Made a score at the local thrift store today

[laurie]

Saw this on the shelf and thought sure, having another little amp is all good for $7.
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2SB175B_1.jpg (139.74 KiB) Viewed 2848 times

[laurie]

Then I look at the back - and there is a schematic.
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2SB175B_2.jpg (157.29 KiB) Viewed 2847 times

[laurie]

And indeed, there are four vintage 2SB175B transistors inside the thing! PNP germanium, as used in some of the Analogman Sunface pedals. Nice.

I don't know the gains yet, but I can feel a couple of fuzz pedals coming on...
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2SB175B_3.jpg (251.89 KiB) Viewed 2847 times

[laurie]

According to the data sheet, these "B" spec devices should all be high gain. I'll have to measure them, and confirm they don't have bad leakage, but I'm hoping a couple of them are good.
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2SB175B data.jpg (45.87 KiB) Viewed 2847 times

[Pepe]

Oh wow! That's a great price for a couple of vintage transistors!

[laurie]

I'm doing the final tests, but all the transistors are measuring a gain of 140 or above.

This means I can make four hot all germanium fuzzfaces.

"For a more compressed and saturated fuzz sound, you can increase the gain of Q2, potentially up to 150-190"

[Pepe]

Very cool! Let me guess: now you're on the search for more of these certain amplifiers on the used market?

[laurie]

Ah... I don't think I'll find any. I'm treating this as a "one off".

[Pepe]

Well, if I were you I'd use ebay and Reverb to be informed in the case that such a unit pops up for sale again.

How many of these have been thrown away without having been used? Like so many other stuff of this kind ... and clunky fuzz pedals that had no battery power anymore ...

[laurie]

The gain calculations:

If anyone is interested I can give a detailed description of the technique and the math.
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2SB transistors.jpg (34.7 KiB) Viewed 2806 times