• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Frank's EC8010/6C45P-GM70 SE Interstage.


2009-03-16 9:56 am
Hi Folks,

After month's of scudding thru the various Forums, I was delighted to come across Frank's EC8010/6C45P-GM70 SE Interstage
schematics posted in Nov.2002.

Why Frank's ?
Well ... not too complicated 2 stages design and above all, one of the few guys out there whose schematic I can safely rely on.

Anyone built it?
Care to share your experience and insight !?


With Regards,



2009-09-24 1:53 pm
1. Do note that you will be using voltages above 1.2kV (translated as DANGEROUS to a newbie)
2. You will need a good interstage transformer (translated as EXPENSIVE)
3. You will need very high voltage output transformers (translated as SUPER EXPENSIVE).

But no one is going to stop you from trying. Just be extremely careful and know what you are getting yourself into.
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EC8010 or this Russkie are no good choices as drivers for a transmitting tube output stage. Way too little headroom. Non linearities due to grid current will kick in around -0,7V at the EC8010. This is one of those designs where you will have significant changes in sound by small changes of op point, especially in the driver.

Sometimes simple can be too simple.

Best regards