Guitar Cables - Influence on Guitar Sound

[jazzbow]

If it's any help I buy yellow cables because they look nice.

[manu68]

Hello

I have change an old whirlwind cable for a Monster cable Jazz.
It is very subjective and hard to explain, but it works better for me. Other said, I prefer this cable , even I don't know why

[billkath]

Pixie dust is right! There's so much rubbish out there on this. From a recording engineers persective-

"Directional" cable-Most use 1 conductor and shield for guitar leads-direction is nonsense then. Shield also functions as signal return. Some manufactures don't make their instrument cable from single conductor plus shield-they use 2, or even 4 conductor and shield. At one end-the input end, the shield is disconnected, and signal return is carried on the second (or second and fourth) conductor. This, of course, leaves the cable "more" open to RF interference. It's a thing we do in studios to reduce ground loops. I can't see how it is of any use between a guitar and an amp, but in studios, where all our lines and patchbays are balanced, it's a way to keep signal and chassis grounds seperate, and for minimizing ground loops. For the others-who are laying out their atoms in nice straight lines? Give me a break!!

Capacitance-very important in long lines-not so important in short lines. Any decent cable will show negligible roll off over a maximum of 18 foot intrument cable. Only the very cheapest cable would that be a problem, and it would be far overshadowed by other factors- cheap connectors and a bad designed shield. Longer than 18 foot and you should be using a DI and balanced cable for the run.

Paul Whites view on it is

""
Another interesting and important fact about guitar cable capacitance is that it doesn’t only act as a low-pass filter. An electric guitar’s pickups are made from coils of wire, which makes them highly inductive. Wire a capacitor across an inductor and you get a tuned circuit, rather like a mixing desk’s mid EQ set to boost. In the case of a typical guitar, the tuned circuit is fairly well damped, because of the resistive parts in the volume and tone circuits and the resistance of the pickup coil itself, but you can still end up with a 1-2dB hump in the response. If you choose low-capacitance cable, the tuned circuit will resonate at a higher frequency, whereas a high-capacitance cable will push the pickup resonance downwards. Either way, the tonality of the pickups will change.
This knowledge can be helpful, because if your instrument lacks sparkle, choosing a low-capacitance cable could improve matters significantly. What’s more, you can check the outcome before spending your money by making up a very short conventional cable (a couple of feet should do the trick) and seeing how your tone changes compared with your standard cable. On the other hand, if your guitar sounds thin and lacking in punch, a standard high-capacitance cable might actually make it sound better.""




Of course-if you are using active pickups, cable capacitance is virtually moot, as you've got a very low impedence which could easily survive a 100foot run with little or no roll off due to cable capacitance.



Shield-cheap cable just has a wrap shield. Better cable has a braided shield. Sheild is important, because a badly shielded cable just acts as an antenna-the longer the cable the better it picks up your local cab firm. Braided cable leaves less chance for holes when the cable is bent over time.

Connectors-poor connectors give poor transfer. Gold-tipped connectors are best when you are not going to be plugging in and out all the time-the gold rubs off and you are left with a rubbish tip. It's really just a marketing thing on cheap connectors.A bit of gold off a poorly conducting base metal. NOT good for guitars and amps. Stick to a decent Neutric. Or your preferred American brand.
Simples.

So-90% of this high end cable stuff is nonsense in the real world.
Buy a decent 1 conductor and shield, with braided sheild, with a low-ish capacitance and good neutric jacks and you'll be fine. But,saying that-cable is part of your sound. That DOESN'T mean you have to get the most expensive cable. It means that you find the cable that works best with your guitar and amp.

Remember-people were making fantastic records for decades before all this nonsense, using bog-standard guitar cable. They didn't have esoteric alloys, directional cable, gold-tipped connectors-they just had talant.

[randyc]

Bill that was an interesting post. The only part that I would modify is the "18 foot cable length" and it's mostly a nit-pick.

