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.

BA-1 with BA-3 front end board
BA-1 with BA-3 front end board
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 March 2017, 11:54 AM   #1
wdecho is offline wdecho  United States
diyAudio Member
 
Join Date: Oct 2014
BA-1 with BA-3 front end board
Default BA-1 with BA-3 front end board

I am revisiting this amplifier of which was my second FW diy project. I say revisiting because I removed the boards years ago to install other boards. I have since found that the j-fets I purchased before the LSK ones became available were fake and I have not heard this amplifier as it should. Another reason is I recently built the F4 and am amazed with the sound it produces which is almost if not the BA-2 amplifier with less output devices. Now I want to rebuild the SE version of the Burning Amp series. I decided to remove the IRFP 240 mosfets I originally installed and buy a tube of 25 and match them better since I like to think I have more experience now building FW amplifiers. I managed to get 15 to .1V tolerance out of the 25. I am using just one set of boards from our store to make a stereo amplifier using 6 output devices instead of 12 but now both boards will have output mosfets that match each other so that if I desire at a later date to build another complete SE BA-1 and have mono's. It would require a massive case to build the BA-1 as described in the article so to me if is more practical to build this project in mono configuration. Right now I am going to build a stereo version using 6 output mosfets per channel.

My personal opinion is that the BA-1 and BA-2 designs are diy projects that may be compared to some of the Passlab designs especially if one builds either with 12 mosfets per channel. At least some of the older Passlab amplifiers.

Last edited by wdecho; 24th March 2017 at 12:01 PM.
  Reply With Quote
Old 26th March 2017, 11:31 AM   #2
wdecho is offline wdecho  United States
diyAudio Member
 
Join Date: Oct 2014
BA-1 with BA-3 front end board
I fired up this amplifier yesterday and as Nelson said "it sounds swell." Right now I am using it much like the F4 amplifier in that it only has the output stage, I have not included the front end yet. I have many different tube preamplifiers and horn speakers so the front end is not actually needed but I do have plans to install the BA-3 front end. I did notice that using it as a stand alone output stage I have close to 5V DC on the input. I decided to install couple of 10uh caps on the input to stop the voltages from affecting the preamplifier circuits. Some of my pres have output caps and some do not.

I thought I had all the resistors I needed in stock to build the BA-3 front end without actually checking so I did not order any when I made a purchase of the other components at Mouser but now I find that I do not have any 330 ohm 3 watt resistors. This is the reason I have not installed the BA-3 board yet.
  Reply With Quote
Old 26th March 2017, 11:45 AM   #3
Zen Mod is online now Zen Mod  Serbia
Official Court Jester
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
BA-1 with BA-3 front end board
you're using this ?

C203 is necessary part of OS , if used standalone

however , then is smart including input shunt resistor , to prevent possible hickups of having floating input cap
Attached Images
File Type: jpg BA-1 OS by ZM.jpg (107.2 KB, 286 views)
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa... by Mighty ZM
  Reply With Quote
Old 26th March 2017, 12:14 PM   #4
wdecho is offline wdecho  United States
diyAudio Member
 
Join Date: Oct 2014
BA-1 with BA-3 front end board
I stuffed these boards years ago when I was less experienced building but I bought the boards from our store and yes I do have those 10uh caps on the board. I was concerned about having DC voltage and wondered if I have a mistake on the board myself. It could possible be that I do not have the input wired correctly. I will double check that separate board and see where I may have gone wrong. From the schematic I should not have any voltage on the input. Thanks Zen.
  Reply With Quote
Old 26th March 2017, 12:31 PM   #5
Zen Mod is online now Zen Mod  Serbia
Official Court Jester
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
BA-1 with BA-3 front end board
triple check ;

if you have 10uF cap on board , then you're probably lacking input shunt resistor

everything is OK , DVM is giving you false input DC offset reading , simply because input side of cap is floating

put there anything between 47K and 220K , and you're done
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa... by Mighty ZM
  Reply With Quote
Old 26th March 2017, 12:34 PM   #6
wdecho is offline wdecho  United States
diyAudio Member
 
