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day 19th April 2005 03:06 PM

want to do PP-GM70
2 Attachment(s)
hello... form THAILAND
I like to do PP-GM70 . I have tube OPT CASE POWER but circuit.
Help me please. where can i fine it.
thank you

kathodyne 19th April 2005 04:43 PM

Indeed, very little to find about it.
Read a couple of times that the gm70 is a beefed up 211
So...maybe you can try 211 or 845 schematics and play with the resistor values a bit

jlsem 19th April 2005 11:38 PM

Try this newsgroup:


day 21st April 2005 09:45 AM

Thank you

dowdylama 21st April 2005 01:33 PM

With the exception of it's unique socket and 20 v filament, the GM70 can be used interchangeably with the 845.

day 27th April 2005 04:28 PM

2 Attachment(s)
this is my finish PP GM70. I use 5751 for pre and phase st 5687 for drive sound is very good

leadbelly 27th April 2005 07:26 PM

Very nice! And very quick assembly!

What design did you use? That bloody forum won't validate my membership for some reason :(

jlsem 27th April 2005 11:53 PM


this is my finish PP GM70
That's gotta be a record...


day 28th April 2005 10:38 AM

2 Attachment(s)
i plan it by use OTL design in drive st and copy 845 in out put
fix bias at -100v at b+ 960v

day 2nd June 2005 02:33 PM

2 Attachment(s)
This is my 2TH PPgm70. it is 5687+300B+interstage+GM70
still working

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