Burning Amplifier BA-1 - Page 34 - 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 18th May 2013, 04:06 AM   #331
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
That is really great.

  Reply With Quote
Old 23rd November 2013, 12:32 PM   #332
NYCOne is offline NYCOne  United States
diyAudio Member
 
Join Date: Jul 2010
Blog Entries: 1
Quote:
Originally Posted by william2001 View Post
Latest incarnation, and maybe last, of this Semisouth bias circuit ... DN2540 cascode (TO-92's, $1.24 @ Mouser) per Walt Jung's Current Regulator's Revisited article in AudioXpress. Rload=100r, Rset=200r trimmer, 300r carbon gate stoppers right at gate pins of the 2540's. 8k series resistor from the top of Rload to the SS gate bus bar, 220r gate stoppers at the gate pins of the power JFETs.

Maybe what I've done here is absolute overkill silly-ness, but it's simple and cheap, and sounds fantastic. Along with a couple of other small changes elsewhere, this is the best sound I've achieved yet. I'm not missing that F5... (PV1.4 = 1.26 X 104 ??? )
I agree with ZM, can you show the current schematic? It would make it a lot easier to follow along.
  Reply With Quote
Old 23rd November 2013, 12:43 PM   #333
NYCOne is offline NYCOne  United States
diyAudio Member
 
Join Date: Jul 2010
Blog Entries: 1
Quote:
Originally Posted by Nelson Pass View Post
They are pure heat. This is a Burning Amp.

You will get a lot more efficiency out of BA#2, which is push-pull
instead of single-ended/constant current source.

If you want more efficiency out of the all-N channel output stages,
we will expect to be doubling the efficiency in a later version.

I'm just re-reading this thread. Did the higher efficiency all N channel see the light of day?
  Reply With Quote
Old 23rd November 2013, 03:11 PM   #334
diyAudio Member
 
william2001's Avatar
 
Join Date: Sep 2001
Location: Midwest
The only big difference between what I've done and the original - is replacing the bias circuit for the upper power FETS with the Cascode Current Source from Walt's article here: http://www.waltjung.org/PDFs/Sources...visit_0409.pdf

I used the circuit on the left of Figure 1. My opinion is this is better suited to the SemiSouth R100 JFETS that I wanted to use.

I made no changes to the front end circuit. And no changes to the bias circuit for the bottom power FETS (still IRFP240's). And my output stage is "2-deep" rather than "6-deep" as shown in the original article. I now use an Aleph J (semi Babelfish) in place of the BA-1 and am enjoying it very much also.
  Reply With Quote
Old 24th November 2013, 05:54 AM   #335
NYCOne is offline NYCOne  United States
diyAudio Member
 
Join Date: Jul 2010
Blog Entries: 1
Quote:
Originally Posted by william2001 View Post
The only big difference between what I've done and the original - is replacing the bias circuit for the upper power FETS with the Cascode Current Source from Walt's article here: http://www.waltjung.org/PDFs/Sources...visit_0409.pdf

I used the circuit on the left of Figure 1. My opinion is this is better suited to the SemiSouth R100 JFETS that I wanted to use.

I made no changes to the front end circuit. And no changes to the bias circuit for the bottom power FETS (still IRFP240's). And my output stage is "2-deep" rather than "6-deep" as shown in the original article. I now use an Aleph J (semi Babelfish) in place of the BA-1 and am enjoying it very much also.
I think your ideas are cool, I just want to make sure I have them right for a try.

You gave up on the 2SK170 CS and the green LEDs with the 2SK117? Is the 240 gone in favor of the Jung Cascode? Even a hand drawn version of your final would be helpful. If not possible, the total changes are:

Remove the IRFP240 completely, add two DN2450 (Cascoded) and Rload=100r, Rset=200r trimmer, 300r carbon gate stoppers right at gate pins of the 2540's. 8k series resistor from the top of Rload to the SS gate bus bar, 220r gate stoppers at the gate pins of the power JFETs?

No other mods (ie my question about the 2SK170 CS and the green LEDs with the 2SK117)?

TIA

Last edited by NYCOne; 24th November 2013 at 06:16 AM.
  Reply With Quote
Old 24th November 2013, 06:34 AM   #336
NYCOne is offline NYCOne  United States
diyAudio Member
 
Join Date: Jul 2010
Blog Entries: 1
Quote:
Originally Posted by NYCOne View Post
I think your ideas are cool, I just want to make sure I have them right for a try.

