Author Topic: Bass cut for Fuzz Face  (Read 106 times)

nonost

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Bass cut for Fuzz Face
« on: December 05, 2018, 06:33:21 AM »
Hi guys. I want to add a bass cut pot to the input of a Fuzz Face and I'm not sure I've understood it well.

I'm using a 1M linear pot with lugs 1&2 tied together to the input circuit, where they meet one lug of the small capacitor. The 3 lug goes to the negative side of the electrolytic cap and then the other lugs of both capacitors together. With that configuration I'm having the full bass sound with the pot fully clockwise but as soon as I turn it counterclockwise I got the thin sound. There's no middle sounds. What am I doing wrong?

I've read this topic http://www.madbeanpedals.com/forum/index.php?topic=20195.0 and tried to do what Rej says but I think I'm doing somethig wrong.

Any help is really appreciate, cheers.

midwayfair

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Re: Bass cut for Fuzz Face
« Reply #1 on: December 05, 2018, 08:58:38 AM »
The input impedance of the fuzz face is about 50K.

The pot that you've put in series with your larger capacitor is 1M. I don't know what the value of the "small" capacitor you've used is, because you don't say.

A pot will turn from 7:00 to 5:00 in a full sweep.

At 8:00, you've created a voltage divider of 50K/50K, attenuating your bass frequencies by half. At 9:00 you've cut it in half again. Then again by half at 12:00, and you've certainly hit the point where it's completely indistinguishable.

It also matters how small the second capacitor is. If it's 10nF, you're probably okay but it's going to sound a little thin since the cutoff frequency is ~300Hz. If it's 1nF, then the cutoff frequency is 3,000Hz.

A 250K pot is more than sufficient for the variable bass input, though 100K will also work pretty well. You're also best off finding a C taper potentiometer for it but that's a different discussion.
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nonost

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Re: Bass cut for Fuzz Face
« Reply #2 on: December 05, 2018, 04:54:33 PM »
Ey Jon. I've tried lots of combinations...for the small cap I've used from 220pf to 220nF, and for the big cap from 1uf to 10uf. I've just tried a 250K log pot and it seems to work better so I will try a couple of C taper pots, maybe that's the problem.

 Thank you very much  :)