Friday, December 23, 2011

Rethinking Oppo noise measurement

Arguing over at AVGuide, I've realized I guestimated the Oppo BDP-95 noise even more incorrectly than previously thought.

My actual measurements were 39dB for player and 37dB for background.  One guy at AVGuide suggests that means the Oppo produces 2dB noise.  That's wrong.

But I was thinking something wrong also.  I was thinking that the noise was dominated by the louder source.

It turns out the loudness is dominated by the larger source only when the larger source is WAY louder.  20dB difference is often used as a criterion for accurate measurement.

If the increase is exactly 3dB, it means the two randomly correlated sources are equal in loudness.  (If they were correlated, it would be 6dB.)

So if the increase is 2dB, it means the background noise is actually louder than the Oppo, but not by much.  I don't know the exact formula, but I guess the extra dB accounts for 2dB of level decrease compared to background.  So the guestimated number for the Oppo chassis loudness playing DVD-Audio disc (measured within 6 inches btw) is around 35dB.

Of course, the randomly correlated and continuous assumptions wrt the background noise can't be trusted so the best way to do measurements is have the background at least 20dB lower.  But at least my guestimate is now somewhat better.

Tuesday, December 20, 2011

Denon 5900 manual and HDMI system

I've been thinking about getting manual for my two Denon 5900 players, especially the one intended for bedroom, now offline because it's noisy.  Perhaps I can clean and/or lubricate the mechanism to make it quieter.   Earlier this year I had both Denon 5900 and 2900 players hooked up in bedroom.  I used the 5900 player for HDCD discs (it didn't sound noisy on slow speed CD format discs) and used the 2900 for high speed SACD and DVD-Audio discs.  But my rack didn't have space for all that and the PS Audio Power Plant Premier, so I took the 5900 out to make room for it, leaving my bedroom system incapable of playing HDCD's except in CD compatible mode.  I had originally purchased the second 5900 to replace, not augment, the 2900.

Looking back through my records, I see I ordered the famously hard-to-get service manual for my Pioneer F-26 tuner from  However their collection is not indexed for Denon service manuals, and you must send them an email.

I found the manual already listed at and ordered a paper copy from them.

Meanwhile I also ordered a new kind of HDMI transmitter/receiver set for the living room.  Although I'm still planning a re-test, it seems that one of my two OWLink systems is no longer working.  OWLink systems are hard to find, and the huge discount deals that I got in 2010 are no longer available.  Other optical HDMI systems for 60 feet are $399 and up.  The more common way of sending HDMI digital video more than 30 feet is to use CAT5 or CAT6 with a suitable transmitter/receiver pair.  There are many such units available, from cheap $30 to over $1000.  Amazon has a generic brand for about $90.  I decided to get the ETS AV961G from Markertek.  Markertek is a top video supply house, so if they carry something, that's an important endorsement.  I checked out ETS and they are a US company that has been making balun-like AV products for extending signal reach since the 1960's.  Unlike the product at Amazon, the ETS requires the less expensive and more widely available UTP (unshielded) CAT cables; in fact the manufacturer doesn't suggest using STP cables that seem to be required for the Amazon product.  Plus, the ETS unit is supposed to have an equalizer adjustment for different cable lengths, according to Markertek.  Another seller says the equalization is automatic and there is no external adjustment.

Monday, December 19, 2011

Hooking up the Power Plant Premier

A few months ago, Music Direct was selling off their B stock of the PS Audio Power Plant Premier at $999, half the original price.  In the new model lineup, you had to get the $3999 model to have the same rated current capacity.  I checked out reviews for awhile, and decided I had to have this for my master bedroom, which is at the end of long circuit that includes my computer room, which no doubt generates a lot of electrical noise.

One of my key thoughts about the Premier is that it would enable me to run my bedroom power amplifier on regulated AC power, which might impart some Krell-like qualities.  My currently non-working Krell FPB 300 has regulated power for the output transistors, a very uncommon feature.  Most power amplifiers have simple capacitor filtered power supplies for the high voltage rails, which could let a lot of the AC line noise interfere.