Join Date: Oct 2014
BA-1 with BA-3 front end board
Zen, looking at the article on page 2 below,

http://www.firstwatt.com/pdf/art_ba_3.pdf

the boards I purchased could be designed around this circuit instead and a cap may be necessary for standalone use. My input wiring seems correct. Opinion appreciated.
  Reply With Quote
Old 26th March 2017, 12:45 PM   #7
Zen Mod is online now Zen Mod  Serbia
Official Court Jester
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
BA-1 with BA-3 front end board
you need to do 2 things :

1. compare sch from p.2 of that document with sch I posted up
2. take few proper pictures of your boards and we can talk easier

3. do not forget to post these pics here
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa... by Mighty ZM
  Reply With Quote
Old 26th March 2017, 12:53 PM   #8
wdecho is offline wdecho  United States
diyAudio Member
 
Join Date: Oct 2014
BA-1 with BA-3 front end board
Will do the Monday. I do believe the board is designed around the newer schematic published 2011 vs the original 2009 schematic but then I will need to remove the bias board and look at the traces. Information and comments from you are much appreciated. It does sound swell with the caps I installed but then it played well even before I installed the caps. I was brave and tried it anyways. If anything smoked it would have given me something to do next week.
  Reply With Quote
Old 27th March 2017, 11:31 AM   #9
wdecho is offline wdecho  United States
diyAudio Member
 
Join Date: Oct 2014
BA-1 with BA-3 front end board
I have not removed the bias boards yet, it is early central time USA, but I have done some research and I have my doubts on which schematic I used to stuff the bias boards with years ago. For anyone that does not know there are 3 boards to stuff to make the complete B1 SE amplifier.The store schematic uses the BA-1 stuffing for the bias board yet Nelson in 2011 provided a new bias stuffing with the BA-3 article. I am going to remove one of the bias boards this morning and do some checking and provide pictures if I cannot figure it out Zen. I played the amplifier last night with a couple of different pres and the sound is outstanding with the 10uh caps I installed on the input but I want to get to the bottom of which schematic was used on the bias boards provided by our store. With my horns being very efficient any preamplifier will provide more than enough power without having the BA-3 pre board installed inside. I have a BA-3 preamplifier to use when I want to as well. I really like the option of using this amplifier as is being just the output stage like the F4. The designer of the bias boards would know but who and where he is at now is anyone's guess.

Last edited by wdecho; 27th March 2017 at 11:39 AM.
  Reply With Quote
Old 27th March 2017, 02:34 PM   #10
wdecho is offline wdecho  United States
diyAudio Member
 
Join Date: Oct 2014
BA-1 with BA-3 front end board
Default BA-1 with BA-3 front end board

P-BASB-1V20-schematic.pdf

P1030669.JPG

It appears that the schematic listed on the store is the one used. The R 219 resistor does not have a value listed but an asterik with it so I assumed it is optional. There is no place on the board for C203 that appears on the schematic you showed Zen. I am left to assume that the configuration of the bias is such that it assumes one is going to use the BA-3 front end in conjunction with the BA-1 boards with it's capacitor stopping the DC. From what I see one needs a 10uh cap on the input when the output stage is used as a stand alone amplifier. Your opinion Zen and anyone's else's is appreciated.

Last edited by wdecho; 27th March 2017 at 02:51 PM.
  Reply With Quote

Reply


BA-1 with BA-3 front end boardHide 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
FS: BA-3 assambled board and super regulator boards DIYspaceW Swap Meet 10 19th December 2016 06:31 AM
FS: Populated Burning Amplifier Complementary bias and output Set for BA-2 and BA-3 DIYspaceW Swap Meet 3 10th April 2016 10:44 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 03:44 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