Tuesday, February 13, 2024

Make Playlist updated

https://sourceforge.net/projects/makeplaylist/

You can download the latest version of Make Playlist (which I abbreviate to "mplay") from Source Forge at the above link.

This is my 3rd update this year which addresses key issues that were bugging me.

For one thing, I've added in automatic reset for music files the way they play by default.  Folders for music albums do not reset automatically (that was a very bad idea, only released in 0.79 then quickly abandoned).  Instead, you must exhaust all the music files in folders you have listed, then mplay automatically resets all files just after the last one is read.

So there is no need for a separate "-reset" operation (unless you want to force one, like the old days, with the new option "-no_reset").

This required a suprisingly large rewrite.  I'd wanted this feature from the beginning, from 2021, but every time I tried to implement it I got bogged down.  A large code re-organization was needed (I added a new file, mplay_libs.tcl, which must be included where the other mplay programs are kept).  But I also kept the changes to as little as possible for now, which is how I was able to get it done.

For another, I found the mixing or blending algorithms in both splay and shufflelinks were not very good.  I had to rethink the entire blending process after discovering that the relative size of the files you are blending, which is not necessarily known in advance when running a script, is a key factor.  So I cam up with 3 parameters which allow a new blending algorithm to adapt to all possible relative size differences.

As always, even if you're only interested in music files, it's necessary to get ideas from all 3 scripts, MakeMusic, MakeVideos, and MakePix to see different techniques for creating playlists in action.  I make a fairly basic script for music playlists, because that's what I need and it's where most people would start, and a very complex one using tricks only a professional music programmer might need (such as mixing playlists) in MakeVideos.  mplay is, by design, capable of creating playlists for many kinds of media programs: any that either accept an .m3u playlist file, or that accept a simple folder of files (which is faked with a set of links to the actual files), and the tricks shown might be used in many music playlist creation scenarios.



Saturday, February 10, 2024

Amplifier on/off

In less than one month I got very tired of using the Aragon 8008 BB amplifier without home automation control of the power amplifier as I had with the previously used Hafler 9300.   It was wonderful to turn on background music from the moment I get up, and ultimately turn off everything upon going to bed, each with the press of a convenient remote button.

The inconvenience of having to manually turn the amplifier on and off grew even greater in the last few weeks as I've had my new projector screen up most of the time, and that means I have to crawl underneath the screen to turn the amplifier on and off.  (BTW, having a video projection system is one of the best things in the world, and it's especially good to have it backed up with high quality audio like my living room stereo.  IMO it's not necessary to have 5.1 channels and that sort of thing.  I use mixed down stereo from my Oppo BDP-205.  It's better to have wonderful 2 channels than mediocre 5 channels.  Wonderful 2 channels is often mind blowing compared to what I've heard before on TV speakers, etc.  But a big projection screen makes the most difference of all.)

To switch the Hafler amplifier I had been using a standard Insteon On/Off module (all my Insteon modules are controlled by my highly programmable Universal Devices ISY994i--without which I would never have standardized on Insteon) and the On/Off module had worked fine for several years switching the Hafler several times a day until I burned out the Hafler itself doing some speaker testing on an arcing Acoustat.  I've switched to using the Aragon amplifier which I'm thinking now I might like better anyway.  (And the arcing speaker is now in my repair "queue").  

With my ISY994i home controller, I control everything within my home with my own programming (which is endlessly being expanded and improved by me) and I do not rely on any external "cloud" like the "Insteon Cloud" which was abandoned by its sadly collapsing manufacturer a few years ago but might be back now under user managed support.  I never trusted "clouds" anyway and personally I avoid using "clouds" whenever I can.  When I upgrade my Universal Devices controller to a newer version I will be able to handle other home control protocols such as Zwave.  But for now, Insteon is all my home control system can support, and Insteon modules are still widely available on eBay and are sometimes being sold off in huge lots for cheap, so it's hardly worth migrating to anything else yet.  The biggest advantage Insteon had was the wide array of different kinds of modules that work together, and low prices (compared to Creston and the like).  Controlled with a Universal Devices home controller, you can make a collection of Insteon devices do just about anything.  I now have about 40 Insteon devices automating my home, and they either work perfectly or I change the programming until they do (adding more repeats or waits if needed).  One advantage of this kind of barely working system is that it's fairly unhackable.  Nobody outside my home could reliably gain control of anything except my Universal Devices controller, which itself is fairly secure and also fairly obscure.  However I'm willing to give up that security advantage when I migrate to newer devices which may be wifi controlled, that's also secure enough IMO.

