Another beast tamed...Acoustat Spectra 22

[tomlinmgt]

Glad to hear you got things sorted out and Morphine is a great choice of music for the 22's. :yes:

As far as upgrades to the interface units..not a lot that can be done there, actually. The few caps that are in them only influence the 80Hz cut off filter circuit and only come into play when the switch is engaged and the main circuit has a single resistor which can be upgraded to a higher quality unit. Not sure what the prior owner means by "rebuild the bias amplifier". I've done quite a bit of research on mods and restoration for the 22's and its interface unit and have never heard of that. There is a bias pot in the interface and its setting can be adjusted which can increase or decrease output, but no "bias amplifier" to rebuild or modify or whatever. The 80hz cut off switch should be inspected to make sure there's no corrosion or bad contact as its part of the main circuit. I changed mine out for a more robust unit...as well as the speaker binding posts.

 

[E-Stat]

And so why do stats need power supplies?

Because they use an electrostatic force to move the diaphragm instead of magnetic. Click here for a primer.

Acoustats step up the signal to about 3 kV while my Sound Labs have adjustable bias up to about 10 kV.

 

[SimplySound]

Glad to hear you got things sorted out and Morphine is a great choice of music for the 22's. :yes:

As far as upgrades to the interface units..not a lot that can be done there, actually...

Thanks Michael... I was up past mid-night like a giddy kid last night! These are something special, Frommer was right about my reaction!

I'll ask the guy I bought them from what he meant. He might have been talking about adjusting the bias rather than rebuilding the bias circuit.

I saw your posts on DIY. I guess you worked with Kevin "Chamberman"? Can you PM me his details? I may have him go through mine just for peace of mind.

Thanks for sharing your experiences. You've been an inspiration to me! And yeah, I'll start a new post and stop stomping all over yours!

 

[SimplySound]

Because they use an electrostatic force to move the diaphragm instead of magnetic. Click here for a primer.

Acoustats step up the signal to about 3 kV while my Sound Labs have adjustable bias up to about 10 kV.

Thanks E-Stat for the reference... that's helpful! That white paper was great Info... Yanno... I was being facetious!

 

[tomlinmgt]

Thanks Michael... I was up past mid-night like a giddy kid last night! These are something special, Frommer was right about my reaction!

I'll ask the guy I bought them from what he meant. He might have been talking about adjusting the bias rather than rebuilding the bias circuit.

I saw your posts on DIY. I guess you worked with Kevin "Chamberman"? Can you PM me his details? I may have him go through mine just for peace of mind.

Thanks for sharing your experiences. You've been an inspiration to me! And yeah, I'll start a new post and stop stomping all over yours!

Kevin's AK screen name is "Mondiafan" and he commented earlier in this thread. Shoot him a PM...I'm sure he'd be happy to help you out. He's a very sharp guy and really knows his stuff. I feel very fortunate to have him as local resource and audio pal.

One thing I want to mention....I've heard that the room/level correction processors like Audyssey can do funky things with panel dipoles like Maggies and Martin Logans (Acoustats wouldn't be any different) because the rear wave kind of "confuses" the processor. So if you get some bizarre results after you run the correction processor understand it's not uncommon.

 

[E-Stat]

Thanks E-Stat for the reference... that's helpful! That white paper was great Info...

There were some small designs that didn't require an external power source.

Acoustat is no longer, but Dr. West keeps producing wonderful stats. They ended my search for a true full range design that dealt with the narrow dispersion issue. If you want to play at truly heroic levels, a 945 will fit the bill nicely.

 

[tomlinmgt]

^^^

Sure would like to hear what a modern day $40k ESL can do. :scratch2: :yes: :drool:

 

[SimplySound]

There were some small designs that didn't require an external power source.

Acoustat is no longer, but Dr. West keeps producing wonderful stats. They ended my search for a true full range design that dealt with the narrow dispersion issue. If you want to play at truly heroic levels, a 945 will fit the bill nicely.

Small steps E-Stat, small steps!

One thing I want to mention....I've heard that the room/level correction processors like Audyssey can do funky things with panel dipoles like Maggies and Martin Logans (Acoustats wouldn't be any different) because the rear wave kind of "confuses" the processor. So if you get some bizarre results after you run the correction processor understand it's not uncommon.

Got it! I played around with the speaker levels last night and I was able to blend them in pretty well. Nice synergy between the high end dynamic drivers of the KEF's and TDL's and the Stats!

 

[E-Stat]

Small steps E-Stat, small steps!

We can still dream, right? While we're at it, why not a double pair of 922s like Ray Kimber used at various shows? 85 square feet of panel area will just about do it!

OTOH, as my system has gotten more transparent, I find less need to truly crank it. Also, line sources reduce their output at a lower rate than do point sources as you move away from them. With the garage system, I get surprisingly clear sound from across my driveway over at my neighbor's house.

 

[SimplySound]

We can still dream, right?

Wow! Hope that setup shows up at the Rocky Mountain Audio Fest in October! :thmbsp:

 

[E-Stat]

Wow! Hope that setup shows up at the Rocky Mountain Audio Fest in October! :thmbsp:

Unfortunately, Ray has pretty much retired his large arrays. For about three years running at RMAF, he displayed an even more ambitious system to showcase his four channel recordings. There he used six pair of the nine foot tall 22 degree model driven by an equal number of Pass Labs X350.5s.

Scroll down a bit for pics...

Dr. West once tested an even larger array at an auditorium in the Salt Lake City area. The nice thing about the SL design is they are single driver full range stats with controlled directivity. Which means they can be arrayed either horizontally or vertically with no combing effects.

How about an array four wide stacked two high?

 

[Mendel]

Interesting thread. I also have Spectra 22 speakers. Mine are the older version with the captive power cords without wall wart transformers. Originally I had a few problems with the speaker. They seemed difficult to drive to high sound levels. There was a volume difference between the two speakers. The high frequencies seemed sharp and the bass was somewhat anemic.
About 6 weeks ago I decided to send the 2123 interfaces to a local tech to be renovated. He preformed the following work:
New Caps and resistors.
New High Voltage Diodes.
New wiring
New binding posts
New power cords
Bias voltage raised to 6KV and equalized for both speakers.
I have had the interfaces back and the speakers running for 5 days. They are transformed! Now I understand what the fuss is all about. These are now the best speakers I have heard. Better than the big Quads, better than the Martin Logans. The imaging is scary real, they just disappear. The bass is much better, the treble much smoother. And they seem way easier to drive, the volume control on my preamp stays below 10 o'clock most of the time now, before it was at 12 or more.
With better passive parts and an increase in bias, these speakers are world class IMO.:thmbsp: