Acoustat Answer Man is here

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First of all, all Spectra 11/1100 used the wall transformer power supply. But there was a significant improvement to the supply, and it is essential that you make sure your set is updated to the latest design, before you go "upgrading" or replacing parts. It's easy to do with commonly available parts. See attached docs.

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Thank you for posting these attachments. I really appreciate not having to hunt this information down.

I looked the documents over. I will make sure that it is all updated. I didn't see a 4.7uf capacitor on my boards but I did see the 47uf and 470uf caps.

I saw this interesting article.
Audio Asylum Thread Printer

Do you think there is any merit to increasing the cap size on the low volt portion of the circuit? Also, should increasing the bias to roughly 6500v provide a benifit?

Thanks!
 
If it would make you happy, you can increase the value of the 470 uF filter capacitor, though I question any supposed sonic benefit in doing so. I would NOT recommend any other changes to the bias circuit. Other circuit values are critical to the circuit's operation and should not be changed. Yes, you can increase the bias voltage, but two potential problems come to mind. First and foremost, since this is a hybrid system, increasing the bias voltage will raise the level of the ESL portion, but not the woofer. So you will change the balance between woofer and ESL. Secondly, especially in humid environments, you may experience greater leakage and arcing. Although this poses no danger to the speaker, it doesn't sound good. You can try it, and if you don't like it, you can always dial the bias down to normal level. I've seen the Audio Asylum article before. Some of it I believe to be snake oil, other changes may be beneficial. Certainly there are better woofers available. I rather doubt that each of the suggested changes were made one-at-a-time to allow evaluation of the actual change, if any, that each modification provided.


Again, I will recommend that you first get the speakers working properly to factory spec, and then you can experiment with changes.
 
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I think if I have to order parts I am going to replace all of the caps. While I am at it, the difference in cost between a 470uf and a higher rated cap is negligible so I may as well increase the size of it.

Since there seems to be no permanent consequence to raising the bias voltage I may try that just for fun. It is my first time playing with planars so It is fun to experiment. I do live in SWFL though so I suspect there is a chance that I may run into leakage arcing like you said.

Regarding the Audio Asylum article, what do you think of the treatment that he did around the electrostatic panel on the top where he implanted the acoustic foam between the panel and the frame? I agree with you about his potential lack of a process when experimenting.

I am going to get them going properly like you said then try a few different things. I don't think I am going to change the woofer out. I will likely get these going well and then sell them off to someone else to enjoy. I don't have a lot of room so I only get one setup. If I had two 2 channel setups, I would definitely hang onto these. I just like playing and learning about audio stuff. I'm hoping to run into a set of acoustats without a cone woofer someday. Maybe something like the spectra 22 or 2+2.

Thank you again for taking the time to read and respond. This is a invaluable thread!!
 
I live in a relatively humid locale, and I'm running one extra rung on my HV ladder. Two extra rungs caused steady periodic crackling noises. I would expect higher humidity would require higher voltage to maintain the same output level as a low humidity environment since leakage would be rise with humidity.
 
I live in a relatively humid locale, and I'm running one extra rung on my HV ladder. Two extra rungs caused steady periodic crackling noises. I would expect higher humidity would require higher voltage to maintain the same output level as a low humidity environment since leakage would be rise with humidity.


In the early days, Acoustat did a lot of field research under conditions of different humidity and altitude, and found that 5000-volt bias was the optimum value with minimum compromise in performance under widely varying conditions. 'Nuff said.
 
Can a Spectra 11 be upgraded to a 22 by adding panels or are different interfaces used? Thanks.


The only common element between the Spectra 11/1100 and it's larger, full range brethren is the ESL panel itself. So yes, conversion is possible, if you change everything except the panel. In other words, not really. If you want a different model, buy a different model.
 
As mentioned in a previous post, yes. But it's a very tedious and difficult process task, and can easily lead to a ruined panel. In my opinion, it's not worth the trouble.

The only common element between the Spectra 11/1100 and it's larger, full range brethren is the ESL panel itself. So yes, conversion is possible, if you change everything except the panel. In other words, not really. If you want a different model, buy a different model.

Thanks AAM, a pair of Spectra 11s went for CDN$299 near me.
 