Unfortunately, when I got everything hooked up and turned on the Premier last Sunday, something was making a horrible buzzing sound.  I disconnected all the things on the switched outlets, and re-hooked one by one.  Only one thing seemed problematical, and that was the Yamaha TX-85 tuner I haven't used in years, but since it sits at the bottom of a bunch of highly interconnected equipment, I simply haven't removed it yet.  So it was easy to leave that unplugged.

But then I plugged in the Parasound HCA-1000A amp I had been using, and it didn't work at all.  Something about the episode with the horrible buzz had somehow broken my power amp.  I'm hoping it's just a blown mains fuse.

Anyway, this was the perfect opportunity to plug in my newer and better amp, the Parasound HCA-1500A, which had been used for awhile in the living room until I got the Aragon.  But as soon as I turned it on, the horrible buzzing came back.  It wasn't connected to anything but AC power from the premier.

Not wanted to break another amplifier, I simply decided to leave the amplifier hooked up to the Monster Power 2000 strip that powers everything not connected to the Premier.  (Both the Monster and the Premier plug straight into the wall.)

So while only intended to make one change, I had to make two: putting line level equipment on regulated AC power, and putting online a better power amplifier.  That helps to make up for the fact I couldn't make the change I wanted to.

It does seem that with these two changes, the sound now has much better depth, a layered depth a bit like the living room system.  The old 1000A amplifier was getting a touch of ripple from deteriorating power supply caps and was making a tiny bit of buzz.  I had previously determined that was not a ground loop problem, it was present even if the 1000A wasn't connected to anything but power and speakers.  The 1500A amp is silent, and that alone makes a big difference.

I can now use the PS Audio remote to turn on and off my system safely.  I haven't been able to use my macro-based X10 system to do that for the past few months because the PC that was handling X10 macros died apparently due to power supply failure.  With the Power Plant Premier, I set a delay on the outlet (actually, the amplifier outlet) that powers the DCX 2496 crossover, so it turns on last.  The DCX itself has a nice muting feature on the outputs, but you can still get a huge pop in the output if you turn the preceding DEQ 2496 equalizer on after the DCX has come on.

Initially I was noticing that both the input and output power were shown as having 2.0% THD.  Then, I just happened to plug in my original style Tensor lamp, and the problem went away (even with the lamp turned off).  Now it shows 2% THD on input and 0.5% on output, which is what one should see with correct operation.

Worried that the problem with power amp might indicate some problem with the output of the Premier, I got out Tek scope and measured through a 1M resistor.  The wave on both AC input and output looked virtually identical.

The heatsinks on top of the Premier do seem to get fairly warm, even with a mere 2.0 amps load.

I still wonder what happened to my 1000A amplifier, and why I couldn't get the Premier to power either of my Parasound amps.  Maybe it's better just power line level anyway.  Although I tend to think of my system as "all digital" there are actually lots of non-digital interfaces:

Denon 2900 analog output goes the #2 DEQ 2496
DEQ 2496 #2 uses analog input
DCX 2496 crossover has analog outputs (driven by barely adequate power supply)

Disc players should be mechanically quiet

I originally bought the Oppo BDP-95 player as my new central video player, to play Blu Ray and other discs in the Kitchen, from which digital AV signals are set to other rooms.  The fact that it has a cooling fan will not be a problem there, because the kitchen (my AV production center) is full of equipment having running fans, not to mention refrigerator.  I might have done just as well with the BDP-93 or some other player, but I just wanted the hottest new model.

When it arrived, I decided to hook it up to my main living room audio system just because it has a high end audio output section, including current best DAC chips and balanced output.  I was immediately hooked, and shortly decided to use the Lavry AD10 to digitize balanced analog output from SACD's and DVD-Audio discs which don't permit you to access the maximum resolution 24 bit digital audio directly.

But it has bugged me all along that the Oppo, which not as noisy as some old DVD players, is not exactly the quietest either.  Notably, the Oppo has a fan, which is audible, though just barely, from listening position.  I figured, however, that the mechanism itself was fairly quiet, perhaps quieter than the Denon 5900 I had been using previously.

I finally got around to comparing the mechanical noise levels of both players when playing one of my favorite SACD's, Santana's Supernatural.  And it turned out that the Denon 5900 makes way less noise, and the difference is very noticeable when playing discs.  The fan is actually the smaller part of it.

When playing this disc, the Oppo has a characteristic woosh sound, as you might expect something spinning at high speed.  It is actually a very pleasant sound, but it is just too loud for good hifi.  I tried using the RTA application of my iPhone to measure this noise, but that did not turn out to be a very good tool for measuring, and as I was trying to measure the noise level, the heater and refrigerator kept deciding to turn on and off, making it difficult to make the measurements.  The noise produced by refrigerator pretty much masks the noise from the player, at around 41dBA everywhere in the room.  When the refrigerator shut off, the Oppo seems to measure about 39dBA from about 6 inches.  When the Oppo was turned off, noise level dropped to 37dBA.  This sounds like a small difference, but from 6 inches the Oppo is clearly and plainly audible above background noise.  I decided to mainly rely on subjective noise level assessments, the SPL meter at hand not being particularly informative.

With the Denon hooked up and playing the same disc, the chassis noise level measured 37dBA regardless of whether player was on or off.  It was obviously much quieter.  If you listen carefully, the Denon noise is more complex and mechanical sounding, with a tonal whine and faint clicking.  But it all sounds about 12dB or so quieter than the Oppo, and that makes a huge difference.  From my listening position, it is much harderto tell whether Denon is running at all, except when it changes tracks and some motor seems to change speeds up and back down.

Actually listening to Supernatural was a revelation.  I had been listening to this disc for a couple weeks on the Oppo, so I was feeling like I've heard it all, but I hadn't.  I first noticed an interesting kind of coherency: purpose.  You could almost sense the two percussionists on the two sides of the room.  I wasn't just hearing the instruments, I had the sense that the percussion instruments were being played by different people, and I could sense the two different people, and what feelings they were trying to communicate.  In short, the music seemed to have purpose.  It wasn't just "there" it was being created by real people, to communicate.  Another description I thought of at the time: integrity.

Later I noticed more typical transparency, I was hearing very low level counterpoint I hadn't noticed before.

Overall, I felt the Denon provided a subtle but valuable improvement in transparency.  But everything I heard could be explained just by the chassis noise level, which is way higher than the electrical noise levels in the output signals from the players.

Consider that a typical peak playback level for me is around 95 dB (and that's generous).  Then an ambient noise level of 39dBA is only 56dB down, enough to obscure musical details, with the music rising out of the fog of whirring chassis noise.

As far as the electrical output, the Denon is spec'd at 120dB S/N whereas the Oppo is probably at least 6dB better than that (some claim around 130dB).  But this is all moot if the chassis noise is only 56dB down.

What's worse, both players are in front of the room, in between the speakers but just slightly further back.  That means that any chassis noise cannot be separated from the musical image by the brain.

I had also been thinking of moving the Oppo back to highly absorptive corner in back of the room to make the noise lower and get it out of the audio image.  That is what I had been doing with the Denon, but I often found it very inconvenient.  Junk also tends to accumulate in that part of the room, and quite often the player was not accessible.  Then I discovered how convenient it is to have my disc player in front of the room along with my other equipment.  It's always accessible, and much more convenient to change discs without getting on knees, etc., as well as operating controls and getting feedback on controls.

Although the Denon isn't silent either, I think it's just quiet enough to keep at the convenient front-of-the-room position, at least for now.  So then I have both convenience and top quality performance.  At some future time, when (and if) I'm ever more organized, I could put my disc player in back of the room again, and then the Oppo might well be a contender again.

The sound of the Denon was possibly slightly brighter than the Oppo.  This could also be explained as the Oppo transport noise masking high frequency details.

While it is a little old, there is nothing inferior about the audio design and performance of the Denon 5900.  Like the Oppo, it has a separate analog power supply for the audio section.  It uses Burr Brown's best DAC's from 2004, essentially identical to the ones in the Denon 5910 which was still being sold as new in 2010.  The ESS 32 bit DAC's used in the Oppo may be slightly better, but I suspect it would be rather hard to hear the difference, assuming the players were not contributing their own mechanical noise to the room.

The Denon output is not balanced, but I run the composite video output through an isolation transformer before connecting to the TV, and composite video is OK for watching the menus and pictures on DVD-Audio discs.  The isolation transformer makes it less necessary to have balanced audio.

One problem is Denon can't play the high rez audio Blu discs in the recent Pink Floyd immersion sets.

Busy December Weekend

I attended important social events on Friday, Saturday, and Sunday.  I was getting over the stress of construction issues with my back yard workshop.  And I got car washed and did a long overdue quick mowing of front lawn.

So I wasn't expecting to get anything done on Audio last weekend.  But I did, I could check off at least 4 items on my Audio to-do list.

Sometimes it just takes a little push to get somethings started.  On Friday night, after coming home from Christmas Party at work, I finally got around to comparing the chassis noise level from Oppo BDP-95 disc player and Denon 5900, both playing the Santana Supernatural SACD I've been listening to for last couple weeks.  The Denon was way quieter (see later post).  That was #1.  I had been intending to do this test for about 10 months, ever since I got the Oppo.

Having hooked up Denon again, I decided, why not try listening to it again.  That was a revelation, I've decided to use Denon as my living room player, and move Oppo to kitchen to become my central video disc player (which was what I originally intended when I bought it anyway).  That was #2.

Then I decided to do some listening in bedroom.  On Sunday I decided to hook up the PS Audio Power Plant Premier I had got a few months back.  I finally did get it hooked up, not without some typical unexpected difficulties.  That was #3.

This wasn't what I planned, but in the process of hooking up Power Plant I broke my Parasound HCA-1000A amp.  (Probably just needs fuse replacement.)  So I hooked up the HCA-1500A amp I bought for the bedroom, but which had been used (until recently) in the Living Room, and had been just sitting around since I got the Aragon amplifier for the living room.  That was #4.  I had to re-adjust bass level by ear because I couldn't re-measure the gain level of the now-broken HCA-1000A.  The bedroom system now sounds much better, and there had been a background hum from the old deteriorating amplifier which is now gone.

The result was both living room and bedroom systems have been significantly improved.  The bedroom now has a bit of the layered depth I get with living room system.

Tuesday, December 6, 2011

HDMI extensions

My whole house entertainment system features video from several sources (DVD Player, Dish box, Harddrive recorder) run through HDMI to displays in Kitchen (where all the distributed video sources are), bedroom, and living room.  Two long HDMI lines are run with OWLink fiber optic HDMI to bedroom and living room.

This had worked well for about two years until a month ago the HDMI link to bedroom stopped working.  After a bunch of tests, including swapping the receiver with the one in bedroom, I decided that the Kevlar-wrapped optical cable (run outside the house from kitchen to bedroom) had gone bad, probably when housecleaner stepped on it.  However, that turned out to be wrong.  Instead, it turned out that, for no apparent reason, the optical transmitter in the kitchen for the bedroom link had gone bad.  When I swapped that for the other transmitter (used for living room), bedroom worked fine.  Since the bedroom link is more important (used every day) I keep the good transmitter running on the bedroom link.

OK, so now my best evidence suggests that one of my two OWLink transmitters has gone bad (it blinks, while the receiver LED stays constant, a typical OWLink failure mode).  But even that is not certain after last week, when I tried to switch my good OWLink transmitter over to the living room link.  THAT did not work, so I had to use a temporary workaround for my party (I used my Oppo BDP-95 for the DVD, normally I only use that player for audio discs).

