Some time ago I acquired a set of old Audiostatic ESL’s. They are (of course) not in good working order so I probably will rebuild them, I've rebuild Audiostatics before so that will not be any problem.
But what wonders me is that this is a model that I have never seen before, nor can I find any references to the model on the web or elsewhere. The faceplate on the back says it's an ES200, but the construction does not look at all like the common ES200R/RS models that I know of. I think it predates the familiair ES100/200/300 series. I disassembled them and construction of the internal ESL element itself is very similar to an ES200 panel, but it looks like it was mostly hand built without jigs or so. White stator wires instead of the usual black ones, the aluminium crossmembers that hold the wires are very uneven spaced and some are even not glued on straight. The frame is unpainted MDF covered in cloth, it stands on two oak stands and is tilted backwards. The interface does have a mirror drive and two audio transformers that look identical to the ones used in the later models, but the input circuit is different, with just a 47uF MKT cap for the mirror drive and not the usual additional RC network.
I would be interested to learn more about this model, so if anyone can shed a light please let me know! So far I draw a blank everywhere I asked.
But what wonders me is that this is a model that I have never seen before, nor can I find any references to the model on the web or elsewhere. The faceplate on the back says it's an ES200, but the construction does not look at all like the common ES200R/RS models that I know of. I think it predates the familiair ES100/200/300 series. I disassembled them and construction of the internal ESL element itself is very similar to an ES200 panel, but it looks like it was mostly hand built without jigs or so. White stator wires instead of the usual black ones, the aluminium crossmembers that hold the wires are very uneven spaced and some are even not glued on straight. The frame is unpainted MDF covered in cloth, it stands on two oak stands and is tilted backwards. The interface does have a mirror drive and two audio transformers that look identical to the ones used in the later models, but the input circuit is different, with just a 47uF MKT cap for the mirror drive and not the usual additional RC network.
I would be interested to learn more about this model, so if anyone can shed a light please let me know! So far I draw a blank everywhere I asked.
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I have them here. I bought this set in 1987 at MijnHifi in Nijmegen. They were designed and released by Ben Peters from Audiostatic and were sold under the namen Audiostatic Megalith. Originally these megaliths used a power adapter, but at the moment I bought them, they were directly driven from te main voltage (used to be 220V that time). This voltage is directly fed to the step-up laddercircuit by a potmeter
, no galvanic separation nor internal fuse.....
I experienced the degradation of its membranes, like any other esl that time, and after 2 replacements I was done with it. Did not use them for a long time. Finally I rebuild them myself and they were playing again (however I used lo-impedant foil). But this is also al long time ago, until today when I decided to try them again. In the older times I removed the mirror circuit and will rebuild it now to restore the circuit to its original situation.
I was looking for some info on the schematics, found your posting and thought: ah, these are mine esl's ;-)
I don't know if it is worth to rebuild them completely. You must decide this for yourself.
I used to have great times listening to the speakers, driven by an AudioInnovations class A tube amp (which I sold too ..... )
We'll see, or better: hear. Hope this helped a little bit. I tried to find original information about these speakers, but did not succeed.
Anyhow, success, whatever you decide to do....
NB I found a nice link of someone who restored the bigger brother of this ESL (named Monolith with reference number ES100)
https://audio-creative.nl/projecten/een-audiostatic-es100-electrostaat-in-de-revisie/
, no galvanic separation nor internal fuse.....I experienced the degradation of its membranes, like any other esl that time, and after 2 replacements I was done with it. Did not use them for a long time. Finally I rebuild them myself and they were playing again (however I used lo-impedant foil). But this is also al long time ago, until today when I decided to try them again. In the older times I removed the mirror circuit and will rebuild it now to restore the circuit to its original situation.
I was looking for some info on the schematics, found your posting and thought: ah, these are mine esl's ;-)
I don't know if it is worth to rebuild them completely. You must decide this for yourself.
I used to have great times listening to the speakers, driven by an AudioInnovations class A tube amp (which I sold too ..... )
We'll see, or better: hear. Hope this helped a little bit. I tried to find original information about these speakers, but did not succeed.
Anyhow, success, whatever you decide to do....
NB I found a nice link of someone who restored the bigger brother of this ESL (named Monolith with reference number ES100)
https://audio-creative.nl/projecten/een-audiostatic-es100-electrostaat-in-de-revisie/
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Thanks for your post. At least it confirms that this was an official model and not some one-off.
Interesting you say they were sold as Megaliths back in 1987. I once found an article in the Dutch magazine Audio en Techniek, edition from May 1985, that includes a review of the (then just newly introduced) Audiostatic Megaliths. The article can be found here: https://archive.org/details/audio-techniek/Audio_en_Techniek_1985_05_mei/
However the ESL shown in this article does not look at all like our model. Which made me believe that these are not Megaliths, but it could be very well Ben Peters modified the design over the years and they indeed are a later Megalith model.
