Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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

"The Tsar" GM70 single ended amplifier
"The Tsar" GM70 single ended amplifier
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 11th February 2018, 06:32 PM   #11
Profi is offline Profi  Russian Federation
diyAudio Member
 
Join Date: Jun 2016
For the pentode, the cathode winding is 10/90 - 20/80. For a triode - up to 10%
  Reply With Quote
Old 11th February 2018, 06:41 PM   #12
dtaylo3 is offline dtaylo3  United States
diyAudio Member
 
Join Date: Nov 2004
Location: coloradao usa
1082 volts. Don't drink beer when assembling or turning on for the first time!
  Reply With Quote
Old 11th February 2018, 06:58 PM   #13
pieter t is offline pieter t  Netherlands
diyAudio Member
 
Join Date: Apr 2009
Quote:
Originally Posted by VladimirK View Post
In this industrial amp similar FB winding is used. Since this approach is not so widely used, it must have some disadvantages. Could anybody tell about disadvantages?

sacthailand.com

"These will help generate very high quality bass response unheard from conventional SE amp since the controlled motion of woofer is greatly increased. Minuet, therefore, redefines superb bass response (thus enhances full body) along with its excellent midrange and high frequency response.

Besides from lowering THD figure, Cathode Feedback circuit of Minuet EL-34SE does not introducing typical high order odd harmonic distortion associated with most global negative feedback. This helps maintaining smooth and liquid sound without hint of sibilance.

Additional benefits of using cathode feedback circuit are:
1) Lowering output impedance
2) Increasing Damping factor
3) Extending frequency response at both ends of audio spectrum"
There are no "disadvantages" apart from the fact that the output transformer is a bit more complex, and voltage gain of the output tube is diminished as a result of local feedback so it requires more from the driver stage.
Your "additional benefits" 1) and 2) are mutually inclusive.
  Reply With Quote
Old 11th February 2018, 07:31 PM   #14
audiowize is offline audiowize  United States
diyAudio Member
 
Join Date: Aug 2005
Location: Seattle
Send a message via AIM to audiowize
The disadvantage is cost. There's also the disadvantage that asking the winder for a "cathode feedback winding" isn't enough, you need to specify the impedance of it, and this is design dependent.
  Reply With Quote
Old 12th February 2018, 02:42 AM   #15
VladimirK is offline VladimirK  Uzbekistan
diyAudio Member
 
Join Date: Feb 2007
Location: Tashkent
The text below explains some additional difficulty about cathode winding:
"Output transformers with cathode winding are more expensive than analogous ones without dividing the primary. For a very simple reason - in order for the cascade to be stable and with low distortions at high frequencies, the mutual leakage inductance of the separated windings must be extremely low. For this purpose, the windings are made in two wires, and a more expensive wire with silk insulation or triple lacquer is used to provide the required electrical strength. Accordingly, the filling factor of the window falls, which leads to the need to increase the dimensions of the transformer.
By the way, the cathode winding, regardless of its ratio over the turns with the anode, with the correct phasing, forms the classical sequential NFB by voltage, an example is discussed in RDH (the chapter of Negative Feedback, the edition of 1952)."
  Reply With Quote
Old 14th February 2018, 11:54 AM   #16
211audio is offline 211audio
diyAudio Member
 
211audio's Avatar
 
Join Date: Feb 2006
Location: Netherlands
Default "The Tsar" GM70 single ended amplifier

The reason for building this amplifier was finding an alternative for the 211 amplifier. My current amp's are running on RCA 211 Tubes (@ USD 1000+ a pair nowadays) so the step to make an amplifier with GM-70 @ USD 25 a pair was the logic thing to do. I can tell you that the GM-70 amp is the better sounding amp. Even with the Svetlana 300B, the TCO of this amp is lower than my 211 mono blocks.

I have also used a CFB for my 211 amps iGoliath 211

The 9K primary was well chosen. If you look at the graphics of the THD and Frequency response on the last page of the article, you can see that there is nothing to complain about.

6H30 - a wonderfull sounding and stabile and very quiet tube. A Sovtek or EH tube is good enough here.

The first stage is build around the Alan Kimmel mu-stage, where V1 Triode can be primary a voltage amplifier and V2 delivers the current.

The OPT's are reasonably priced... that is below €300,= a pair. You can inquire about the specs and pricing here: Home - Vlaartronic

The driver setup was copied from the Audio Note Ankoru SE 845 (edition 12, page 10) There's a link to the schema within the article's text.

Last edited by 211audio; 14th February 2018 at 12:24 PM.
  Reply With Quote
Old 14th February 2018, 12:40 PM   #17
211audio is offline 211audio
diyAudio Member
 
211audio's Avatar
 
Join Date: Feb 2006
Location: Netherlands
Something is missing: (Sound Practices: edition 12, page 10)
  Reply With Quote
Old 14th February 2018, 12:57 PM   #18
Profi is offline Profi  Russian Federation
diyAudio Member
 
Join Date: Jun 2016
how % is a CFB?
  Reply With Quote
Old 15th February 2018, 09:23 AM   #19
211audio is offline 211audio
diyAudio Member
 
211audio's Avatar
 
Join Date: Feb 2006
Location: Netherlands
As I recall, It's a winding with an impedance of 16R. I will check it out for you.

Last edited by 211audio; 15th February 2018 at 09:31 AM.
  Reply With Quote
Old 15th February 2018, 07:51 PM   #20
211audio is offline 211audio
diyAudio Member
 
211audio's Avatar
 
Join Date: Feb 2006
Location: Netherlands
And 16 Ohm it is.
  Reply With Quote

Reply


"The Tsar" GM70 single ended amplifierHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Who know "NO LIMITS" Power Amplifier Stereo Class A Technology-J.Serva/Single Ended tiefbassuebertr Solid State 2 5th August 2017 08:16 AM
Single-ended amplifier with balanced input on the lamp GM70 FEDOSOFF Solid State 0 12th February 2014 06:43 PM
"CA-10", new Single Ended Power amp Device based on Aleph or ZEN ? tiefbassuebertr Pass Labs 1 29th September 2010 06:55 PM
"Mighty Mite" Single Ended Amplifier wrenchone Tubes / Valves 13 20th October 2008 04:57 AM
Using Telefunken "Tank" transfomers for a single ended el84 amp? ark Tubes / Valves 13 8th March 2004 11:32 PM


New To Site? Need Help?

All times are GMT. The time now is 12:22 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki