Cables 101: Instrument vs. Speaker Cables

Started by Elantric, July 19, 2012, 01:40:33 PM

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Elantric

Cables 101: Instrument vs. Speaker Cables
By Jeff Gorham
http://www.notreble.com/buzz/2010/07/19/cables-101-instrument-vs-speaker-cables/
Many people who have been playing for an extended period of time may be guilty of this. Many may have learned quickly, or still do it after 30 years of playing. But what happens when you use an instrument cable instead of a speaker cable to run your amp? And, furthermore, what are the differences between them? This month we'll explore the intricacies of cables, both of their composition, and of their purpose and function. We will also learn about the effects of making such a mistake, and why we should avoid this problem at all costs (well, the cost of going to the nearest store to get a REAL speaker cable, anyway).
Cable Construction

Most cables are made of a copper core with some sort of metal connector (often nickel) and a polyester or rubber coating. Many high-end cables often use oxygen-free copper cores (very pure, for exceptional signal transfer) with gold connectors (gold transfers electrical currents well, and also resist corrosion). One can also get a variety of "gauges", or cable thicknesses.

Generally speaking, a heavier gauge is preferred, as it allows the most signal to transfer (think of a water hose; a bigger hose allows more water to flow through). Also remember that shorter distances are easier on your signal. Just like the water hose that can lose water pressure, if it's a really long hose, if your cable is too long, you can lose some of your signal and tone.

The main difference between the construction of an instrument cable or a speaker cable is that an instrument cable is shielded, whereas a speaker cable is not. This is due to each cable's purpose and function.
Cable Purposes and Functions

Instruments put out a very weak signal path as compared to an amp. For this reason, instrument cables are shielded in order to keep unwanted RF interference (extraneous noise caused by other electronics nearby) to a minimum.

Amps put out a lot of power. Therefore, there is less of a need to keep out RF interference, as the signal is already powerful enough to resist the phenomena on its own. This is why speaker cables are generally unshielded.
The Dangers of Mixing and Matching

So what happens when you make the mistake of using the wrong cable for the wrong function? If you use a speaker cable in place of an instrument cable, you will get a lot of noise from your amp, monitors, even (theoretically) your cell phone. You will probably hear a constant, high-pitched squealing sound and a lot of static. This is because there is no shielding to preserve your instrument's signal, and all that RF interference will "join" your instrument signal in its path to your amp.

Using an instrument cable in place of a speaker cable, however, is much more serious. Since the amp is attempting to put out far more power than what the cable is made to handle, the amp (and speakers, for that matter) get a little confused.

If you remember from my article "Speaker Impedance: How to Properly Match Your Amp Head with Cabinets",
http://www.notreble.com/buzz/2010/05/27/speaker-impedance-how-to-properly-match-your-amp-head-with-cabinets/
amps are pretty "smart" in that they know at what impedance to run. Unfortunately, this instrument cable problem just throws a huge curve-ball to the amp, and it strains itself to push through the cable. The result can be damage to your speakers, your amp, or both.

So you have to ask yourself: Is it REALLY worth saving ten bucks on the cable at the risk of ruining my $500+ rig? I doubt it. Just go to the nearest music store and buy a speaker cable. Again, there are options like oxygen-free copper, gold connectors, and heavy gauge speaker cables that can be expensive, but any cheap speaker cable will be better than using an instrument cable.

beggar

dear sir /madam   i wonder if there is a difference between microphone and speaker cables if they are all xlrs   how can i tell them apart??  thanks

admin

If you are talking about XLR cables that connect to Self Powered PA Speakers  - These are the same as XLR  Mic cables

gumtown

Back in the 80's and 90's much of my power amp output and passive speaker gear all used XLR connectors.

It was fairly easy to determine an XLR mic lead from an XLR speaker lead as the mic lead had a male XLR one end and a female XLR the other end.
The speaker leads had female XLR on both ends.

But some of my first PA systems also had jack mic inputs, and required XLR to jack mic leads,
but I also had some passive speakers with jack sockets, so had XLR to jack speaker cables.

There was also a monitor amp with jack outputs too, so there was also jack to XLR and jack to jack speaker leads.

Recipe for disaster really !!
This opened up the possibility the power a mic from a power amp, speaker leads used for inputs and mic leads used for outputs.
More confusion where the XLR-jack mic leads were wired different from the XLR-jack speaker leads, so they were not functional when interchanged.