So now that it seems I have misdiagnosed the problem twice, perhaps my second set of OWLink components is actually still working, or needs something trivial like a new power adapter.  But I wouldn't count on it.

If it still works, the optical link is worth keeping.  It has one very beneficial extra feature: it does not introduce any kind of ground loop into the related systems.

Meanwhile, I've been looking at new options.  Getting a new OWLink setup is one of them.  But rather expensive and hard to find (possibly even the 3 or so websites that still claim to have them are sold out).  Until today, the lowest price seemed to be $599, but today I discovered I could get one at for a mere $399.  That's still awfully high, but still worth considering.

Other alternatives:

2) CAT-5,6,7 based HDMI transmitter and receiver (CAT-7 said to be best)
3) 2 30 foot copper HDMI cables and a relay
4) Other optical system

There are many varieties of (2).  Some of the (very expensive) ones use only one CAT5,6,7 cable.  Using just one CAT5,6,7 requires some subtle multiplexing.  Most of (2) use two CAT5,6,7 cables.  I've now found one as cheap as $70 available at Amazon.  I'm worried that if shielded twisted pair (STP) wire is required, the shielding could introduce a ground loop.  Official specs say that STP should be grounded on both ends through the connector (there is no ground pin on CAT5,6,7 wiring).

3) Here's a relay available at that permits two HDMI cables to be joined.

4) I've seen some other optical systems priced as low as $299 for 10m, $499 for 20m.  Typically the transmitter/receiver modules are permanently attached to the cable in the cheap sets, and detached in the more expensive sets, which can go up to $1500 (and I thought OWLink was expensive).  Detached is better, since you could replace cable w/o replacing the adapters.

Monday, December 5, 2011

Listening Angle

I measured the listening triangle of my most forward listening position (which I've decided has better bass...stronger bass...than sitting just a few inches further back).

The speakers are 61 inches apart (center-to-center) and 51 inches from the listening position.  That makes for an angle between 60 and 90 degrees, which sounds good for high quality stereo reproduction.  The exact angle seems to be:

angle(radians) = asin (30.5/51)  ;# 30.5 is 61 / 2
angle(degrees) = 360/3.14 times above

73 degrees

First, fix the rattles

I should have done this long ago.  The photo above was made after fixing the bookcase rattling by moving bookcases away from leaning on wall and removing junk on the left bookcase so it could be filled nicely with books and magazines, almost all the ones that were originally there.  (I never got around to photographing the bookcase before the change, it was almost unimaginably stuffed with random junk.)

The two big bookcases at the rear of the living room were rattling on deep bass tracks.  I'd noticed the rattling, and assumed it was coming from the walls.  But the walls usually were not doing the rattling, I discovered on Sunday.  It was the two big bookcases at the rear of the living room, or something on them.

I started clearing off some of the bricabrac at the top of the center bookcase, including my Fisher MPX-100 unit which I still haven't gotten around to testing.  Then I noticed a serious issue.  Both bookcases were actually leaning against the rear wall of the room.  That leaning meant that any wall vibration (and there is plenty of that) would shake the bookcase and all of its contents.  The bookcases are very heavy, but some of the nick nacks were light and flimsy, like a still-in-box Barbie Ferrari (I'm both a model car collector and a doll collector, and a red Ferrari is the iconic car of the iconic doll).  To mitigate bad karma, I also had a remote control Ford Focus on top of that.  BTW, I'm taking the Ferrari down for now, and it's been replaced by a removed-from-box remote control Tesla model car (barely visible on the top at the left edge of left bookcase in front of a white doll).

The corner bookcase would be very tough to clear out because it's jammed in partly behind my keyboard table.  But I managed to get it off the wall mainly by shifting the magazines in the bottom two rows toward the front.  That got it about 5mm away from the wall at the very tip.  Fortunately I think that's enough to handle even the worst vibrations of wall and bookcase.  Or at least it shouldn't happen often.

