Shielded wire on pots?

[sopapo]

Hello to all,
I would like to know how can I use shielded wire on the sustain pot of a Big muff variant to try to minimize noise,.
I know that in the ende, this can have no effect in the noise, the noises issues are very complex, but this is diy, and i am the belt and suspenders kind of person 🤣 and like the extra peace of mind that this kind of thing give me...
I have built a clone of a clone of a Big muff  its a dice works muff diver, the sustain pot is in the standar big muff location, one lug from the first stage, center to the second stage and the third to ground through a 1 k resistor

I have certain hum and Buzz noise. Is a noisy design, I know,ts something that bugs me, because i have made an extra effort to build with care to have the minimum noise posible.... shielded cable on  four inputs and outputs ( from Jack to switch and from board to switch), a healthy DC filter (220uf  plus 50r) , metal film resistors and caps, bc549b trannys and the ground scheme is something that I have read from RG keen (no input power switching, all the grounds to the same spot on the pcb, isolated output Jack and only one Contact from the ground to the enclosure)
Thanks for all

[FiveseveN]

Is the noise still there when you turn your guitar's volume pot to zero?

[GibsonGM]

What are you powering it with? Does the 'buzz' remain if you power it from a battery?

[idy]

Shielded wire is kind of a hassle to work with for me... Commonly used on input jack, sometimes footswitch, I believe you are supposed to ground only one end of the shield.

And when I have used shield it was to keep output wire from feeding back with intput wire, making things oscillate. Not to make a fuzz less hissy.

But what everybody else says: find out where the hum is coming from, give the situation a good shake down before you start with shielded wire and soldering iron. Or not.

And pictures. These people love pictures. hard to advise on until we see enclosure etc.

[anotherjim]

The sustain pot doesn't have a grounded lug 1, so it isn't that straightforward - there are 3 wires to screen. What I do is use, not a twisted pair, but a twisted trio (both good names for bands). Twisting the wires is plenty good enough inside an enclosure.
Making tight & neat twists is pretty easy, just ask if you need to know.

[sopapo]

Thanks for your answers, fiveseven, no when I turn down the volume there isnt any noise, neither if I unplug the input of the pedal
Im powering with a voodo labs power supply, its a very clean power supply, and works wonder with all effects.... in this proyect I made the decision to not install battery clip, I never use batteries, but for troubleshooting I can see is a good thing....
Idy, I have made what I think is the usual debugging (minus audio probe) I have reflow al solders and have look with a magnifyng glass for bad or cold solder joints. Yes you are right¡¡¡ when I finish my work shift I will take pictures and post it here.
AnotherJim, do you mean that in this case its better to twist wires to use shielded cable?? This is the thing that lost me, I would need a three conductor plus ground wire and shield cable to do this, which I dont have... using a  shielded twisted cable and a single shielded one toguether??
Thanks to all for your time

[FiveseveN]

when I turn down the volume there isnt any noise

Then the pedal is fine and the noise is from your pickups, only exacerbated by the high gain nature of the circuit.

The sustain pot doesn't have a grounded lug 1, so it isn't that straightforward

One could move the 1K resistor offboard, on the pot (or just skip it, really) and have ground available that way. Mic cable is shield + 2 conductors of course and there are slim variants, and just as common is USB cable with shield + 4.
But yeah, once you're inside a metal can it's more about crosstalk. Funny how folk don't worry as much about shielded jacks, seems like a bigger surface area.

[GibsonGM]

What the others said. Being such a high gain, dirty circuit....any noise that comes in on the input is going to get massively amplified and end up...like what you're hearing.   

If I'm playing out, I stomp my dirt box as the song comes in.  If recording, I use a gate.  I don't think there are too many other options, sorry!   You COULD try shielding your guitar, checking out the area you're in for sources of noise that may make things worse (fluorescent lights, being near a computer...).

I shield every guitar I own, and find it makes a LOT of difference! Esp. with single coils!

[anotherjim]

No shield, just twisting 3 wires together. Keep it simple. It works. The same goes for the other pots. This is just something I do "just in case" and it is easier than messing with shielded cable.
The Muff will amplify any noise that comes in, but that, of course, won't necessarily be the Muffs fault.

[Rob Strand]

It all all depends on your test set-up.  If you have a finished pedal inside a metal enclosure then grounding the pots isn't going to do much because the pots are already grounded.   If you have a PCB sitting on the bench with open wiring then grounding the pots can help.    However, in such a set-up you will be getting noise from all over the place.   The way around that is to place the PCB over a grounded metal sheet (don't short the connections to the metal sheet!).   A  sheet of kitchen aluminum foil can work fine for a test.  You may still need to ground the pots.   Most people here that have been doing this for a while have an open metal enclosure (of sorts) with mountings for pots and switched, all of which are grounded to better approximate the final metal enclosure.

[sopapo]

Thanks my friends, I will try to twist the wires of the three other pots ( this special versión have two tone controles) but also will try to use a twisted shielded cable on the sustain pot ,silly me didn't think of the trick of putting the 1k resistor on the pot, if this
Dont work i will use twisted wire aswell...
Another cuestión, when using shielded cable in this situations, the ground only has to be conected on one end ...there is a preference on which end? Ex. in the input wire from Jack to 3pdt I connected the shield on the Jack sleeve, but on the wire from 3pdt to board, i connected the shield to the switch ground, It was easier for me this way..
Note that the effect is fully inclosed and working in a hammond box..

[bartimaeus]

to be honest, i see no reason to try those mods.

as FiveseveN said, the noise is from your pickups.

any high gain fuzz is going to amplify the noise at the input. no avoiding it.

shielded cable inside a grounded enclosure is just silly imho. the enclosure is the shield. do you really have something inside the pedal that's sending out ambient noise? it can make sense inside a complex rack unit with an internal power supply or something. but for a guitar pedal it's just a waste of energy.

if you were getting crosstalk, then you'd want to improve your layout. but that doesn't seem to be the issue.

i'm not trying to be rude, i just want to be clear so you don't spend your time re-wiring a pedal that works.

[GibsonGM]

It occurs to me that we should maybe draw a distinction between shielded wire in an enclosure with high risk of coupling ("crosstalk")  between circuit elements IN the enclosure (ex: a high voltage, multi-stage tube amp, where this frequently done) vs. lower voltage circuits with lower risk of such problems.   

It's Not nuts to shield the input wire of high gain effects like a BMP in a preventive approach ("peace of mind"), but it doesn't sound like coupling is the problem here. And good layout, as bartimaeus points out, will probably be the best cure or preventative for that.

[antonis]

Are BJTs placed in sockets..??

[sopapo]

Hello, Bartimaeus, i see your point, O l know its not an important issue, but I would like to optimize the most this noise situation,  i see reputed makers of pedals that use shielded wire inside  his pedals..
No, its not a crosstalk issue, this problema dont arise even at Max gain, Iits not the typical squealing at high gain..
Antonis, yes the bjts are in sockets, It can be problematic??

[antonis]

Antonis, yes the bjts are in sockets, It can be problematic??

Not necessarily but I'd try a smear of solder between every pin and respective holder..

[anotherjim]

Depends on the build really.
In a big enclosure like 1590BB it's easy to route wires to minimise the proximity of input to output signals. In a 1590B, it gets a bit tighter and the PCB input might benefit from screened wires. A complication is it's going to be two pieces as the stompswitch is in between.
If high gain AND non-inverting, the potential for feedback squeal via stray coupling is very real. However, one of the closes places where input and output meet is the stompswitch. Wiring a 3PDT so the LED switching is in the middle contact row can be enough to separate input from output and prevent feedback.

If you look inside traditional hardwired tube amps, signal wiring from input jack to the first tube grid was screened and they didn't spend money doing that unless it seemed worthwhile.

[Rob Strand]

Another cuestión, when using shielded cable in this situations, the ground only has to be conected on one end ...there is a preference on which end?

There's a few different scenarious.    I'll only run through a few.

As general rule you don't want to be connecting shields to the chassis ground at both ends.

There's also two quite different cases:
- The thing at the end of the wires has a ground connection *to the part*. 
   For example, a volume pot.
   Here the shield is connected to the PCB and the *pin* of the volume pot,
   but generally not to the shell of the pot.   (There are a few exceptions which
   are done for convenience more than good practice, for example soldering grounds
   to the back of the pots in guitars.)

- The thing at the other end of the shielded wires does not need a ground connection.
   Example a gain pot in the feedback loop of an opamp.  Here you only connect the
   shield at one end.    Shielding of this type cans also cause problems!  Shielding
   adds capacitance between the shielded wires and ground.  In a feedback loop that
   extra capacitance can cause oscillations.

[FiveseveN]

Shielding adds capacitance between the shielded wires and ground. 

Speaking of which, if you want to go all out the shield's potential can also be something more useful than ground:

[bartimaeus]

Hello, Bartimaeus, i see your point, O l know its not an important issue, but I would like to optimize the most this noise situation,  i see reputed makers of pedals that use shielded wire inside  his pedals..
No, its not a crosstalk issue, this problema dont arise even at Max gain, Iits not the typical squealing at high gain..
Antonis, yes the bjts are in sockets, It can be problematic??

i see where you're coming from. but shielded wire inside the enclosure is meant to prevent crosstalk within the pedal. if crosstalk is not the issue, then adding more won't help.

and remember, many reputed makers got started on forums like this and freestompboxes. dig back far enough and you'll find famous makers saying some really silly things, which they no longer believe. i don't mean to say it's all lies haha, just be careful