2 Stage GM-70 amp in A2... possible? - Page 3 - 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 19th December 2012, 10:24 AM   #21
diyAudio Member
 
Join Date: Oct 2010
Location: se england
I dont know if you could use the mu output from a cascoded dn2540etc with a da or other hi mu linearr triode underneath? Or perhaps the design that rod coleman uses?
Imho i think its probably not worth it for the extra db or two.
Enzo
  Reply With Quote
Old 19th December 2012, 10:51 AM   #22
diyAudio Member
 
Join Date: Sep 2009
wokie dokie... point taken. :-)
  Reply With Quote
Old 19th December 2012, 05:16 PM   #23
JZatopa is offline JZatopa  United States
diyAudio Member
 
Join Date: May 2003
Location: Chicago
Quote:
Originally Posted by Vincent77 View Post
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.
The noise seems to be so minor that it has little to no affect on the sound. Just check out the videos of it playing. The time of SMPS is here, if you can find the right ones.
  Reply With Quote
Old 19th December 2012, 06:02 PM   #24
ColinA is offline ColinA  United Kingdom
diyAudio Member
 
Join Date: Dec 2005
Location: Shropshire

If god had intended us to to use S.M.P.S

He would not have invented mercury-arc rectifier valves (tubes)

J.M.H.O.

Unless you are scared to use them.
__________________
Judge quality with your ears not instruments or simulators
  Reply With Quote
Old 23rd December 2012, 10:50 PM   #25
diyAudio Member
 
Join Date: Jun 2008
In MJ third Ed page 138, he discusses using a 6SN7 or 7N7 with a CCS in place of the load resistor. This enables you to use a flat load line at say 8ma and you can swing more than 300 volts pp that way at very very low distortion. (Ed. You would need to use the other half of the triode as a first stage)

I've been considering that circuit to drive an 845. It seems better than the 300B from a cost and distortion standpoint. I've not tried it yet and don't know how well it will work.

Also, I don't know if it will drive the big triode without a cathode follower. Anyone have an opinion on that?

Last edited by Captn Dave; 23rd December 2012 at 11:01 PM.
  Reply With Quote
Old 23rd December 2012, 11:59 PM   #26
diyAudio Member
 
Join Date: Oct 2010
Location: se england
Mu followers seem to be a four letter word these days, but if you have 1000+v to play with, need a flat load line and low driving impeadence they seem to fit the bill to me. i use one in my gm70, 6e5p for both load and gain stages with a 25w 15k vishay bulk foil as the load and 22.5ma/180v. b+ is regulated 700v (dont suppose it needs to be) down from 930 for the outputs, sounds pretty good to me, though i intend to try different gain valves and topoligys in the future.
I hope to put some measurements together over christmas.

enzo
  Reply With Quote
Old 24th December 2012, 12:53 AM   #27
JoshK is offline JoshK  Canada
diyAudio Member
 
Join Date: May 2004
Location: Toronto, ON
Haven't analyzed the 211 vs GM70 close enough to know if they require different drive, but on the surface they are similar.

https://lh3.googleusercontent.com/-T...S5-PSUincl.jpg

Thomas says he gets a bit of class A2 from the 211 and that is 2 stages san SMPS.
  Reply With Quote
Old 24th December 2012, 05:52 AM   #28
dgta is offline dgta  United States
diyAudio Member
 
Join Date: May 2011
Quote:
Originally Posted by quikie22 View Post
Was wondering if a 2 stage amplifier would be able to achieve A2. Any ideas?
Sure. If this was a question on an exam, with no other specs attached, I would say no problem. I will define the input requirements so I can easily achieve that.

If you're actually trying to design something, then the answer is "depends". You need to specify the input to be used and the definition of "stage". And any other restrictions you want to place on it, like how far into A2 are we talking? How much distortion, etc.
  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 08:55 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