The left bookcase, which was not just packed but stuffed with books, VHS, cassettes, junk, magazines, etc., was unloaded down to the bottom two rows, then shifted out from the wall by an inch.  As I was doing this, I was rocking the bookcase and trying to determine where it would be absolutely free of rocking back to the wall.  I think now I moved the bookcase out too far, it is more than an inch out further out than the other bookcase.  In fairness, however, I would move the other bookcase out another half inch if I could, and the center bookcase needs to be almost this far out to make the electrical outlet near the floor accessible.  I don't plan to change it now, but I think I moved it out about 1/2 inch more than necessary.  I think when I added back all the books, and moved the magazines out to the edge, the bookcase leaned forward more than I was planning.

Keeping the bookcases from leaning against the back wall fixed the #1 rattle problem in the room.  Rattles take away greatly from the sense of dynamic range.  Of course when you fix one rattle, other softer rattles become apparent.  Another one that needs fixing is the door of the air handler for my HVAC system, which rattles on certain loud bass notes.

Now it has been written (by an acoustical treatment maker) that bookcases do not make for very good sound absorption or diffraction, which most rooms need a lot of. That may be true (and I'll think about it some more later) but when a bookcase has a rattle, it's like negative sound absorption.  Very negative to the listening experience.  Getting back to No Effect is a big step forward from that.

To be free of rattles, a bookcase should not be leaning on or touching anything but the floor.  Otherwise, when the surface it is touching moves because of acoustical vibration, and/or the bookcase itself moves because of acoustical vibration and it moves away from the surface, there may be moments where the pressure momentarily releases, and you get a rattle between the two.  Also, the surface may cause the bookcase to shake a bit, causing stuff, particularly the kind of flimsy stuff I used to have on top of my bookcase, rattle.

Now that neither bookcase is touching a wall, it is incredible how much the wall vibrates during deep modal bass notes, but the bookcase seems perfectly still.  The bookcase panels may themselves have some resonances, but they would be at higher frequencies that don't so much cause rattling, and the bookcase is made of particle board and heavy paper, which are very lossy and vibration damping materials.

If I have increased the sound level that would cause loud and annoying rattling by 10dB, it is much like (or perhaps even better than) increasing my system dynamic range by 10dB, or almost like reducing modal resonances by that much (which is very hard to do).

I discovered the need for this when testing 1 vs 2 plugged ports in my right subwoofer.  I decided NOT to bother with measurements, but to go ahead and make the change to 1 port because it is well known to be better (see earlier posts), but why not listen?  As I was listening to the 1-plugged-port case, which makes bass slightly louder down to about 15Hz, I noticed the back-of-room rattles.  I got the idea (though not confirmed) that I might be hearing worse rattling with 1-plugged-port than with 2-plugged-ports.  At the same time, I also thought I could hear the improved dynamic range of 1-plugged-port.  So I thought to myself, why not see if I can fix the rattle?

Now actually it seems to me that a bookcase can have some desireable bass trapping qualities (if not as good as engineered bass trap).  To get this, you first need to abolish rattles, because if it rattles it is worse than useless acoustically.  Then, the books, should be pulled out to the edge, to get them as far away from the wall as possible.  Heavy books or magazines should also fill as much of the frontal area as possible.  Behind the books, there will be trapped air, and behind that, my bookcases feature a lossy paper back, which serves a bit like a panel or membrane resonator.  The trapped air behind the books is squeezed in and out by vibrations of the panel, and the released energy is lost moving the books and bookcase panels.  This does in fact operate like a bass trap.  An engineered bass trap would likely use fiberglass in front instead of books to do the lossy absorbing, but would otherwise be similar.

Actually, the bottom two shelves of my bookcases are filled with very heavy paper Stereophile and The Absolute Sound magazines...probably better than books for a bookcase acoustical damper.

Friday, December 2, 2011

Accurate Stereo

In this great post, Sigfried Linkwitz describes accurate stereo reproduction.

With the listener in the "sweet spot" a virtual sound scene should open up in front of him.

