Preamp concept

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#82
It is not impossible to achieve gain 40 dB (100x), in this case you need to decrease value of resistor between emitters of input pair to some 20 Ohms. But distortion will get into percents, i.e. 100x higher than original circuit.

I would recommend no more gain than 30 dB (30x approx.), this is for resistor 200 Ohms between emitters of input pair. You will have to play DC game again.
 
#83
I see.

How about making 2 "preamp concept" in series, each have gain of 10 (that makes total =100X), will this have the same "percent" distortion?

If it is the same, it is better to make 1 with 100X gain, due to simplicity.

This is difficult for me to decide, since the whole thing is non-feedback, distortion raise is confusing 😀
 
#85
Hi, PMA,

This is the McIntosh schematic that makes me think about transistor based ccs. The final's voltage is +/-35V.

If you notice in the attachment, something is strange. The output rail is only +/-35V, but McIntosh loaded the differential with 47k to +105V and load the VAS with 3k6 to +100V.

It is certainly more difficult and more costly to make additional 105V, just to drive 2 nodes with small mA requirement, compared to making transistor based ccs that can work from 35V.

If it is not important reason, I'm sure they won't do it. But they do it the hard way.

In your opinion, why McIntosh do it the hard+expensive way?
 

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