Burning Amplifier BA-2

[Zen Mod]

did you tried what I wrote in post #914 ?

 

[tinitus]

if reg is situated near BA FE , you don't need additional decoupling.......

ah, power supply
sorry, I thought you were talking about output cap C3

 

[nikosgrgr]

I have fix the problem regarding DC-Ofset on both channels.
Bad solder connection of the cabling in between bias pcb & output pcb.
Sometimes the root cause of a problem has the most simple solution and because it is so obvious we do not take it under consideration us the first action that needs to be performed.
Second problem current searing on left channel (40 mV bracket in between the 10 mosfets)
According to Zen Mod we are still good.
Is it worth it to start changing mosfets or just live them as they are (is it worth the effort sonically speaking).

 

[Zen Mod]

just leave them as is and enjoy

let say that difference of +/-8% in current isn't worth prolong waiting to hear it

when you have a chance ( and bug is obviously there , so you'll buy them more , for sure ) to buy more mosfets , then match them tightly and replace

 

[nikosgrgr]

just leave them as is and enjoy

let say that difference of +/-8% in current isn't worth prolong waiting to hear it

when you have a chance ( and bug is obviously there , so you'll buy them more , for sure ) to buy more mosfets , then match them tightly and replace

Thanks a lot!!!!!! Dear Zen Mod

 

[Backbones]

if reg is situated near BA FE , you don't need additional decoupling , especially with shunt regs , where too much of capacitance on output is counter-productive

if reg is situated at more than , say ,10cm from BA FE , you'll need some local decoupling , just in case

Many thanks.
Listening to the BA-2 front end before and after the reg was installed showed that there was no alteration in the overall personality of the sound except for a lowering of background noise and improvement of low level detail. The distance between reg and FE is about 4cm.

 

[Backbones]

if reg is situated near BA FE , you don't need additional decoupling , especially with shunt regs , where too much of capacitance on output is counter-productive

if reg is situated at more than , say ,10cm from BA FE , you'll need some local decoupling , just in case

Happy New Year to everyone.

I'm thinking of trying some decoupling so what value of capacitance should I try?
Chris

 

[Backbones]

Anyone interested in using the Salas SSLV1.1 to power their BA-2 front end might be interested in my latest findings here: http://www.diyaudio.com/forums/power-supplies/192625-sslv1-1-builds-fairytales-89.html

In fact I was wrong to suggest that the difference between the regulator and the front end was only 4cm as posted above, it was nearer 9cm on one side. None of us is perfect.

 

[Backbones]

If one is using a shunt regulator on the BA-2 front end, is it necessary to keep C205 and C206 along with R210 and R211, which are acting as filters for the input ripple current?

 

[Zen Mod]

keep them as close as you can (BA FE pcb and shunt pcb ) and leave those RC cells out

 

[Backbones]

keep them as close as you can (BA FE pcb and shunt pcb ) and leave those RC cells out

Thanks Zen,

To be specific does this mean remove C205 and C206 and jump R210 and R211?

 

[Zen Mod]

I hate when I find that I close recently opened file .........

grumbgrumb


found it again ......... and - yes !

short R210 and R211
remove C205 and C206

if needed - put instead some nF ones ..... depending what scope is saying

 

[Backbones]

Thanks Zen. No scope just my ears.

 

[Zen Mod]

then trust them

 

[oiphy]

help biasing deep 6... with ba3

seems I run in to a problem here...
trying to bias the output stage alone ( no ba3)..... get almost 10A in to the psu from the rectifier, and 1.5v over the 1ohm source resistor ????
it starts out at 0 but in maybe 10 sec it skyrockets up... no diffrence if I adjust p101 or p102
HELP... what do I do?
anyone?? ideas???
thanks

 

[Zen Mod]

post exact sch of that what you made

 

[oiphy]

zen mod

post exact sch of that what you made

Having problem with pics today but its in article BA3 page 3 ba2 push pull output stage bought from diy shop, with the separate biasboard. if it helps..... take pics of the amp tomorrow so its easylier to se if i DROPT A BOMB. anyway input apreciated even today
thanks

 

[Zen Mod]

post pictures and take your time

less smoke that way

 

[oiphy]

measured the psu.....50v wtf i happening..

that is a little high isn't it?

 

[Zen Mod]

you need to sort first your PSU without output stage