[dcs]

Greetings,
OK, this evening I (rather nervously) started setting up the bias on my recently built AKSA 100.  I think I've made sense of the readings, and after scanning Hugh's instructions I am pretty sure that I know what must be done.  However, as this is my first build, it would be great if one of you fine folk could confirm my assumptions please:

1. Voltage drop across R25  and R26 (with trimmer wound fully anticlockwise) is 4.2V and 4.1V on the right channel, 5.3V and 5.4V on left.
The Right hand channel biases up to give 5V drop over R25, but as the left hand channel voltage drop is already 5.3V I guess I need to increase R12B empirically as per the instructions.

2. Output offset is 134mV left and 126mV right (before adjusting trimpot).  This seems a little high (although it is within spec I understand from other posts that ideally this should be as close to 0mV as possible) - so I should increase R3 (to around 110K?)

3. Voltage between R5/R6 and earth is 23 V on both sides.  Spec states that this should be 28V  Is this too low, or will this voltage rise with the adjustments outlined in 1 and 2 above and/or should I remove C4 and re-measure.

Many thanks,
Dave

[AKSA]

1. Voltage drop across R25  and R26 (with trimmer wound fully anticlockwise) is 4.2V and 4.1V on the right channel, 5.3V and 5.4V on left.
The Right hand channel biases up to give 5V drop over R25, but as the left hand channel voltage drop is already 5.3V I guess I need to increase R12B empirically as per the instructions.

This should be fine on all scores.  It's a little higher on the left channel, but no problem overall.  You can now switch off, insert the fuses, then crank it up gain and start setting up the bias.

2. Output offset is 134mV left and 126mV right (before adjusting trimpot). This seems a little high (although it is within spec I understand from other posts that ideally this should be as close to 0mV as possible) - so I should increase R3 (to around 110K?)

Offset is not important until the fuses are installed.  It is the last measurement you make, in fact.  I should change the instructions to reflect this;  it really is meaningless without the fuses in place because the rail voltage is considerably reduced until they are in place.

3. Voltage between R5/R6 and earth is 23 V on both sides. Spec states that this should be 28V Is this too low, or will this voltage rise with the adjustments outlined in 1 and 2 above and/or should I remove C4 and re-measure.  

Once again, not relevant until the fuses are in place.  You'll find it will rise by at least four volts with the fuses in place.

Hope this is helpful, congratulations on coming thus far, are you pleased with your build, Dave?

Cheers,

Hugh

[dcs]

Hugh,
Many thanks for you 'real time' reply - I was able to go to bed with a smug grin on my face knowing that I am (hopefully) only a little time away from audio testing (that's if a decent bottle of red doesn't find itself open tomorrow night - I'll definately be opening one after testing if all goes well).  And yes, the build experience has been excellent.  Thanks Hugh.

Dave