Burning Amplifier BA-2

diyAudio Editor
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Here it is! The new Burning Amplifier BA-2.

The Burning Amps are modular in that you choose a Gain Stage and an Output Stage to create the amp of your dreams.

The input "Gain Stage" section which increases the voltage can be used for any of the Burning Amps. The first gain stage is no longer in production, but the Second, confusingly called the BA-3 is available in the diyAudio Store.

So you can combine the gain stage with either one of two "Output Stages" which are also available in the Store.

One output stage is single ended and the combination with a gain stage is the BA-1 Amp. The output stage consists of 2 small PCB's and two longer ones.

One output stage is complementary and the combination with a gain stage is the BA-2 Amp. The output stage also consists of 2 small PCB's and two longer ones. but they are all different than the ones for the BA-1 output stage.

Single-ended amps are quite inefficient, and only operate in pure Class A. The are the Audiophile Purist choice and probably have a small sound quality advantage, depending on your preference.

Complementary amps are more efficient, and transition smoothly from pure Class A operation to Class AB when more power is required

The BA-2 is the second Nelson Pass design in the Burning Amp series. This one is a complementary output amp that uses much of the gain circuitry from the previous single ended BA-1.

I really enjoyed Nelson's detailed explanation of how it works, and how in even greater detail than before he answers the perennial questions "How hot is too hot?" "How to avoid a literal burning amp by firing it up correctly," and "How some design decisions affect the sound".

Finally, he gives us hints as to how the design can be adjusted and varied even by those of us who aren't experts. I'm getting all kinds of ideas and you will too. You don't need to have gotten a gift chassis from Nelson at the Burning Amp Festival in order to make a Burning Amp, just this article....

Mark
 
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Hi Mark,
There's a slight omission I believe.
Connection from the Vbias to the gates of the output mosfets is missing from the output stage schematic.
Regards,
George

EDIT: We have corrected the article END EDIT
 
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Official Court Jester
Joined 2003
Paid Member
like this .........

btw - Papa just giv'sya basic of output stage of XA amps ( at least my small , often hurting , brain alarms on that ....... :rofl: )
 

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diyAudio Editor
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There Shall be Boards...

Because the front ends are the same for the BA-1 and BA-2 with only a slight difference, we are pretty committed to making the front end boards for both amps the same, and then two different types of bias boards, one for the BA-1 and one for the BA-2. With this type of layout you can also have the Burning Amp Gain Stage (BAGS) in a separate box as Nelson mentions. He also hints that the BAGS will work with some future BA amps......

I'll be interested in some power supply designs for the gain stage. Is a Shuntie a good idea? I'm sure we will hear..

Nelson had mentioned that they would be similar so we decided to wait before continuing on board developement. Cviller is starting the revised layout right now..

Mark
 
Official Court Jester
Joined 2003
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....
I'll be interested in some power supply designs for the gain stage. Is a Shuntie a good idea? I'm sure we will hear..

......
Mark

well - I have slight impression that Shunty isn't adequate from two (or more ? :rofl: ) reasons :

one is that probably not entire BA population will be capable ( or just patient enough ) to solder and activate damn thing :devily: ,
second one is that Papa isn't so keen on kwayzee shunt regs ; not that he can decide instead of anyone what is good for your own amp , or not ..... but this playground is certainly his Oyster ..... :spin:
third one - something as Shinyy or any other recently here discussed (semi-complicated and just halfasShuntyoverkill ) shunt reg will suffice , both sound and tech wise ......

edit :

there is always possibility to use old approach - just let da bloody thingie bleed ..... connecting some 25W shunting resistors across FE PSU :devilr:
 
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If our gate drive is limited to about 9 volts by Zener Diodes D1 and D2, why couldnt we run the front end of 24V and the output stage off say +/- 70v? with lower bias. 6-8 pairs should be good for 200 watts of class AB power I would guess judging by other commercially available designs.

And i ask this question in ernst from a learning perspective. what is the stopping factor. I feel as if i am missing a bigger part of the picture. I have often heard N.P talk about never letting the gates get about 20V or the mosfets blow up. and that all that is needed is 4-5v on the gates. so that sounds like not much voltages is needed to turn a mosfet fully on. so what is the limiting factor?? why couldn't we use a low voltage supply for the front end and a higher voltage/current supply for the output stage???

(I have this big beautiful but sadfully dead Stasis chassis sitting here begging for a project!)


Zc
 
Official Court Jester
Joined 2003
Paid Member
....... why couldn't we use a low voltage supply for the front end and a higher voltage/current supply for the output stage???
.....


Zc


:headshot:

re-read article few times .....

even if I didn't , I can bet that Papa explained that entire voltage swing is coming from front end .....

output stage is follower ........ not having voltage gain
:D

edit:

anyway - you can still increase voltage for entire gadget , but with usual Voodoo needed for input diff stafge - cascoding with small bjts ....... blahblah
 
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