So far I have not decided whether to rebuild them or use them for parts. I suppose the cloth will degrade the sound more or less compared to the later open ES200R/RS models (that I also own). In addition the build qualitiy is not exactly great regarding tolerances. And I do have too much ESL's already. But I do have a suitable tensioning frame for the ES200 and some mylar left somewhere, so maybe I will go for it anyway.
The lack of transformers between mains and HV supply is common in all later Audiostatics, at least for the European market. The US models do use a wallwart adapter as safety regulations were probably different over there and did not allow this.
If you need help with the original schematic let me know, I can draw it from the PCB, not very complicated. I think it is almost identical to the later ES100/200/300 (see attachment) except for some component values.
Interesting you say they were sold as Megaliths back in 1987. I once found an article in the Dutch magazine Audio en Techniek, edition from May 1985, that includes a review of the (then just newly introduced) Audiostatic Megaliths. The article can be found here: https://archive.org/details/audio-techniek/Audio_en_Techniek_1985_05_mei/
However the ESL shown in this article does not look at all like our model. Which made me believe that these are not Megaliths, but it could be very well Ben Peters modified the design over the years and they indeed are a later Megalith model.
So far I have not decided whether to rebuild them or use them for parts. I suppose the cloth will degrade the sound more or less compared to the later open ES200R/RS models (that I also own). In addition the build qualitiy is not exactly great regarding tolerances. And I do have too much ESL's already. But I do have a suitable tensioning frame for the ES200 and some mylar left somewhere, so maybe I will go for it anyway.
The lack of transformers between mains and HV supply is common in all later Audiostatics, at least for the European market. The US models do use a wallwart adapter as safety regulations were probably different over there and did not allow this.
If you need help with the original schematic let me know, I can draw it from the PCB, not very complicated. I think it is almost identical to the later ES100/200/300 (see attachment) except for some component values.
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A layer of grille cloth also damps the fundamental diaphragm resonance a bit. That is usually a positive, and the most significant impact of adding a grille to a typical ESL.
You are right, the original Megalith does not look al all like our model. Anyway: I had a demo with these Megaliths as presented in the article (thanks also for this link, this is the article that pointed my attention to Audiostatic, while in fact I was totally crazy about Magnat's MPX-088, with the MP-02 plasma tweeter. Pitty for me I could not have them in my room due to the terrible ozon-production). As said before, I ordered a pair of these Megaliths (the ones in the article) at Mijn Hifi. At the moment they came out of production, they appeared to be "our model". Explanation by Mijn Hifi: this was an technical and esthetical (in term of WAF, I think you know that means Wife Accepation Factor
) improvement on the original Megalith. For me this was acceptable and I took these ESL's home...Ok, so far about the model aspect.
Thanks for your offer to help with the schematic, but I do have a circuit diagram yet. And yes: drawn from the pc board.
Kind of sad is, that when I started testing the electronics yesterday, it appeared that 2 of my step up transformers have a disconnection somewhere in their secondary winding. And no, it is not the soldering joint. I will try now by using amplimo esl-transformers which I have too. (Long time ago I built ESL's myself and still have some parts). Another option might be to use 1 step up transformer per speaker. In that case I have to simulate the center tap...
Well, that's all for now. Thank you again for your reaction and the link to the article in Audio en Techniek
Sorry to hear you have bad transformers. Not uncommon to have open secondaries on Audiostatic transformers. I had this as well a few times. The set from this topic has a bad one as well but I do have a spare somewhere. I think it's caused by overdriving them, which often occurs when the coating fades away and sensitivity drops. The user compensates by cranking up the volume and doesn't even realize how much energy he is putting in.
The Amplino's will do fine but you will lose a lot of sensitivity as stepup is much lower. If you want to keep them original, it's not difficult to find second hand Audiostatic stepup transformers. They use the very same transformers in all their models including the newer ones. Place a request for transformers on Marktplaats, just check the sec resistance before buying (around 1100 ohms on a good one). Or look for a complete set of speakers in poor condition that needs a rebuild and use it for parts. A broken set can often be found for 100 euros or less.
The Amplino's will do fine but you will lose a lot of sensitivity as stepup is much lower. If you want to keep them original, it's not difficult to find second hand Audiostatic stepup transformers. They use the very same transformers in all their models including the newer ones. Place a request for transformers on Marktplaats, just check the sec resistance before buying (around 1100 ohms on a good one). Or look for a complete set of speakers in poor condition that needs a rebuild and use it for parts. A broken set can often be found for 100 euros or less.
Thank you again for your reply. This weekend I got the ESL's in operation with the amplimo step-ups. Of couse the sensitivity is much lower compared to the 1;150 ratio of two audiostatic transformers. But at least... everything else still works fine and I realized again what I have been missing the last ten years....
As you suggested: I will try to find 2 second hand step-ups.
and I realized again what I have been missing the last ten years....As you suggested: I will try to find 2 second hand step-ups.