GM 70 Schematic needed! - Page 2

enzoastro · 11th November 2012, 09:12 PM

I used an antek 400-400 500ma toride for my gm70 amp, choke input gave mw 670v with the gm70's drawing 120ma each and 45ma for the driver stage, which is mu follower with 6e5p at 22.5ma/180v/3.7Vgk.
fitting a few small value caps at the ps input got me to 800v.

i now have the antek 500-500v 400ma to give 900v with very little capacitence, i like to think of it as choke input with snubbing caps ;-)

hope that may be of helkp
enzo

gaborbela · 12th November 2012, 06:26 AM

Hello djn
How much power you get out from these circuit?
About 15-17W, of course deepened on the bias set up.
I was thinking to build these 2 stage amp but after I changed my mind and I sold the 12GN7A tubes.
Otherwise very nice clever circuit.
Greetings Gabor

djn · 12th November 2012, 12:54 PM

Thanks Gabor, some where in that range seems right. I am only driving my midrange horns with this amp and they are 113db eff. so if I got 10wpc that would be fine. I just wanted something simple.

gaborbela · 12th November 2012, 04:50 PM

Quote:

Originally Posted by enzoastro

I used an antek 400-400 500ma toride for my gm70 amp, choke input gave mw 670v with the gm70's drawing 120ma each and 45ma for the driver stage, which is mu follower with 6e5p at 22.5ma/180v/3.7Vgk.
fitting a few small value caps at the ps input got me to 800v.

i now have the antek 500-500v 400ma to give 900v with very little capacitence, i like to think of it as choke input with snubbing caps ;-)

hope that may be of helkp
enzo

Hello
Can you lead (i have the parts number) me to that transformer . I did look his stock and I only find 400mA.
Thank you very much
Greetings Gabor

vuki · 12th November 2012, 05:30 PM

Gabor, you won't have any problem with 400mA transformer.

enzoastro · 12th November 2012, 05:36 PM

Ant-4400

gaborbela · 12th November 2012, 06:22 PM

Quote:

Originally Posted by vuki

Gabor, you won't have any problem with 400mA transformer.

Hello
I just wanted to be sure.
Thank you

enzoastro
When the transformer part number start with #4 that is 400mA.
Greetings G

enzoastro · 12th November 2012, 06:24 PM

400va not ma ;-)

gaborbela · 12th November 2012, 06:35 PM

I'm sorry I missed that.
You right.
Your transformer did good job? I mean didn't got to warm after few hours etc...

Greetings Gabor

gaborbela · 12th November 2012, 07:41 PM

Hello
To avoid the further confusion I would like to use these transformer to that amplifier PS.
Antek - AS-4T400
I don't know how I messed up the mA with VA.
Once more I apologize.

Greetings Gabor

12th November 2012, 12:54 PM	#13
djn diyAudio Member Join Date: Oct 2004 Location: Waterford Michigan	Thanks Gabor, some where in that range seems right. I am only driving my midrange horns with this amp and they are 113db eff. so if I got 10wpc that would be fine. I just wanted something simple. __________________ My "Art" website http://home.comcast.net/~djnagle/site/

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11th November 2012, 09:12 PM	#11
enzoastro diyAudio Member Join Date: Oct 2010 Location: se england	I used an antek 400-400 500ma toride for my gm70 amp, choke input gave mw 670v with the gm70's drawing 120ma each and 45ma for the driver stage, which is mu follower with 6e5p at 22.5ma/180v/3.7Vgk. fitting a few small value caps at the ps input got me to 800v. i now have the antek 500-500v 400ma to give 900v with very little capacitence, i like to think of it as choke input with snubbing caps ;-) hope that may be of helkp enzo

12th November 2012, 06:26 AM	#12
gaborbela diyAudio Member Join Date: Sep 2005	Hello djn How much power you get out from these circuit? About 15-17W, of course deepened on the bias set up. I was thinking to build these 2 stage amp but after I changed my mind and I sold the 12GN7A tubes. Otherwise very nice clever circuit. Greetings Gabor

12th November 2012, 05:30 PM	#15
vuki diyAudio Member Join Date: Jun 2002 Location: zagreb, croatia	Gabor, you won't have any problem with 400mA transformer.

12th November 2012, 05:36 PM	#16
enzoastro diyAudio Member Join Date: Oct 2010 Location: se england	Ant-4400

12th November 2012, 06:24 PM	#18
enzoastro diyAudio Member Join Date: Oct 2010 Location: se england	400va not ma ;-)

12th November 2012, 06:35 PM	#19
gaborbela diyAudio Member Join Date: Sep 2005	I'm sorry I missed that. You right. Your transformer did good job? I mean didn't got to warm after few hours etc... Greetings Gabor

12th November 2012, 07:41 PM	#20
gaborbela diyAudio Member Join Date: Sep 2005	Hello To avoid the further confusion I would like to use these transformer to that amplifier PS. Antek - AS-4T400 I don't know how I messed up the mA with VA. Once more I apologize. Greetings Gabor