Linkwitz details 3 cases, the traditional equilateral triangle with speakers and listening position, a wider listening angle of 90 degrees given by making the distance to speakers 0.7 times the width (W) between the speakers, and a long distance 2W which loses imaging detail but can be pleasant and is less sensitive to sitting off axis.

This is where I've been this year.  I started at my old 2W position, moved in for something close to 0.7W, and now am pretty close to 1W (though I suspect it's about 0.85W).  I've observed the same things he describes.

Online Jazz

Discussion of Bag End E-Trap

Asymmetric Port Tuning

At the very close new sweet spot (VCNSS) listening position, the image is very transparent and 3D, and the bass seems about right on Bass E (see earlier post about this recording).  Elsewhere in room, the bass is very boomy.  I thinking of getting an active bass trap for that.  I now think Living Room sounds better than Bedroom on Bass E.

Right now I have one subwoofer tuned with 1 port plug (15Hz) and the other tuned with 2 port plugs (10Hz).  I'm thinking of changing 10Hz to 15Hz, because that is the tuning most recommended by Ilkka from his distortion tests, and even SVS themselves no longer recommends the 10Hz tuning on the newest edition.

Adding these plugs has seriously improved my bass in Living Room.

But now I'm also wondering if there isn't an advantage of having the Subwoofers tuned differently.  One problem with stereo subs is that most bass material is actually mono, and therefore if played back through two speakers there can be comb filtering.  If the subs are tuned differently, there is a small amount of random phase between the two subs which could suppress the comb filtering effects.

So when I remove the second plug from the right sub, I should test not only that sub, but the whole system, looking particularly for evidence of comb filtering effects.

I've ordered a tiny amount of Auralex open cell foam.  Just to get started.  I was going to get a pair of Auralex 12" cubes, which are in an inexpensive $80 two cube kit, but decided to get 4" cornerfill (4x4x24) instead.  It seems like nobody actually stocks the cubes, they're drop shipped often with no explanation of what shipping will cost, but Sweetwater had the 4"cornerfill, which I'll call sticks, at a nice discount price with free shipping.

The sticks can be placed in the corner behind the left subwoofer.  The bass in that corner is so intense the wall and windows rattle,  and it would be great if that could be ameliorated somewhat.   I'll arrange the 4" sticks similar to a triangular LENRD in the corner.  A real LENRD would probably be slightly too large, and LENRD's are not available except in $300 sets of 8.

Auralex foam is auralex foam.  There is nothing special about the shaping on the surface of a LENRD, a flat surface would work just as well (or better) for bass.  What really counts is the total volume and where you can squeeze it into your room layout, and the more the better, stuffing all corners would be nice.

Thursday, December 1, 2011

To Do List

Usually when I make a To Do List, it winds up that everything listed gets bypassed for the next thing that actually gets done.  But years later, many of the things got done anyway.  I don't take these things very seriously, they're just ideas.

1) Subwoofer tuning: though some more measurements might be nice, I've pretty much decided now that one port plug tuning (15Hz) is the best for the PB-13 Ultra's in my living room.  So I can just change to this and be done with it.

2) Deep bass tuning...short of full on room correction, which I have mixed feelings about, continuing to check out the bass in various ways and doing tuning with parametric EQ's, crossover adjustment, etc., can be helpful to the deep bass (below 80Hz).

3) Supertweeters.  Currently offline.  Put back online in far HF augmentation mode.  Adjust by ear and measurement.  Decide again if they are actually beneficial.  This year I have been adjusting HF balance by changing Acoustat angle...this is very effective, might have eliminated need for supertweeters (though I doubt it).

4) Bass traps.  Start experimenting with bass traps, possibly including active bass traps (e.g. Bag End).

5) FM Notch Blend Filter.  This has been stalled because I lost the drilled panel I created a few months ago.  Meanwhile, KPAC is now doing station upgrades, which may obviate the need, or require something different.  Last I checked, KPAC was operating at a fraction of normal power, and either stereo or mono sounded horrible.