I knew from both the ratings and previous experience that it was not good to use Insteon modules with the Aragon amp.  Last time I tried using an Insteon module with the Aragon, the Insteon module started acting very funky within a few days, turning it self on and off randomly.  I had a similar experience with an Insteon module switching my 1000 watt amateur radio power supply.

And the ratings of the Insteon (15A resistive, 3/4 HP) are not encouraging because the Aragon is anything but a resistive load, especially when it's being turned on and off.  With it's two 1100 VA transformers, the startup load of the Aragon quite possibly exceeds 15A for a brief instant upon turn on.  My calculation suggests around 18 amps (2200VA / 120V).

There aren't many automatic AC switches that advertise handling more than 15A.  Furman makes a 20A trigger switched dual output (CN-20MP) but it's extremely pricey ($394) and it uses an actual 20A plug with the horizontal blade that doesn't fit into standard 15A outlets.  I'd need to get a new outlet, which raises three additional issues: (1) cost for installation by electricians, (2) I detest 20A outlets because in my experience the greater number of "angles" causes more arcing when you plug into them, and (3) the amplifier circuit currently uses my favorite Pass & Seymour 15A industrial grade wall outlets which grip tighter than anything else--except, and often unfortunately, Insteon On/Off module outlets, you have to pull on plugs so hard to get them out it can break the module--Insteon should have made stronger cases for their modules--I've broken about 5 of them--and I had never physically broken a single X10 module prior to migrating to Insteon, the problem was that X10 just no longer worked in a home filled with switching power supplies.

Furman also makes a 15A model which gets around the 20A plug issues (CN-15MP), but would it be robust enough?  (My guess is probably, but it also is very expensive, just a bit less than the 20A model, it lists for $350 though sometimes is sold for around $250).  And there is another company (Lowell) which makes 15A and 20A switchers which are much like the Furman units except 40% lower in price, which is still a lot, and the 20A version has the same plug issue.

Then I realized I already had in my junk pile an Xantech AC-1, nominally rated at 15A.  Checking out it's detailed ratings, I see now it can handle up to 30A peak inrush current.  Well that's exactly what I need.

(The Xantech is considerably more expensive than an Insteon On/Off Module, and is much simpler, having only a DC trigger input to switch the output.  But it's a very robust looking metal box.  Sadly these are no longer made, but can still be found.  Before they were discontinued, they were priced about the same as the 15A Lowell units and less than the Furman ones.  There are also AC switchers made by Niles which look about the same as the Xantech.)

So I hooked it up.  To generate the 12V DC trigger voltage, I used a Sony 12V AC adapter (rated at 300mA, an old unit originally intended for charging portable telephones) which itself is switched on and off with an Insteon On/Off module.  That gave a very nice 1 second delay from turn-off to amplifier shutdown, indicating some degree of regulation in the AC adapter and thus an ability to ride out tiny power glitches.  (Unregulated AC adapters can sometimes keep the rated voltage for minutes, which is inconvenient if you are trying to use them to generate DC trigger voltages).

It's working great, and I expect it will last a long time since it seems to be used within ratings.

*****

Without some kind of automatic switching it's tedious to try to keep background music running most of the time, and I am more and more believing that is a good idea.

I think it is very good to have background music running nearly all of the time (except when you are watching movies or doing "serious listening").  As long as the music doesn't include words it rarely interferes with concentration either.


Tuesday, January 16, 2024

makePlaylist (mplay) version 0.79 released

I've talked about it, posted a video of it, and now it's available for download.

https://sourceforge.net/projects/makeplaylist

This allows you to automatically generate random playlists.  Now you can preface or mix in newer files in various ways, combine folders with weighting factors, and mix in favorites.  It makes for very infinite and very interesting scripting possibilities, with examples given.  One program included figures out how much of the last playlist you actually played and allows you to reset the history for those files that weren't actually played. 

Works immediately on older Macs* or Linux, on other systems Tcl must be installed first as all the programs are written in Tcl.  The example scripts are written in (linux/mac) bash.

(*Since I use an old Mac running 10.13.6 myself, I'm not sure about the status of Tcl in newer Mac releases.  I think it may not have been included by default with M1 macs, but not sure.  It's still available for nearly everything because Tcl is a very lightweight programming language, lightweight but powerful.  But you may need to download and install it first, and I have no recent experience with that myself because it was always included on Macs I have used.)

UPDATE: since I first made this post a few days ago, mplay has already been updated to version 0.79 which fixes a lot of things that had been bugging me



Sunday, January 14, 2024

New EQ, Day 3

 After messing with the "Background" subwoofer EQ (again, last time was a few months ago) in the right channel, which I had been re-EQ-ing because of the new speaker, but the subwoofer hadn't actually change...

I decided I first needed to test and make similar changes on the left.  Measurements at the doorway and the table showed overly bulging response at 31.5 Hz.  It looked better cut back to zero as with the right channel.

But listening to Grouse, We Want To Be Loved, I decided this all made the deep bass line, which reaches down to 31.5 Hz, a bit less easy to follow.  So I restored boosting at 31.5 Hz in both channels in background to about +2dB.  (In the Serious Listening EQ, it's boosted 5dB because of suckout at listening position.)

Also, I could not confirm with pink noise any serious issue at 20 Hz, so I decided to reduce the cut there from -4dB to -2dB.

Current settings:

Left (last one adjusted)

20 Hz    -2dB

25 Hz    +2dB

31.5 Hz +1.5 db

Right

20 Hz   -2dB

25 Hz    0dB

31.5 Hz  +1.5dB

I think I might make both channels more like the Left settings, mainly boosting 25 Hz at +2.  Otherwise, the response IS falling at 25 Hz relative to 31.5.  Even with that +2 boost it is falling at 25 and 28 Hz relative to 31.5, but it is falling only ever so slightly at 28, which is a good improvement.

But it was too late to go any further.  Actually, once again, for best results I need to sweep this with an oscillator, or use a LF tuned keyboard (as I have done before).

Just like a down sloping high end, required because of the higher side reflectivity of small rooms, a slightly tilted up bass is generally required, it's just a question of how much and exactly where.  Finer adjustment of the hinge points may mean less boosting is needed to retain musical coherency.  There is probably some perceptual compensation for room gain, and the total room system output should invert that compensation.

Now, morning after, taking a look at the graphs confirms my memory and shows some other interesting things.  First, what it looked like with the old boosting (which I think was +5db, maybe only +3dB), in the kitchen doorway:

Left 2+2 with +5dB deep boost at kitchen doorway

Reducing the 31.5 Hz boost to 0dB but the 25 Hz boost at +2dB, it looked like a much flatter high plateau in the deepest bass (though I later re-raised 3.15 part way to +1.5 for musical reasons, not measured).



+2dB at 25 Hz, 0dB at 31.5

One thing overlooked here last night was the incredible broad depression from about 80 Hz to 300 Hz.

It's almost as if (and I have tried that at times) attempting to compensate for the lack of 125 Hz in the right channel by giving it some extra oomph in the other, which only "partly" works.

That looks like the next thing which needs to be investigated.  What the hell is going on at 125 Hz.?

With the background EQ, in the doorway, it's nice looking now in the right channel but part of a long depression in the left.

Saturday, January 13, 2024

EQ'ing new speaker, part 2

 In the last post, I purported to show how removing most of the boost I had given the Acoustats a few years ago, +3dB and 1/3 octave at 1013 and 853 Hz, fixed the balance problem between new and old speakers.  It seems like the newer speaker doesn't need that boost, perhaps because of tighter diaphragm.  My initial approach was to cut those two boosts by 1-2dB to +1.5dB at 1013 and +2 at 853.  But there was still a troubling difference around 500Hz, the newer speaker having a suck out at that point.  At first I thought it was because the 853 Hz boost wasn't wide enough.

Fixing that was very problematical.  Boosting 500 Hz, with +3dB in a 1/6 octave GEQ boost, produces a peak around 600Hz that's even more alarming than the depression it replaced.


So the issue is we need to push 500 Hz up, but 600 Hz down.  It looked to me like the down part was actually the most important, and I found a 1/6 octave cut at 563 Hz worked pretty well.  After doing that, the peak seemed to move up to 800 Hz so it was clear I needed to remove any boosting from 853 Hz at all, so that as of January 13 at 4am the newer speaker EQ now looks like this:



Which measures (with the iPhone 8s held about 1 foot from the back of the chair, something I'm now trying to be more consistent with)

New Left 2+2 with EQ updates above

Even the Analyzer app thinks I've nailed the EQ at 1kHz, not that I trust such things.  But it's reasonably uniform from about 200 Hz to 2kHz where it starts an intended downturn pretty much as intended.

