Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Pass Labs This forum is dedicated to Pass Labs discussion.

Burning Amp BA-3
Burning Amp BA-3
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 July 2013, 06:28 PM   #1051
generg is offline generg  Germany
diyAudio Member
 
generg's Avatar
 
Join Date: Jul 2009
Location: Near Frankfurt
Burning Amp BA-3
was it so alogical?

there is the S connection in BA-1 controlling the bias....

and he wants to use not only one outputboard but two...

both outputboards show the S pin on both sides and he asks if is it enough to connect one of the S pins of the first output board and must the S pin of the second board also connected to the S pin of the first board....?

really difficult without pictures I understand .....

I looked for the pictures at the shop, but the quality is so bad you can not see the S pin.....
Attached Images
File Type: jpg BA-1.jpg (457.1 KB, 384 views)
__________________
and the First Wtt is......a really First Class PSS Idea
  Reply With Quote
Old 17th July 2013, 06:45 PM   #1052
bcmbob is offline bcmbob  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Bay City, Michigan
If a second output board (six additional power transistors) is added in series, is there a need to connect the "S" pads between those two output boards. Or is sensing only the first resistor on the OB closest to the bias board sufficient?
Attached Images
File Type: jpg SSS.jpg (103.7 KB, 376 views)
File Type: jpg 20130717_144748.jpg (25.5 KB, 348 views)
File Type: jpg 20130717_150041.jpg (71.4 KB, 342 views)
File Type: jpg 20130717_150106.jpg (44.0 KB, 336 views)
__________________
Bob M.
"Arrange Whatever Pieces Come Your Way."

Last edited by bcmbob; 17th July 2013 at 07:06 PM.
  Reply With Quote
Old 17th July 2013, 10:11 PM   #1053
william2001 is offline william2001  United States
diyAudio Member
 
william2001's Avatar
 
Join Date: Sep 2001
Location: Excelsior Springs, Missouri
No need to connect the "S" pads together. The bias circuit is only looking at the voltage drop across that one resistor to control how much the bottom set of power transistors are conducting. The important thing is that all of those are well matched of course so that they share the current equally.

This is a beast of an amp regarding heat dissipation, remember you can easily dial in the amount of idle current by the value of R131 if needed as stated in the article. I forgot what I ended up with there, 30k or something, lower value=less current/heat.

Last edited by william2001; 17th July 2013 at 10:23 PM. Reason: added info
  Reply With Quote
Old 17th July 2013, 10:22 PM   #1054
evanc is offline evanc  United States
diyAudio Member
 
Join Date: Sep 2009
Location: New Jersey. About 1 hour from NYC and 1 min. from the beach
Burning Amp BA-3
Bob,
When you're done with this thing I won't have to ask how it sounds...I'll be able to hear it at my house.
__________________
http://www.evancotler.com
  Reply With Quote
Old 17th July 2013, 10:51 PM   #1055
bcmbob is offline bcmbob  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Bay City, Michigan
Thanks William, that keeps wiring simple. I didn't match the power transistors but I did get a matched set from buzz for the front end. If I like the sound I'll be happy to circle back and upgrade as necessary. My plan is to get the amp operational as stereo first, and then add the second output boards after I get a feel for what's happening.

The heat management is at the core of this build and will be interesting indeed.

evanc, I have no frame of reference for the power/slp, but my long standing curiosity will soon be answered. Should I be scared
__________________
Bob M.
"Arrange Whatever Pieces Come Your Way."
  Reply With Quote
Old 17th July 2013, 11:07 PM   #1056
evanc is offline evanc  United States
diyAudio Member
 
Join Date: Sep 2009
Location: New Jersey. About 1 hour from NYC and 1 min. from the beach
Burning Amp BA-3
not scared .... excited.
What do you use for speakers?
__________________
http://www.evancotler.com
  Reply With Quote
Old 18th July 2013, 12:01 AM   #1057
bcmbob is offline bcmbob  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Bay City, Michigan
My mains currently are the Sunflowers, a bit on the low efficiency side. The second pair is my DIY 15 year standard that has two Vifa 6.5" and a Morel MDT 30 tweeter in MTM. Crossovers done on Leap system by Masisound. They can play REALLY loud and handle a lot of power with a very nice presentation. Both will probably be overpowered but one always needs an excuse to build something new.
Attached Images
File Type: jpg BobsSunflowers1.jpg (88.3 KB, 107 views)
File Type: jpg SSPX0106.jpg (88.2 KB, 102 views)
__________________
Bob M.
"Arrange Whatever Pieces Come Your Way."

Last edited by bcmbob; 18th July 2013 at 12:04 AM.
  Reply With Quote
Old 18th July 2013, 09:00 AM   #1058
AndrewT is offline AndrewT  Scotland
R.I.P.
 
Join Date: Jul 2004
Location: Scottish Borders
post 1051
Is the S pin the trace that connects to R132?

+D, +v, -V & OUT are all labeled.

S pin should have a label and show a terminal on the schematic. Leaving it unlabeled is confusing !
__________________
regards Andrew T.
  Reply With Quote
Old 18th July 2013, 09:46 AM   #1059
generg is offline generg  Germany
diyAudio Member
 
generg's Avatar
 
Join Date: Jul 2009
Location: Near Frankfurt
Burning Amp BA-3
Yes Andrew, the S Pin is that trace ging to R132......and it it seems to be unimportant how many pairs are behind the first pair giving the sense S to the neg bias circuit, isn't it?

__________________
and the First Wtt is......a really First Class PSS Idea
  Reply With Quote
Old 18th July 2013, 10:11 AM   #1060
AndrewT is offline AndrewT  Scotland
R.I.P.
 
Join Date: Jul 2004
Location: Scottish Borders
Yes, but it does rely on adequate matching of semiconductor devices and resistor devices.

If one wants to check the current imbalances of the output stage semiconductors, then the resistors MUST be matched to far better than the tolerance you expect of the semiconductors
Aim for better than 1% range of resistor values (+-0.5%) and preferably +-0.2%.
__________________
regards Andrew T.
  Reply With Quote

Reply


Burning Amp BA-3Hide 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
Burning Amplifier BA-1 Variac Pass Labs 356 17th January 2017 11:54 PM
Burning Amplifier BA-3 Nelson Pass diyAudio.com Articles 39 14th October 2016 11:36 AM
Burning Amplifier BA-1 Nelson Pass diyAudio.com Articles 3 24th October 2011 02:53 AM
WTB: Burning Amp BA-1 or BA-2 jdubs Swap Meet 0 23rd March 2011 03:16 AM
FS: two burning amps (one each BA-1 and BA-2) without drivers Eric Weitzman Swap Meet 15 17th February 2010 02:35 AM


New To Site? Need Help?

All times are GMT. The time now is 01:01 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki