Matching Aleph input devices as a part of the complete amplifier?


Retired diyAudio Moderator
2002-01-21 2:42 pm
near Atlanta, GA
I was reading the volksamp aleph 60 manual and I noticed this:

"The input devices are the same as the originals, but significant improvement is to be found in the manner of matching the input devices. Previously the input differential transistors were merely matched to each other, but beginning with the Aleph 30 and 60 they are now matched both to each other and to the rest of the amplifier circuit. We select the input devices as part of the complete amplifier, swapping them in and out until the best performance is achieved. Tweaking the input stage in this manner and with other adjustment techniques we have been able to significantly lower the noise floor and improve the power supply noise rejection of the amplifier."

Would this help the performance of the Aleph 2 amplifiers that I am making?

If so, how exactly is it done, the matching of the devices?

Also, of those who build an aleph amplifier, how many IRF9610 devices should I buy to match them properly?

One more thing, I am planning on buying 100 IRFP240 transistors, and matching sets. Would anyone here be interested in buying matched sets for their alephs, assuming I get good matching. I am planning on using the expensive hp curve tracers that they have here at Georgia Tech.

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2001-01-14 1:19 am
My sugestion is that you should look for lower DC offset at the output when changing the input devices. But I'm noy sure in what I'm saying. I hope Mr. Pass will give us his explanation. I'm also interested in the working of the resistors marked with *, and their approximative values.