I'd still be interested in pushing down the region from about 600 to 800 Hz slightly, I don't believe that should be louder than 1kHz.  And possibly broadening the EQ right around 1kHz which is slightly depressed.  But I've already gone beyond the level of fine tuning which should be done with RTA.  I need to switch over to doing oscillator sweeps so I nail the critical frequencies where change is actually needed.  RTA is simply too approximate, you can't really see what is going on, though it's useful for getting the big picture.

But I think this is already pretty darn good and far better matching the right speaker than when I started.

I also took a brief look at the funky dips at 40 and 70 Hz.  Those are because I have been using the "Background listening" Bass (subwoofer) EQ for these measurements which has a suck-out at the listening position but sounds better (less boomy) everywhere else in the house.  

Measurements roughly confirmed this.  I decided for now upon two different places to measure the background EQ, the doorway to the kitchen (which is about equivalent to the couch) and the kitchen table.

At the doorway, the response rises with decreasing frequency below 180 Hz, peaking around 38 Hz.  I've needed to roll off 20 Hz in the background response to prevent the whole house mode that occurs around 20 Hz, which I can feel, for example, at the sliding glass door (which perhaps I should also measure...).

Kitchen Doorway with pre-existing 25-31.5 Hz boost

This is pleasant actually, gives a kind of loudness compensation for background listening, and requires little change from the 'flat' response at the listing position with the Listening Position EQ setting.

But I felt the rise including 31.5 Hz was just too much.  

It was pointless to boost 31.5 and 25 Hz at all, since that boosting was actually causing them to stand above everything else so much.  So I dialed those boost back to zero in the right channel of the Background EQ.  Even with 0dB boost at 31.5kHz, there is still a bulge there, dropping lower (by design) at 25 and 20 Hz.

Kitchen Doorway with no boost 21-31.5 Hz

That was fine at the dining room table position too, showing the slightest peaking around 31.5 Hz even with no boosting.  But the dining room table shows a huge notch at 56 Hz, a peak at 125, and another smaller notch around 180 Hz which need further exploration.

Dining Room Table

I do most background listening from here, so it should be better than this.  And certainly the recent removal of boosting 31.5 Hz is only to the good as well.  20 Hz is doing fine suggesting the cut there is of no harm here.  Save for 56, 125, 180, and 720 or so other, Background EQ'ing looks all to the good.

Thursday, January 11, 2024

The White and Black 2+2's

My blog photo now represents the new living room system reality.

I'm using one white Acoustat 2+2 from my original pair of 2+2's that I bought in 2019.

It's mate had an issue I was long aware of, but mostly thought I'd solved.  I don't believe I had.

On some recordings, there was a terrible resonance with some combination of bass frequencies.  I first heard it on the Grouse album 'We Want to be Loved' with the track 'Suicide kills me'.

I pretty much eliminated the issue with my 125 Hz 8th order crossover, which also resolved what seemed to be other issues resulting from rear-reflection and Acoustat resonances.

When testing the new black 2+2 I just bought in December 2023 before purchase, I noticed a similar issue with 'You Know Too Much About Flying Saucers' on Hello Waveforms by William Orbit, on one of the new speakers.

Well that same new speaker had a continuous but almost inaudible arcing problem I could only hear with my ear right up to the speaker.  I could not smell anything and believed the ozone emanation was trivial, not unlike with a small motor perhaps.  So I figured it was fine in the well ventilated but rarely used living room, but perhaps not so fine in the bedroom.

But rapid ABX switching of the speakers, and/or leaving the speakers connected to the running amp while plugging it in, or some other experimental mistake, I blew out my Hafler 9300 in one channel.

I don't really know that the arcing speaker was at fault.  Perhaps the ABX switching itself is unsafe (but it never hurt the Hafler or Aragon before, only the Krell).  But the coincidence of having an amp fail within a month after connecting to this arcing speaker makes me wonder.

(Also, the guy I bought it from, I well knew was having endless weird problems related to the 2+2's if not other things.)

Now perhaps the problem only occurs when the speaker was being charged up (though once again, that was never a problem before).  I'm resolved now to plug and unplug acoustats from AC power ONLY WITH THE SPEAKER LEADS DISCONNECTED.  You want the HV to stabilize before connecting an amp to it, especially if there is an occasional shorting issue.

