Important parameters LTP transistor matching - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Solid State Talk all about solid state amplification.

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 17th April 2016, 07:33 PM   #1
diyAudio Member
 
Join Date: Sep 2009
Location: Pretoria
Default Important parameters LTP transistor matching

Hi guys.
When matching Long Tail pairs for an amplifier (BJT), which parameters do you match for? Obviously Vbe is important, but what about gain?
When designers use current mirrors to match the current through each transistor isn't Vbe the only parameter to consider?
I'm asking this as a noob. I usually match at Ic of 2,5mA.
Thanks in advance.
  Reply With Quote
Old 17th April 2016, 07:52 PM   #2
diyAudio Member
 
JonSnell Electronic's Avatar
 
Join Date: Dec 2012
Location: The Jurassic Coast, England. GB
Send a message via Skype™ to JonSnell Electronic
As long as the Hfe is more than you need, all should be OK. If you are using a balanced pair, then Vbe will be best matched.
__________________
Support for Flying Mole Class D, PMC DS-001 (Hypex),Valve Equipment and designs both new and old. www.jonsnell.co.uk
  Reply With Quote
Old 18th April 2016, 10:05 AM   #3
AndrewT is online now AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
I explained in a post yesterday how to check the currents and voltages around the input LTP and why these voltages result in output offset.
D.Self shows a similar calculation in his power amplifier book. He also shows how close the device currents need to be to minimise distortion in the LTP.

When you do this, you begin to see why the output offset and current balance becomes dependant on the LTP device parameter matching.
100W Ultimate Fidelity Amplifier
__________________
regards Andrew T.
Sent from my desktop computer using a keyboard

Last edited by AndrewT; 18th April 2016 at 10:09 AM.
  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
How important is N to P ch Mosfet matching for an F5Tv3 nashbap Pass Labs 19 12th December 2014 06:04 PM
ltp transistor matching east electronics Solid State 16 7th January 2009 06:33 PM
How important is complementary transistor pair matching in class B amp? caesar148 Solid State 10 15th October 2004 08:06 PM
Matching LTP FETs for Best Sound? Dave S Pass Labs 3 23rd March 2004 12:16 PM


New To Site? Need Help?

All times are GMT. The time now is 03:46 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2016 DragonByte Technologies Ltd.
Copyright 1999-2016 diyAudio

Content Relevant URLs by vBSEO 3.3.2
Wiki