Acoustat Answer Man is here

Gess I was not clear.............
This was my point.......... or his point......
drill a hole....bolt the speaker back together ...
the reworking of the panels with new mylar.......hehe....that may be true but it shows some one did...
This was the first
place I saw anyone even talk about reworking these panels...........or that Acoustats coating was..in a liquid form ...made.by Ampex and was the same material used on recording tape ..
the more info the better................it may be old news to some.....but I read a lot of talk about how good these Acoustat panels are an how well that thay heldup....
most know how big I am on good bias an how it can make or brake the ESL...
but this Ampx coathing may be the key........well it a big one anyway....Yummie
 
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Mr Answer Man....
My Acoustat 2+2 are awesome , but now that winter is down here they distort when humidity is very high, especially after heavy rainfall.
I replaced the HV caps and diodes with HV rated devices, made a big difference and brought them back to original sound. I also made the final cap bigger, for a considerable increase in dynamics I thought. From memory I think it was 0.05uF. Maybe I have too much voltage now and is causing distortion when humidity high? Have you experience of distortion in winter?
 
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AcoustatAnswerMan said:
If memory serves correctly, the original binding posts were made by Superior Electric. The main criteria for replacement is that the post fits into the same D-shaped (or was it double-D?) hole, and that the threaded terminal on the back is the same length and thread size as the original. This way the posts will mate to the standoffs inside the enclosure, which in turn connect to the PC board. I think Acoustat cut off the solder-terminal on the end of the post before screwing on the standoffs so that it wouldn't bottom-out inside the standoff.
Click to expand...

Thank you for the information AcoustatAnswerMan.
Has anyone here changed binding posts? What did you use that fits? Cardas, WBT, Vampire, Furutech, etc?
Is this something a novice can do (I have a simple soldering gun but not much experience) or do I need a tech?
Appreciate any help.
 
I did the mod on the bias........added cap....I felt it worket an made the sound smoother.............but in the end.... I felt it rooled the topend down....or maybe it was pulling the bias down...........
One thing is for sure driving Acoustat 121 interfaces t00 were. you get sound brackup in the panels......or with low bias....well cook the res.an tranfourmers.......Ezey.........good luck
 
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Mendel24 said:
Thank you for the information AcoustatAnswerMan.
Has anyone here changed binding posts? What did you use that fits? Cardas, WBT, Vampire, Furutech, etc?
Is this something a novice can do (I have a simple soldering gun but not much experience) or do I need a tech?
Appreciate any help.
Click to expand...


Hi Mendel:

I changed the binding posts on my Acoustat 3s to dual banana type but had to drill the holes in the casing/metal-work larger to accommodate the larger circumference of the binding post insulators. (Since the holes are larger now, Cardas or Vampire post can be used also (not sure about WBTs/Furutech/etc.). The ones that were used are similar to these from Newark-In-One.

4109 - KEYSTONE - BINDING POST, DUAL, SOCKET, 30A, TURRET, BLACK/RED | Newark element14

Note: The whole process did take more time as the ones on mine were tampered/replaced at one time and the excess soldering done took additional time to remove. (Plus, the access area was a bit cramped with that large higher frequency control close to the binding posts.) Maybe there is more room to maneuver on your Spectra 33s?

Sincerely,
K.D.
 
SPW-1 DONE

Well then I got the SPW-1 and the speakers all done and they sound great. I will be compiling pics and info from the teardown and rebuild of the SPW-1 specifically so that people might be able to rebuild theirs. So far it sounds great for vintage 90's gear.
 

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audiobasic2000 said:
Hi Mendel:

I changed the binding posts on my Acoustat 3s to dual banana type but had to drill the holes in the casing/metal-work larger to accommodate the larger circumference of the binding post insulators. (Since the holes are larger now, Cardas or Vampire post can be used also (not sure about WBTs/Furutech/etc.). The ones that were used are similar to these from Newark-In-One.

4109 - KEYSTONE - BINDING POST, DUAL, SOCKET, 30A, TURRET, BLACK/RED | Newark element14

Note: The whole process did take more time as the ones on mine were tampered/replaced at one time and the excess soldering done took additional time to remove. (Plus, the access area was a bit cramped with that large higher frequency control close to the binding posts.) Maybe there is more room to maneuver on your Spectra 33s?

