Hi,
Mr. Glenn Croft never releases the circuit diagrams of his amplifiers.
I very much he even draws any; he didn't 15 years ago so I doubt he would now.
However, if you have a working unit it's not that hard to do it yourself as everything is hardwired.
Cheers, 😉
Mr. Glenn Croft never releases the circuit diagrams of his amplifiers.
I very much he even draws any; he didn't 15 years ago so I doubt he would now.
However, if you have a working unit it's not that hard to do it yourself as everything is hardwired.
Cheers, 😉
Hello ,
I have a original Croft Circuit diagram from the Croft "OTL Power Amp Serie 3" with two ECC 83 and four PL 519 .
Regards , AlexK.
I have a original Croft Circuit diagram from the Croft "OTL Power Amp Serie 3" with two ECC 83 and four PL 519 .
Regards , AlexK.
Hi,
First of all, thx for the scans.
The diagram seems to have been drawn by the Italian distributor or at least some of it was.
However, there's some mistake on it as apparently the warning about the printer error on scan # 3 was completely misunderstood and subsequently ignored : the partial line that remained due to this printer error was again redrawn and prolonged so it actually connects R7 to R19.
This line needs to be erased as it puts the 300V B+ of the bottom ECC83 straight on the grid of the PL519, distracting the -40V bias that would still leave the grids of the bottom part of the SEPP stack at a valve killing 260V.
Please check this for yourselves as I could have overlooked something and don't have an amp to check this either.
Note also that if you continue the same printer error line straight to the right you'll also notice that the cathodes and heaters of the bottom PL519s are shorted together.
This of course can't be right....
All in all, while I'm of course happy to have a copy of the circuit, I find the design rather disapointing.
Even to the point that I'm having trouble to believe this is actually a Croft design.
I'll spare you the rest of my complaints with it...
Cheers,😉
First of all, thx for the scans.
The diagram seems to have been drawn by the Italian distributor or at least some of it was.
However, there's some mistake on it as apparently the warning about the printer error on scan # 3 was completely misunderstood and subsequently ignored : the partial line that remained due to this printer error was again redrawn and prolonged so it actually connects R7 to R19.
This line needs to be erased as it puts the 300V B+ of the bottom ECC83 straight on the grid of the PL519, distracting the -40V bias that would still leave the grids of the bottom part of the SEPP stack at a valve killing 260V.
Please check this for yourselves as I could have overlooked something and don't have an amp to check this either.
Note also that if you continue the same printer error line straight to the right you'll also notice that the cathodes and heaters of the bottom PL519s are shorted together.
This of course can't be right....
All in all, while I'm of course happy to have a copy of the circuit, I find the design rather disapointing.
Even to the point that I'm having trouble to believe this is actually a Croft design.
I'll spare you the rest of my complaints with it...
Cheers,😉
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