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Thanks AAM, a pair of Spectra 11s went for CDN$299 near me.

These Acoustats hit outside their weightclass when it comes to what they seem to sell for used. I bought my pair for $80. Of coarse they need a decent amount of repair work, they are cosmetically in good condition. I can see the real potential even with them not being completely fixed yet.
 
Do you have any information on the bias pots used on the spectra 11 boards? I would like to replace mine. The stuff they wipe on top has gotten between the dial and it's body which makes it very hard to turn.

Thanks!


Sorry, I don't have any specs on the trim pot, but it's a pretty generic style. You should find a replacement at Digikey or Mouser.
 
Do you have any information on the bias pots used on the spectra 11 boards? I would like to replace mine. The stuff they wipe on top has gotten between the dial and it's body which makes it very hard to turn.

Thanks!


Sorry, I don't have any specs on the trim pot. However, it's a pretty generic style, so you should have no trouble finding a suitable replacement at Digikey or Mouser.
 
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First of all, all Spectra 11/1100 used the wall transformer power supply. But there was a significant improvement to the supply, and it is essential that you make sure your set is updated to the latest design, before you go "upgrading" or replacing parts. It's easy to do with commonly available parts. See attached docs.

View attachment 864437
o
View attachment 864438

View attachment 864439

I updated the interface as described in the documents. The only change I made was switching the 470uf cap for a 1500uf cap. The bias incresed on both interfaces.

One interface now reads 46 volts and the other reads 78 with the pots maxed out.

What should be my next step? I was thinking of checking the voltage on both the interfaces part by part to see where the drop is. One thing I noticed is that one interface looks like it was built before the other. As in, it has older looking components on the board.

Thanks for all of your help. The speakers are starting to sound pretty good. I just need to get the bias up the rest of the way on the one that is still too low.
 
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When I had issues on my Spectra 11, I ended up changing that 8 pin IC (looks like an Opamp). You may just need to make sure it is electrically connected - take voltage readings pin for pin from common ground and compare to the other working interface (bias at 75v sounds about right). may just need to resolder bad 8 pin connection, as I dont think mine needed replacing after replacing it...just a bad solder joint
 
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I have had my Acoustats 6600's for a number of years and worked perfectly, however one of the speakers has very low output any ideas where to start? I do have replacement transformers, ultra sonic supply board and a high voltage board in reserve.

The first thing I would check would be the Bias voltage going to both speakers. If you read above, the update that acoustat Answer Man suggested that I do helped to increase the bias voltage on the interconnects. I am not sure if the update applies to your speakers.
 
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When I had issues on my Spectra 11, I ended up changing that 8 pin IC (looks like an Opamp). You may just need to make sure it is electrically connected - take voltage readings pin for pin from common ground and compare to the other working interface (bias at 75v sounds about right). may just need to resolder bad 8 pin connection, as I dont think mine needed replacing after replacing it...just a bad solder joint

My next step is to pull the interfaces off and start comparing voltages on the two units like you suggested. I reflowed a lot of the connections just because I thought it was a good idea. I suspect I may have an issue with the diodes as that seem to be a common issue.

I may grab a few other parts to replace on the board for good measure such as the small 3300pf caps on the high volt side of the transformer. There are also some diodes on that side as well.
 
It's not necessary to connect the panels, but unless you have a high-voltage probe, you'll have no way to verify if the bias supply is working if you don't have panels connected.

I don't see a great need to use a Variac to slowly increase the voltage. The power supply contains no electrolytic capacitors that would need to reform, as would be the case for other electronics.

My advice would be to connect the panels, apply AC power, charge 'em up for a few minutes, and play music to verify operation.

Hi Mr Acoustat Answer Man, I have repaired a few connection issues with the wires running to the panels from the supply on both 2+2's.
I then powered the speakers up and let them charge for a while.

On playing music I have found that one speaker has bass that is distorted and pops and its happing from all of its panels. The top two panels on this speaker sound fine for the mids and tops.

The other speaker is fine for bass, mids and tops.
But both speakers have a low sound output from the two bottom panels then the top two panels.

I have swapped the power supplies over and the issues move with it. What do you think maybe causing the above problems?