Fuzzdog Sumble / Simble Overdrive Build Help - Cap change

[kurauk]

Hi, first time poster, long time reader.

http://pedalparts.co.uk/docs/Sumble.pdf

I am building a Fuzzdog Sumble and one of the capacitors on what I believe is the input stage is a 8n2 (C2 on schematic). I thought I had some but it turns out my collection doesn't include any. I assume changing it's value would be okay but I wondered what expected effect on the circuit and sound? Any help and advice would be gratefully received.

Cheers

Kura

[idy]

Welcome to the forum!

That inout cap affects how much bass gets through. Going up to 10n would let a bit more through; it would move the "high pass" filter down about 20%, about what a musician would call a "major third." These simple filters are very subtle and you might not notice.

You could make a nearer value cap by putting two caps together. In parallel they "add", so 4.9 and 3.3 in parallel would make 8.2...etc

If you put them in series they get smaller, but the math is trickier, uses reciprocals.
Here CT means total capacitance. For two caps its 1/CT=1/C1+1/C2, so...
.12=1/C1+1/C2... easy way is find a vale twice what you want. They don't make 16.4n? try 15n caps.. you end up at 7.5n
I am way overthinking this for you....

[kurauk]

@idy thank you for the concise reply. Exactly what I was after and I hadn't thought about combining two caps.

Thanks

[antonis]

It's quite difficult to combine 2 film caps on particular layout..
(those box caps have short legs which can't be placed on the same pad..)

Try to measure actual capacitane of 10nF or 6.8nF (in case you have some), especially in case of K or M tolerance mark..

[Elektrojänis]

The highpass is mainly formed by that C2 and R6. If I fed the numbers correctly to one of the online RC-filter calculators, the -3dB frequency is about 40Hz, so it is well below the lowest fundamental frequency on guitar tuned to E-standard.

If You make it 10nF it will be about 33Hz. If you make it 6.8nF it will be about 50Hz. I doubt that either will make a big difference. Palm muted notes (which might have some inharmonic low frequencies on the attack) might get a little tighter with 6.8nF and little looser with 10nF. It is well possible that you wont even notice though.

[kurauk]

Hey everyone, thanks for the replies, all of which are very helpful. I was just looking at doing this and realised that combining the polyboxes might be a little difficult for me. So I will go with a 10n as that is all I have in that range.

Thanks again.