You gave up on the 2SK170 CS and the green LEDs with the 2SK117? Even a hand drawn version of your final would be helpful. If not possible, the total changes are:

You added two DN2450 (Cascoded) and Rload=100r, Rset=200r trimmer, 300r carbon gate stoppers right at gate pins of the 2540's. 8k series resistor from the top of Rload to the SS gate bus bar, 220r gate stoppers at the gate pins of the power JFETs?

No other mods (ie my question about the 2SK170 CS and the green LEDs with the 2SK117)?

TIA
I now realize you keep the 240 as one output, but I could benefit from a schematic.

I'm just not good enough to follow what's still in and what's been replaced. I'm not sure if you put the SS or the IRFP240 at the top or bottom. I realize you mentioned the words, I just want to make sure I see the top the same as you.

Working from the NP schematic: did you replace Z201, R213, P202, C209 and R214 and use that to bias the IRFP240 or the SS (top of the circuit), or did you replace R216, R217 C207, Q204, R219, R218, and use the Jung circuit to bias the IRFP240 or the SSR100 (bottom of the circuit)?

Last edited by NYCOne; 24th November 2013 at 06:42 AM.
  Reply With Quote
Old 26th November 2013, 12:05 AM   #337
diyAudio Member
 
william2001's Avatar
 
Join Date: Sep 2001
Location: Midwest
I only changed this part of the circuit.. replaced with that circuit I linked to. Those previous iterations with the K170's and LED's and all that were just me experimenting.

This circuit establishes the bias voltage at the gates of the SS R100's. The 8k series resistor I refer to would be at R128.

SemiSouth on top, 240's on bottom. And by "2 deep", I mean I have a matched pair of R100's on top, and a matched pair of 240's on the bottom. My source resistors are .34 ohms (pair of .68 ohm resistors in parallel at each location).

I hope this clears up the confusion. Just be careful and make sure you understand what's going on here if you were going to try this, I wouldn't want to see someone blow their $$$$ JFETS.
Attached Images
File Type: jpg only change.jpg (94.7 KB, 241 views)
  Reply With Quote
Old 26th November 2013, 08:35 PM   #338
NYCOne is offline NYCOne  United States
diyAudio Member
 
Join Date: Jul 2010
Blog Entries: 1
Quote:
Originally Posted by william2001 View Post
I only changed this part of the circuit.. replaced with that circuit I linked to. Those previous iterations with the K170's and LED's and all that were just me experimenting.

This circuit establishes the bias voltage at the gates of the SS R100's. The 8k series resistor I refer to would be at R128.

SemiSouth on top, 240's on bottom. And by "2 deep", I mean I have a matched pair of R100's on top, and a matched pair of 240's on the bottom. My source resistors are .34 ohms (pair of .68 ohm resistors in parallel at each location).

I hope this clears up the confusion. Just be careful and make sure you understand what's going on here if you were going to try this, I wouldn't want to see someone blow their $$$$ JFETS.

Thanks.

I'm just getting back to finishing my J2 clone. Then I'm going to give BA1 a shot. I read a fair amount about the CCS and I'd like to try the R100s in the BA1. I'm hoping to compare the BA1 with SS against J2 and SIT.
  Reply With Quote
Old 27th May 2014, 06:49 AM   #339
damped is offline damped  India
diyAudio Member
 
Join Date: May 2014
I'm a newbie taking the first tentative steps.
"R201 through 204 form the balanced inputs networks. R201 = R203 and R202 = R204, and the gain is R203/R201."
does not agree with the schematic diagram. Can someone clarify this please?
  Reply With Quote
Old 27th May 2014, 08:27 AM   #340
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
you need to be creative , reading Papa's articles ; what's few typos between friends ?



however , according to

Click the image to open in full size.

that need to be

R201 through 204 form the balanced inputs networks. R201 = R202 and R203 = R204, and the gain is R204/R202
__________________
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

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-2 Variac Pass Labs 1125 1st July 2014 02:39 PM
Burning Amplifier BA-1 Nelson Pass diyAudio.com Articles 3 24th October 2011 03:53 AM
Burning Amplifier BA-2 Nelson Pass diyAudio.com Articles 5 14th September 2011 07:11 PM


New To Site? Need Help?

All times are GMT. The time now is 04:40 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