Author Topic: What gain really does for sound: Volume or "life vs lifeless".  (Read 2777 times)

Thecomedian

What gain really does for sound: Volume or "life vs lifeless".
« on: December 22, 2012, 05:43:43 AM »
https://www.smallbearelec.com/HowTos/BreadboardSiFF/BreadboardSiFF.htm

In using these schematics, tweaking and reversing poles to use PNP Ge transistors mp25a, which have a datasheet rated gain of between 20-40 (I cant test them, no meter to do so), I found that this particular circuit was MUCH less noisy with the hissing business than the previous NPN circuit I used 2n2222's from a 1980 box that came from radio shack. An aside, I have heard PNP's will have less noise introduced in them because the "holes" are moving, instead of electrons. I haven't verified that, but the gain of 2n2222's is so high in comparison it might just be that.

So the question I have is this: On reading the section about tweaking the design to get more voltage, or ensuring you have the proper gain for Q1 and Q2, the author states that it will sound "lifeless and unfocused" if the gain isn't right, and if the Voltage is normally 1.6v on Q2-C rather than 4.5 or so. I'm trying to understand what this means, and why it should work like this.

It seems to me like the gain only really matters for output volume and such.

It also seems like what causes the circuit to sound better or worse is how long the transistors remain in cutoff or saturation, vs how long they remain in stable mode.

I base these on the fact that the PNP Ge's only have a low gain rating, but they sound really good, and I can bias them with more or less Q2 collector voltage until they sound incredibly harsh.

I don't understand what the author means relating gain to distortion quality otherwise. it seems to imply only high gain transistors of 90-120 would create usable or pleasing distortion. Is that true?
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