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Andy Armstrong, Soft Fuzz, in: Hobby Electronics, July 1983 🇬🇧
Posted: 26 May 2022, 18:07
by modman
Re: Andy Armstrong, Soft Fuzz, in: Hobby Electronics, July 1983 🇬🇧
Posted: 29 May 2022, 23:46
by Manfred
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Re: Andy Armstrong, Soft Fuzz, in: Hobby Electronics, July 1983 🇬🇧
Posted: 31 May 2022, 13:40
by Manfred
The value of R2 with 470 ohms was immediately suspicious to me, the circuit needed a high input level until the output signal began to clip, with 470 kiloohm then worked at lower levels.
Also, the frequency response showed that 470 Ohms must be the wrong value.
With 470 Kiloohms, the frequency response was then hi-fi and not suitable for guitar, there are still some things to improve.
R1 should have at least 560 kilohms I think that here also a digit "0" was forgotten in the value.
Re: Andy Armstrong, Soft Fuzz, in: Hobby Electronics, July 1983 🇬🇧
Posted: 31 May 2022, 16:17
by Frank_NH
That seems right, Manfred. R2 is supplying the reference voltage for biasing IC1a, so 470K should be correct. The input resistor looks like an anti-pop resistor, so 1 meg would work there.
I'm curious to see what the soft clipping looks like. This is an unusual soft clipping feedback network which could potentially provide a more interesting distortion than the typical diode arrangement. I guess I should sim this in LTSpice too!
Re: Andy Armstrong, Soft Fuzz, in: Hobby Electronics, July 1983 🇬🇧
Posted: 01 Jun 2022, 02:11
by Manfred
Frank_NH wrote: ↑31 May 2022, 16:17
That seems right, Manfred. R2 is supplying the reference voltage for biasing IC1a, so 470K should be correct. The input resistor looks like an anti-pop resistor, so 1 meg would work there.
I'm curious to see what the soft clipping looks like. This is an unusual soft clipping feedback network which could potentially provide a more interesting distortion than the typical diode arrangement. I guess I should sim this in LTSpice too!
Re: Andy Armstrong, Soft Fuzz, in: Hobby Electronics, July 1983 🇬🇧
Posted: 01 Jun 2022, 14:33
by Manfred
Re: Andy Armstrong, Soft Fuzz, in: Hobby Electronics, July 1983 🇬🇧
Posted: 07 Sep 2022, 02:01
by mictester
It's really worth listening carefully to this circuit. It's not really a "fuzz", it's far too smooth for that - it's a "tube-like" overdrive. If you add basic tone controls to the tail end of this, it will very effectively emulate a number of pedals. I've built (many times) a tweaked variant of this. The "zeners" in the feedback circuit come from a National Semiconductor data book from the 70s. The rest of the circuit (apart from the obvious mistakes) is pretty standard....
It's a worthwhile build, and you'll be pleasantly surprised by just how good it sounds - even on chords.
SoftFuzzComponentSide.pdf
SoftFuzz.zip