Then I came up with the brilliant idea of shrink sleeve different colours for each lead type around the plug ends.
I did
Yellow = XLR-XLR mic leads.
Blue = XLR-XLR speaker leads.
Green = XLR-jack mic leads.
Red = XLR-jack speaker leads.
I even wrote a unique number on each lead end so it could be identified without having to trace out the cable.

Roll on to the 2000's and much of the gear was getting retired and replaced, all amp outputs are now Speakon, all passive speaker cabinets are Speakon (some gear retrofitted with Speakon).
All mic inputs are XLR.
So now things are much simpler, speakon for speakers, and XLR mic cables for inputs for both Desk and powered monitors. 
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

gumtown

I also recall back in the early 80's at student flat party, where a tube amp head and speaker cabinet were used as the sound system with a tape deck plugged in.
The speaker cabinet was connected with a regular shielded guitar cable.
The sounds were cranked for quite a while, probably at about 20% THD, when suddenly the sound died... silence.

Some then noticed the speaker lead had developed a bulging bubble in the middle, then it suddenly bust open with a squirty hiss,
filling the room with smoke.

First hand experience at seeing the result of a guitar cable used for driving a speaker.  ;D
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

shawnb

I saw a guy use an old-school lamp power cord with 1/4" jacks on each end as a guitar cable. 

Some folks just don't care...
Address the process rather than the outcome.  Then, the outcome becomes more likely.   - Fripp

gumbo

Quote from: gumtown on July 19, 2017, 03:54:16 PM
I also recall back in the early 80's at student flat party, where a tube amp head and speaker cabinet were used as the sound system with a tape deck plugged in.
The speaker cabinet was connected with a regular shielded guitar cable.
The sounds were cranked for quite a while, probably at about 20% THD, when suddenly the sound died... silence.

Some then noticed the speaker lead had developed a bulging bubble in the middle, then it suddenly bust open with a squirty hiss,
filling the room with smoke.

First hand experience at seeing the result of a guitar cable used for driving a speaker.  ;D



It's always important to CONTAIN the smoke...
(absolutely proven with old-English car electrics)   ;)

...once it gets out, there's usually consequences !
Read slower!!!   ....I'm typing as fast as I can...

gumtown

As everyone knows,
smoke is the active ingredient that makes electronics work,
once it escapes, things stop.
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

OldGuitarDude

Quote from: gumtown on July 19, 2017, 11:20:49 PM
As everyone knows,
smoke is the active ingredient that makes electronics work,
once it escapes, things stop.

..... and it's very difficult (if not impossible) to get it all back in there  ;D

vtgearhead

Quote from: gumbo on July 19, 2017, 05:53:16 PM
It's always important to CONTAIN the smoke...
(absolutely proven with old-English car electrics)   ;)

...once it gets out, there's usually consequences !

Wasn't it Joe Lucas who said people shouldn't drive after sundown anyway?  My Dad owned an English Ford Cortina in 1968.  You're not exaggerating :-).

gumbo

Why do the Poms drink warm beer ??

...because Joe Lucas made the fridge...     ::)
Read slower!!!   ....I'm typing as fast as I can...

Headless68

@ Gumbo - your memory is going, our English beer was cold :-)

@ Ford Cortina's, the best thing for them was smoke, followed by fire :-)

gumbo

Quote from: Headless68 on July 22, 2017, 12:56:24 AM
@ Gumbo - your memory is going, our English beer was cold :-)



...that was because it was snowing that day.....   ::)
Read slower!!!   ....I'm typing as fast as I can...

admin

#13
Quote from: admsustainiac on July 19, 2017, 03:14:14 PM
If you are talking about XLR cables that connect to Self Powered PA Speakers  - These are the same as XLR  Mic cables



True , but many Line6 users also use the L6 Link connection from HD500 or Helix  to their Line 6 powered Stagesource speaker or PowerCab + or DT 25/ DT50 amp and those employ AES/EBU 110 ohm cable with XLR connections
https://line6.com/l6link/



BladesToyShop

Quote from: gumbo on July 19, 2017, 05:53:16 PM

It's always important to CONTAIN the smoke...
(absolutely proven with old-English car electrics)   ;)

...once it gets out, there's usually consequences !

Yes, must never let out the "magic smoke". It's critical for operation of any electronics.