.  So it's not loud, but still not acceptible either.

Close to the player, the noise is quiet strong within the first foot, then decaying rapidly.  (But still, as I said, just audible from listening position.)

The fact that it produces an audible noise means that it cannot serve as a high end component in-front-of the loudspeakers.  It might be OK somewhere else, like in the back corner where the Denon 5900 is right now.  But why have a component with signal to noise ratio of -135dB when it produces audible physical noise?

The Oppo actually seems to have quieter mechanism than the Denon, and might actually be quieter playing discs.  Tests will have to be done.

If I do keep an Oppo in the living room and get a second one for the originally planned video hub in the Kitchen...  The Oppo fan noise will either have to be fixed or the player moved to a less critical location.

I think the corner-back location seems to cover up DVD-player noises, which is why the Denon is there right now, and the Masterlink (which has fan and hard drive whine).  It may well work fine for the Oppo there.

But then the cabling/ADC issue is not solved as I was thinking in the past couple days.  A different approach is needed.  One of the following:

1) Use the existing MSB ADC in the back of the room.  While not as good (I think) or as nice as the Lavry, it still works pretty well, about as well as I can test with RMAA/Juli@through the balanced input.  The problem has been lack of gain, but with a 6dB boost from balanced outputs on the Oppo, it becomes much less needing of a booster-preamp (the currently defunct Aragon 28k having previously been used in that capacity for the unbalanced outputs of the Denon 5900).

2) Run approximately 25' balanced audio cable from the Oppo in the back corner to the Lavry in front.  With Belden 1800F at 13pf/ft, this is dooable, consider less than 300pf capacitance, which should not be a problem for the balanced outputs of the Oppo.

3) Buy a second Lavry AD10.  If I am spending hundreds of dollars on balanced cables and a new $380 balanced audio switch, that money might be better invested in a second super quality ADC.  I have no problem switching numerous digital inputs on my Tact.

I would probably not be moving the Denon 5900 to the front of the room either, because of the aforementioned drive noises (it's still quieter than a 2900 and much quieter than a 2910).  So even if I don't buy second Oppo, I'm pretty much stuck with back-of-the-room location.

I think my intial testing of balanced cables (due to arrive next week) will be front of room because I am working on a packing project in the back of the room.  Then I will likely move the Oppo to the back of the room and use the short balanced cables for a balanced connection to the MSB PAD-1 ADC.  At that location, Denon and Oppo could be compared using the MSB, to help decide how important it would be to have second Oppo, and memory of the previous use of Oppo with Lavry might help determine how important a second Lavry (or long cables and switch to use the current one) would be.


On modifying the Oppo, I have no plans to do that, but it might well be possible.  It wouldn't be entirely surprising if Oppo introduces an upgrade fan or fan controller.  The BDP-93 is fanless, and the only differences being the much larger audio board (probably of little consequence for heat) and it's linear power supply.

The fan sounds much noisier than current SOTA in computer fans, which are essentially inaudible.  Typically a very low noise sleeve bearing or magnetic or hydro bearing (ball bearings are the noisiest) is speed reduced to the minimum necessary speed (often 1000rpm or lower), then noise is reduced down to 10dBA or less.  At such low levels, lack of fan tonality may be more important than actual dBA reading. Scythe is a leading manufacturer of super quiet fans, and there are many others.  Sleeve bearings must be kept horizontal (fan blows air out the back, not down to the floor).  There is now a large literature on this subject and the competition to make the quietest fans has been intense.

The Oppo BDP-95 seems to have been designed in a vacuum of awareness of the importance of minimizing fan noise and existing available solutions to the fan noise problem.  The fan seems of pedestrian quality and has distinct tonal clicking sound.

Another solution might be to operate the player with cover off, or with linear power supply made external.

The existing noise could also be reduced by having damping on wall behind player.  But even with that, I fear it would be too noisy in the front of the room, where it can be placed within 1ft of the best ADC I have, the Lavry, and it's nice to keep the Lavry AD10 in the front of the room for testing other stuff, like tuners.