6) Kenwood KT-6040: fix time constant to US standard.  When KPAC is fixed, I need to change put Pioneer F-26 back online as main tuner, and then use 6040 as whole-house tuner through Sonos.

7) Oppo vs Denon: do comparisons of Denon 5900 and Oppo BDP-95 playing various kinds of high resolution audio discs.  Simple start would be comparison of mechanical noise on DVD-Audio discs.

8) Move Oppo (or Denon) to back of room to lessen impact of mechanical noise from chassis drive and fan.  Use remote extender to enable nice control, and have some sort of connection to TV (hdmi?).

9) HDMI link: currently one OWLink transmitter seems to have died, but it might actually be a power supply problem.  This is not an audio problem, but I do need to fix some sort of HDMI link from kitchen to living room to watch video sources from kitchen including Cable.  Another test of the OWLink might help, or buying new kind of CAT-5 based balun.

10) Set up HCA-1500A amp in bedroom, along with PS Audio Power Plant Premier regenerator.

11) Make CD copies of a set of cassettes I have (using Nak and Masterlink).

12) Set up turntable in bedroom (using Linn, Panasonic, Behringer).

13) Krell: re-test, take apart, photograph, reassemble, send in for repair.

14) Koss phones: make adapter cable for Stax amp, photograph amp, get optimal cables for phones and install with Stax plug; disassemble and photograph second E90 unit, measure E90 bias in operation.

15) Get PSX800 turntable repaired, install new Dynavector 17D3 cartridge.

16) Replace old cap on left Acoustat with Solen (already done on right).

17) Send in Ivie IE30 for repair.

Bass even better up closer

For my monthly party last Sunday I moved listening chair from center of living room.  On Tuesday I moved it back, but positioned to the tape markings I made about a month ago, and NOT to the most recent super-forward listening position.

When I moved up again to that position on Wednesday, the imaging on the Bass E album was fantastic.

Now I've marked all the new positions (chair and speakers) with masking tape.  Other speaker and chair positions are still marked as well.

My ear now lines up with front edge of sidewall bookcase.  The slightly back position puts it in line with the second book.  Anywhere in between those positions is fine, though with the forward position I can lie back and still have great image, and I think the slightly wider speaker angle is better.  There is a slight tendency to miniaturize the image, I imagine a large 5 foot thick fishtank at the front of the room that the musicians are playing in.  But not so bad, actually, and the coherency is wonderful and brings the kind of 3d transparency that headphones can have.

While the bass does sound a bit boomy on this recording around the room, particularly at the Kitchen doorway, in the listening position(s) it settles down very nicely, rounded but not boomy.  Still, the need for acoustic or other bass treatments is still obvious.

At the listening position, living room system bass now sounds very similar to bedroom system bass, which has long been a reference after it was carefully tuned by manually set parametric filters.  I listened to Bass E on bedroom for awhile.  It is quite amazing what the comparatively compact SVS 1646 subwoofer can do.  That unit has always amazed me, I had never been so amazed by my pair of SVS PB13 Ultra's, until recently discovering the benefits of plugging at least one port.

A recent review of the newest PB13 Ultra shows that SVS no longer recommends plugging two ports with the 10Hz cutoff, and no longer provide the 10Hz cutoff.  They recommend all ports open, one port plugged, or all 3 ports plugged.

Here are some measurements of the PB13 with two ports plugged (10Hz tuning) at Home Theater Shack.  While the flatness of response is superb, the distortion gets very high at 110dB.  Ilkka doesn't recommend the 10Hz tuning except for music listening at low to medium levels.  He feels the added extension is barely noticeable but the added distortion (if you are playing loudly) is very noticeable.  Here are the measurements of the PB13 with 15 Hz (one port plugged) tuning.  OK, comparing the two, it's indeed easy to see the lower distortion at levels above 100dB.  Ilkka feels the added extension in the 15Hz mode is worth it compared to 20Hz mode (no ports plugged) and causes only a tiny loss in clean output above 20Hz.