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

problem with EL84 PP amp
problem with EL84 PP amp
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
Thread Tools Search this Thread
Old 16th March 2005, 09:56 AM   #1
resident is offline resident
Account Disabled
Join Date: Sep 2004
Location: Earth
Unhappy problem with EL84 PP amp

A friend of mine has build the attached amp from SDS labs .
But it doesn't work.
The outputs of the phase splitter are too much different! Measurements with voltmeter saw as that we have the same voltage at the grid and at the cathode of the phase splitter.
Not the desired 2V that are needed for bias.But around 100mV difference!
An other strange thing is that the first tube works with 0,5mA!
After all these I'm thinking that the 4K75 at the cathode of the first stage is too big.What do you say?
Any help?
Attached Files
File Type: pdf el84sch.pdf (60.4 KB, 80 views)
  Reply With Quote
Old 16th March 2005, 12:31 PM   #2
SY is offline SY  United States
On Hiatus
SY's Avatar
Join Date: Oct 2002
Location: Chicagoland
problem with EL84 PP amp
That first hole is being run pretty lightly, but 0.5mA is not unreasonable.

What are your measured B+ rails for the first and second stage?
"You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."
  Reply With Quote


problem with EL84 PP ampHide 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
5W EL84 drive EL84 SE Audio_idiot Tubes / Valves 31 31st May 2012 09:38 PM
el84 - 807 ? then_dude Tubes / Valves 19 8th December 2005 10:32 PM
EL84 DPP and Full Range problem PTSOUNDLAB Tubes / Valves 6 18th August 2003 07:23 PM
EL84 BIAS problem - again.... Buhl Tubes / Valves 4 28th November 2002 11:31 PM

New To Site? Need Help?

All times are GMT. The time now is 07:58 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio