Natural Sound
- Thread starter PeterA
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Is that a polarity switch (affects both channels) or does that only affect one channel? If the former, that is more common these days. If the latter, thanks for the update- good to know.
I'm sure if properly done that can be a revelation! ESLs have always been very fast speakers and this would make them even faster.A small point. You need a direct drive amp for electrostatics to realize the charge the stators need (+/- )a direct drive amp is a "form" of OTL
OTLs as we mostly know them parallel tubes to get to the typical impedance of standard speakers, say 4-16 ohms whereas direct drive work off thousands of volts on the plates to provide the stators they serve with the polarizing voltage they need- eliminating the step up transformer.
If we use regular tube amps on electrostatics we typically have step down transformers on the amps with step up transformers on the panels resulting in what can be a real loss in finesse, resolution and slam.
I would hazard a guess that if @Lagonda tossed his step up transformers and MBLs for his ML Statements with a direct drive OTL he would plotz and never look back.
For the past 12 or 13 years I have been messing with direct drive amps and with the Acoustat servo charge amps a long time before that.
Once you get rid of that lossy step up transformer you are liberated in ways you can not imagine.
I eventually made a direct drive amp for the Beveridge model IIIs which had a traditional step up transformer in them +/- 1600v 3.2kV full swing.
Wow what an experience. Due to that experience , have been pulling out what's left of my hair on reworking a pair of original Beveridge Model IIs and re-designed the boards with newly designed power transformers - these are pretty lethal but the dynamic expression is really un-comparable to any transformer coupled electrostatic
The commercial company is:
Mono OTL - Twinstatic Audio
Mono OTL direct drive amplifier for ESL loudspeakers Spin-off from the Acoustat upgrade is a complete new mono direct drive amp, based upon the Acoustat Servo-charge Amp + upgrade. The amplifier is build in a 19” inch rack with handles. The special low capacitance cable to your ESL-speaker...twinstaticaudio.nl
We got asked a few times about building a direct drive amp for ESL. Its problematic on a commercial scale since to protect the user from very high Voltages, the amp really should be integrated into the speaker like the old Acoustat. The problem with that is if you want more power you have to replace both the amp and speakers.
Here
Mono OTL - Twinstatic Audio
Mono OTL direct drive amplifier for ESL loudspeakers Spin-off from the Acoustat upgrade is a complete new mono direct drive amp, based upon the Acoustat Servo-charge Amp + upgrade. The amplifier is build in a 19” inch rack with handles. The special low capacitance cable to your ESL-speaker...
twinstaticaudio.nl
OK- that's cool!Here
Mono OTL - Twinstatic Audio
Mono OTL direct drive amplifier for ESL loudspeakers Spin-off from the Acoustat upgrade is a complete new mono direct drive amp, based upon the Acoustat Servo-charge Amp + upgrade. The amplifier is build in a 19” inch rack with handles. The special low capacitance cable to your ESL-speaker...
4600Volts is a lot of Volts! Makes me curious how they expect it to be hooked up.
Polarity switches affecting only one channel were more common back in the late 1950s and early 1960s when companies were adapting to that new fad called “stereo.” Enthusiasts who already had a good mono system could add just a few components to go stereo, e.g. a second mono amp and a separate FM multiplexer box as well as a second speaker of course. Often the new amp or even the new speaker was not the same model as used in the mono system, and since nothing was standardized back then, it was about a 50/50 proposition that the new channel would be in phase with the original mono gear. The phase or polarity switch on the new stereo preamp let the user determine which polarity sounded best. You have to wonder if some people chose the reversed phase position because it sounded the most different from what they were used to.
The problem is when the recording is made there's no way to know the absolute polarity as there a microphones that invert phase and those that don't, along with mic preamps, tape machines, LP mastering equipment and digital recording equipment. So you need a switch to know which is right, but again it really only works if the original recording was done it true stereo.
So far the only preamp I know of that had a phase switch to correct if you had one speaker connected out of phase is the Citation 1.
Right. So how to they connect to the speaker? I've not seen a connector like that on ESLs. Most of them I'm aware of would need to be modified.
you have to bring your ESL to them and they will convert it there. As far as I know.
There are no photos to be found on the internet pity.
This was the case with my corner horns built in the late 1950's. They were sold individually. David Karmeli, my dealer, spent twenty (20) years looking for a matching speaker, same design, same year, and finally found one. He then sold them to me as a pair. Later iterations were sold as pairs, at least that is my understanding.
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Oh they still make it…cool.Here
Mono OTL - Twinstatic Audio
Mono OTL direct drive amplifier for ESL loudspeakers Spin-off from the Acoustat upgrade is a complete new mono direct drive amp, based upon the Acoustat Servo-charge Amp + upgrade. The amplifier is build in a 19” inch rack with handles. The special low capacitance cable to your ESL-speaker...
Yes, David Karmeli is very patient and determined.
For the benefit of the rest of us , might you extrapolate a little further upon your statement ?
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Right- its a pretty good bet that 50% of recordings are inverted. But it really isn't important unless the recording is in true stereo and most aren't.
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