I have a set of acoustat model 3 speakers and it seems like I have no bass coming from the left speaker. I was under the impression that since the speakers were full range if its working at all it should be all frequency but I know almost nothing about how the transformer is set up. I have mk-121 blue medallion interfaces. Anyone have this issue before or have an idea of what It may be? I have already taken a look at the panels and they seem to be intact and I see little to no evidence they need to be heat treated ( no wrinkles or looseness). I never really noticed since I had not tried them full range until recently. I have been running them with 2 svs subs but the sound they get full range while not as punchy sounds much more real and has a better image then using the subs. I will more than likely be replacing thees speakers with an LX521 system in the coming months so I don't want to spend a ton of money fixing what I feel will soon be my second choice but I do need a project to tide me over until that build 🙂 . I have been reading up on electostats lately but I am by no means an expert so I apologize in advance for any crazy questions
I may ask.
I may ask.
As a first step, check the low frequency tap inside the interface. This is a terminal strip with multiple positions, with a wire that should be pushed onto one of the terminals with a female spade clip. This wire may be disconnected, making poor contact, or set to the wrong position. For the Model 3, it should be set to the terminal with the orange wire for 'normal' base response.
The two audio transformers inside the interface do overlap in operation, and a loss of bass may indicate a problem with the LF transformer and/or its associated components. If the above hint does not solve your issue, next check the condition/value of the 1-ohm resistor in series with the LF transformer primary, and then the two larger 50K-ohm resistors located on the PC board. If all of these components check okay, then your LF transformer may be bad.
It is very unlikely that your problem could be caused by the panels themselves.
The two audio transformers inside the interface do overlap in operation, and a loss of bass may indicate a problem with the LF transformer and/or its associated components. If the above hint does not solve your issue, next check the condition/value of the 1-ohm resistor in series with the LF transformer primary, and then the two larger 50K-ohm resistors located on the PC board. If all of these components check okay, then your LF transformer may be bad.
It is very unlikely that your problem could be caused by the panels themselves.
Thank you I'll have some time to take them apart in the next few days and I will check that out do you know if it is possible/cost effective to replace the transformer?
Grab an ohm meter and check for continuity / resistance on the primaries of the LF transformer. Then check the continuity / resistance on the secondaries of the LF transformer. They should not be open, and be relatively low resistance. Post your results here.
I find it hard to believe its the LF tranny can go out.
I find it hard to believe its the LF tranny can go out.
I was not getting any reading on my meter at all but I am very new to this so I could have been connected to the wrong leads. I also found out I don't have the medallion transformers even though the sticker says I do they must have been swapped out at some point. The transformers in my interface are wrapped in brown paper. I sent an email out to Roy A. Esposito as he is able to provide the medallion upgrade but he said he is pretty backed up with work at this time so I would like to try and get everything at least working while I wait on getting the upgrade.
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What's the part number stamped on the transformer? There were a few Medallions that did not have the black-paper wrapping.
Unfortunately, the LF transformer can fail, especially if overdriven. It is the Achilles heel of the MK-121 interface. The HF transformer and bias transformer are much more reliable.
The Medallion version of the LF transformer does have better arc-resistance than the non-Medallion version, but is still susceptible to over-driving. It can develop over 10,000 volts between phases on the secondary.
Unfortunately, the LF transformer can fail, especially if overdriven. It is the Achilles heel of the MK-121 interface. The HF transformer and bias transformer are much more reliable.
The Medallion version of the LF transformer does have better arc-resistance than the non-Medallion version, but is still susceptible to over-driving. It can develop over 10,000 volts between phases on the secondary.
WOW....10kv... I new it was high ...I bet at high humidity...or low bias...mabe much higher...like driving a dead short....after time..that well kill any Acoustat LF tran..
thanks
thanks
I will have to take another look, I scheduled my upgrades with Roy for April but that is a long time to go with a broken speaker. I am going to see if I know anyone with more electronics experience to help me take a look. All of my knowledge is in woodworking and dsp I have never built a "real" crossover or transformer.
I have seen the large power resistors in series with the output of the bass transformer fail and go open, so maybe check those as well.
Take care,
Doug
Take care,
Doug
So I ended up taking it into a local shop and they tested the interface and said everything was working. I know this is not the case because if I swap my working interface onto the same panel everything is fine. Is there something the technician would have likely missed? Or was I just scammed. On another notes I now have a new interface but its an older model the mk121-2 that is working so I am no longer worried about breaking the interface in the original post all ideas are welcome as I would like to have a matching pair if I can.
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Knowledge of how to properly test an Acoustat interface is a rare commodity, so your technician may just be ignorant, not dishonest.
The fact that you swapped interfaces and the problem went away certainly points to a problem in the interface. The transformers should be the same in the -2 version of the interface. If you have already eliminated possibilities as previously discussed (LF transformer tap, measuring resistors, etc.) then you probably have a bad LF transformer. You can temporarily connect the -2 interface to your speaker to make sure it's in good working order. Then, take the LF transformer out of the -2 and replace the one in your 'bad' interface. Report back if you are still having troubles.
