ECC88 tube buffer NEEDED ! - 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 12th December 2011, 10:34 AM   #1
diyAudio Member
 
Join Date: Jun 2009
Default ECC88 tube buffer NEEDED !

Hi
I have about 10 ecc88 tubes from different brands (philips bugle-boy, avirex, toshiba, svetlana & sovtek) . I want to make some tube buffers so i can give an analogue kind of sound to digital sources (like cd players).
Does anyone have a simple circuit to share with me?
Many Thanks
Vassilis
  Reply With Quote
Old 12th December 2011, 10:38 AM   #2
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
Search for a thread started by Wavebourn in which he presented a circuit which allows you to adjust how much distortion to add to a signal.
  Reply With Quote
Old 12th December 2011, 11:39 AM   #3
bigwill is offline bigwill  United Kingdom
diyAudio Member
 
Join Date: Dec 2004
Location: UK
Seconding DF96, a (properly designed) ECC88 buffer / follower will not have a sound and you may be disappointed.
  Reply With Quote
Old 12th December 2011, 01:05 PM   #4
diyAudio Member
 
Join Date: Aug 2010
Location: Near Eindhoven, the sanctum of the pentode. and among that other things.
Send a message via Skype™ to v4lve lover
ecc88 is terribly lineair if you want coloured sound go for something whit horrible distortion btw dont forget it was made to operate at about 90vdc plate so dont go higher
  Reply With Quote
Old 12th December 2011, 01:10 PM   #5
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
Run a 12AX7/ECC83 from a +12V supply and you can get as much distortion as you want. Or use a low gain remote cutoff valve like EF92 as a cathode follower - plenty of second order distortion so it could sound quite 'musical'.
  Reply With Quote
Old 12th December 2011, 04:30 PM   #6
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Seems like the ECC82 run on a low plate voltage might also be a choice. Generally if you want to warm up bad digital sound it means designing a bad (distorting) tube amplifier stage to do that - hence the many comments to that effect. Ideally you would want to bias for maximal 2nd harmonic..
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 12th December 2011, 04:50 PM   #7
diyAudio Member
 
Join Date: Jan 2002
Location: nowhere
Quote:
Originally Posted by v4lve lover View Post
... btw dont forget it was made to operate at about 90vdc plate so dont go higher
I've used these at > 200V with no issues. Usually I run them at 50-140V on the plates depending on usage, but they can take 200V and more. Look at some old HP oscilloscope schems, and you'll see them with b+ up to 400V.

With only 40-50volts you'll probably get some 2nd Harmones but it might not be enough to hear. Also at such low voltages you may start to pull some grid current, but an iPhone or other digital devices will probably handle that fine.
  Reply With Quote
Old 12th December 2011, 05:23 PM   #8
diyAudio Member
 
Join Date: Jun 2010
Location: St. Petersburg
Quote:
Originally Posted by vmed_cha_gr View Post
I want to make some tube buffers so i can give an analogue kind of sound to digital sources (like cd players).
You can get good interpolated DAC instead might be a much better option.

Wadia decoding computers are good could be purchased second hand form Audiogon at decent price. Pioneer Legatto Link fairly inexpensive however not on a par with Wadia or dSC.

6DJ8 and similarities like ECC88 tubes were designed to be used in oscilloscopes like Tektronix.

BTW I am owning Graaf 13.5 II powered by 6922 it is the best preamp I ever heard.

You can Google ECC88 mu-follower to let your tubes be implemented.
  Reply With Quote
Old 12th December 2011, 10:03 PM   #9
ChrisA is offline ChrisA  United States
diyAudio Member
 
Join Date: Jan 2008
Quote:
Originally Posted by vmed_cha_gr View Post
Hi
I have about 10 ecc88 tubes from different brands (philips bugle-boy, avirex, toshiba, svetlana & sovtek) . I want to make some tube buffers so i can give an analogue kind of sound to digital sources (like cd players).
Does anyone have a simple circuit to share with me?
Many Thanks
Vassilis
If you find a good design it will not do what you want. The "tube sound" requires that the tube be used to provide some gain. Even bette if the tube provides some gain in an open loop with no NFB.

The common way to do that is found in most guitar amps. The use the tube to provide abot 50X voltage gain and then squash all of that with a voltage divider (aka "gain pot"). Such a stage can produce at least 10% THD. More if you abuse it.

But almost all buffer designs you see will be very conservative and will sound just like a short length of good wire.

What you want is easy to design. build a common cathode gain stage with a smallish plate load and then a 10:1 resistive divider.
  Reply With Quote
Old 12th December 2011, 10:12 PM   #10
ChrisA is offline ChrisA  United States
diyAudio Member
 
Join Date: Jan 2008
Quote:
Originally Posted by kevinkr View Post
Seems like the ECC82 run on a low plate voltage might also be a choice. Generally if you want to warm up bad digital sound it means designing a bad (distorting) tube amplifier stage to do that - hence the many comments to that effect. Ideally you would want to bias for maximal 2nd harmonic..
YES. Exactly. Don't think "HiFI". Look instead to musical instrument amps for inspiration and ideas. These kinds of amps are NOT designed to reproduce music, but to create music. Very different goals.

In technical terms what you are looking for is adding a bit of compression to transients so they clip softly and in a 'musical way' and at the same time actually adding some low numbered harmonics.

BTW "maximal" 2nd harmonic might be more than you want. But adding 5% to 10% is not unreasonable.
  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
SONOS + DAC + 125ASX2 Icepower - buffer needed? Simes123 Class D 1 23rd October 2011 05:10 PM
Tube socket for ECC88, drawing peranders Tubes / Valves 7 10th August 2009 01:59 PM
is an input buffer needed for a sallen-key filter? oraz Solid State 2 12th May 2008 07:39 PM
buffer stage ECC88 or ECC83? KevinTams Tubes / Valves 4 27th August 2005 12:09 AM
ecc88 tube pover supply-rect. marijan Tubes / Valves 8 15th June 2005 09:50 AM


New To Site? Need Help?

All times are GMT. The time now is 04:51 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