Burning Amp BA-3

X0 FE for sure

Maybe X0 at the FE as Gerd said but I saw 7815/1915 regulated IC bottom IRF side.
 

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P1 and P2 are to adjust unison , to set current through Q3 and Q4 , nothing to have with "power"

if you need more power , you need bigger amp - meaning higher PSU rails etc.

do you , by chance , means at needing more gain, not power ?

yes more gain..... and i want the heatsink to run a little hotter
we are talking of the bias board here? pot 2 is dc offset ??? pot 1 bias??
 
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for more gain , increase R13 at front end pcb

second question - you need to point me to exact schematic of output stage you're using , so I can pinpoint proper pots


r13 is now 330 ohm ...suggested value to start with... 0 gain preamp
this is build by the first from the shop ...by the book...
i have super bad memory so dont really know

can you see it on pictures?
Stig Linlokken - closeups | Facebook
 
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With 330ohm at R13 gain is about 15, not zero. The driver board has gain in it's standard configuration.


Do you want the amplifier to play louder? Increasing the heat (bias) won't make any change to that.

Actually I experienced higher gain (or at least higher volume output) when increasing the bias on the BA3 front end. I remember reading Nelson saying that bias and gain are related in the outputs of the FE.
 
Hi, I have a question. I bought a ba-3 with follower ready made. The DC outset is far too low on the left channel. Right channel is perfectly stable, but the left is drifting to minus and I can´t get it to 0. If I increase bias on p1 DC outset decrease. I appreciate if someone could guide where to start my troubleshooting.
I am a noobie so please be gentle. thanks in advance.
 
Slow drift can be down to temperature variations. And unlikely to be a bad joint.
Sudden changes can be the result of unheard oscillation.

Monitor output offset and output Noise+Hum over an extended period from completely cold to fully warmed up.
Do not attach speakers until you are sure it is operating correctly.
 

6L6

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Rubber Soul -

Please pose well-lit, in-focus photos of your amplifier.

Which PCB does it use?

Which P1 are you adjusting?

Where are you measuring offset, front-end or output?

What are your actual measurements of DC offset on the speaker output with a cold amp and after 30min?