MXR El Grande Bass Fuzz

[fx-fidden]

Great, I think that is working good!

The 87/113 change the frequency, but the Freq pot at noon don't boost nor cut: is flat. So you can't hear difference if you change the frequency 87Hz or 113Hz. That's ok.

I have to say that the Freq pot make all the difference, indeed, just at very higher and very low setting.
It's harder to find, but if you can you should to buy a W100k pot, the tape will be act better than a simply linear pot.

[Alamondm]

In my opinion the frequency pot is the best feature of this layout. With it the tone is very tweakable. I may have to get some W taper pots but the way it is now is working great. Thank you for all you have done.
Matt

[fx-fidden]

I'm glad the layout works fine.

[Feral Feline]

Great work guys!

I got W100k pots from Tayda, IIRC. Pretty sure I've seen them at Small Bear, too.

[fx-fidden]

Long time ago I bought them from Tayda, too. I bought the one with longer shaft. Now I need to cut, so I never do it!

I'm seeing another one type, PCB mount kind of, a bit different, but at least the shaft is normal.
Do you think we can cut those long pin easily? I guess yes. Next time I'll buy those!

[Feral Feline]

Looking closer at the new layout, there's a 12k between op-amp pins 1 & 2. On the schematics I've seen, including the one posted at the beginning of this thread and Güero's schematic (and layout), pins 1 & 2 are connected [ edit: jumpered] and that 12k (R34) is between pins 6 & 7, which is currently jumpered on the layout.

I'm guessin' you're getting more gain with the 12k on the first op-amp, and the second one is buffering... yes/no?

If so, would be fun to leave the 12k where it is and put another 12k on the second op-amp between 6 & 7.

GAIN!

[fx-fidden]

I looked "just quickly" my layout and the schematic in this topic. What you said is right and wrong at the same time.
The pins 1 & 2, and the pins 6 & 7 doing the same work, and those are two indipendent stages you can use like you want, I simply swapped just because it was easier in my layout use them like that.

The jumpered non-inverting input and output is indeed a buffer, and the one with the 12k, I think it's a gain stage to boost and cut the Freq control. Even if I should check these stages to see what happen if I change them a bit.

I'll let you know.

[fx-fidden]

So, as I thought that 12k controls the amount of the boost/cut of the Freq pot. Now it's about +/-15db, if the range is too big to use it you can reduce the resistor. If you want to exagerate  you can increase it.

If you add a resistor where the pins are jumpered it does nothing, because you need to go to the ground too. But if you do it, or if you add even a resistor and a cap line to the ground, you mess up the frequency boost and it doens't work as it should.
I'm not sure what exaclty do that stage in particular, but it's part of the frequency filter.