Author Topic: A few basic questions about wire  (Read 1498 times)

dano12

A few basic questions about wire
« on: February 10, 2006, 09:24:57 AM »
As I'm starting to build more of my own stuff, a few basic questions about wire have arisen:

1. Is it ok to twist two or three wires together for leads from the pcb to pots or switches? I remember from my first tube amp project that there were some do's and don'ts. Does this apply to pedals?

2. Has anyone used ribbon cable to improve layout and lead dress in a pedal? Could I use strips from computer-type peripheral ribbon cables in a pedal to clean up the arrangement?

3. I remember from tube amps that signal path wires should be kept to as short a length as feasible to decrease noise. Is the same general concept true within the confines of a standard size stompbox enclosure?

I guess I'm wondering what the balance is between great lead dress and signal noise/degradation?

Thanks!
-dano

dano12

Re: A few basic questions about wire
« Reply #1 on: February 11, 2006, 08:22:50 AM »
>bump, can anyone help out the noob? ;)

R.G.

Re: A few basic questions about wire
« Reply #2 on: February 11, 2006, 09:28:33 AM »
Quote
1. Is it ok to twist two or three wires together for leads from the pcb to pots or switches? I remember from my first tube amp project that there were some do's and don'ts. Does this apply to pedals?
For opamp and bipolar pedals, it's generally OK to do this. In tube amps the grid impedance is so high that twisting wires can cause crosstalk, treble loss or oscillation. Bipolar and JFET stuff is lower impedance. However - MOSFET circuits can cause problems, because their gate impedance is even higher than a tube's grid. Also, effect circuits tend to need less treble response than tubes, so treble loss may not be as severe. This answer is only the broadest of generalities, of course. The only good answer is - try it, see if you like it.

Quote
2. Has anyone used ribbon cable to improve layout and lead dress in a pedal? Could I use strips from computer-type peripheral ribbon cables in a pedal to clean up the arrangement?
Yes. Yes.
Quote
3. I remember from tube amps that signal path wires should be kept to as short a length as feasible to decrease noise. Is the same general concept true within the confines of a standard size stompbox enclosure?
Yes, heavily tempered by what is and is not possible. It may not be possible to make wires only 2" long and still open the box. As short as feasible is good.

Quote
I guess I'm wondering what the balance is between great lead dress and signal noise/degradation?
In my mind, this is not a balancing act. Great mechanical dress that causes signal noise or degradation is not acceptable unless you're making sculpture, not audio equipment. Great wire routing for signals is not acceptable if I can't assemble the box and service it.
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.

Mark Hammer

Re: A few basic questions about wire
« Reply #3 on: February 11, 2006, 09:31:59 AM »
Brother Keen beat me to the punch by mere seconds, but dammit, I wrote this out and I'M GONNA POST IT!! :icon_twisted:

As I'm starting to build more of my own stuff, a few basic questions about wire have arisen:

1. Is it ok to twist two or three wires together for leads from the pcb to pots or switches? I remember from my first tube amp project that there were some do's and don'ts. Does this apply to pedals?
Sure.  I do it all the time.  Ideally, you don't bring leads together or in close proximity where high gain signals are travelling, or where there is the possibility for stuff from the output to find its way - even in minute amounts - back to the input.  Sometimes that can mean NOT twisting/bunching, and sometimes twisting can mean that THIS cluster of wires is moved well out of the way from THAT cluster.
Quote
2. Has anyone used ribbon cable to improve layout and lead dress in a pedal? Could I use strips from computer-type peripheral ribbon cables in a pedal to clean up the arrangement?
Sure.  Plenty of companies will mount all the pots on a daughter board and run a ribbon cable to the main board.  If it's good enough for them, it's good enough for us.
Quote
3. I remember from tube amps that signal path wires should be kept to as short a length as feasible to decrease noise. Is the same general concept true within the confines of a standard size stompbox enclosure?
Pretty much.  There have been a number of instances reported here where people complained about this whining noise and that one, only to find that when the wiring was "cleaned up" the whining went away.  All that said, you don't have to go nuts about it, because unlike with amps, you HAVE the option to filter out any noise further down the line.  Moreover, you can easily service an amp when the leads are nice and short, but shorts leads can easily make for a pedal that is hard to get at on the inside.  Of course, at the end of the day, the board itself, and the planned panel layout, has to make short leads possible.  I've seen plenty of cases where the pads for various controls and switches forced you to criss-cross wires, which in turn forced you to use longer leads than you'd like just to be able to GET leads to the controls on the panel.

