quad el84 or PP el34 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs 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

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 September 2010, 11:31 PM   #1
diyAudio Member
Join Date: Feb 2009
Default quad el84 or PP el34

Im trying to decide if the pain of going over 400 volts is worth it.

I want to make a oddwatt/simple el84 type setup with a ccs in pp arrangement. However my test el84 setup with b+ of 230,ccs of 83ma for the pair and 7200ohm primaries in pentode mode, wasnt loud enough to drive my dayton reference MTM's with very complicated crossovers.

I figure thats 9 watts of plate dissipation with the current setup. Now the el84 can do 12 watts plate, and i have the nice russian 6P14P-EV on hand. I also have a set of winged-C el34's. The el34 dissipates 25 watts.

So the question is, do i do 2 pair of el84's with half the primary impedance, or do i do a normal el34 setup?

The oddwatt uses 450volts with an 8k primary and a ccs of 125ma. So thats a plate dissipation of 28watts with half the recommended load(??? he normaly does 80% of max plate).
If i just doubled up the el84 and upped the voltage to 300 that would give me about 12 watts of plate, and i would need 4k primaries. So thats about the same power as the el34 setup. But the B+ means i can use way less expensive caps and even some silicon regulators if i want.
  Reply With Quote
Old 17th September 2010, 05:09 AM   #2
diyAudio Member
Wavebourn's Avatar
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn

I would not go with CCS in cathodes to drive speakers with complex crossovers. I would use EL84 tubes with fixed bias instead, and local feedbacks by voltage across them.
Either one pair of EL34, or 2 pairs of EL84, the end result will be similar, but less tubes means easier bias adjustment.

Also, 6P41S would be a good option for this case. They are cheap and wide available currently, greatly under-priced. With +140V stabilized screen grid voltage it looks like 2 of EL84 in parallel.

Just my +2 cents.
The Devil is not so terrible as his math model is!
  Reply With Quote
Old 17th September 2010, 07:37 AM   #3
Ian444 is offline Ian444  Australia
diyAudio Member
Join Date: Nov 2008
Location: Brisbane QLD
You need more B+ to get the max out of a pair of EL84, say aim for 320V across the tube, that will give a lot more power than 230V B+. Also, if you use fixed bias and a standard LTP or cathodyne phase splitter, that will get you out of Class A into AB for around 15W per channel. Oddwatt is limited to Class A, I built one and liked it, but Class AB will give more power. It depends on your needs/desires in which direction you go.
  Reply With Quote


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
EL84 PP output transformer for 6L6 PP class A engels Tubes / Valves 8 30th May 2007 09:45 AM
Which do you prefer - EL84 UL PP or EL34 Triode PP - and why? ray_moth Tubes / Valves 4 23rd February 2007 12:22 PM
El34 PP Vs. El34 PSE alexmoose Tubes / Valves 47 6th September 2006 05:44 PM
EL34 Vs. EL84....... honsten Tubes / Valves 1 23rd July 2004 10:35 AM

New To Site? Need Help?

All times are GMT. The time now is 09:04 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2