EC8010 you mean a TL074 not 72.
You are right about the noise, but it doesn't make a difference here since the signal level is quite high.
Frank, everybody keeps mentioning about problems with this amp
The only I have seen is to stay away from Sylvania 6HB5. This brand is very flaky is this configuration.
Indeed like Sy mentioned, it is a very very dangerous amp : deadly.
Only the well experienced can handle this one.
Zelter, the dimensions of the HV transformer core are :
5cm wide
11,5cm high
9,5cm long
It's ouput is 2kV ac, with a voltage doubler the resulting is 4,8kVdc.
Oh, and talking about speaker cables, Final sells specially designed HV cable with 3 leads for ESL.
They have them in 2 sizes.
Dick
You are right about the noise, but it doesn't make a difference here since the signal level is quite high.
Frank, everybody keeps mentioning about problems with this amp
The only I have seen is to stay away from Sylvania 6HB5. This brand is very flaky is this configuration.
Indeed like Sy mentioned, it is a very very dangerous amp : deadly.
Only the well experienced can handle this one.
Zelter, the dimensions of the HV transformer core are :
5cm wide
11,5cm high
9,5cm long
It's ouput is 2kV ac, with a voltage doubler the resulting is 4,8kVdc.
Oh, and talking about speaker cables, Final sells specially designed HV cable with 3 leads for ESL.
They have them in 2 sizes.
Dick
yep,
thats why the Acoustat X amp has capacitors in the output, which I strongly suggest.
Besides this, a dc on the stators would mean a smaller voltage difference between the stators and foil. Hence, less efficiency.
To compensate, a higher bias voltage would be necessary.
My Acoustat ESL's also have a wire stator made of isolated wire.
So I'm not so affraid of being electrocuted, the panel is pretty safe in normal use.
Dick
thats why the Acoustat X amp has capacitors in the output, which I strongly suggest.
Besides this, a dc on the stators would mean a smaller voltage difference between the stators and foil. Hence, less efficiency.
To compensate, a higher bias voltage would be necessary.
My Acoustat ESL's also have a wire stator made of isolated wire.
So I'm not so affraid of being electrocuted, the panel is pretty safe in normal use.
Dick
Another opamp you might try with the Acoustat servo is a relatively new one by Burr Brown, the OPA404KP quad. Digikey is now carrying it, it's a jfet input. Also cleaning up the front end circuit to go along with that may help too, i.e. better resistors & caps, even modding if you know what you're doing. As for the HV section, I found that a Caddock in the feedback resistor section stabilized the bias immensely, as well as opened up the sound. The amp isn't perfect, but a tweakers dream if you just want to put the effort into it.
About Sasha's point
I'm with Sasha about wanting to see an all-tubed circuit for this. It also must be very interesting how it's incorporated onto the stock board. Seeing the EQ and biasing solutions would get my attention. I know that a fellow named Danny Fanny has done work along these lines before as well as Joe Curcio having quite the background and also made appearances in this forum.
djmiddelkoop, what panels will your revamped amp be used with, if you don't mind my asking?
I'm with Sasha about wanting to see an all-tubed circuit for this. It also must be very interesting how it's incorporated onto the stock board. Seeing the EQ and biasing solutions would get my attention. I know that a fellow named Danny Fanny has done work along these lines before as well as Joe Curcio having quite the background and also made appearances in this forum.
djmiddelkoop, what panels will your revamped amp be used with, if you don't mind my asking?
RetroAudio,
I use Acoustat panels removed from a Spectra 11.
For these panels a new sturdy housing is made.
Acoustat panels are so well made, they seldom have problems, are almost indestructible and are everlasting.
The low end is a subwoofer with Peerless XLS10, also in a seperate enclosure.
Sasha, I will post the schematic shortly.
I use Acoustat panels removed from a Spectra 11.
For these panels a new sturdy housing is made.
Acoustat panels are so well made, they seldom have problems, are almost indestructible and are everlasting.
The low end is a subwoofer with Peerless XLS10, also in a seperate enclosure.
Sasha, I will post the schematic shortly.
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