Can I use 2 conductor cable for instrument cable?

[vanessa]

I was reading a post about Belden 9271 cable being great instrument cable. I also read that the Grateful Dead used it for what seems like everything. I was looking into the specs on it http://bwccat.belden.com/ecat/pdf/9271.pdf and it's a 2 conductor with shield which looks great for microphones but can I use this for instruments cabling? If so do I solder the two conductor wires together? Or just cut one off?

[LyleCaldwell]

Yes. One conductor is your signal cable.  The other conductor is your ground.  The wrapped shield is the shield, which is only connected at one end to the ground conductor.  This is called "semi-balanced" and is a great way to get good noise rejection without the cost of balanced gear.

[Processaurus]

I'd use both center conductors for carrying the signal, because if one breaks, it'll still work.

If you wanted to be ultra hi-fi (which is a little ridiculous with something as noisy as guitar pickups)  you can make the semi balanced arrangement, where one center conductor carries the signal, and the other carries the ground from your source.  The shield is only connected to the sleeve of the plug that goes to your amp/effects.  The idea is that the noise the cable shield picks up is kept seperate from the signal ground as much as possible.  The cable can only be used oriented one way, or it defeats the purpose of this.  Too much trouble for me, but some people swear by it.

[vanessa]

The 'semi-balanced' wiring is something I've not heard of (I love this forum, I learn something every day).

So if I were to use the standard 228 Switchcraft right angle plug where you use the sleeve jacket as your source shielded ground and the plug tip as signal, on one end you tie both the source ground and the shield strands soldered to the sleeve jacket and on the other end leave the shield strands off soldering only the source ground to the jacket sleeve and the signal to the tip?

[LyleCaldwell]

Right.

I would disagree with Processaurus' suggestion as it will double the cable capacitance.

[vanessa]

So you would connect the two (shield and source ground) together to the jacket on one end and leave the shield off on the other?

[Peter Snowberg]

Here you go. 

http://www.dself.dsl.pipex.com/ampins/balanced/balanced.htm

[LyleCaldwell]

So you would connect the two (shield and source ground) together to the jacket on one end and leave the shield off on the other?

Right.

[vanessa]

I just read somewhere that you want the grounded end (shield) to be on the source (instrument) and open end (shield) to be on the amp side.

[guitar_199]

Other way around.  Always orient the cable so that the connected ( sleeve+sig grnd ) is towards the amplifier.  If you use effects....then towards the effects.

[Mark Hammer]

The specs on the cable don't look awful.  Just keep in mind that 2-conductor cable more or less assumes that it is carrying the signal of a very low (by guitar standards) impedance source.  What works for a 600 or even 150-ohm load is not necessarily God's gift to 10k loads.

[vanessa]

Here are two places I found were they say it will be un-grounded at the amp side, grounded at the instrument.

http://www.wildwestelectronics.net/mocaproaufa.html

http://www.rane.com/note110.html   (scroll down to Floating, Pseudo, and Quasi-Balancing).

[LyleCaldwell]

Vanessa,

The truth is you have to listen to see which orientation is quieter.  The actual gear used introduces a lot of variables.

Note: I'm only talking about the directionality of a cable with a telescoped shield, ie, "semi-balanced."  A normal mono or stereo cable does not exhibit directionality, no matter what salesmen/the gullible may say.

[DuncanM]

Following on from Mark's comments
I made up some guitar leads using 2 core mic cable and it was only after a few months that I happened to notice that they were killing the high end...
Switch back to a "proper" lead and the zing was back.
This only applied to the lead between the guitar and the first effect - the pedals had a low enough ouput impedance to drive the cable but the pickups didn't...

[Mark Hammer]

Bingo.

[LyleCaldwell]

Following on from Mark's comments
I made up some guitar leads using 2 core mic cable and it was only after a few months that I happened to notice that they were killing the high end...
Switch back to a "proper" lead and the zing was back.
This only applied to the lead between the guitar and the first effect - the pedals had a low enough ouput impedance to drive the cable but the pickups didn't...

Were you using both conductors as hot or doing the telescoped shield with one conductor as negative?

[Peter Snowberg]

Bingo.

LOL! That has got to be the shortest post by Mark I've seen. Even there it is totally spot-on. 

Welcome to the forum DuncanM! 

The Dead were always pushing the technology envelope so Jerry, Phil, and Bobbie all had preamps on-board.

[DuncanM]

I was using the two cores together as signal and the screen as earth - that's the way I've done it for more years than I care to remember...
The cable was a 50m drum from RS components here in the UK and I was lucky enough to be given it...
Neutric connectors, about 4 metres long and DEFINITELY kills the very high end.

And I know how to solder too. 

I might just go and try it with one core signal and one core earthed with the screen to see if that does reduce the capacitance.
I would have thought that it would also double the resistance of the signal path with no overall improvement, but I may be wrong...

[guitar_199]

Please understand, I'm not posting this to be mean-spirited or anything like that...... it's just for the sake of  discussion.  I looked at the references you sent, thought about it, and I'd still put the tied end at the amp...and here is why.

The whole reason for doing this method of cable building is to "drain off" noise..... sort of "intercepting" itt preventing it from ever radiating into the signal pair.  If you connect the tied end at the guitar..... any noise that is picked up on the shield MUST drain somewhere... and the only place it can is at the tied connector...currently plugged into the guitar.  When it does.....it will "hop a ride" back along the signal return wire inside the cable sort of defeating the purpose.   If you plug it in at the amp end the shield will be drained directly to the amp jack ground which, according to theory, will be giving the signal return wire a quieter ride back to the amp.   Just thinking about it.......  in the case of plugging the tied end into the guitar..... that means that any noise that is picked up.... will appear on the signal ground cable... and possibly coupling over to the signal wire depending on the capacitance between the two leads.   If you have a 15 foot cable.... you "sort of" have a 15 foot capacitor.   If you drain it at the amp end.....the noise will hit ground at the amp jack and that will be all.  Less chance of coupling the noise over to the signal cable.    And, with the relatively high impedance of an amp input it doesn't take much to get that noise in to the amp.

The best advice yet is....  try it both ways!   Let your ears be the judge.  Theory is a funny thing sometimes.     Sometimes it works....... sometimes it gets proven ( or at least demonstrated ) NOT to work!!!!  BUt give it a shot becuase the good news is that all you have to do is turn the cable around.  You dont have to rebuild it.   Have fun.

[DuncanM]

WOW, who would have thunk it....

Like Processaurus, I was always led to believe that to minimize the risks of breaks in the lead you should double up the two cores to produce one big core with redundancy built in.

However, I can hear a difference between THAT way of doing it and the "single signal core / earthed core + screen" method.

The single core with earth sounds airier and has a sparkle that the paired cores lacks.

I think Lyle is right - single core has less capacitance and sounds brighter.
You're never too old to learn something...

In my experience, most leads fail at the connector - so you might want to incorporate some heatshrink or Hellermann to reinforce the joint in the jack.

Also, looking at my "good" leads made from whirlwind cable, the insulation around the core is MUCH thicker than the insulation aroung the cores of the mic cable. I guess THAT would help produce less stray capacitance in guitar leads.