Original Single Transistor Fuzz Circuit

[Rob Strand]

Thanks for the documentation! I knew roughly the attributes of pickups but that is very in depth and informative. Do you think that I should get into the habit of modelling these or are they just factors to keep in mind during the design process?

In general it's best to try not to rely on having the impedance model present.   There are cases where you have to have it in place in order to judge the effect.

However, you have to be aware that including the impedance model will impose the guitar response on *all* simulations.   Normally we think of the guitar response as be implied so when we see a flat response amplifier we interpret that as letting the guitar response pass through without it being modified.   When we include the impedance model it captures the interactions between the guitar and circuit but the guitar response is not removed.   It's possible to factor out that effect by normalizing all plots by the guitar response into an amp (not the circuit).   Not sure if you will understand the finer points here it's a little tricky - that's why it's best to try not to include the impedance model in all simulations!

[camzilla]

If you are using a plug-in breadboard try connecting the aluminium base plate to the circuit ground.  If not get some kitchen foil and place it under the circuit, add an insulator between the foil and the circuit, then connect the foil to circuit ground.

Mains powered supplies can promote capacitively coupled noise.   Normally when you connect the pedal to an amplifier which has a mains earth connection this type of noise is largely removed.   If the amp or audio interface device doesn't have a mains earth connection it's possible for this type of noise can show up.

I currently have the same circuit on a breadboard with the plate grounded and fully built on a soldered perfboard inside a grounded enclosure. They exhibit the exact same noise and behavior.

However, you have to be aware that including the impedance model will impose the guitar response on *all* simulations.   Normally we think of the guitar response as be implied so when we see a flat response amplifier we interpret that as letting the guitar response pass through without it being modified.   When we include the impedance model it captures the interactions between the guitar and circuit but the guitar response is not removed.   It's possible to factor out that effect by normalizing all plots by the guitar response into an amp (not the circuit).   Not sure if you will understand the finer points here it's a little tricky - that's why it's best to try not to include the impedance model in all simulations!

I understand. Modeling a pickup means the "flat" frequency response would appear that of the pickup and what not. That would be difficult to decode, makes sense thanks.

[PRR]

The high pitched whining noise only appears with the power supply not with the battery, but also the noise only appeared when my guitar cable was plugged in. Furthermore, with my guitar plugged in using a 6 inch patch cable the noise is not present.

Your power supply whines (many do). Just like radio/TV (if you remember), a longer cable picks-up more.

So talk about this power supply. Made for electric guitar work? Or an old answering-machine wall plug?

[antonis]

OP already spoke

[Rob Strand]

I currently have the same circuit on a breadboard with the plate grounded and fully built on a soldered perfboard inside a grounded enclosure. They exhibit the exact same noise and behavior.

Do you know if the ground on your amp or audio interface has a connection to mains earth?

[camzilla]

Your power supply whines (many do). Just like radio/TV (if you remember), a longer cable picks-up more.

So talk about this power supply. Made for electric guitar work? Or an old answering-machine wall plug?

I posted a link in an earlier response.Its an isolated guitar pedal power supply, but it is cheap and Amazon brand.

Do you know if the ground on your amp or audio interface has a connection to mains earth?

I was testing on a boss katana mk1 which has a 3 prong cable, so I believe it is grounded to the mains earth.

[Chillums]

You could try a different outlet that's not on the same circuit/breaker.   Also try turning off all CFL/florescent lights in the area as the drivers/ballast in them are very noisy.

[Rob Strand]

I posted a link in an earlier response.Its an isolated guitar pedal power supply, but it is cheap and Amazon brand.

So far:
- RC filter supply filter doesn't work.
- shielding doesn't work.
- mains ground path present.   Should measure to confirm.

It would be easier to just use another power supply.    Trying to bullet proof your pedal against bad power supplies is difficult.  It's difficult to diagnose and it's messy to add parts to your circuit to work around a bad power supply.

When I see "buzz noise" cases like this sometimes there's an issue with the guitar wiring or shielding which promotes the buzz getting in.   A boost or fuzz pedal is obviously going to boost the buzz, especially if it doesn't have much high frequency filtering.

Another thing you can try is adding a 220 ohm (1/2W) load across the 9V power rails.  Put it across the 9V DC power supply (not the pedal supply).    Some switch mode power supplies don't work well without a load.   Normally you get noise in the form of whistle or whining, so I have doubts it will fix your issue, but you have nothing to lose trying it.
I went over a few of your posts and at some point the buzz turned into a hiss;

Eliminating that dropped the noise to a subtle hiss.

I'm assuming that's still the case.

Maybe you should try the RC filter on the supply again, and maybe the 220 dummy load isn't a bad idea either.