Typical guitar cables have an associated capacitance of around 20 picofarads per foot. That will never be a problem with line-level impedances but some guitar amplifiers have input impedances as high as 470k, which would limit the bandwidth of an 18 foot cable to less than 1 kHz - not acceptable.

For the more typical input impedance of 47k, an 18 foot cable might (as they say) "lose a little sparkle", since it will have a bandwidth of around 9 kHz.

There's more to the story, however. A longtime forum member (Tie-dyed-Devil), who unfortunately has been too busy to post for a while, wrote an interesting discussion on this topic and I believe it can be found on his website (Lamkins.com, IIRC). He points out that cable capacitance, conjoined with pickup inductance can create unpredictable resonances. The interaction is very complicated - there are so many variables that it's impossible to predict the result without very detailed knowledge of guitar pickup, cable characteristics and amplifier input impedance.

Best recommendation for guitarists: keep the cables short for repeatable, consistent performance. (Not important for low impedance applications which excludes most guitar pickups).

(correction: lamkins.net not lamkins.com, for those who are interested in David's original material on cables.)

cheers,
randyc

[TieDyedDevil]

Pixie dust is right! There's so much rubbish out there on this.

Indeed!

Paul Whites view on it is

""
Another interesting and important fact about guitar cable capacitance is that it doesn’t only act as a low-pass filter. An electric guitar’s pickups are made from coils of wire, which makes them highly inductive. Wire a capacitor across an inductor and you get a tuned circuit, rather like a mixing desk’s mid EQ set to boost. In the case of a typical guitar, the tuned circuit is fairly well damped, because of the resistive parts in the volume and tone circuits and the resistance of the pickup coil itself, but you can still end up with a 1-2dB hump in the response. If you choose low-capacitance cable, the tuned circuit will resonate at a higher frequency, whereas a high-capacitance cable will push the pickup resonance downwards. Either way, the tonality of the pickups will change.
This knowledge can be helpful, because if your instrument lacks sparkle, choosing a low-capacitance cable could improve matters significantly. What’s more, you can check the outcome before spending your money by making up a very short conventional cable (a couple of feet should do the trick) and seeing how your tone changes compared with your standard cable. On the other hand, if your guitar sounds thin and lacking in punch, a standard high-capacitance cable might actually make it sound better.""

All true. I'd take issue with just one of Paul's details: the resonant peak can be more than a couple of dB. It depends upon the Q of the circuit, which depends partially upon the resistance in the circuit.

But that's just splitting hairs...

I actually did an experiment to *prove* to myself that *small* changes in cable capacitance *don't* make a difference. The thesis was that you'd have to hear a few dB difference in any given frequency band in order to detect an audible difference. Moving the resonant peak by some small fraction of an octave should be pretty difficult to hear.

I was surprised at the results. In a non-blind test with randomization, using 3 players / evaluators, 3 guitars and 3 amps, we heard differences amongst cables that had "hardly any" difference in capacitance.

My first reaction was: "that's impossible". Upon reflection I realized that our ears are much better at hearing *relative* differences in amplitude than they are at hearing absolute differences. This is why, for example, a mastering engineer might apply a half dB of EQ at certain frequencies to improve the sound of a recorded track. That half dB is relative to what's going on in adjacent frequencies, so we can readily hear the relative difference. On the other hand, changing the volume of the *entire* track by a half dB won't be detectable *at all* by the typical listener.

I don't want to give the impression that these small differences yielded one cable that was preferential. In A/B testing we heard differences. But these were, again, relative between pairs of cables. We'd listen to one cable, change to another, and notice that *something* sounded *different*. There was no consensus *at all* regarding qualities like "better" or "worse".

I really want to emphasize that these differences were detected by critical listening and that *none* of the differences was dramatic. In other words, while the cables sounded slightly different in an A/B comparison, not one of them had a particular sonic signature such that a listener would be able to identify a cable by its sound alone.

I'm still not entirely convinced that some of the differences we "heard" weren't subtle shadings of player technique, and not the cables *at all*. Frankly, picking technique plays a much more important difference in tonality than any cable I've ever "auditioned".

