Adding a buffer in front of a fuzz

[lazerphea]

Hi all!
I bought my first perfboard, and I was thinking about soldering the Hemmo fuzz I have on my breadboard.



For what I've understood it has a low input impedance, so I thought I could put in front of it an opamp buffer like this one:



Do you think this could be a good idea? I'd remove C2 from the opamp circuit and connect the output to the input of the Fuzz. Is this ok?

I still have a couple of questions:
1) I have only dual opamps at the moment (MC4558CN and CHN4558C): can I use them, ignoring one half of them?
2) I'd like to add a led to indicate when the pedal is on (in this case, I  switch it on by inserting the input jack): where do I have to position the 2.2K resistor in series with the led?

Thanks to everyone willing to answer to my questions!

[flo]

People say that you got to use a Fuzz Face directly connected to the passive guitar pickup outputs without buffers in between for "that" good fuzz sound.
Try a search for it. For instance:
http://www.chrisbrownguitar.com/gear-pages/56-fuzz-face-fixes-and-mods.html

Signal Buffers Before The Fuzz - With a buffer before the fuzz face you will most likely end up with an input impedance that is too high and also the fuzz face will no longer be able to interact with the guitar pickups. If the FF doesn't can't load the pickups it loses it's response to your picking and volume control which causes an unnaturally harsh tone.

I have not tried this myself.

[oskar]

Do you think this could be a good idea? I'd remove C2 from the opamp circuit and connect the output to the input of the Fuzz. Is this ok?

I still have a couple of questions:
1) I have only dual op amps at the moment (MC4558CN and CHN4558C): can I use them, ignoring one half of them?
2) I'd like to add a led to indicate when the pedal is on (in this case, I  switch it on by inserting the input jack): where do I have to position the 2.2K resistor in series with the led?

Thanks to everyone willing to answer to my questions!

1. yes. the unused OP-amp is tied like a buffer, short out/inverting input. noninverting input to a ref. voltage.
There's an unused OP-amp in this schematic.
http://www.tonepad.com/getFile.asp?id=88
EDIT! Watch out, I checked up on this. Yes the unused OP should be tied to a ref. voltage but it has to be within it's limits. No op amp will go to one of it's rails so it should be given a reference ( Like R1/R2 in your buffer above )
2. When components are connected in series their position is interchangeable. V+ - R - LED - ground = V+ - LED - R - ground
If you follow through with it and use a polar cap in between the stages ( I would use a nonpolar like a 100n ) then the caps positive pole would face the most positive side, in this case the OP's 4.5V.

[lazerphea]

People say that you got to use a Fuzz Face directly connected to the passive guitar pickup outputs without buffers in between for "that" good fuzz sound.
Try a search for it. For instance:
http://www.chrisbrownguitar.com/gear-pages/56-fuzz-face-fixes-and-mods.html

Signal Buffers Before The Fuzz - With a buffer before the fuzz face you will most likely end up with an input impedance that is too high and also the fuzz face will no longer be able to interact with the guitar pickups. If the FF doesn't can't load the pickups it loses it's response to your picking and volume control which causes an unnaturally harsh tone.

I have not tried this myself.

Uhm... interesting! I thought low input impedances were always a no-no!

[lazerphea]

Do you think this could be a good idea? I'd remove C2 from the opamp circuit and connect the output to the input of the Fuzz. Is this ok?

I still have a couple of questions:
1) I have only dual op amps at the moment (MC4558CN and CHN4558C): can I use them, ignoring one half of them?
2) I'd like to add a led to indicate when the pedal is on (in this case, I  switch it on by inserting the input jack): where do I have to position the 2.2K resistor in series with the led?

Thanks to everyone willing to answer to my questions!

1. yes. the unused OP-amp is tied like a buffer, short out/inverting input. noninverting input to a ref. voltage.
There's an unused OP-amp in this schematic.
http://www.tonepad.com/getFile.asp?id=88
EDIT! Watch out, I checked up on this. Yes the unused OP should be tied to a ref. voltage but it has to be within it's limits. No op amp will go to one of it's rails so it should be given a reference ( Like R1/R2 in your buffer above )

Thanks man, but it seems I don't need the buffer anymore!

2. When components are connected in series their position is interchangeable. V+ - R - LED - ground = V+ - LED - R - ground
If you follow through with it and use a polar cap in between the stages ( I would use a nonpolar like a 100n ) then the caps positive pole would face the most positive side, in this case the OP's 4.5V.

Sorry, I didn't explained my concern clearly: what I wanted to ask was where in the circuit should I have to add the R-LED combo, but from your answer I understand I have to tie it to the V+. Thanks!

[Ben N]

The low input impedance is, as suggested above, deliberate, and you probably wouldn't like it otherwise, although you can certainly experiment just by putting something buffered, like a Boss pedal or an fet-based booster, ahead of your breadboarded fozz and playing it. If that sound floats your boat, great!

A high inout impedance facing the output impedance of the guitar is generally a good idea when preserving your clean signal is what you are trying to accomplish. But the point of a fuzz is anything but preserving your clean signal, and most fuzzes rely on a low input impedance to focus the sound and reduce hash and fizz. The only caveat is that you should definitely use a true bypass, meaning that the effect input is entirely isolated from the bypassed signal; otherwise the low input impedance will load down yours signal even when the fuzz is bypassed, and that would be bad.