My guess would be that it's either a bad solder joint or, albeit less likely, a damaged resistor (loose metal end cap).
Hi Guys,
Yes the fault follows the wires, the problem is originally in the right channel, if I swap left and right outputs the problem moves from the right speaker to the left, swapping inputs does not affect the channel problem. I reflowed every joint throughly today and the problem persists, once the volume is raised to a loud level the right channel fades out. I've tried three different pots so far to rule a faulty pot, same issue with all three. There is something really odd going and I'm really tired of screwing around with this board. I think I'll abandon this board and use the case for a DCG3 build. Thanks everyone for your help.
Paul
Yes the fault follows the wires, the problem is originally in the right channel, if I swap left and right outputs the problem moves from the right speaker to the left, swapping inputs does not affect the channel problem. I reflowed every joint throughly today and the problem persists, once the volume is raised to a loud level the right channel fades out. I've tried three different pots so far to rule a faulty pot, same issue with all three. There is something really odd going and I'm really tired of screwing around with this board. I think I'll abandon this board and use the case for a DCG3 build. Thanks everyone for your help.
Paul
Power supply powered up ok. +24volts/-23.7 volts. Not sure what is causing negative side to be down .3 volts but this should be ok right?
I'm having problems adjusting my BA-3 bias. One chancel can be adjusted to 0.92V without any problems. Other channel is impossible to get over 0.52V.
Have triple-checked all component values and everything is ok.
Any suggestions?
Have triple-checked all component values and everything is ok.
Any suggestions?
Ok then - let the smoke 
out. 😱 
Had four smokes actually. Thought I was ready, conneted AC and smoked all four (R10/R11 22ohm) biasing resistors...
You guys see whats wrong? Q4 / Q3 the right way around?
Was no separate place to connect power ground - thought it's the same ground as signal - not so? Power giving +/- 26,7 DC withiut load.
out. 😱 Had four smokes actually. Thought I was ready, conneted AC and smoked all four (R10/R11 22ohm) biasing resistors...
You guys see whats wrong? Q4 / Q3 the right way around?
Was no separate place to connect power ground - thought it's the same ground as signal - not so? Power giving +/- 26,7 DC withiut load.
Attachments
That is the error - your Mosfet are in the incorrect locations. The J313 is P-channel and the K2013 is N-channel
That's OK.
Thanks 6L6! That's what I suspected... 🙁
I'll correct that - hope nothing else busted than the resistors...
I'll correct that - hope nothing else busted than the resistors...
Got the BA-3 up and running!
Luckily nothing else fried than the resistors... 😀
Listening to it now. too early and late at night to say much about the sound, other the 'not bad'. 🙂
Thanks for the help!
Luckily nothing else fried than the resistors... 😀
Listening to it now. too early and late at night to say much about the sound, other the 'not bad'. 🙂
Thanks for the help!
Maybe in the thread but couldn't find it... 😱
How do you get less gain out of this thing? Have the 50K pot hardly turned... Resistors to tinker with?
How do you get less gain out of this thing? Have the 50K pot hardly turned... Resistors to tinker with?
double R10/R11 , rebias
halve R13
edit:
read this : http://www.diyaudio.com/forums/diyaudio-com-articles/186018-what-gain-structure.html
halve R13
edit:
read this : http://www.diyaudio.com/forums/diyaudio-com-articles/186018-what-gain-structure.html
Zen Mod, read the article and some comments in the thread.
So you are saying that lowering the gain of the pre will make the S/N ratio worse? But if there is nothing I can do about the power amp (which, I suppose, would be the best option), wouldn't it still be better to let the signal from DAC come out louder (pot turned more open) and have the pre produce less gain?
So you are saying that lowering the gain of the pre will make the S/N ratio worse? But if there is nothing I can do about the power amp (which, I suppose, would be the best option), wouldn't it still be better to let the signal from DAC come out louder (pot turned more open) and have the pre produce less gain?
I wrote what to do with BA3 to lower gain
article is there to give you broader perspective on gain strategy, not to give you special clue to BA3 per se
you got it backwards ........ generally speaking , S/N is always worse with more gain
article is there to give you broader perspective on gain strategy, not to give you special clue to BA3 per se
you got it backwards ........ generally speaking , S/N is always worse with more gain
however ...... be aware (you and everyone else) , BA3 is really more higher gain/higher amplitude stage , than it is eenyweeny 3x/2Vpp stage
it is somewhat constipated when using it in that way
it is somewhat constipated when using it in that way