But that kind of thing can't be prevented, for example, if there is a temporary power failure, when the power is restored once again the interfaces with be charging, mostly likely with the speaker leads connected.

So, I consider the second black 2+2 with arcing to be unsuitable for use except with "expendable" amplifiers.  Perhaps things like one of my two HCA-1000A's.  Not that special.  AND MOST CERTAINLY NOT WITH MY ARAGON 8008 BB !!!  WHICH HAS UNOBTANIUM TRANSISTORS!

And then I decided also that on complex music, the arcing 2+2, even if the arcing wasn't audible, still made for it sounding fatiguing after awhile, which I determined might well be traced to the arcing causing unstable membrane voltage.

Now the faulty black 2+2 has been moved off to my bedroom so it can be easily accessed for repairs.  I've decided it's the first 2+2 I want to fix, though it might be harder to fix.  I want to end up with two of the black ones, because I think they are better somehow, tighter membranes perhaps.  They were much later production, most likely made in Arizona instead of Florida, though not as far as I can tell using the later improved coating.  Perhaps other construction details had been improved.  Or perhaps they were just less used.

I can now mostly rule out the issue being a difference in interfaces, because I have been using one of my old Red Medallion interfaces with the new 2+2's, and my white 2+2's had a C mod done on them by a well regarded Acoustat refurbisher.

But it is true, though I often forget and doubt it means much, that the white 2+2 I am still using still has the non-Medallion transformers.  I plan to swap it with the other large-interface I have which has the a recently made Medallion transformer I installed in my first attempt to repair it, before I noticed that the issue was that the 'crossover' board had been connected incorrectly.  I then didn't bother to take out the Medallion transformer, I figured it was better anyway, even though there was now a mismatch with Medallion HF on one side and not the other, which I could never tell that any difference resulted from that.

THEN, I will have Medallion HF on both sides.  There will still be a lack of Medallion LF on one side, but that is said to be even less important for the sound.  It seems one of the primary purposes of the Medallion upgrade was to prevent transformer failure with improved insulation.  It may have also resulted in tighter coupling, and the improved sound was hyped, but never taken by anyone as a kind of 'night and day' difference, the old non-Medallion transformers sounded great too, and just doing the "C" mod alone is supposed to make a far bigger sonic difference than the Medallion transformers, though they're great if you got 'em.

Anyway, even right now there's still a difference between my good white and black 2+2's, despite both having "C" mod, and probably not just because one has Medallion's and the other not.

Now in these response I'm going to show, ignore the bass below 125 Hz, that's may look bad because of the new 'background' EQ that was operating in the bass, which produces a suckout around 45 Hz at the listening position.

(Update, I've discovered an error in the sub 1kHz eq, the left and right don't match in the GEQ section, it looks as if I've simply failed to dial in the Right channel, which is possible, back after my chairside EQ died.  It's unlikely the two channels previously needed lots of eq in the left channel and none in the right, in fact the right white speaker, now removed, was very problematic wrt EQ.  That explains some of the weirdness below 800 Hz in the right channel.)

I've always turned the HF level on the white acoustats to about 12 o clock, when I now understand 'flat' is supposed to be 3 oclock.  So what would 12 o'clock be?  I'd guess around -2.  I previously thought 12 o'clock sounded best and was supposed to be flattest.  (I'm applying a vast amount of HF downwards EQ above 2kHz too, without that and the HF adjustment it would be about flat to 17kHz.)  I have a smallish room which probably requires downward HF EQ.  It's not a particularly lively room, just about balanced perfectly for conversation.

To match it I've dialed the interface on the black units down to the lowest HF level the compact interface permits.  It's a very limited range of the 16 ohm resistor.  I'm guessing that level is around 2dB also.  And lo with these settings the frequencies 10kHz and above are fairly well matched.)

Also note that EQ from before IS being applied, as well as the 8th-order phase corrected crossover at 17kHz for my supertweeters when I no longer have supertweeters, but I haven't gotten around to taking it out and think it might improve the sound anyway because of the phase correction.

That EQ was dialed in by ear with the original white 2+2's, which seemed to need a 3dB (!) boost at 1kHz to sound good, also at 850 Hz at 3dB.  Otherwise, the midrange sounded weak, perhaps not just with regards to it's immediate surroundings.  Prior to EQ 2kHz measured higher than 1kHz, even with 2kHz dialed down.

