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.

 

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