Quote
I guess I'm wondering what the balance is between great lead dress and signal noise/degradation?
The general relationship is as you'd expect: neatly and brevity help.  The bigger question is whether, for all their trouble and compromise they require, they will improve the noise situation enough to justify that effort, compared to other things.  Once again, it will depend on the situation.  For example, compressors need as clean and quiet an input signal as you can afford, or else they end up boosting the noise tremendously the moment you stop playing,  My sense is that lead length, twisting, etc. will have considerably LESS impact on noise that the cable you use to feed the compressor.

dano12

Re: A few basic questions about wire
« Reply #4 on: February 12, 2006, 07:01:44 PM »
Wow guys, thanks for the detailed responses. This will be very helpful in my current project!

Ortiz

Re: A few basic questions about wire
« Reply #5 on: February 12, 2006, 07:57:23 PM »
Another question. What gauge wire do you all normally use?

formerMember1

  • Guest
Re: A few basic questions about wire
« Reply #6 on: February 12, 2006, 08:25:07 PM »
Quote
Another question. What gauge wire do you all normally use?

I could take care of this question.  :D

22AWG seems to be what many like, it is small, and easy to strip.  24AWG is smaller and may be harder to strip and less strong. 

Smallbear has the best wire IMHO.  It is stranded and partly bonded, it is strong, and can be bent in angles without breaking etc,..also is cheap and comes in many colors.  The insulation does melt/bubble if you solder to long, but that only happens to me when rewiring a switch or replacing a switch/jack a couple times.

I use the 24AWG  off smallbear and like it very much.  I have no trouble stripping it.  I was never able to use wire strippers on any of my wire without kinking the wire itself.  I use a wire stripper that came with my cold heat soldering cordless iron that works great.(the iron sucks BTW, don't bother)
you are better off using snippers.

here is a pic of the wire in my wah i built, (BTW the LED isn't that bright, just looks that way) I seperated the in and out wires on each side of pedal and twisted the battery leads.

http://i30.photobucket.com/albums/c317/_!_19/7774062a.jpg
« Last Edit: September 14, 2006, 07:44:34 PM by aron »

no one ever

Re: A few basic questions about wire
« Reply #7 on: February 12, 2006, 10:28:07 PM »
Quote
Another question. What gauge wire do you all normally use?

I could take care of this question.  :D

22AWG seems to be what many like, it is small, and easy to strip.  24AWG is smaller and may be harder to strip and less strong. 

Smallbear has the best wire IMHO.  It is stranded and partly bonded, it is strong, and can be bent in angles without breaking etc,..also is cheap and comes in many colors.  The insulation does melt/bubble if you solder to long, but that only happens to me when rewiring a switch or replacing a switch/jack a couple times.

I use the 24AWG  off smallbear and like it very much.  I have no trouble stripping it.  I was never able to use wire strippers on any of my wire without kinking the wire itself.  I use a wire stripper that came with my cold heat soldering cordless iron that works great.(the iron sucks BTW, don't bother)
you are better off using snippers.

here is a pic of the wire in my wah i built, (BTW the LED isn't that bright, just looks that way) I seperated the in and out wires on each side of pedal and twisted the battery leads.

http://i30.photobucket.com/albums/c317/_!_/7774062a.jpg


very neatly done. are you done with that one yet?  :icon_biggrin:

i got the 24 awg for my wah, and it kept breaking and breaking... PITA to strip... so bad experience for me.

22awg from my local shop, however, works WONDERS! strips very easily, very bendable, and very neat looking.
« Last Edit: September 14, 2006, 07:44:23 PM by aron »
(chk chk chk)

formerMember1

  • Guest
Re: A few basic questions about wire
« Reply #8 on: February 12, 2006, 11:18:11 PM »
 :icon_cry:
« Last Edit: September 14, 2006, 07:44:49 PM by aron »