Well, it seems the 1kHz boost is simply not needed with the good black 2+2.

Taking that out, or even just cutting it back to 1dB was sufficient to fix the 'balance' problem I had fixed by ear the day before by cutting the left channel 2dB in my Tact.  (But if I dialed it back to 0dB, I'd then need to cut the right side to get it to balance, so I'm now using 1dB boost at 1kHz for the black 2+2, pending further investigations.)

Now, it would be hard to believe that the Acoustats were originally voiced with a 3dB suckout at 1kHz.  I think that correction may have been needed because of membrane aging on the white 2+2's.

The result is that images are nicely behind the speakers as they should be, much clearer images than I've ever had before thanks to the speaker swap, removing the supertweeter towers, and possibly other recent changes.

Anyway, prior to adjusting the 1kHz EQ down in the right channel, here is how the white and black speakers now on the left and right sides respectively measured:

Left Channel with White 2+2

Right Channel with Black 2+2

You might notice as I just did that the actual level of the 1kHz bulge in the right channel doesn't actually reach quite as high as the narrower bulge in the right channel.  True, but the above measurements are WITH a -2dB reduction in the right channel level, as I needed to achieve left to right balance.

Don't pay much attention to irregularities above 2kHz as the measurement device is only being held in approximately the same position each time.

After taming the midrange bulge by tamping down the +3dB EQ at 1kHz to +0dB, it's looking a little different:

Black 2+2 with 0dB boost at 1kHz

But now 1kHz is lower than 800kHz, so I decided to up 1kHz to +1dB and cut the +3dB boost at 800Hz to 1.5dB, resulting in this:

Black 2+2 with less EQ at both 800 and 1000 Hz

That's the best yet in terms of flatness through the 700-1500 Hz range, and with these changes it no longer needs a -2dB overall level reduction in this channel.  Apparently the image shift was caused just by the boosted midrange.

However, noting that there's still a measured boost in the left channel, I'm wondering whether THAT is correct too.  But exploring that will require subjective testing, the way I arrived at the need for a boost there in the first place.

Sound level measurements with RTA are never definitive, only a guide to what's probably right.

But it occurs to me now that perhaps I boosted the midrange mostly because of issues with the right channel white 2+2 that has now been replaced.  It might have had quite a suckout in the midrange which I was compensating for by boosting both channels.

Meanwhile, I should also address the sub 1000 Hz issues that are apparent in these graphs.





Sunday, December 31, 2023

Electrostatic speakers and Bass EQ

This is two separate topics I was thinking about yesterday.

It seems like the good channel of my newest Acoustat 2+2's sounds louder than my older 2+2's, and this is true regardless of interface used.  Substituting a plain vanilla C mod interface makes it sound more like my older C modded 2+2, but still not identical.

(Note: I have not tested speakers in identical or equivalent positions yet.  The speakers are very hard to move and I may not even get around to such rigor until I've removed the two 'bad' speakers from the room, one from the older pair and one from the newer pair.  Then I will have a pair of speakers, one old and one new, in equivalent positions ("left" and "right") though not actually identical, and I will be forced to level match and EQ match them for good stereo, and only THEN will I be able to state with better authority how the old and new speakers differ.)

I'm thinking electrostatics can age in various ways:

1) The HV can droop.  I wouldn't have thought this to be a problem because all my interfaces (except my original 1+1's which may be the best sounding of all) have been refurbished by knowledgeable people.

2) The membrane can stretch.  I was previously thinking this would only be a problem if there were actual 'slapping,' otherwise the panel would just move to where it was supposed to regardless of stretching.  BUT that was wrong, in fact the resistance of the panel to movement is a critical part of its operation.  Stretched membranes can cause bad resonances and intermodulation.

3) The insulation on the stators (if applicable, as with Acoustats) can weaken and break.  In serious cases you get periodic arcing (as with the bad new speaker) and then the speaker develops level dependent distortion.  But there could be distortion from mere 'weak' spots that weren't arcing as such.

Every panel is also going to vary from every other panel in minor construction details that result in slight resonances at different slightly different points.  (Though, by and large, I'd expect most brand new speakers to be almost the same, but diverging with aging.)

ALL speaker units differ, even if made by the same manufacturer on the same day in sequential serial numbers.  However, you'd expect that the closer you get to being on the same day in sequential numbers, the closer they are likely to be.  So units made years apart in different factories are likely to be different than their mates made at the same time.

I'm thinking because of how large electrostatic speakers effectively have been hand-made they probably differ more in their tiny resonances and such more than factory made dynamic drivers.   OTOH the electrostatics generally have (less so nowadays) less distortion and resonances to begin with.

Funny I've never read anything from Linkwitz about using electrostatic speakers.  He made dipolar speakers using dynamic drivers.   So I don't know what he thought about electrostats.  But his methodology for picking out the better drivers was ultimately quite simple.  You have to listen to them.  Only then can you tell if the particular set of defects every speaker has is problematic or not.

For rigorous testing, playing one speaker by itself on a mono signal is the most revealing.  (Linkwitz also may have recommended female voice, which I hardly ever listen to.)

And so I've been doing, with the good (non-arcing) unit for a few days now.  Playing just that one speaker.  And this convinces me that although it may sound different from my older pair, it's still very good if not significantly better.  It was the arcing speaker that made the new pair fatiguing.

The new good speaker just seems to have remarkable clarity and musicality.  I'm afraid I might have to 'dumb it down' with EQ to make it match the other one, but it will probably still sound better, more headroom, etc.

I'm thinking this may be because it has a tighter membrane.  Or maybe other construction details varied, as this newer speaker likely was made in a different factory.  However it doesn't have the '5 wire' connection that would indicate the new kind improved wire insulation, if I'm understanding that correctly.

*****

I've just made another tweak to my 'background' EQ.  (I lost my original 'background' EQ when my chairside EQ unit died, so perhaps I'm just 'recovering' what I had previously done, which I had to guess at first.)

This proved necessary when I was listening to some bass records including 'Bass Erotica' which was almost unlistenable before making them, and afterwards could (for the first time) be cranked way up and enjoyed much more, with the bass lines becoming easy to follow.

I'm now cutting 50 Hz by 5dB, and the flanking frequencies of 40 and 63 by 4.5.

I believe is needed because of the room modes around 45 and 52 Hz.  In the center listening position, these modes don't get amplified (in fact, they get attenuated) so I don't cut them in the primary EQ (as when I last did it, I was running the oscillator while sitting in the listening chair..previously I had often done tuning while listening near the DEQ, which is more like the room boundary).  So they have to be cut in the background EQ now.

Which brings to mind how many EQ systems deliberately have multiple presets.  I am now thinking it is a requirement that if you use EQ at all, and if you listen to background music on your main system at all, you must have separate EQ's for serious listening at the listening position and casual listening everywhere else.

I need this in particular because my listening position is anti-modal.  Near the center of the room, the larger modes cause cancellations instead of augmentations (they augment at the peripheries).

I choose to listen in the center of the room anyway so I can be as close to the speakers as required for the widest possible stereo separation.  That opens everything up in an incredible way.  A friend clued me into this.  I was previously a back-of-the-room listener, with speakers in front, and that felt 'natural.'

I could in principle achieve similar separation with the speakers in the middle of the room, and listening in the back.  From the standpoint of getting good bass (and especially getting the best possible bass out of electrostatics) that is far better.  Then I would not be listening from an anti-modal position, and I might even get away with no EQ and no subwoofer too.  (Though any time a subwoofer is being used, you are almost certain to need EQ anyway simply because of that, subwoofers excite room modes in ways that panel speakers avoid.  But if the panel speakers were in the center of the room, you might get away with only one EQ for both serious and background listening.)

But that just doesn't fit my home and my lifestyle.  I do not have a 'dedicated' listening room.  I have a living room I walk through about 100 times a day, and have movie parties in 1-3 times a month.  Speakers in the middle of the room would mess everything up, and Acoustat 2+2's are not very easy to move around.

Then people tell me I could simply "enlarge" my living room.  Geez.  I have enough trouble keeping up with home issues as it is.  Last year I spent $21,000 on foundation repair and related issues.  It was because of the fear of issues like that I built an entirely separate climate controlled storage building with its own very heavy duty foundation ten years ago.  I didn't want to tack more rooms onto my already struggling house.  (I had bigger plans for the storage building, but in the end it became just a storage building, because I needed that.)  As serious of an audiophile as I am, the changes needed to enlarge my living room are basically unthinkable.  And I have other major home improvements already long in the queue, such as a new patio cover and carport.

Ultimately I think it's not bad at all for me to figure out how to fix these sorts of problems either.

Anyway, with these changes, it seems I can play anything at any level and enjoy it much more in the background now.