Can you use Microphone cable as instrument cable?

[Osiris]

Long story short, I need a new cable and looking through my box of odds and sods I found a suitable length of microphone cable - [url="http://www.maplin.co.uk/p/van-damme-yellow-tour-grade-classic-xke-microphone-cable-priced-per-metre-n64dl"]Van Damme 268-025-040 classic microphone cable[/url]. I've also got some spare Neutrik 1/4 inch jacks too.

Can I make up a lead to use between the bass and amp with the above mic cable (and possibly another when using my pedal board)?
If it's OK to do it, how would I wire it up as it has 3 inner cores (2 shielded and one that isn't) compared to the usual 2 of a regular instrument cable?

Is there any reason why this would be a bad idea?

[BigRedX]

It is perfectly fine to use "Mic" cable to make up unbalanced instrument leads.

If the two shielded conductors are twisted together then you should connect one to earth along with the screen. Convention dictates that the conductor with the red sheath is "hot" and that is the one that should be soldered to the tip terminal of the jack plug. However it doesn't matter which of the two is connected to the tip and which to the sleeve along with the shield conductor so long as you make sure you do the same at each end of the cable.

If the two shielded cables are not a twisted pair then connect both of them to the tip and just connect the screen to the sleeve.

HTH

[Huge Hands]

I used to do this a lot, as I used to be able to get loads of spare mic cable from my old work. I used to connect the two inner signal cores together at each end to the tip, and the shield to the usual.

It will work, but you will get the usual naysayers going on about incorrect impedance etc.

I found that in venues with poor/noisy electrics, they were much more susceptible to picking up noise and hum than proper instrument cables, but for messing about practicing in the house, it should be fine.

[rmorris]

In short - Yes - you can use Mic cable.
Just wire the 'spare' inner conductor to either tip or shield. Either is fine but just make sure to do same at both ends
It's quite usual to use two core cable for unbalanced connections just because it's more usual to have mic cable readily available in pro audio.

Is there a catch ?
Well, yes there can be,
Proper 'Instrument' cable isn't simply a shielded single core cable.
It should also have a ' semiconducting' carbon based sheath between the insulation of the core and the screen.
This is the bit that you are normally advised must be cut back when terminating to a connector so that it doesn't touch the signal.

What's it for ? Moving a cable generates a signal due to small changes in the cable geometry / capacitance / static electricity etc (Wikipedia is your friend to read more...)
The magnitude of the signal for a given disturbance depends on the electronics at either end of the cable.
Basically higher impedance circuits end up with more noise.
And, of course, 'standard' Bass/Guitar pickups are pretty High Impedance and so are Amplifier / Pedal inputs. So the signals can be a problem - think 'swishing' and 'crackling' noises.
So how much of a problem you get with a given cable depends on your bass/amp setup and how much the cable moves.
On a bass it's inevitably going to move. Between fx and Amp etc it'll likely not be moving much. Plus Impedances are lower so probably okay.

It doesn't affect mic signals ? The same thing happens but impedances are much lower (typ Mic Z is around 150 Ohm) so less noise.
But it's also helped by the typical 'cotton' fillers you see inside a mic cable. These help maintain the relative geometry of the cable to an extent ( as well as affecting the way a cable 'handles') so you do get some help there.

As it happens I think I've recently seen some Mic cable available that has a semiconducting screen (don't quote me) but in general they don't.

[Osiris]

Thanks for the helpful insight, folks.

It sounds to me that the sensible thing to do is to whip up a cable or 2 and see how they perform in regards to any potential unwanted noise. The worst case scenario is that i end up having to buy a new cable so it's hardly the end of the world

[Osiris]

Quick update; I whipped up a cable earlier, it's just over a meter long to use from the output of my compressor into the front of my amp. Doesn't appear to be noisy in the slightest even when giving it a good shake about! Did a quick A/B test against a proper instrument cable and there was no notice difference in tone, volume, noise or anything else. [size=4] [/size]