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 December 2008, 08:19 PM   #1
pftrvlr is offline pftrvlr  United States
diyAudio Member
 
Join Date: Feb 2007
Location: SoCal
Default Optimal operating point for 7N7/6SN7?

The typical operating plate current for 7N7/6SN7 looks to be 10ma. But due the limitation of the PS, it can only set to around 5ma. Will the distortion be high?

The 6SN7 is used as the first stage voltage amplification of CD signal.

Thanks.
  Reply With Quote
Old 14th December 2008, 08:44 PM   #2
diyAudio Member
 
Tubes4e4's Avatar
 
Join Date: Jul 2005
Location: Leverkusen
Hi pftrvlr,

never mind - using 6SN7 and brothers at Ia=5mA you definitely can get an extremely linear swing using an RL of at least 27k and a reasonable supply voltage.

More information on maximum expected input swing, needed stage amplification factor and maximum available supply voltage certainly would help to give specific operating point suggestions.

Regards,

Tom Schlangen
__________________
If in doubt, just measure.
  Reply With Quote
Old 15th December 2008, 01:50 AM   #3
diyAudio Member
 
Join Date: Nov 2005
For the first stage with a line-level signal, 5mA will be fine! The Williamson amp drives triode KT66s with 6SN7s running about 5-6mA. No problem
  Reply With Quote
Old 16th December 2008, 05:41 AM   #4
pftrvlr is offline pftrvlr  United States
diyAudio Member
 
Join Date: Feb 2007
Location: SoCal
I re-cal the operating points in the p-spice, and here is what I got

Plate 160v
Cathode 5.5V
Current 3.0mA
Plate reisistor 51K

I need to keep the plate voltage at around 160v, because it direct couple to the next WCF stage.

Will it be better off to reduce the plate resistor and increase the plate current to 5ma? The gain is not important.

Thx.
  Reply With Quote
Old 16th December 2008, 10:25 AM   #5
kuka_v is offline kuka_v  Russian Federation
diyAudio Member
 
Join Date: Jun 2007
I would like to suggest:

1:
Ups =400v
Up= 131v
Ip=9.5mA
Ug=-2v
Rpl=28kOm

or

2:
Ups =230v
Up= 107v
Ip=6.5mA
Ug=-2v
Rpl=18kOm

In both cases about 0.00 % distortion....
  Reply With Quote
Old 16th December 2008, 04:43 PM   #6
Sheldon is offline Sheldon  United States
diyAudio Member
 
Join Date: Dec 2003
Location: San Diego
Quote:
Originally posted by pftrvlr
Will it be better off to reduce the plate resistor and increase the plate current to 5ma? The gain is not important.
Three mA current is plenty, as long as your next stage doesn't load the output too much. I'd stick with the larger plate resistor. Or try both and see what sounds best to you. Easy enough to clip in parallel plate and cathode resistors.

Sheldon
  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
Calculating operating point of a DHT Pyre Tubes / Valves 2 26th February 2009 10:09 PM
6N6P and 6SN7 Operating point suggestions dsavitsk Tubes / Valves 2 17th September 2006 12:50 AM
Best Operating point for a 2A3? sgerus Tubes / Valves 10 2nd August 2006 12:31 AM
6sn7 operating points AudioGeek Tubes / Valves 15 8th September 2005 12:59 PM
Suitable operating point for 6SN7 as a differential driver ? ray_moth Tubes / Valves 15 27th October 2004 08:50 AM


New To Site? Need Help?

All times are GMT. The time now is 02:23 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