quieter (in terms of unwanted noise) transistors for a superfuzz

Started by mordechai, February 23, 2011, 01:51:00 PM

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mordechai

I've seen some interesting discussion regarding transistor choices for tone in the superfuzz circuit.  My question at this point regards quieter operation.  Does anyone have experience with alternatives that reduced some of the unwanted noise?

Further...if I understand correctly, the characteristic tone is achieved in large part by the parallel transistors connected to the diodes...would changing the choice of transistor (some or all) in the earlier stages of the circuit have a strong affect on this as well?

LucifersTrip

Quote from: mordechai on February 23, 2011, 01:51:00 PM
I've seen some interesting discussion regarding transistor choices for tone in the superfuzz circuit.  My question at this point regards quieter operation.  Does anyone have experience with alternatives that reduced some of the unwanted noise?

What do you mean by noise? hiss/hum, wailing. Those problems are many times solved by small caps in strategic spots.
I haven't built the superfuzz, but diff transistors definitely produce diff amounts of noise. Since your guitar/amp setup is diff that others, it's best to experiment with everything [trial & error] and rely on your own ears.

Quote
Further...if I understand correctly, the characteristic tone is achieved in large part by the parallel transistors connected to the diodes...would changing the choice of transistor (some or all) in the earlier stages of the circuit have a strong affect on this as well?

changing any transistors, especially to ones with much different hfe's should affect the sound...again, experiment..it's fun
always think outside the box

digi2t

I found a cap, between 100pF and 470pF to taste, across the B and C legs of the tranny really helps cut down on the hiss in fuzz pedals.
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R.G.

The superfuzz is not well designed for low noise as an entire circuit.

Without doing a redesign, about all you can do is to use metal film resistors, particularly in the first/input stage, and use low noise transistors, like the 2N5088, 2N5089, or MPSA18. These are all quite high gain, so they may or may not do nice things for your "tone", although much of the gaggling about the tone of this or that transistor is misplaced.
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.

mordechai

Quote from: R.G. on February 23, 2011, 08:41:05 PM
The superfuzz is not well designed for low noise as an entire circuit.

Without doing a redesign, about all you can do is to use metal film resistors, particularly in the first/input stage, and use low noise transistors, like the 2N5088, 2N5089, or MPSA18. These are all quite high gain, so they may or may not do nice things for your "tone", although much of the gaggling about the tone of this or that transistor is misplaced.

R.G., how would you compare the 2n5088 to the 2n304 in terms of low noise? You've mentioned that you've used both in super fuzz builds...do you have a preference?

R.G.

Quote from: mordechai on May 23, 2011, 10:39:56 AM
R.G., how would you compare the 2n5088 to the 2n304 in terms of low noise? You've mentioned that you've used both in super fuzz builds...do you have a preference?
The 5088 was designed and specified for low noise applications. The 3904 was a general purpose device.

Use metal film resistors on the first two transistors, at least.
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.

Perrow

I have (by sheer luck) an original Shin Ei Superfuzz. I must say that when engaged, "unwanted circuit noise" is pretty much drowned out by wanted ditto  ::)

But maybe that's just me.
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