The fact that you swapped interfaces and the problem went away certainly points to a problem in the interface. The transformers should be the same in the -2 version of the interface. If you have already eliminated possibilities as previously discussed (LF transformer tap, measuring resistors, etc.) then you probably have a bad LF transformer. You can temporarily connect the -2 interface to your speaker to make sure it's in good working order. Then, take the LF transformer out of the -2 and replace the one in your 'bad' interface. Report back if you are still having troubles.
I tested out the -2 interface and it works 100% I think I am just going make a modified mounting system to hold the panel in place since the things are so hard to come by I dont want to chance messing it up by taking it apart. That being said I think I will take apart the other interface and do a component by component test of it to 100% rule anything out. And hopefully a nice set of medallions will show up on ebay. Thanks for all the suggestions and help once I get around to taking it apart and testing everything I may post some pics and what have you so if anyone else has this issue they can take a look.
.look at the orange wire. in the pic....that gos to the bass tran....two wire coming in one gose to the 1ohm res....an the other just pluges in to the bar strip....if you have the interface setup to run the panels...like norm....just pull the one wire off the bar strip.......an move it to the red wire plug in...that well tell if the tran is working....good luck
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Man I that.... that...sucks......I lost 3-5 bass 1 high frc ....an even a bias trans.....over the years trying mods an paper drying out an opening up an letting the wire move an come lose under the paper.......2 were bass medallions .... I have 4 medallions high frc trans.....I like the older first ones....why.............. I don't have all .medallions ..... my two M3 interfaces I am using are old brown trans....
well your getting to know how these things work.......maybe more than you wont... ............it is all about the sound......I have Apogee Stages there full range ribbons running.....ESL are out........good luck......
well your getting to know how these things work.......maybe more than you wont... ............it is all about the sound......I have Apogee Stages there full range ribbons running.....ESL are out........good luck......
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It's been a learning experience so far. I have been interested in building some full range esl's for a while just for something different other than a standard box speaker and I have just been so impressed with the acoustats. I have been reading some of the info out there on segmented wire esl's and I'm pretty confident on building the panels but I still need to learn more about the interfaces. I have the electro static cookbook but it's slow going.
I got say ....30 years ....Acoustat X with there sevro tube amps.....was my frist....
then the Quad 57s.... jazen....then soundlab....Martinlogan.......only like flat panels now...my M3s are 3ea 9" panels.....I have re-worket ML panels.....
these guys have Diyed...a lot of cool looking panels...not a lot of full rang ones..
I have worket on minny ESLs but to bild my own.................I well pass on full rang...
One thing I would do for any ESL.......get your bias setup out of the interfaces....an get it setup so you can set the bias....like from 4-7k....that way you can to get most output.. best sound.....in the end the bias makes the ESL.....get the bias up... its ezer on the tran an parts....low bias well kill tran.....an sound bad...have fun good luck
then the Quad 57s.... jazen....then soundlab....Martinlogan.......only like flat panels now...my M3s are 3ea 9" panels.....I have re-worket ML panels.....
these guys have Diyed...a lot of cool looking panels...not a lot of full rang ones..
I have worket on minny ESLs but to bild my own.................I well pass on full rang...
One thing I would do for any ESL.......get your bias setup out of the interfaces....an get it setup so you can set the bias....like from 4-7k....that way you can to get most output.. best sound.....in the end the bias makes the ESL.....get the bias up... its ezer on the tran an parts....low bias well kill tran.....an sound bad...have fun good luck
I'll have to look into that I have seen mods to boost the bias power. I'm a big fan of dipole bass and the esl has a great sound for most of what I listen to. I don't listen to a lot of thumping bass and I have been unimpressed with the hybrid esl's I have listened to compared to the full range. I may build a dipole woofer to try that in comparison never listened to that as part of a hybrid system.
Esl sound is hard to beet ....but I am a nut...I like all types of sound,tone...loud..
full room wall to wall..top bottem...it just me here...... I put room up 18'X40'h 14.....with a 18xh7'movebel wall...room now is 18'x25'.....40' all open above 7'......
But I also got into the full rang Apogee ribbons.......vary esl like...sound great with tube amps...little power ....play loud...deeeeeeeeeep esl type bass...setup now speakers are 14'wide......full middle.....great image....
lot fun...got have it you know...fun
full room wall to wall..top bottem...it just me here...... I put room up 18'X40'h 14.....with a 18xh7'movebel wall...room now is 18'x25'.....40' all open above 7'......
But I also got into the full rang Apogee ribbons.......vary esl like...sound great with tube amps...little power ....play loud...deeeeeeeeeep esl type bass...setup now speakers are 14'wide......full middle.....great image....
lot fun...got have it you know...fun
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