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-   -   Aleph 3 on Peter Daniel A30 boards... (http://www.diyaudio.com/forums/pass-labs/94523-aleph-3-peter-daniel-a30-boards.html)

Skorpio 18th January 2007 12:05 PM

Aleph 3 on Peter Daniel A30 boards...
 
I am building the A3 on the A30 boards and there are some differences I would like some help with:

Regarding the Aleph current source:
There is no capacitor around the bipolar control transistor on A3, but 1nF from B-C on A30.

Should I install it on the PCB?

The feedback resistor is 820R on A30 but only 750R on A3. Is that because A3 has only two output sets and A30 three?
The same with the series resistor for output current measurement. A3 has 4x0.47R in parallel (0.12R) and A30 has 6 in parallel (0.08R).
I would like to have 6 mounted to get the lowest series resistor/best power handling, but at the same time use only two set output devices...

Should I use the 750R or the 820R feedback resistor then?

Regarding input and feedback resistors/capacitors:

A30 uses 100K/10K sets for both input and feedback. A3 uses 1K/10K feedback and 1K/22K input. On A30 the 100K feedback is decoupled by 10pF. On A3 there is no capacitor here, but a 1nF between gate and drain on bottom output device.

Can I install a capacitor in parallel with the 10K feedback and should the value be 1nF? Or should I go for the original A3?


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