Instrument Cable

Speaker vs. Instrument Cables - A Simple Guide

May 26, 2016 13 Comments

Instrument Cable

 Even the most experienced musicians forget essential parts of their rig from time to time. A drummer I know forgot his drum sticks at an out of town gig, and I myself have showed up to play at a local show having forgotten to bring my bass amp head (I had to use a DI that night)! It’s something that happens to the best of us. Fortunately, if there are other bands on the lineup or a helpful soundman, they may be obliged to help you out lending you the item you forgot, especially if it is something like a cable.

Use the Right Cable for the Job

If you’re at the gig or studio and realize that you’ve made the understandable mistake of forgetting your speaker or instrument cables, or you’ve found out one has gone bad, it’s essential to make sure that the new one that you borrow or buy is the proper one for the job. While standard ¼-inch speaker and instrument cables may look similar, they have a few key differences in construction that make it so you cannot use them interchangeably.

The construction is fairly simple. It consists of a copper core coated with polyester or rubber, with nickel, gold, or other metal connectors. High-end cables like Carvin Audio’s C20P shielded guitar cable utilize an oxygen free copper core for optimal signal transfer and to reduce the aging process of the copper. The key difference between instrument and speaker cables are instrument cables are shielded with much smaller wires and speaker cables are unshielded with larger wire gauges.

Since an instrument cable is used to connect your instrument to the amplifier in a high impedance environment, shielding is essential. Shielding surrounds the signal wire in and “shields” it, reducing interference from other electronics and radio signals nearby. Speaker cables do not need shielding since the signal from your amp is so large and the impedance of your speaker is so low, that any additional RF noise and outside interference will be insignificant.

What Happens if You Use the Wrong Cable?

Using a speaker cable in place of an instrument cable will add a lot of unwanted noise to your setup. Since it’s unshielded, your guitar signal will be accompanied by buzz, hum, and interference from the surrounding electronics- including hum and buzz from your own amplifier’s transformer, your band mates’ amplifier and the PA speakers. Not to exclude the lighting system, cell phones and those cool beer neon signs hanging all around the bar. You’ll be a one person noise rock band, and not in a good way.

Using an instrument cable in place of your speaker cable can cause catastrophic damage to your amplifier. While your amp will still work initially, the high amount of current going through the instrument cable’s small gauge wire can actually melt the cable! Furthermore, this may cause a short, damaging your amplifier.

Another issue with using shielded cables for speaker cables is they introduce a capacitive element that can destabilize your amplifier. Most amplifiers have improved to withstand using the wrong type of cable for a short time, but no one likes to test their amplifier’s stability at a show. This can cause some crazy results in some amps leaving it damaged and you paying the repair bill.

Telling the Two Cables Apart

While most manufacturers make it clear which one is which by labelling it clearly on the cable, there may be instances where you won’t be sure. If this is the case, simply unscrew an end of it. A speaker cable has two independent wires, one connected to the tip and one to the sleeve. These wires will likely be red and black or white and black. There should be no braided wires or a foil rap present let alone connected to any pin. The two wires should be of significant size also. Typical wire gauge for a 1/4-inch speaker cable is 16 or maybe 18 gauge. If it’s an instrument cable, you will see one or two wires covered in some form of shielding. The shielding can be a braided wire mesh or foil wrap around the one or two wires. If the ¼-inch connector is a TRS end (this is a stereo end with a Tip, Ring, and Sleeve, like on head phones) then you know it is not a speaker cable.

If you’re in a bind, make sure you use the proper cable! While it’s easy to be tempted to substitute one for the other, it’s never worth it.



13 Responses

Michael Vaughan
Michael Vaughan

October 14, 2019

Sandy,

You can use an instrument cable to carry “line” level audio around without too much problem other than interference. From my understanding they start losing some of the signal past 18 feet as well due to capacitance (that was the old guitar cable length I remember being cited anyway).

Buffered in/outs should make up for loss but instrument cables don’t handle interference like a balanced XLR cable does. Instrument cables also suffer even more from interference if run parallel with other cabling which makes them less than ideal.

You aren’t going to run into the issue of turning the cable into a fuse like you would by using an instrument cable for speakers though, the amount of power going through the instrument cable is minuscule and is measured in milliwatts.

Danny N,

You can connect virtually anything to a 1/4" cable and change it from 1/4" to RCA to 1/8" to XLR and back again if you wanted. It does lose the interference properties of the XLR cable as well as the ability to provide phantom power but it should work fine at reasonable lengths.

Dan,

The term balanced comes from the method of connecting each wire to identical impedances at source and load. This means that much of the electromagnetic interference will induce an equal noise voltage in each wire.

