I got tell you.....40year I been playing with Audio speakers....none have ever sound so good....just soo ......not right at times...but in the end Acoustat are a one of a kind sound....I have done every mod I ever heard....lot of fun....
they give me good time
they give me good time
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Yeah, I've been doing it for 40 years too, horns, direct radiators, lots of planars, but Acoustat are the bees knees.
This is what I posted on Sound Lab speaker owners board.
I have done something I believe nobody ever did before. I would like to document here in case someone else wants to do the same.
It all started two years ago and some of people used AU90 transformer to replace Sound Lab stock transformer. What they did basically was to extend the cut off frequency of high/mid transformer down to about 200 Hz. Sound Lab redesigned their high/mid transformer later on. The cut off frequency of their new transformer is also down to about 200 Hz. After reading some of articles about electrostatic speaker designs, I got the idea that to use two stock high/mid transformers and to connect them primary in parallel and secondary in series. I also wrote to Dr. West to seek advice. He was very kind and advised me that both primary and secondary should be connected in series. Therefore, it moves the cut off frequency down to 250 Hz from 500 Hz.
I also did other modifications.
I completely discarded the passive crossover and am using an electronic crossover.
For the mid frequency coil, I used 8 awg magnet wire to make two coils. The heavier the wire, the better sound. One is 7.0 mH with iron core. Another one is 0.5 mH with air core. I do this because I think air core coil has more transparent and open sound than iron core, but I can’t make a huge air core coil because it will get too big for me to handle and its resistance will get high, too.
Anyway, I enjoy my speakers more than ever now.
Here is the diagram for your reference.
I have done something I believe nobody ever did before. I would like to document here in case someone else wants to do the same.
It all started two years ago and some of people used AU90 transformer to replace Sound Lab stock transformer. What they did basically was to extend the cut off frequency of high/mid transformer down to about 200 Hz. Sound Lab redesigned their high/mid transformer later on. The cut off frequency of their new transformer is also down to about 200 Hz. After reading some of articles about electrostatic speaker designs, I got the idea that to use two stock high/mid transformers and to connect them primary in parallel and secondary in series. I also wrote to Dr. West to seek advice. He was very kind and advised me that both primary and secondary should be connected in series. Therefore, it moves the cut off frequency down to 250 Hz from 500 Hz.
I also did other modifications.
I completely discarded the passive crossover and am using an electronic crossover.
For the mid frequency coil, I used 8 awg magnet wire to make two coils. The heavier the wire, the better sound. One is 7.0 mH with iron core. Another one is 0.5 mH with air core. I do this because I think air core coil has more transparent and open sound than iron core, but I can’t make a huge air core coil because it will get too big for me to handle and its resistance will get high, too.
Anyway, I enjoy my speakers more than ever now.
Here is the diagram for your reference.
Attachments
Thanks for the pic...........Yes this bi-amping-wireing has been done...for years.to these back plates......the diff AU90 transformers have work well...then Dr west came out with his new high frc tran.....some like it...the AU90 sounds best to me......
Soon I well tiying togather the secondarys center taps... an adding a 10mg ohm 5 watt.. res to ground...after all on the secondary side we need them to work as one tran...letting them talk to each other well be a good thing for getting the best sound........in a pr of SL M1 back plates...the stock centap setup ties the output tran down..I think this well get the best output an best sound yet...
Thanks for any an all input on get better sound out of ESLs
Soon I well tiying togather the secondarys center taps... an adding a 10mg ohm 5 watt.. res to ground...after all on the secondary side we need them to work as one tran...letting them talk to each other well be a good thing for getting the best sound........in a pr of SL M1 back plates...the stock centap setup ties the output tran down..I think this well get the best output an best sound yet...
Thanks for any an all input on get better sound out of ESLs
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Hi tyu
You posted this in the past and I want to clarify
quote:
BUT...don't get the added pos-neg 121 input post... revised....you can kill your amp an or kill a stepup trans...
I want to biamp my acoustat Model 3.
Only question is after I disconnect the neg and pos wires from the high and low transformers, I can hook each transformer's pos and neg to a seperate amp? Taking care - pos to pos, neg to neg.
I will be running the amps from a preamp that has outputs for 2 amps.
An Aragon 4004 will be driving the low tran, and EAR509 monoblocks for the high tran.
I can adjust the level of the EARs since they are more sensitive than the Aragon.
Will be adding protective fuses on the sprk wire for both the trans.
Your input plus any input from other members will be appreciated
You posted this in the past and I want to clarify
quote:
BUT...don't get the added pos-neg 121 input post... revised....you can kill your amp an or kill a stepup trans...
I want to biamp my acoustat Model 3.
Only question is after I disconnect the neg and pos wires from the high and low transformers, I can hook each transformer's pos and neg to a seperate amp? Taking care - pos to pos, neg to neg.
I will be running the amps from a preamp that has outputs for 2 amps.
An Aragon 4004 will be driving the low tran, and EAR509 monoblocks for the high tran.
I can adjust the level of the EARs since they are more sensitive than the Aragon.
Will be adding protective fuses on the sprk wire for both the trans.
Your input plus any input from other members will be appreciated
![acoustat[1].gif](/community/data/attachments/767/767660-8f9a62f46ad115a631e142282d806333.jpg?hash=j5pi9GrRFa)
![MK-121C_Xovr5B15D6[1].gif](/community/data/attachments/767/767663-b61290756439acf8e85d5f20fbafc384.jpg?hash=thKQdWQ5rP)
Thanx for the schema tyu, when i went in, it was pretty obvious how it had to be done.
Ephrain, with the XO still in the transformer housing you really should use 2 identical amplifiers.
dave
Ephrain, with the XO still in the transformer housing you really should use 2 identical amplifiers.
dave
Hi
Thanks for all your swift responses.
Will double check everything again and update my impression.
I will switch back and forth, since everything will be open and spread out, in order to hear which combination will give the best result, single amp or 2 amps
Thanks for all your swift responses.
Will double check everything again and update my impression.
I will switch back and forth, since everything will be open and spread out, in order to hear which combination will give the best result, single amp or 2 amps
Hi,
Finally got time to do the experiment.
Connected everything as shown.
The Aragon is full dual mono, which I connected to the bass audio transformers.
The EAR509 monos were connected to the treble transformers.
I have on my preamp 2 left and 2 right outputs which ar basically paralled outputs.
Connected the 2 left channels : one to the Aragon, the other to the EAR
Same for the 2 right channels.
This did not work!!!
I heard music only from the EAR amps,i.e. only the trble transformer.
If I connected oONLY ONE SPEAKER biwired with one SINGLE MONO EAR and one channel of the Aragon, it worked.
The moment it was set up with all channels, only the treble transformer produced sound.
Any ideas?
Finally got time to do the experiment.
Connected everything as shown.
The Aragon is full dual mono, which I connected to the bass audio transformers.
The EAR509 monos were connected to the treble transformers.
I have on my preamp 2 left and 2 right outputs which ar basically paralled outputs.
Connected the 2 left channels : one to the Aragon, the other to the EAR
Same for the 2 right channels.
This did not work!!!
I heard music only from the EAR amps,i.e. only the trble transformer.
If I connected oONLY ONE SPEAKER biwired with one SINGLE MONO EAR and one channel of the Aragon, it worked.
The moment it was set up with all channels, only the treble transformer produced sound.
Any ideas?