Fuzz War / OCD Combo Pedal High Pitched Squealing Issue

[Hexjibber]

Hi guys,

Having an issue with a high pitched squeal coming from the Fuzz War part of a Fuzz War/OCD combo (OCD is working fine) and just wanted to ask a question.

I've wired it up like this, except without the battery: (my mate wanted to able to switch between circuits with one switch, not turn one off and then the other on, makes sense to me)



I've read a number of posts that say with high gain pedals if the input and output are too close together that this can cause a high pitched oscillation/squeal, given that everything is wired pretty closely on the 3PDT, do you think this might be my problem? If so would there by any way of solving it? Or could it be a grounding issue?

Here's a pic so far in case it's of any use! Wiring has got a bit messy since I started trying to diagnose the fault! Also I haven't trimmed a lot of the leads yet in case I need to pull them out again.



Just thought it was worth asking the question as I'd like to have as many different things to try when I get home later!

Would appreciate any advice anyone has!

Cheers!
Graham

[Noise_Ninja]

that could be the power supply. try it with a battery. if the squealing still are present read this http://sound.westhost.com/noise.htm

and use as short shielded wires as possible.

Hope it helps.

[Hexjibber]

that could be the power supply. try it with a battery. if the squealing still are present read this http://sound.westhost.com/noise.htm

Hope it helps.

Thanks for the reply man, don't think it will be the power supply as I'm using a Carl Martin Pro Power with isolated outputs, I just unplugged one pedal which is working fine on my board and put this one in it's place.

The effect still works fine underneath the squealing noise and doing things like adjusting the tone knob changes the pitch of the squeal, very odd.

Will have a read of that article, cheers!

[Noise_Ninja]

yup i don't think it is the power supply when it's a pro power 

I think your wires are too long, and they don't look shielded.

but its a cool project.

[Hexjibber]

I think your wires are too long, and they don't look shielded.

but its a cool project.

I'm still very much a novice when it comes to wiring, hence the spaghetti! I've not had to use shielded wire in any of my previous builds, something I should look into? Which would be the wires that require shielding?

I think it will be cool pedal once I get over this problem, it's driving me crazy at the moment though!

[Noise_Ninja]

it's a good idea to think about shielded wire. the wires that need the shielding the most would be the wires where the signal passes through. but interferens can happen in the DC pathway to.

but shorter wires will maybe do the work.

the longer wires the bigger chance to get som interferens on them. so maybe you dont need the shielding.

hope the help remove your crasyness i know the feeling. i work at a place that makes radio, and damn its hard to remove the interferens some times

[Hexjibber]

it's a good idea to think about shielded wire. the wires that need the shielding the most would be the wires where the signal passes through. but interferens can happen in the DC pathway to.

but shorter wires will maybe do the work.

the longer wires the bigger chance to get som interferens on them. so maybe you dont need the shielding.

hope the help remove your crasyness i know the feeling. i work at a place that makes radio, and damn its hard to remove the interferens some times

Thanks man, I will look at trimming down my excess wire, I'm sure it can only help!

Wow, that must be very annoying working in that environment sometimes, fair play to you!

[GibsonGM]

Some 'rules' for you: 

make signal runs as short as possible
cross wires, if you must, at right angles only
use shielded wires for signals...ground only ONE end of each wire (doesn't matter which)
try to pass in/out wiring away from the PCB
Carefully check each circuit to see if you have ground loops going on...

You can 'chopstick', or use a pencil to move wires around a little...you may find a 'sweet spot' where the squeal stops, letting you know which wire is the culprit.

If the above doesn't help, I'd try to find a way to ground the input of the board not being used.  That's a pretty sure-fire way to shut them up!  May even take a 4PDT switch to do that!   

[Noise_Ninja]

yeah sometimes it's a pain in the ass. but it's a nice job because i learn so much that i can use when making pedals.

[Hexjibber]

Some 'rules' for you: 

make signal runs as short as possible
cross wires, if you must, at right angles only
use shielded wires for signals...ground only ONE end of each wire (doesn't matter which)
try to pass in/out wiring away from the PCB
Carefully check each circuit to see if you have ground loops going on...

You can 'chopstick', or use a pencil to move wires around a little...you may find a 'sweet spot' where the squeal stops, letting you know which wire is the culprit.

If the above doesn't help, I'd try to find a way to ground the input of the board not being used.  That's a pretty sure-fire way to shut them up!  May even take a 4PDT switch to do that!   

Thanks man, those are some good tips, really appreciate that!