Since the amplifier at the receiving end measures the difference in voltage between the two signal lines, noise that is identical on both wires is rejected.

Balanced can also come from differential signals (signals inverted relative to the other). In addition this also prevents ground loop problems, by separating the shield/chassis from signal ground. -Snipped from Wikipedia for their simple explanation.

Unbalanced audio only uses a signal and a ground wire (the ground acting as a reference point and an antenna) unlike balanced which has two wires transmitting signal and thus two versions of the same signal to compare.

I hope this helps.

Sandy Cook
Sandy Cook

March 18, 2019

I didn’t see anything about using a speaker cable vs instrument cable with regards to connection to a powered speaker. It seems to me that an instrument cable should work fine from a Mixer to a Powered Speaker.

Danny Niederberger
Danny Niederberger

July 18, 2018

Now that leaves me with one question. Let’s say I want to record in a live setting using a direct connection from the mixer to my camcorder. The cable I possess for this purpose is a 1/4" M to XLR M that is labelled as shielded and balanced. Is this cable okay or should I be using something different?

Cecille
Cecille

September 26, 2016

What cable should be used to connect a speaker to a mixer?

Jim King
Jim King

July 20, 2016

Thank you! I’ve wondered about this for years. I’m going straight down to my sound cellar and label all my cables today.

David Gibeley
David Gibeley

July 13, 2016

Speaker cables really should have insulation around the metal knurled part of the plug. Amplifier outputs are often bridged, and there can be significant DC voltage present on the outer conductor. If you grab it while touching anything grounded, you are going to get a jolt. Put heat-shrink tubing over the metal knurled part for safety.

Paul
Paul

May 30, 2016

Very helpful article. Explains some of the issues we are having when our band practices in basement. Hums, proximity to each other, stepping on cables, etc. keep the information coming. I enjoy all my Carvin stuff!!!

luther (Lu) allen
luther (Lu) allen

May 27, 2016

my carvin 1200 amp …amp 1 is down (low)…what is good temporary amp to use to power my 4.10s and 1.15 speakers until my carvin is repaired?

Philip Hughes
Philip Hughes

May 27, 2016

Thanks for the info! I constantly have this argument with other players, and always seem to run into this problem. I guess that’s why my gig bag keeps getting bigger from carrying extra “just in case” cables!

Tommy B
Tommy B

May 26, 2016

Most, which means there are exceptions, speaker cables have the words
“speaker cable” written in some form periodically, maybe every foot or 2 feet, for the length of the cable. As an example: “Pro-Co Power Plus 16 – 2 Speaker Cable”! The “16-2” refers to the gauge/thickness (16 gauge) of the cable and the number of cables/wires “2”! The higher the gauge number, the thinner/smaller the wire. For speaker cables I prefer 14 or 12 gauge wire.

Some audio cables can be identified the same way with “audio cable” written on the outside of the cable. One other indication of an audio cable is that the end jacks might be molded, that is…they cannot be unscrewed to view the internal wiring. Be careful with these because it is easy to crack
them if stepped on or rolled over with a speaker dolly wheel, etc. If it gets cracked, replace it with a metal end jack! It might work for a while, but that crack started diminishing the integrity of the jack and the wire connections.

I have NEVER seen or owned a speaker cable with a molded end jack!
Actually, I have never bought any cable with a molded end except patch cables for my rack which once put in place, usually never get removed.

Finally, never, never, never, remove a jack by pulling the cord…ALWAYS remove it by pulling the jack! You might get lucky a few times but sooner or later your laziness will leave you holding the cable while the jack is still inserted into your speaker, amp, etc.

Dan
Dan

May 26, 2016

Could you do an article explaining the differences between balanced/unbalanced cables and when and how to use them for connecting EQs, effects, etc.? This is always a foggy issue for me…thjanks

Mike
Mike

May 26, 2016

This article is factually correct and could be very helpful for those new to the live sound world. Pictures would go a long way towards making clear the difference between a 2-conductor speaker cable and a 3-conductor instrument cable. Additionally, I realize that there’s still a ton of 1/4"-equipped speaker cabs out there and Speakon connectors have not quite yet reached everyone’s ears but: When was the last time you saw an 18-gauge 1/4" SPEAKER CABLE?

Add up all the above and to this old hand, it seems like you have advertising hacks with no technical background writing your newsletters…or worse yet, recent college grads that don’t play an instrument, have never manned a mixing board or even worked in a live sound environment. Carvin is way better than that. You can do better.

ps
And it’s “foil wrap” not “foil rap.”

Glenn Tietjen
Glenn Tietjen

May 26, 2016

Useful article. I have it my to do list to tag all of my cables, so this will be very helpful when doing so.

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