2 Stage GM-70 amp in A2... possible? - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 18th December 2012, 05:37 PM   #11
diyAudio Member
 
Join Date: Feb 2010
Location: Helsinki
Sure it's possible!

Input stage: 6SL7 with gyrator load.

Then a MOSFET source follower (perhaps loaded with a CCS) driving the grid. Follower sets the grid bias for the GM70. Downside is you'll need a negative supply, but that's not too bad.
  Reply With Quote
Old 18th December 2012, 07:55 PM   #12
diyAudio Member
 
Palustris's Avatar
 
Join Date: Aug 2006
Location: Cape Cod
That's three stages.
  Reply With Quote
Old 18th December 2012, 09:13 PM   #13
djn is offline djn  United States
diyAudio Member
 
djn's Avatar
 
Join Date: Oct 2004
Location: Waterford Michigan
I am doing a 12GM7A into a GM70. Should work well. I don't know what A1 and A2 really means, but my compression drivers are 113db efficient and the GM70 should put out about 12WPC so that will work just right.
__________________
My "Art" website http://home.comcast.net/~djnagle/site/
  Reply With Quote
Old 18th December 2012, 09:27 PM   #14
joda is offline joda  Italy
diyAudio Member
 
Join Date: Feb 2005
Location: roma
yes, possible
regards

gm70 a2 amp.JPG
  Reply With Quote
Old 19th December 2012, 06:48 AM   #15
diyAudio Member
 
Join Date: Sep 2009
Interesting circuit concept joda. I guess if I have a high gain preamp, I could skip the first step-up transformer....
  Reply With Quote
Old 19th December 2012, 07:03 AM   #16
JZatopa is online now JZatopa  United States
diyAudio Member
 
Join Date: May 2003
Location: Chicago
Here is a 2 stage GM70 amplifier that I think is a wonderful design by Greenvalve. I have asked him to elaborate on it but unfortunately he currently isn't able to spend much time discussing it. This amp exemplifies what I think the future of audio needs to start looking like. That is, using every modern technology and technique to get the best sound. We need to stop holding onto tradition for the sake of tradition and start looking at using the best design for the job. If I were to try to undertake such an amp the only thing I might do different would be a powerdrive, ala tubelab, instead of a choke; using a power jfet. Hope it helps you out.

Greenvalves - The Maxium GM70
  Reply With Quote
Old 19th December 2012, 07:11 AM   #17
cotdt is offline cotdt  United States
diyAudio Member
 
Join Date: Oct 2005
Send a message via AIM to cotdt
If you use a preamp, then that is 3 stages.
  Reply With Quote
Old 19th December 2012, 07:27 AM   #18
diyAudio Member
 
Join Date: Mar 2011
Location: Jarna
Quote:
Originally Posted by DJNUBZ View Post
Here is a 2 stage GM70 amplifier that I think is a wonderful design by Greenvalve. I have asked him to elaborate on it but unfortunately he currently isn't able to spend much time discussing it. This amp exemplifies what I think the future of audio needs to start looking like. That is, using every modern technology and technique to get the best sound. We need to stop holding onto tradition for the sake of tradition and start looking at using the best design for the job. If I were to try to undertake such an amp the only thing I might do different would be a powerdrive, ala tubelab, instead of a choke; using a power jfet. Hope it helps you out.

Greenvalves - The Maxium GM70
With that amount of SMPS i hope they´re high quality.

If not top notch and properly implemented HF noise and transmitting tubes can end up as a gigant oscillator.

That´s perhaps the main reason for using non effiecent EI-core transformers, their good rejection and bad coupling of HF noise.
  Reply With Quote
Old 19th December 2012, 07:50 AM   #19
diyAudio Member
 
Join Date: Sep 2009
thanks DJnubz

wow... a high gain transmitter driving another transmitter.... that sounds like an idea....
any other candidates for the driver tube apart from the 826? the 826 curves show it to be less than linear....
  Reply With Quote
Old 19th December 2012, 09:52 AM   #20
diyAudio Member
 
Vincent77's Avatar
 
Join Date: Jan 2011
Location: Bruxelles
Quote:
Originally Posted by DJNUBZ View Post
Here is a 2 stage GM70 amplifier that I think is a wonderful design by Greenvalve.
That design produces about 10W in A1... And the stacked SMPSs are a bad idea, IMHO, as the noise also adds up.


As for the JAC music schematic posted by joda above, it's a joke meant to sell a ton of expensive iron to naive people.

Last edited by Vincent77; 19th December 2012 at 10:01 AM.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
GM-70 All done MelB Tubes / Valves 32 1st February 2013 11:50 PM
FS: GM70 ( GM-70 ГМ-70 ) Russian audio triode radiostar Vendor's Bazaar 0 23rd February 2011 07:12 PM
GM-70, A2, biamping victor_2 Tubes / Valves 10 20th November 2010 11:30 PM
6C33C and GM-70 Colt45 Tubes / Valves 21 21st November 2002 12:38 AM


New To Site? Need Help?

All times are GMT. The time now is 01:23 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2