Burning Amp BA-3 - Page 87 - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

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 23rd October 2012, 02:32 PM   #861
diyAudio Member
 
Join Date: Sep 2008
Quote:
Originally Posted by buzzforb View Post
NS,
.
buzzforb,

Can you use the FQA19N20C / etc matched mosfet set in the BA-2 power boards as shown in Nelson's circuit diagram or do you neeed to change the components?
  Reply With Quote
Old 23rd October 2012, 02:40 PM   #862
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
I think that was what the original BA2 output stage used. Either way, You can use any fets in the output, you just might have to make some adjustments to bias circuit. With either Fairchild or IRF, you are OK. I have use laterals and needed to make some changes.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 23rd October 2012, 02:48 PM   #863
diyAudio Member
 
Join Date: Sep 2008
Thanks. I'm thinking of building another amp. The BA-2 I am very happy with but as I had another chassis I thought why not a BA-3 as well that I can play around with. Just wondering whether Nelson isn't planning something.

Could I get away with a 300VA transformer for two channels (one output board each) set at about 400mV bias? Presently I am using a 300VA transformer for each channel but maybe I could reduce the weight.

Last edited by Backbones; 23rd October 2012 at 02:50 PM.
  Reply With Quote
Old 23rd October 2012, 03:52 PM   #864
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
Should be OK, assumingit is not getting pushed hard very often. I think you might be surprised how much you like BA3. Make sure you fiddle wth P3.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 23rd October 2012, 04:57 PM   #865
nkdk is offline nkdk  Denmark
diyAudio Member
 
Join Date: May 2009
@buzzforb
Hi, what is the best way to fiddle with p3, hook up at functions gen. and scope, ore are there other ways to do it ??

nkdk
  Reply With Quote
Old 24th October 2012, 12:05 PM   #866
diyAudio Member
 
Join Date: Sep 2008
Quote:
Originally Posted by nkdk View Post
@buzzforb
Hi, what is the best way to fiddle with p3, hook up at functions gen. and scope, ore are there other ways to do it ??

nkdk
You may have problems finding the point of minimum distortion without the right equipment but it's what you can hear and whether it sounds good to you that really matters. So set it up so you can adjust P3 and then have a listen and then try another position for P3. Worked for me.
I found you didn't have to keep adjusting P1 and P2 or worry about dc offset each time you moved P3. Obviously once you have a sound you like then balance-off the rest of the circuit.
  Reply With Quote
Old 24th October 2012, 07:50 PM   #867
diyAudio Member
 
Join Date: Oct 2008
Default which 2sj74 to use

Dear everyone,

Which versions of the 2sj74 and 2sk170 should I use.
Should I use the GR BL or V version? There is considerable difference in price.

BTW do they need matching?

Your advise is very much appreciated
  Reply With Quote
Old 24th October 2012, 08:34 PM   #868
tinitus is offline tinitus  Europe
diyAudio Moderator R.I.P.
 
Join Date: Nov 2005
Quote:
Originally Posted by noSmoking View Post
found this wish I found it earlier,lol
he, thats mine
sure hope its correct
  Reply With Quote
Old 25th October 2012, 10:52 AM   #869
diyAudio Member
 
Join Date: Sep 2008
Quote:
Originally Posted by Alettagla View Post
Dear everyone,

Which versions of the 2sj74 and 2sk170 should I use.
Should I use the GR BL or V version? There is considerable difference in price.

BTW do they need matching?

Your advise is very much appreciated
Idss currents of the GR are less than the BL, which in my experience are difficult to find, which might explain the cost. Nelson used the BL I believe with an Idss of about 10mA. Mine come in at 8mA. If you use the GR you will have to have P1 and P2 as 1K not 500R. I don't know about the V.
They don't need matching but I did anyway.

Last edited by Backbones; 25th October 2012 at 10:54 AM.
  Reply With Quote
Old 3rd November 2012, 11:47 AM   #870
diyAudio Member
 
Join Date: Sep 2008
The first time I built the BA-2 power boards I used ER74, 3W 1R wirewound resistors and everything sounded good but going over the BOM now I see these resistors are specified as metal oxide. Any reason other than possible inductance issues with the wirewound?

Also in the BOM there is only note of four of these resistors rather than six.
  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
Burning Amplifier BA-1 Variac Pass Labs 341 22nd September 2014 04:07 AM
Burning Amplifier BA-3 Nelson Pass diyAudio.com Articles 34 27th June 2014 05:36 AM
Burning Amplifier BA-1 Nelson Pass diyAudio.com Articles 3 24th October 2011 03:53 AM
WTB: Burning Amp BA-1 or BA-2 jdubs Swap Meet 0 23rd March 2011 04:16 AM
FS: two burning amps (one each BA-1 and BA-2) without drivers Eric Weitzman Swap Meet 15 17th February 2010 03:35 AM


New To Site? Need Help?

All times are GMT. The time now is 11:56 PM.


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