Wim's DC EL84 amp - Page 2 - 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 27th October 2005, 07:14 PM   #11
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
Quote:
Originally posted by jackinnj
hate to think of pulling the shards out ---
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  Reply With Quote
Old 28th October 2005, 08:39 AM   #12
moamps is offline moamps  Croatia
diyAudio Member
 
Join Date: Oct 2002
Location: Croatia
Hi,

At second sight:

- Ia metering on only one tube
- no one PS bypass cap on board
- R23's gnd may be routed to ECC88's "9" pin
- reversed 200R trimmers.

Regards,
Milan
  Reply With Quote
Old 28th October 2005, 08:57 AM   #13
diyAudio Member
 
Join Date: Dec 2001
Location: Eindhoven
Quote:
Originally posted by jackinnj

This is version 4 -- with the ECC88 current source -- but I am going to outboard the -150V/+206V supply -- so both halves of the ECC88 are used for two amps on one board.

Dave -- I agree, the 60 mil trace width will poop out under the pressure of 7 tubes in parallel.

Hi

I'd sugest to connect both EL84 cathodes to each other, and leave the decoupling caps out.

This requires tightly matched valves and good DC balance from the driver.

best
__________________
Guido Tent
www.Tentlabs.com
  Reply With Quote
Old 29th October 2005, 09:40 AM   #14
diyAudio Member
 
Join Date: Oct 2004
Send a message via MSN to VanguardVillage
Default where is the schematics?

can i have a look ?
  Reply With Quote
Old 29th October 2005, 10:25 AM   #15
diyAudio Member
 
Join Date: Mar 2003
Location: Zürich
can i have a look ?

Here it goes:

http://www.wdehaan.demon.nl/tubeamps/el84dc/
  Reply With Quote
Old 28th December 2010, 01:40 PM   #16
diyAudio Member
 
Miniwatt's Avatar
 
Join Date: Nov 2004
Location: Den Haag
This came up on Google, I'm preparing to build the last version in the article.
Just one small question: what's the function of the (volt?) meter and resistor between the cathodes of the power tubes? And what range should it be, 100 V?

Cheers
  Reply With Quote
Old 28th December 2010, 01:54 PM   #17
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Link to article here: http://www.wimdehaan.nl/downloads/dccoupledamp.pdf

FWIW other comments not withstanding I would build the circuit as described in the article, and then modify if so inclined. High quality cathode bypass caps are a must however..

The meter is used to establish overall DC balance in the amplifier. Meter is a 50uA-0-50uA type as mentioned in the early paragraphs of the article.
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan

Last edited by kevinkr; 28th December 2010 at 02:02 PM.
  Reply With Quote
Old 28th December 2010, 05:23 PM   #18
diyAudio Member
 
artosalo's Avatar
 
Join Date: Feb 2010
The article is based on one assumption: (quote of the author)
" I believe that coupling capacitors have a major influence on the overall sound quality of an amplifier."

Have we so far got any evidence that this would be the case ?
I have not seen such.

That could be an interesting and distinctive project to build, but the test results published at the article do not show any excellence over normal construction with coupling capacitors.
  Reply With Quote
Old 28th December 2010, 05:28 PM   #19
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Quote:
Originally Posted by artosalo View Post
The article is based on one assumption: (quote of the author)
" I believe that coupling capacitors have a major influence on the overall sound quality of an amplifier."

Have we so far got any evidence that this would be the case ?
I have not seen such.

That could be an interesting and distinctive project to build, but the test results published at the article do not show any excellence over normal construction with coupling capacitors.
Actually I believe this based on long experience designing audio gear, but I also believe it is much easier to find an electrically blameless and good sounding film coupling cap than it is to find an equally good sounding cathode bypass cap regardless of cost. (By good sounding I mean transparent, and audibly artifact free. And yes I have done some single blind testing with coupling caps and a small listening panel. The result of that is that I now use mostly teflon/foil coupling caps. The Russian FT-3 is good and not too expensive a place to start. I use TFTs and Vcaps mostly.)
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan

Last edited by kevinkr; 28th December 2010 at 05:32 PM.
  Reply With Quote
Old 28th December 2010, 05:36 PM   #20
diyAudio Member
 
Miniwatt's Avatar
 
Join Date: Nov 2004
Location: Den Haag
I got rid of a gain stage (and thus a coupling cap) in my power amp because my preamp has enough gain, and that really cleared things up. So much so I got very interested in dc coupling. But no 'scientific evidence'..

(And I started thinking..)

Everyone will agree looking through an open window gives a better view then through glass. You can debate which sort of glass is the clearest, but no glass is always better..
  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
5W EL84 drive EL84 SE Audio_idiot Tubes / Valves 31 31st May 2012 08:38 PM
El84 Pp Tobruk Tubes / Valves 1 1st May 2007 12:05 PM
EL84 PP Diy. Pls help me!!! BigOx Tubes / Valves 24 11th June 2006 06:09 AM
el84 help inquisitive Tubes / Valves 14 26th March 2005 07:19 AM


New To Site? Need Help?

All times are GMT. The time now is 07:46 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