Sincerely,
K.D.
Click to expand...

T hank you for the info K.D. Sounds a little beyond my skills I think. Time for a tech to change the posts, the first cap in the audio path, upgrade the monster cable, and check the bias voltage.
Anyone with any other suggestions for maintenance/upgrades on the Spectra interfaces?
 
tyu said:
I did the mod on the bias........added cap....I felt it worket an made the sound smoother.............but in the end.... I felt it rooled the topend down....or maybe it was pulling the bias down...........
One thing is for sure driving Acoustat 121 interfaces t00 were. you get sound brackup in the panels......or with low bias....well cook the res.an tranfourmers.......Ezey.........good luck
Click to expand...

????? you have a lot of experience with Acoustat, I wish you would take a bit more time to explain , your posts always leave me wondering what you are trying to say.
 
Andy is the man... he,ll ck in......with info on stock Acoustats.....for you..
I am a mod guy...I do.. any an all things to get the best sound out of the old panels an interfaces.....this is not for everyone........
But for sure you don't wont to kill any transfourmers......I got 4 dead bass tran...myself.....after almost 30years........
Bias being pulldown by humidity....
or just low bias....makes the tran- parts work harder...all parts get hoter...
So how do I an others deal with this.....add more bias....I run my bias over 6k...an drop the stock bias feed res from 500mg..... to 10mg.....an run AC in my home to get rit of humidity...........but that me........
As you see the stock bias is less the 5k...then after the bias feeder of 500mg... when your driving the 2+2 you have about 3-4k.....good luck
 
"Anyone with any other suggestions for maintenance/upgrades on the Spectra interfaces?"
I have the Spectra 3s with the older type bias.....I got the bias up...dropet feeder res lower.... I run the 3s fullrang.....with the better Spectra transfourmers that use NO crossovers..
I like that sound better than the Spectra split panel setup.....
lots good info here thanks to Andy an others...................good luck
 
Mendel24 said:
T hank you for the info K.D. Sounds a little beyond my skills I think. Time for a tech to change the posts, the first cap in the audio path, upgrade the monster cable, and check the bias voltage.
Anyone with any other suggestions for maintenance/upgrades on the Spectra interfaces?
Click to expand...

Changing the type and/or brand of binding posts on the Spectras is a bit more complicated than on the older models. The older models had the binding posts simply connect to soldered wires on the inside of the chassis, so with a little metalwork modification, nearly any binding post could be retrofitted. On the Spectras, the binding posts connect to metal standoffs inside the chassis, which make both a mechanical and electrical connection to the crossover/switch board inside. So it is possible to make changes, but it requires a lot more work.

There isn't much to do on the Spectras in terms of upgrades, in my opinion. If you have the switch in the 'Above 100Hz' position (for use with a subwoofer) you might consider replacing the electrolytics (100-uF and 47-uF in parallel) with a film capacitor of similar value, provided you can find one that will physically fit. When the switch is in the 'Full Range' position, this capacitor is shunted by a 1-ohm resistor so I doubt there would be any sonic value in upgrading it.
 
supra said:
Mr Answer Man....
My Acoustat 2+2 are awesome , but now that winter is down here they distort when humidity is very high, especially after heavy rainfall.
I replaced the HV caps and diodes with HV rated devices, made a big difference and brought them back to original sound. I also made the final cap bigger, for a considerable increase in dynamics I thought. From memory I think it was 0.05uF. Maybe I have too much voltage now and is causing distortion when humidity high? Have you experience of distortion in winter?
Click to expand...

Although I am not in favor of any modifications to the bias supply, I doubt that the added .05-uF capacitor is causing your problem, provided that is it connected as shown in your other post. However, if there is any doubt, remove the added capacitor and see if the situation improves.

When the Acoustat panel was being developed, extensive research and field-testing was done to make sure that there would be little or no performance change in conditions of high and low humidity, and high and low altitude. I think the design was successful in that regard, as I have operated Acoustats in both Florida (with god-awful high humidity and near sea-level) and in Arizona (with skin-cracking dryness at about 1200 feet above sea level). I have never noticed any difference in performance between these two very different climates or any seasonal changes.

If you mean a crackling or similar noise on large bass notes when you say 'distortion', this may be caused by an increased tendency of the air to ionize
under high humidity, which might cause (non-destructive) high-voltage 'sizzle' under large excursions. This condition may be aggravated by dirty panels, so perhaps a thorough vacuuming and/or blowing out with compressed air might help the problem.
 
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Thank you for the information Andy!
Now we come to the panels themselves. I have read a lot on the internet regarding the retentioning of Acoustat panels with a heat gun or hairdryer. Some people swear by it, while others claim it can destroy the panel. I do not recall seeing your view on the subject Andy.
So to hair dry or not that is the question. If yes, I would appreciate a description of the technique (from anyone who has done it with success). My Spectras are naked right now so now is the time. I do see some wrinkles in the mylar (especially on the bass panel for the right hand speaker. As this speaker seems ever so slightly less dynamic than the left side I'm thinking retentioning might help).
Any advise or opinions welcome.
 
AcoustatAnswerMan said:
Although I am not in favor of any modifications to the bias supply, I doubt that the added .05-uF capacitor is causing your problem, provided that is it connected as shown in your other post. However, if there is any doubt, remove the added capacitor and see if the situation improves.

When the Acoustat panel was being developed, extensive research and field-testing was done to make sure that there would be little or no performance change in conditions of high and low humidity, and high and low altitude. I think the design was successful in that regard, as I have operated Acoustats in both Florida (with god-awful high humidity and near sea-level) and in Arizona (with skin-cracking dryness at about 1200 feet above sea level). I have never noticed any difference in performance between these two very different climates or any seasonal changes.

If you mean a crackling or similar noise on large bass notes when you say 'distortion', this may be caused by an increased tendency of the air to ionize
under high humidity, which might cause (non-destructive) high-voltage 'sizzle' under large excursions. This condition may be aggravated by dirty panels, so perhaps a thorough vacuuming and/or blowing out with compressed air might help the problem.
Click to expand...

There in a shed workshop so quite possible they are dirty, I'll give a them a vacuum , thanks for that.
 
Mendel24 said:
Anyone here have an opinion on retentioning accoustat panels with a heat gun or hairdryer? Thanks.
Click to expand...

Re-tensioning the Mylar diaphragm is certainly possible. This is not to say that ALL Acoustat speakers require it sooner or later, but in cases where there is excessive 'slapping' on large bass notes, re-tensioning can be beneficial. Note the emphasis on 'excessive' slapping - all full range ESL's will exhibit this behavior at a certain drive level, so the point here is that re-tensioning can help fix a speaker that slaps at a drive level lower than average for that model.

Using the average hair drier will probably not yield the temperatures desired, so I recommend using an industrial heat gun, which typically has a much higher temperature but a lower air volume than a hair drier.

The grille cloth needs to be removed and the panel discharged prior to the process. The heat can be applied to either front or rear of the panel, but I recommend the front since the felt blocks on the rear can interfere with the even application of heat. The key idea is to keep the source of heat moving constantly over the entire surface of the panel to slowly build up the temperature of the diaphragm.

Yes, the process can be over-done and the diaphragm can be destroyed by excessive temperature. So it is far better to heat the diaphragm in stages to see if it solves the problem. If not, repeat the process and apply a little more heat and re-test.

The re-tensioning process has been discussed several times throughout this thread. Other participants have suggested an optimum shrinking temperature for the Mylar diaphragm material, and the possible use of an infrared thermometer to gauge the temperature. Further research is left up to the reader.
 
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I am still trying to get my Acoustat Spectra 1100's to work. I did the bias adjustment. I did the 2nd method for testing the voltage. It came out to 8.1 volts at the red ESL terminal. Andy's documentations says I should be getting 75 volts at this point. This means I am getting approx 600 volts. (It should be at 5000 volts). This makes sense because the volume of the speakers seems to be 1/10 of what it should be. I did get a little more volume when I did the bias adjustment. How can I get more? (speak to me like the amatuer I am). Thank you to everyone on this forum 🙂
 
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