Can I use a signal / Instrument cable as a speaker cable?

A lot of people ask us, “can I use a signal / instrument cable as a speaker cable”?

NO!

You DO NOT want to do that, look at this picture….

The cable on the left is a speaker cable, consisting of 2 separate wires. The cable on the right is a signal / instrument cable.
See how on the signal cable, you have a center strand that is surrounded by an outer set of copper strand. This is called the shield and literally shields the center strand from RFI (radio frequency interference) among other interfering frequency generating items.
Signal cables consist of smaller gauge wire where the wire that wraps around the center core or positive wire creates the shield. The smaller gauge wires that create the shield and the core are not made to carry electrical current, they are made to carry signals. Using a signal or instrument cable (same thing) can and will eventually cause serious damage to your amp. Since the smaller gauge wires in a signal cable are not made to carry electrical current, the small gauge wire strands heat up, get hot, and can eventually melt internally. When this happens, it will create a short within the cable, shorting out the positive and negative sides of the current / voltage going out of your amp.

Using a signal cable for a speaker cable

Okay, so…. maybe it isn’t that drastic BUT the amp repair cost can be!

Speaker cable on the other hand, simply has positive and negative sides. The positive side is what gets the wattage to your speaker’s voice coil and the other (negative) side is what grounds your speaker. If you use a signal or instrument cable in place of a speaker cable, you “might” be okay for a time but why take the risk?

Here you can see how speaker cable is just 2 strands of larger gauge wire with no spiral wiring around an insulated core.

If you use a speaker cable as a signal cable, you have no shield, so you would be allowing interference to leach into your signal path and tone. Using a speaker cable as an instrument cable offers no shield for the signal = no RF shield for your tone. At the very least, it IS going to affect your tone with hum, buzz, interference, and turn your guitar into a big antenna.

Another really bad side effect of using a speaker cable as a signal cable is, since there is no shield on the “grounded side” if you are sharing electrical outlets with PA system or other amplifiers, when you touch the strings of your guitar and anything else plugged into the same breaker, you are completing a circuit or as most would say “My vocal mic is shocking the crap out of me!”

So, you are holding 2 cables, neither of them says “Instrument cable” or “Speaker cable” anywhere on them. How do you tell which is which? Well, the easiest way is to unscrew the barrel on one of the ends of the cable. With an instrument / signal cable, you will see the spiral shielding twisted together and soldered to the tung of the plug and the strands in the insulated core of the cable soldered to the tab (above the tung). If you do not see the wires that are soldered to the tab of the plug coming out of an insulated core, assume you are holding a speaker cable.

Signal cable showing the shielded core soldered to the tab
Here you can see the shielded core coming out of the insulator, it is the top wire in the clear insulator , soldered to the tab of the right angle plug and the spiral shielding is soldered to the tung of the plug.

If the cable is well made and has heat shrink tubing covering everything and you cant see anything, a good rule of thumb is that a speaker cable is generally more rigid and is going to be thicker than a signal cable.

A signal cable with heat shrink tubing covering everything
This is a signal cable with heat shrink tubing covering everything

 If you still can’t tell, plug the cable in question into your guitar and then into your amp, this won’t hurt anything, if it is a speaker cable, it will just expose your signal path to interference and sound bad.