Burning Amplifier BA-2

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#204
Thanks for pointing out this error. But it is not the caps, but the supplies that are marked wrong see attachment.
 

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#207
.....some news, frontend works fine🙂. I changed the feedbackresistor to 100kOhm, more gain for stripped F4. The outputstage is very similar to BA2 as far as I can see.

I was interested to compare the frontend as a pre with pumpkin. I did not forget to make the feedback from the output to D.
Sound is brighter, all singers seem to be younger, very good stage and more pointed.
Pumpkin darker, more dynamic, more colour, more crazy details.

Hi Zen Mod, how could I drive the BA1 outputstage with pumpkin? I am sooo cuuuurious to hear a single ended stage!

The points -D and +D from BA-1 are possible inputs for pumpkin without frying anything?
 
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#210
generg said:
Hi speedy Zen Mod,

the link

http://www.diyaudio.com/forums/diyaudio-com-articles/154777-burning-amplifier-ba-1-a.html

thanks Gonzales
Click to expand...

what's missing , for your purpose , in BA1 output stage is - biasing network for both halves (upper and lower ) ;
they're incorporated in BA1 front end , so - besides unnecessary complication to bring BA1 output to operation "just" as test bed for mate with :Pumpkin: , I can't see any further benefit in using that , instead of F4 output stage .

in fact - maybe you need some more heat in your room , but I already told you most efficient heath & sound-vise solution - make another F4 and make full balanced setup .

:devily:
 
#212
cviller said:
Zen mod, thats not entirely true... the biasing has been moved out of the frontend circuit exactly for this purpose on the BA boards.
Click to expand...

sorry - I was looking just on schematics in Papa's article ;

as one of rare spoiled kids without interest in BA amps ....... I'm guilty ... as Sin itself ...... :clown:

have you exact schematic - generated to coincide with board , so I can help generg to try what he want ?
 
#214
tnx cviller

@ generg

presuming that circuits from left and middle picture(s) in cviller's post are incorporated on same pcb - just shoot upper gates from positive :Pumpkin: output ; you must have output cap in place on :Pumpkin: pcb .

ground neg output ........ or shoot another BA1 output channel with it ..... and make bridged amp :rofl:
 
#217
hm, cviller....

I just saw the schematic from Nelson Pass shows a local feedback for BA-2 and a global feedback for BA-1. R204 (47k) for BA_1 comes from Out of the output stage. R204 (47k) for BA-2 comes from the output of the gainboard.

In your version of the gainboard the feedback is always the way BA-2 is described. Even when I use BA-1 biasboard?

Nelson Pass writes in the BA-1 description "We will be operating this output stage au naturale, outside of any feedback loop,..."


Correct? Is the difference between the two ways important or is there a fault in the BA-1 schematic??
 
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#220
Just want to ask a trivial question here regarding the power supply.
What are the reasons for and against for using a single bridge rectifier over two bridge rectifiers.
Sometimes Nelson uses two sometimes he uses one.
I was under the impression that using two was the preferred option.
 
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