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Variac 1st September 2009 02:48 PM

Burning Amplifier BA-2
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....


gagnou 1st September 2009 03:54 PM

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.

EDIT: We have corrected the article END EDIT

Zen Mod 1st September 2009 04:31 PM

1 Attachment(s)
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: )

Zen Mod 1st September 2009 04:35 PM

Papa wrote :


Get over it. **

Zen Mod 1st September 2009 04:44 PM

2 Attachment(s)
for lazy boyz :D

Zen Mod 1st September 2009 08:26 PM

whazzat with Spoiled Kids ....... ?

new Forum scheme is preventing them for spotting New Candy ........


Variac 1st September 2009 08:50 PM

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..


Zen Mod 1st September 2009 09:34 PM


Originally Posted by Variac (
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..


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:

udailey 1st September 2009 09:49 PM

Foghorn Leghorn... nice! :)

Melon Head 1st September 2009 10:04 PM

Thanks again Nelson.

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