6sc7 vs. 6su7 in LTPI duty - 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 24th November 2006, 06:51 AM   #1
diyAudio Member
 
aletheian's Avatar
 
Join Date: Apr 2004
Location: Philly
Default 6sc7 vs. 6su7 in LTPI duty

I have a few of each (GE for the 6sc7 and Tung-Sol for the 6su7) and wondered which I should tinker with in a LTPI with a FET CCS driving a class A PP el34 output section. They seem fairly similar in performance on paper, but does anyone have experience with their sonics or op points where they are most comfy?
__________________
Heghlu'meH QaQ jajvam!
  Reply With Quote
Old 24th November 2006, 12:28 PM   #2
diyAudio Moderator Emeritus
 
ray_moth's Avatar
 
Join Date: Jan 2004
Location: Jakarta
Yes, they have almost identical mu and Rp but there is one big difference betwen them, namely, the 6SC7 has a shared cathode and the 6SU7 has separate cathodes. For LTP application this doesn't matter, of course, unless you want to use separate resistors between each cahode and the long tail, to compensate for any DC imbalance or to provide a little current NFB.

The 6SU7 is basically a 6SL7 selected for good matching. This tube makes an excellent-sounding LTP with a current of between 500uA and 1mA in each half. Use it with a CCS, as you say. 6SU7 is unsuitable for driving any kind of low impedance load or anything requiring significant voltage swing. It is far better to follow it with a 6SN7 differential driver.

PP El34s in pentode mode with cathode bias might be OK for 6SU7 to drive directly but with fixed bias or if strapped as triodes, they would impose too much of a load. I imagine a 6SC7, having similar characteristics, would be much the same.
  Reply With Quote
Old 24th November 2006, 07:52 PM   #3
diyAudio Member
 
aletheian's Avatar
 
Join Date: Apr 2004
Location: Philly
Good info. I'll consider a 6sn7 between the LTP and the el34's... shouldn't bee too much of a problem. Are you referring to a DC coupled follower setup with the bias voltage applied to the cathodes, or an AC coupled voltage amp setup (probably with a negative voltge "ground" refrerence) with the signal from the plates feeding the grids?
__________________
Heghlu'meH QaQ jajvam!
  Reply With Quote
Old 25th November 2006, 01:17 AM   #4
diyAudio Moderator Emeritus
 
ray_moth's Avatar
 
Join Date: Jan 2004
Location: Jakarta
I'm sorry, I don't understand your question.
  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
mid for 3 way duty pvl1 Multi-Way 6 22nd June 2008 12:12 AM
Summing at the LTPI memphissound Tubes / Valves 2 11th January 2008 04:36 PM
What of these for sub duty? leadbelly Subwoofers 25 22nd December 2004 07:31 PM
Battery bias a 6SU7 in the 300b billies tom1356 Tubes / Valves 2 16th October 2004 02:32 AM


New To Site? Need Help?

All times are GMT. The time now is 09:57 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