cable construction?

[travelin travis]

What is the difference in mic/instrument/speaker cable? I know mic cable has 2 conductors and a shield and instrument has 1 conductor and a shield but what would happen if I used mic cable as instrument cable? Would it be noisy?

 

[apl]

If you use mic cable to make instrument cables, use 1 conductor to the tip and the shield to the sleeve. Leave the other conductor out of it. It'll work fine, but it's more expensive than using one conductor.

 

[dgatwood]

Hooking an instrument up through a mic cable with a straight-thru adapter is probably not the best thing to do. The cable impedance is wrong. Not that it matters much at short distances, but you'll probably be happier if you use a line matching transformer on both ends.

Using balanced cables for instruments (with transformers) is a really good thing to do if you need a really long cable run, as running unbalanced audio more than about 20 feet isn't a bright idea if you can help it. For short runs... it probably doesn't matter what you do. You could probably run bell wire for up to five or six feet and not notice much difference....

As for speaker cable, I've used them as instrument cables for really short runs (as in 20 feet or less) in a pinch, though there's a definite hum if you do. They are unshielded for two reasons that I'm aware of:

1. higher power-carrying capacity (since the wires can be a larger gauge), so you end up with less voltage drop over a distance (which would otherwise seriously dampen bass reponse)

2. higher power across the line means that noise is smaller relative to the signal level, so shielding doesn't make much difference anyway.

As a side effect, unshielded cables have lower capacitance. I'm not sure what difference that ends up making, but I'm sure there are some EEs here who could say more.

 

[travelin travis]

Hooking an instrument up through a mic cable with a straight-thru adapter is probably not the best thing to do. The cable impedance is wrong. Not that it matters much at short distances, but you'll probably be happier if you use a line matching transformer on both ends.

i was referring to putting 1/4" plugs on a piece of mic cable. this is'nt something I planned to do, I was just wondering if there is a difference in mic cable and instrument cable construction other than the additional conductor wire on a mic cable.

 

[boingoman]

Hooking an instrument up through a mic cable with a straight-thru adapter is probably not the best thing to do. The cable impedance is wrong. Not that it matters much at short distances, but you'll probably be happier if you use a line matching transformer on both ends.

Using balanced cables for instruments (with transformers) is a really good thing to do if you need a really long cable run, as running unbalanced audio more than about 20 feet isn't a bright idea if you can help it. For short runs... it probably doesn't matter what you do. You could probably run bell wire for up to five or six feet and not notice much difference....

As for speaker cable, I've used them as instrument cables for really short runs (as in 20 feet or less) in a pinch, though there's a definite hum if you do. They are unshielded for two reasons that I'm aware of:

1. higher power-carrying capacity (since the wires can be a larger gauge), so you end up with less voltage drop over a distance (which would otherwise seriously dampen bass reponse)

2. higher power across the line means that noise is smaller relative to the signal level, so shielding doesn't make much difference anyway.

As a side effect, unshielded cables have lower capacitance. I'm not sure what difference that ends up making, but I'm sure there are some EEs here who could say more.

Dude, not to bust your chops, but I hope this post is a joke. Almost every single piece of info is way wrong.


It would take an hour to correct it.

Do the board a favor and delete it.


If it isn't a joke, you need some serious help. I will answer , but jeeez.....

 

[alexthacowboy]

well i use mic cable for all, i think 1 pair snake cable is the most usefull one.

i bougth a roll of canare snake cable (1 pair), and i use the cable, to build:

inserts
pairs of TRS's (balanced, i use this config to connect synths)
2 TS to 2 RCA (to connect cd's, turntables)
XLR to 1/4 tS
XLR to 1/4 TRS
single micro cable ( xlr to xlr here i joint the peir ALA Quadmic cable)
single instrumen cable 1/4 TS to 1/4 ts.

i found i pdf in rane site for wiring and 1 for grounding, i forgot where i downloaded but i gonna uplaod to my site and u can daowload (RANE copyrigth).

http://www.riesgodecontagio.com/wiring.zip

download and u get a nice reference.

hopes this helps.

 

[mshilarious]

If it isn't a joke, you need some serious help. I will answer , but jeeez.....

Ah, I'll take a shot at it:

Hooking an instrument up through a mic cable with a straight-thru adapter is probably not the best thing to do. The cable impedance is wrong. Not that it matters much at short distances, but you'll probably be happier if you use a line matching transformer on both ends.

The 2 conductors in a mic cable are the same gauge as the single conductor the comparable instrument cable. In both cables, the conductors are shielded with the ground cable. Since the cables are the same gauge, the impedance is the same, and in any case extremely trivial compared to the impedance of the mic/instrument. I'm not sure what you mean by a straight-thru adaptor, but if you wire as apl described, you'll be fine.

Using balanced cables for instruments (with transformers) is a really good thing to do if you need a really long cable run, as running unbalanced audio more than about 20 feet isn't a bright idea if you can help it. For short runs... it probably doesn't matter what you do. You could probably run bell wire for up to five or six feet and not notice much difference....

This is mostly OK; yes, if you need to send an instrument signal a long distance, it should be converted to balanced low impedance, for two reasons: with a high impedance instrument signal, cable capacitance can cause some highs to bleed off, and interference can become more of a problem. This is done with a direct box, or DI box, which can use transformers or an active circuit.

As for speaker cable, I've used them as instrument cables for really short runs (as in 20 feet or less) in a pinch, though there's a definite hum if you do.

Not too surprising

They are unshielded for two reasons that I'm aware of:

1. higher power-carrying capacity (since the wires can be a larger gauge), so you end up with less voltage drop over a distance (which would otherwise seriously dampen bass reponse)

Rather than "power carrying capacity", I would simply say lower impedance. The voltage drop, however, isn't bass response, it's volume. Maybe there is some inductance going on, I don't know, but it's the volume loss you worry about.

2. higher power across the line means that noise is smaller relative to the signal level, so shielding doesn't make much difference anyway.

OK.

As a side effect, unshielded cables have lower capacitance. I'm not sure what difference that ends up making, but I'm sure there are some EEs here who could say more.

In a very low impedance circuit like a speaker, none. I'm not sure if speaker cables really have lower capacitance; I never paid any attention, because it doesn't matter for speakers, but a quick web search informed me that speaker cables and guitar cables are both about 100pF/m. Perhaps if speaker cables were shielded, their capacitance would be higher, but it still wouldn't matter.

 

[boingoman]

Ah, I'll take a shot at it:

Yer a good man, probably better than me.

I would add, mostly as points of interest (to some):

The impedance of a mic/instrument cable is irrelevant at audio frequencies, and the resistance difference between 20 and 24 gauge cable is so slight at the lengths we normally use that you wouldn't really notice the level difference. You might unconsciously nudge your gain up a fraction to compensate, but not anything extreme.

In speaker cables, low resistance/large gauge serves another function besides power transfer. It allows the amp to control the speaker better in the low end. A speaker cable with a high resistance can result in floppy, uncontrolled bass.
This may account for the perception of decreased bass, as it loses it's definition and punch.

 

[travelin travis]

Alexthacowboy, thanks for uploading those pdf's. I'm guessing there are alot of people that don't know about the chassis/signal ground thing difference. Before reading this, I did'nt know that a proper shield is connected to chassis ground.

I have a mic pre that has a 2 prong ac power supply. So the shield in the mic cable really is'nt doing much of anything since the pre has no proper ground?

 

[travelin travis]

have any of you put together your own isolation transformers? or, do you know of any low cost, good quality pre mades? will isolation transformers even make a difference if equipment is'nt properly grounded? by properly grounded I mean what is mentioned in the pdf's that alexthacowboy posted.

 

[boingoman]

have any of you put together your own isolation transformers? or, do you know of any low cost, good quality pre mades? will isolation transformers even make a difference if equipment is'nt properly grounded? by properly grounded I mean what is mentioned in the pdf's that alexthacowboy posted.

I've never put one together.

Ebtech makes decent gear. Hum eliminator

Yes, one of the purposes of an isolation box is to prevent ground loops. The two pieces of gear are not connected directly. If a ground loop is the source of the noise, an iso box should get rid of it.

The same thing can be accomplished with a DI that has a ground lift.