So-90% of this high end cable stuff is nonsense in the real world.

You're being far too generous to the high-end cable vendors.

Remember-people were making fantastic records for decades before all this nonsense, using bog-standard guitar cable. They didn't have esoteric alloys, directional cable, gold-tipped connectors-they just had talant.

Yes!

[billkath]

Bill that was an interesting post. The only part that I would modify is the "18 foot cable length" and it's mostly a nit-pick.

Typical guitar cables have an associated capacitance of around 20 picofarads per foot. That will never be a problem with line-level impedances but some guitar amplifiers have input impedances as high as 470k, which would limit the bandwidth of an 18 foot cable to less than 1 kHz - not acceptable.

For the more typical input impedance of 47k, an 18 foot cable might (as they say) "lose a little sparkle", since it will have a bandwidth of around 9 kHz.
randyc

Yes-agreed. But these days-very few amps have an input impedance of that low. Most amps these days would be around the 1-1.5 MOhm mark. High out impedance on the guitar-low input impedance input on an amp? That's when capacitance starts to really make a difference.

[randyc]

I don't think so, Bill. Take a look at any of the online Fender schematics for example, all are readily available. Input impedance runs from about 47k to about 68k. Magnetic pickup impedance is around 10k, shunted by the volume and tone control potentiometer adjustment value.

The highest input impedance I've ever seen is my Epiphone Galaxie 25. It is 1 Megohm and it's also the noisiest amplifier I own. Noise is proportional to the square root of input impedance (guitar + amplifier). The higher the impedance, the noisier the amplifier.

cheers

[Doctor Jeff]

Fascinating discussion as always.

BTW I know nothing about electrical engineering, but my son is an engineering student at UW so maybe someday he will explain all this to me.

Comment: I was surprised on the Vovox website to see testimonials by Steve Swallow and Kurt Rosenwinkel. I mean, I understand testimonials and endorsements and the like, but these guys are not your average joes. Interesting.

[randyc]

Hi Bill,

Perhaps you're looking at the grid bias resistor (sometimes referred to as the "grid leak resistor") on the schematic. That resistor can be any value from 470k up to 10 Meg but it's not very significant to the overall input impedance in most amplifiers.

The input impedance of an amplifier is comprised of all resistors in the input circuit. (It's actually more complex than this but let's keep things simple.) Your Twin (ACTUALLY, I should say MY Twin) has a series resistor of 68k at the input, shunted by another 68k resistor to ground, shunted by the 1 Meg grid resistor to ground. The total input impedance is the series-parallel combination = 131,670 ohms or 131.7k.

The ONLY Fender amp that I'm familiar with that has an input impedance greater than this might be the Blues Junior (I'm not positive because my schematic is too fuzzy to determine the exact values).

If you like, I can describe how to actually measure the input impedance. It's a simple matter so long as an audio generator, an inexpensive DMM and calculator are available. (Had you downloaded my free book "Design of Vacuum Tube Amplifiers", the topics of input and output impedances are described in detail and reviewed in several chapters.)

cheers,
randyc

P.S. Sorry, I didn't look at those attachments before I wrote. The solid state amplifier clearly states 1 Meg input impedance. The Twin manual states the correct impedance in one place (which is the value I calculated above) but also notes a 1 Meg impedance. I can't reconcile the differences since I have only schematics for my OLD Twin. I don't contradict what you've attached but I do contradict the generalization about the input impedance. A measurement is the best way of getting to the facts

[randyc]

Tell you what - all of these old Fenders have the same input circuit. It won't take too long to pop open one of mine and take a look inside. Back in a while

[randyc]

Bill, my apologies - Although I didn't disassemble an amplifier, I just fired up the old Bassman, connected a load and a signal generator and made an impedance measurement. You are absolutely correct. It is 1 Megohm.

