Page 1 of 2
Made a score at the local thrift store today
Posted: Sun Aug 10, 2025 7:37 pm
by laurie
Saw this on the shelf and thought sure, having another little amp is all good for $7.
.

- 2SB175B_1.jpg (139.74 KiB) Viewed 6393 times
Re: Made a score at the local thrift store today
Posted: Sun Aug 10, 2025 7:38 pm
by laurie
Then I look at the back - and there is a schematic.
.

- 2SB175B_2.jpg (157.29 KiB) Viewed 6392 times
Re: Made a score at the local thrift store today
Posted: Sun Aug 10, 2025 7:40 pm
by 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...
.

- 2SB175B_3.jpg (251.89 KiB) Viewed 6392 times
Re: Made a score at the local thrift store today
Posted: Sun Aug 10, 2025 7:44 pm
by 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.
.

- 2SB175B data.jpg (45.87 KiB) Viewed 6392 times
Re: Made a score at the local thrift store today
Posted: Sun Aug 10, 2025 8:16 pm
by Pepe
Oh wow! That's a great price for a couple of vintage transistors!

Re: Made a score at the local thrift store today
Posted: Mon Aug 11, 2025 2:16 am
by 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"
Re: Made a score at the local thrift store today
Posted: Mon Aug 11, 2025 6:22 am
by Pepe
Very cool! Let me guess: now you're on the search for more of these certain amplifiers on the used market?

Re: Made a score at the local thrift store today
Posted: Mon Aug 11, 2025 12:46 pm
by laurie
Ah... I don't think I'll find any. I'm treating this as a "one off".
Re: Made a score at the local thrift store today
Posted: Mon Aug 11, 2025 1:50 pm
by 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 ...

Re: Made a score at the local thrift store today
Posted: Mon Aug 11, 2025 5:22 pm
by laurie
The gain calculations:
If anyone is interested I can give a detailed description of the technique and the math.
.

- 2SB transistors.jpg (34.7 KiB) Viewed 6351 times