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

6SN7 push pull flea amplifier project
6SN7 push pull flea amplifier project
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 1st July 2018, 02:10 AM   #221
rongon is offline rongon  United States
diyAudio Member
 
rongon's Avatar
 
Join Date: Jul 2009
Location: Across the river from Rip's big old tree...
6SN7 push pull flea amplifier project
Quote:
Originally Posted by kodabmx View Post
I usually use LM317 or TL783. Wouldn't those work in an LTP?
Yes, they work, and they certainly are easy to install.

Walt Jung's AudioXpress articles describe the use of constant current sources/sinks. Part 1 describes the basics of operation:

http://waltjung.org/PDFs/Sources_101_P1.pdf

Part 2 compares LM317 constant current source/sink with a DN2540 based constant current source/sink, complete with measurements, etc.

http://waltjung.org/PDFs/Sources_101_P2.pdf

The LM317 CCS is okay, within its limits. It gets inductive as frequency goes up; its impedance goes down above 10kHz. That means an LTP with an LM317 (TL783) in its tail will have balance that gets worse above 10kHz, introducing harmonic distortion on higher frequencies. Perhaps bypassing it with a film cap helps?

The single DN2540 CCS works well and has more constant impedance with frequency.

Later updates in AudioXpress compared the cascode DN2540-LM317 against the cascode made with two DN2540s. The version with the two DN2540s performs better. That's the preferred high voltage CCS these days.

--
  Reply With Quote
Old 1st July 2018, 03:42 AM   #222
Carlp is online now Carlp  United States
diyAudio Member
 
Join Date: May 2006
Location: A New England
6SN7 push pull flea amplifier project
Yes, and I've used them (DN2540) in the tail of an LTP front end. But the output stage baffles me...
  Reply With Quote
Old 1st July 2018, 01:39 PM   #223
kodabmx is offline kodabmx  Canada
diyAudio Member
 
Join Date: Oct 2011
Location: Toronto
When it's bypassed by a giant cap I think of it as basically a programmable "smart" resistor.
  Reply With Quote
Old 1st July 2018, 01:43 PM   #224
kodabmx is offline kodabmx  Canada
diyAudio Member
 
Join Date: Oct 2011
Location: Toronto
Quote:
Originally Posted by rongon View Post
Yes, they work, and they certainly are easy to install.

Walt Jung's AudioXpress articles describe the use of constant current sources/sinks. Part 1 describes the basics of operation:

http://waltjung.org/PDFs/Sources_101_P1.pdf

Part 2 compares LM317 constant current source/sink with a DN2540 based constant current source/sink, complete with measurements, etc.

http://waltjung.org/PDFs/Sources_101_P2.pdf

The LM317 CCS is okay, within its limits. It gets inductive as frequency goes up; its impedance goes down above 10kHz. That means an LTP with an LM317 (TL783) in its tail will have balance that gets worse above 10kHz, introducing harmonic distortion on higher frequencies. Perhaps bypassing it with a film cap helps?

The single DN2540 CCS works well and has more constant impedance with frequency.

Later updates in AudioXpress compared the cascode DN2540-LM317 against the cascode made with two DN2540s. The version with the two DN2540s performs better. That's the preferred high voltage CCS these days.

--

Great info. I remember reading these articles when I was younger If only they made a DN2540 with a built in Vref like LM317 so you didn't need basically a trimpot to adjust current.
  Reply With Quote

Reply


6SN7 push pull flea amplifier projectHide 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
Chinese amp: 2A3 6SN7 6SJ7 5Z5P push pull Alexontherocks Tubes / Valves 16 7th May 2013 04:37 AM
6SN7 & 6V6 Push Pull - increase gain laosei Tubes / Valves 18 26th February 2013 08:01 AM
6sn7 driving Push Pull Parallel kt88's? ruben alstad Tubes / Valves 58 21st November 2012 11:08 PM
VTV Push-Pull 6SN7/KT88 Amp: DIY or China? 88man Tubes / Valves 5 18th October 2009 02:27 PM
YAPPAP (Yet Another Push-Pull Amplifier Project) arnoldc Tubes / Valves 16 6th July 2006 02:51 AM


New To Site? Need Help?

All times are GMT. The time now is 12:28 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki