Cables 101: Instrument vs. Speaker Cables

Instrument CablesMany 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“, 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.

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  1. Long time ago I used an acoustic 370 Head and 4×15″ cabinet at 2 ohms. Instrument cables just went up in smoke. :-)

  2. Paul D

    You’d be surprised at the amount of amps I see come into my shop with blown output transistors due to using an instrument cable for the speaker connection. I am a big fan of better cables as the last longer than cheaper ones. However the idea of them sounding better is crap. I had compared a $100 “studio pro” instrument cable to a $40 “fasto-flex” same thicknes, length, and connectors. There were no differences in sound quality, nor were there any differences in noise levels. If you want to buy the $100 one be my guest…I’ll buy a the lesser one and a few sets of strings!

  3. John Vinter

    I’m sorry Paul D – but I NEED to correct you, as what you write here about one instrument cable not sounding better than another is crap – THAT statement is TRUELY CRAP. I don’t care how manny shops you own, and I don’t know if you only tested those two cables, or if you used an electric guitar or an eletronic keyboard for testing (or you have a hearing disorder? ;-) but a statement like that displayes your lack of knowledge and experience.

    You are right about ONE thing though: Paying 10 times more for a cable does NOT ensure good or better sound quallity, but I gues it improves your chancees. ;-)

    I have been a pro musician for a lifetime – amongst other things I play the tuba, severel electric basses, and an electric homemade 5 string doubble bass. My father who is a musician too, playes the tuba, accoustic doubble bass and a homemade electric 5 string doubblebass.

    The both of us has been experiencing a lot with microphones, amps AND cables, and there is NO DOUBT! Its not like: “Hey.. there COULD be a difference” – no its like: “WTF, changing a single cable makes it sound like playing two completely different bassees!”

    There may not be the world of a difference when testing electrical guitars, keyboards and other electronical instruments, where the sound is more or less made in an electronical way, and having a lack of overtones/harmonics made by the instrument body itself.

    But there is no doubt: When testing acoustic instruments with their fullbodyed acoustic sound coming from their “finger print”/combination of dominating acoustic harmonics – making us able to determine one instrument from another. There can bee an extraordinairy difference between how the instrument sounds throug two different cables. Especially regarding the low freqency instruments, physically demanding more of the equipment, to reproduce their true sound.

    When testing cables in combination with my basses, especially the doubble basses – I have experienced playing on my usual cable which made the bass sound ok – but then I changed and tried out another (new) cable – and suddently the sound of my instrument opened up – the harmonics of the instrument came up front, and suddently it was possible to hear the real woody-soul-sound of the bass.
    Trying to go back to the first cable, makes you feel like “No, no – NOOOO – what happened to the georgeous bass-sound I just had?”

    As I said earlier, Paul D is right about ONE thing: Just buing a new more expensive cable does NOT ensure you a better sound, many of the cables actually sounds alike, no matter the price. (But I gues the chances might be better, with the more expensive cables, the factures more likely have better tecnicians, with better knowledge and ears ;-))

    The right sound is a combination of instrument, cables and euipment (off cause ajusting can make a diference too ;-))

    – So what you need to do is bring your instruments and equipment to a musicstore (unless you are on such a good term with your local dealer, that he will allow you to bring his bunch of different cables home, to decide) – and test all their different cables against your own. MAYBE you wount find a better sounding cable than the one you have allready – but keeping experimenting every time you stumble over a new cable – eventually you will have an experience like:
    WTF – Are my instrument really able to sound THAT GOOD!

    Good sounding instruments – inspire you to play better!

    John Vinter

  4. Greandal

    Output power (speaker) cables are generally not shielded because of capacitative effects that increase with the length of the cable. What is a bandpass filter? A capacitor that is chosen to “pass” the freqs in the signal above or below a certain point.

  5. shanky

    i’m really confused. so should i use the speaker cable to connect the amp and the speaker or the instrument cable? should i use an instrument cable or speaker cable for the guitar and amp?
    i currently use an instrument cable for connecting my bass to the amp .

    • rey

      1- use SPEAKER CABLE from amp to speaker

      2- use INSTRUMENT CABLE from instrument to amp

  6. jon

    Vinter your comments might carry more weight if you knew how to spell!

    • Mort

      They’d carry even more weight if they referred to a statement actually expressed in the article. The author never once compares cheap cables to fancy ones. But his declaration regarding the benefits of using a cheap speaker cable over a fancy instrument cable to connect an amp to a speaker is inarguable. Unless, of course, you are playing a doubble bass!

  7. I have been playing ever since Nixon was president and I have seen guys use guitar cables as speaker cables (I was guilty myself until I learned better). When you say something to them They look at you like your making it up or that you don’t know what your talking about. Vinter, If your going to rant learn how to spell. Plus, it’s just a article on cables, nothing to get all worked up about.

  8. Dave Wood

    The same goes for power and extention cords. It does make a difference, grounding is very important. I carry an outlet tester to make sure. Could you please write an articale on this subject?

  9. recall back in the day a working stiff like myself has a teen would paly bass threw a Marshall guitar amp, now adays how many guitar amps can really handle a bass without fear?

    • Bill from Boomhower

      Back around ’70 or so, I played a ’68 Gibson EB3 with rotosound round wounds thru two long coiled instrument cords soldered and taped together for extra length.
      I plugged that into a Sunn 1200S 200w tube guitar amp, and used an instrument cable from amp to the six 12″ Vega speakers.
      We played 3 piece hard rock in bars for a long time with that rig.

      Back then most guys used an Acoustic 360 with 18″ folded horn cabs. You could get out of your car parked a block or two away, and hear the bass before anything else in the band, yet up close the bass wasn’t all that loud. Wasn’t like that with humbuckings, round wounds, tubes and 12s, let me tell you.

      Nowadays, I have many nice and expensive basses, but love playing my hot tossed Peavey Fury thru a couple of high quality cables, into a Gallien Krueger micro bass 150, with 150w and a 12″ speaker. A 23lb combo amp, about the size of a Big Buddy heater.
      I still have big stack amps, but now use appropriate cords for them.

      I may have learned about all this cable etiquette late in life, but I played that Dunn like that forever, without any problems. 3 piece rock in beer bars gets loud as He’ll too.

      Happy trails man!

  10. There often is a marginal audibly discernible difference for most people between shielded instrument cables that are mid-priced to high priced, however, there is significant difference in between mid/high priced cables and the really cheap (or sometimes free and included with low to mid-priced instruments) instrument cables. Usually the cheapies are very thin, flimsy, super flexible and tend fail at the plug connections in short order (leaving you with no signal or intermittent signal from your instrument to your amp).

    Where these cables really have a very audible difference from higher priced/quality instrument cables is noise. As you move the cheapie instrument cable around, because of its thin wires and poor shielding, you can hear mid to high frequency thumps as the cable slaps against the ground/amp/anything. Also, their shielding is insufficient to ward off other types of interference which manifests itself as noise (i.e. static, whines, buzzing, hiss, hum, music, running elephants, etc…).

    In short, there is a difference in performance of various quality/priced instrument cables. GENERALLY, MOST folks can’t tell a huge difference between mid to high-priced instrument cables, however, ALMOST ANYONE can tell the difference between these cables and the real cheap ones–if nothing else, it’s obvious to everyone when after a few days your freebie instrument cable completely stops sending sound from your instrument to your amp. :)

  11. BTW, great article. No one wants to shell out hundreds to fix their amp due to using the wrong $10 cable! Usually the higher the output in watts from your amp, the faster it burns out if you are using an instrument cable to hook it to your speaker cab (kind of like the bigger they are the harder they fall!).

  12. John Vinter–please pay heed to this informative article. I have a store and sell–low end–top end–and you know what–testing has proven–low end with heavier gauge wire and quality connectors is equal to any of the high end over-priced cables. Great piece !

  13. Interesting that a simple question can cause such a ruckus. That being said…my ear tells me there is a difference between cheap cables and more expensive cables. Say the ones that your local music store gives out for free and Planet Waves Classics. Not wanting to put all my trust in my ears I grabbed my old faithful multi-meter and checked resistance. Well…..sure enough the cheap cables had much higher resistance…hhhmmmm….would that mean less signal throw it at the same length as a better cable? Do we really need to answer this. Now I use a higher grade cable then the classics, though it has the same low resistance the outer protection layer is thicker and the ends are attached better. Both the mid priced and higher priced cables are guaranteed for life and I did have a few of the mid priced one fail. Good to their word they where replaced with a smile as soon as I returned them. That however did mo no good while I was scrambling to find another cable to plug in the instrument at the concert. I have not in 4-5 years of constant use had one of the higher end cables fail. Am I paying to much in your opinion? probably. In my opinion, the piece of mind knowing I don’t have to scramble is worth the few extra bucks. You can go ahead and jump on me now, just don’t get ticked when it has no effect.

    Yes, use a speaker cable between the amp and cab
    and an instrument cable between the amp and instrument :0)
    End of transmission

  14. slash

    im using a live wire elite speaker cable from my marshall amp head to marshall cabinet. however, when my guitar is silent, i hear a humming noise in the background. am i using the wrong cable or is that just how it is? thanks for the responses.

    • DJ_AL_Z

      I was having the same issue its the peice of crap live wire i would go back and get a more reliable cable

  15. Marko G.

    Thanks for sharing this. I just got a Magnatone Super 59, and I had a feeling like the instrument cable was fishy. I appreciate the info, thanks!!

  16. KevMan

    *You’re x3

  17. JustAl

    What about going from a mixing board to an amp? Since the board’s output is not powered, would using the shielded (instrument) cable be better? At our church, the setup is such that the mixing board sits in the back of the church and the amps are in a cabinet on the stage. The cables we use to connect the board to the amps are 40-50 feet long.

    Thank you,