I'm puzzled because the schematic values calculate to 131k, as noted previously and as one of your manuals also notes. There is something in the jack switching that I'm not getting but I will get it before this day is over

I appreciate you holding your ground on this subject - us old dogs can still learn a trick or two if someone is stubborn enough to make us MEASURE things.

cheers,
randy

[randyc]

The lower figure that you mention-the 131kOhm, is for the padded input-the Lo input on most guitar amp inputs.
Are you sure you are looking at the correct circuit-you're not just looking at the lo side?

I just measured the other port - 131k.

I've been using Fender amplifiers since 1962 and NEVER realized that the two jacks were two different impedances, what a dummy! It is always good to learn something each day, even when one has chemo-brain and for that, many thanks, Bill !

[randyc]

Almost forgot, the 1 Meg isn't consistent. I didn't measure these solid-state amplifiers, just took the info off the manuals:

Peavey Envoy 110: 44k or 220k (depends on input channel)
Sunn "Beta": 50k or 100k (depends on channel selection)
Univox 4100: 150k

[billkath]

I just measured the other port - 131k.

I've been using Fender amplifiers since 1962 and NEVER realized that the two jacks were two different impedances, what a dummy! It is always good to learn something each day, even when one has chemo-brain and for that, many thanks, Bill !

Yep. My brains more than addled today as well, knowing I have to play to a group of 150 women golfers tonight. Won't be to much jazz tonight-a lot of old show tunes, I guess, and some singalong stuff. Perry Como, Matt Monroe, and me, who's not fit to turn their sheet music! Better dust off those leather jeans, I suppose-they expect it!

About the lower impedance input, though-it's still 10 times the impedance of a line input on nearly any console in the world. I can't tell you the amount of times I've screamed at people not to be plugging electric guitars and basses into line inputs on a console let alone mic inputs. They just don't get that they're loading their pickups and wrecking their tone.

[billkath]

Almost forgot, the 1 Meg isn't consistent. I didn't measure these solid-state amplifiers, just took the info off the manuals:

Peavey Envoy 110: 44k or 220k (depends on input channel)
Sunn "Beta": 50k or 100k (depends on channel selection)
Univox 4100: 150k

Man-that's crazy low- the Peavey and the Sunn. Still work without too much stress, but you're then back into what we were talking about-the capacitance of the guitar cable will have a significant effect on the guitar's tone through the amp.

[randyc]

No, it's the other way 'round. Higher impedance = less bandwidth for the same capacitance.

BW = 1 / (2*PI*C* Z)

C is capacitance in farads, Z is impedance in ohms and BW is in Hertz.

Simplifying, however, Z is actually the parallel combination of both the guitar pickup and the amplifier input impedance, for short runs of cable.

The pickup impedance being on the order of 10k, the amplifier impedance becomes less important, as follows:

10k || 100k => 9.1 k while 10k || 1 Meg => 9.9k

Theres less than 10% difference for a 10:1 change in amplifier impedance.

cheers,
randyc

[randyc]

I keep marveling about that Fender input switching arrangement and I played with it for a bit longer before disconnecting everything and storing the amplifier. This is interesting (I guess everyone else in the world knew it but me):

Jack 1 (nothing plugged into Jack 2): 1 Meg
Jack 2 (nothing plugged into Jack 1): 131k
Once a source is plugged into Jack 1 then Jack 2 becomes 1 Meg !
Jack 1 and 2 both plugged into something: both are 1 Meg

I'm sure that the Fender guys had something specific in mind when they came up with that configuration. Can someone please explain to me?

[Archie]

I just happen to have the manual for my new Princeton Reverb reissue handy. On the specifications page it lists input impedance at 1 meg ohms. Of the two inputs, it lists input A as "full sensitivity" and input B as -6dB, but notes "both inputs become equal in sensitivity when used simultaneously."

[TieDyedDevil]

I'm sure that the Fender guys had something specific in mind when they came up with that configuration. Can someone please explain to me?

Sure. That switching configuration dates back to the early `60s.

Leo Fender believed that distortion was to be avoided. Input 2 was intended to help keep the amps from distorting when used with higher-output guitars (e.g. Gibsons).

Using both inputs at the same time was actually fairly common. Guitarists had few qualms about sharing an amp back then.