211 biasing voltages preferances - 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 14th April 2005, 07:27 AM   #1
diyAudio Member
 
Join Date: Apr 2005
Location: AUD
Question 211 biasing voltages preferances

Please
your preferred voltages for your 211 valve amp (not parallel)

example:

Volt Plate 950v
Volt grid -50
Amp plate 58ma
  Reply With Quote
Old 14th April 2005, 09:30 PM   #2
Radames is offline Radames  United States
diyAudio Member
 
Join Date: Apr 2005
Location: New York
Default Load

Hi,

The example values give a loadline of around 12.5KOhms. The OPT will be tricky that way.

May be a 10KOhm line with same Eg, a bit higher current (65mA or so) and 974 Ep could work. The will put the THD figure a bit higher (not much though) but squeeze more power out.

Alternatively a 11K, 9.5K or even 20K loads could be used, as Lundahl makes transformers with that primary Z.

Post your results if you have any. I want to learn more about experiences of people operating 211s.

Cheers,

Rada
  Reply With Quote
Old 15th April 2005, 07:52 AM   #3
diyAudio Member
 
Join Date: Apr 2005
Location: AUD
Default thanks so far but

thanks, based on an existing transformer (amp is built), just verying the -grid but keeping 950v as a referance what would be the ideal ma
  Reply With Quote
Old 15th April 2005, 03:22 PM   #4
Radames is offline Radames  United States
diyAudio Member
 
Join Date: Apr 2005
Location: New York
Hi,

I am a beginner of this and I have never built an amplifier. I am just designing one with 211 tubes and model the tube behavior and parameters in Matlab. So take my comments as comments from somebody in the process of learning about tubes and amps. Don't go mod your big $$$ amplifier based on what I say!

Anyhow, after the safety advisory, with the Ep at 950 with a 12.5KOhm loadline and 58 to 59mA you must have an Eg aorund -50V and 100V of grid swing or so, and a B+ a bit higher than 1000V (assuming SE topology and >250Ohm primary DCR for the OPT).

Keeping the loadline slope, and Ep at 950 you could only go higher on Eg (closer to 0). If you go lower, the distortion figure will get worse unless you reduce B+ and allow less grid swing.

At 58mA you are still a bit far from the limit of the tube. Assuming you want to reduce a bit its life, you could put the grid up to -45V to get the operating point pretty much on top of the dissipation limit curve of 75W (that's the data I have from one of the many 211 datasheets and it may not represent your tube). The current will be around 78mA and your OPT may not take it.

Without doing a major mod of the B+ supply you will loose a bit of power and like 10V of grid swing. The distortion figures may improve though.

So I guess that between -50V/58mA to -45V/78mA you could go anywhere in the middle.

Hope this helps.

Rada.


PS: Is it a SE I assume? What OPT you used to build it? Thanks.
Attached Images
File Type: jpg 211line.jpg (35.1 KB, 112 views)
  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
voltages on a zen v.9 gionag Pass Labs 5 28th May 2008 04:42 PM
low-biasing or high biasing in Class-AB amps Workhorse Solid State 124 18th October 2005 05:45 AM
PSU cap voltages lawbadman Solid State 4 3rd January 2004 01:37 PM
TV set voltages? setmenu Everything Else 10 20th March 2003 02:36 AM


New To Site? Need Help?

All times are GMT. The time now is 03:17 AM.


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