I'm hoping it's a ground issue that I can resolve relatively easily. The weird thing is initially I'd mistakenly got two resistors in each other's spots which was causing a big volume drop and splattery gain, no squeal though, I swapped them round to their correct spots in hope that would be the end of it but then the squealing started to happen. I'm still in the early days of building and this has been the first time I've had to properly trouble shoot a pedal so is testing my patience!

[Hexjibber]

Carefully check each circuit to see if you have ground loops going on...

I just want to be sure I understand the whole ground loop thing, as to be honest how it all works is still a bit confusing to me!

I have done a very crude diagram showing how this pedal is wired up in terms of the ground part, does this shed any light on to my problem for you more experienced builders? I'm not sure if the one from the daughter board to the input jack (on the left) is the one causing a loop of some kind?

The daughter board I'm using on the 3PDT bypass switch (as opposed to the circuit switching one) has ground points on it which I think of as the star ground effectively.

[Noise_Ninja]

Carefully check each circuit to see if you have ground loops going on...

I just want to be sure I understand the whole ground loop thing, as to be honest how it all works is still a bit confusing to me!

I have done a very crude diagram showing how this pedal is wired up in terms of the ground part, does this shed any light on to my problem for you more experienced builders? I'm not sure if the one from the daughter board to the input jack (on the left) is the one causing a loop of some kind?

The daughter board I'm using on the 3PDT bypass switch (as opposed to the circuit switching one) has ground points on it which I think of as the star ground effectively.

this look like a ground loop to me.

try discornnecting the Daughter board to the jack input.

[Hexjibber]

this look like a ground loop to me.

try discornnecting the Daughter board to the jack input.

I wired it up like this last night, it's how I wire the ground in all my pedals with the exception of the ground from the Fuzz War board to the input jack, problem still persists though

You can 'chopstick', or use a pencil to move wires around a little...you may find a 'sweet spot' where the squeal stops, letting you know which wire is the culprit.

I tried this and the input and output leads of the OCD altered the pitch of the oscillation slightly when prodded, I have them heatshrink bound together, could this be a problem? I have at least figured out the problem seems to be with the OCD oscillating and not the Fuzz War but I'm still no closer to figuring out what is causing it

This is a cry for help from a desperate man!!

[rousejeremy]

Ground everything to one point. Power, Fuzz, OCD, Daughter board, output jack, twist all those ground wires together and solder them to the input jack sleeve.
I had a Fuzz Factory that did the same thing you are describing and it was from running grounds all over the place. It seems the higher gain pedals don't like ground loops.

[Hexjibber]

Ground everything to one point. Power, Fuzz, OCD, Daughter board, output jack, twist all those ground wires together and solder them to the input jack sleeve.
I had a Fuzz Factory that did the same thing you are describing and it was from running grounds all over the place. It seems the higher gain pedals don't like ground loops.

Thanks man I will give that a go! I'm guessing because I have two high gain circuits in one box this could the cause of my woes!

[duck_arse]

cut that heatshrink! seperate the input and output wires of the ocd from each other, as far as is possible. you could try sheilded wire on one or the other of these, if you have any.

[Hexjibber]

cut that heatshrink! seperate the input and output wires of the ocd from each other, as far as is possible. you could try sheilded wire on one or the other of these, if you have any.

Ok man will do! Thanks for that!

[Hexjibber]

Hi guys, quick update on this problem;

Tried wiring all the ground leads onto the input jack as suggested but alas the squealing remained. Cut the heatshrink that was binding the input and output wires from the OCD together, slightly reduced the squeal but it's still very much there.

I wired up each pedal separately to check all was ok and they work fine, the squeal comes back whenever they are both connected to ground, any ideas what would be causing this?

Cheers,
Graham

[duck_arse]

power supply interaction. did you link us to a circuit diagram? if you look over at amz ....

http://www.muzique.com/lab/hum.htm

you will see the following diagram .....



if you put one of these filters between supply in and V+ on each of your boards, you might just have a fixx. it wouldn't hurt, anyway. the values shown are not critcal, use whatever you have on hand. good luck.

[Hexjibber]

power supply interaction. did you link us to a circuit diagram? if you look over at amz ....

http://www.muzique.com/lab/hum.htm

you will see the following diagram .....



if you put one of these filters between supply in and V+ on each of your boards, you might just have a fixx. it wouldn't hurt, anyway. the values shown are not critcal, use whatever you have on hand. good luck.

Thanks man, something else to try so much appreciated! After reading that article I had a quick thought, my Carl Martin power supply has two outputs that supply 350mA instead of 150mA, pretty sure I tested it in one of these but could it cause an issue? I didn't think it would as I normally have a Harmonic Percolator in that slot and have no issues.

Here's the schems to both pedals if that helps at all

OCD:


Fuzz War


Thanks again for the reply!