Testing/measuring guitar cables

[boroman]

I'm wondering, is there any "*right* technique of testing guitar cable quality?

I've ran like a hundred tests of 6 cables (via FuzzMeasure) - from lowest grade $10 ones to Sommer / Vovox.

1. If tests were "active" - so when signal is out of the preamp and back to the preamp - there's NO difference in the frequency spectrum,
2. If those were "active" going via pedalboard with buffer on - NO difference in the frequency spectrum
3. If those were "semi-active" going via pedalboard with buffer off - there is lost of high frequency but almost identical on all cables.

Not to mention that in points 2 & 3 you have inpiut cable, output cable and a lot of pedlaboard connections.
What is the procedure to send completelty passive signal to preamp via cable - that will tell the qualy of ONE cable. E.G. when you have guitar you generate passive sound from your strings to the pickups via magnetic field. But that can't be tested. I've read couple of tests that somoeny put a p-bass pickup in series with a passive 250k pot to do it, but it also a "semi-active" circuit as you send already buffered and avtive signal from preamp to the pickup and back to the preamp. That test tells nothing to me...

So, how to do it right? Has anybody ever thought about it?

(By the way - as you see - there is ABSOLUTELY NO DIFFERENCE iin quality of different cables when circuit is active, so when you you a buffer/booster like a first thing in the pedalboard, you'll have no loss in the signal.)

[nickb]

The salient quality issues that spring to mind are

Cable capacitance
Measured as capacitance per unit length. The source impedance forms a low pass filter with the cable capacitance. I'm not aware of a relationship between quality and capacitance as it's a consequence of geometry. The 'active' test would have a low source impedance so the frequency loss is minimal. If I had an unbuffered source and a requirement for a longer than usual cable I would go for one with a low capacitance per unit length.

Screening effectiveness
Usually specified as a percentage coverage, more is better. You would need to measure the signal induced in the test cable when placed near in a AC electric field e.g. near a wire carrying a (large) AC signal. Generally better screening is more expensive and less flexible.

Mechanical noise
Voltage is generated generated when terminated into a known impedance and cable is subject to movement. Crude test: plug in using the unbuffered test and thrash the cable around and see how loud it is.

Durability
Only time will tell how long it is before it fails due to tugs, trips, running over with flight cases and general abuse. One would hope that more expensive is better, but who knows.

Flexibility
Often I've found cheap cables are rather stiff and difficult to use.

[pdf64]

...1. If tests were "active" - so when signal is out of the preamp and back to the preamp - there's NO difference in the frequency spectrum,
2. If those were "active" going via pedalboard with buffer on - NO difference in the frequency spectrum
3. If those were "semi-active" going via pedalboard with buffer off - there is lost of high frequency but almost identical on all cables.
...

Have a read of https://www.buildyourguitar.com/resources/lemme/
My take is that the only scenario in which a 1/4" jack cable's electrical characteristics really matter to the guitar sound is when it's carrying the actual signal from the instrument, ie rather than a buffered / processed version thereof.

[Helmholtz]

so when you you a buffer/booster like a first thing in the pedalboard, you'll have no loss in the signal.

And that's the main reason for using a buffer/buffered pedal. They essentially eliminate loading effects by the rest of the signal chain.

[Justin Thomas]

I'm such a low-tech doofus... I have never paid for any of the booteeky cable brands, though I've bought some nice Rapcos with fancier nicer coverings.

I never consider electrical characteristics. I play a Tele through a stereo chorus & a distortotron or two. I can use the supposed high cut. Or I'm playing bass, which...

What I've noticed watching others is that the main problem is in durability - gimmicky disconnects & built-in mute switches, cheaply-made (but fancy-looking) plugs (looking at you, Neutrik...), and shielding style.

Cheaper cables are more likely to develop shorts & microphonics if they are beat up/stepped on, so try not to roll your road case over your cables. I find non-Switchcraft plugs to not suffer the abuses of repeated soldering & reattachment. I love cloth-braid-covered cables, but the coveri gs are kind of a pain in the butt to work with. And then flexibility is nice, cuz sometimes I'm in some pretty cramped quarters.

In all honesty, though, I don't remember the last cable I bought that wasn't a specialty one. I grab old GOOD ones that others don't feel like fixing or that I find in the trash, & slap a couple Switchcraft plugs on em & run. Sometimes I can get 3 or 4 nice patch cables out of one that's been trashed, or a couple 15-20' ones from a longie.

Jusrin

[The Dude]

In general, I agree. I've never noticed any dramatic difference in sound quality of any reasonable quality cable. IMO, the cable thing is overblown and expensive booteeky cables are over-hyped. I also agree that durability is of more concern.

[nevetslab]

Having built my fair share of Guitar Cables over the years, and had worked at Marshall Electronics for a short spell, they being a distributor/cable assy mfgr of Mogami Wire & Cable, as well as producing Mic and Instrument cables there, I came to really like the Mogami W2524 & W2319 Instrument cables. Very low noise, trouble-free if not abused, and have lasted a very long time. I've built them with both the Switchcraft 280 & 285L T/S ends, as well as with the Neutrik NP2X-AU-Silent (straight) and NP2RX0-AU-Silent (right angle) shorting plugs at the instrument end, allowing silent disconnect from the amp while changing instruments on stage/rehearsal.

Mogami_W2319 & W2524 HiZ Instrument Cable.pdf
Switchcraft 280 T-S plug.pdf
Switchcraft 285L_T-S Plug, large cable OD.pdf
Neutrik_NP2X-AU-SILENT_Assy.pdf
Neutrik_NP2RX-AU-SILENT_Assy.pdf

The ready-made Mogami guitar cables with either the Silent or normal T/S ends work very well, and are well-made. Not cheap, but, perform very well, testing as nickb and Helmholtz have pointed out. Keeping the cables away from the roadies who like to tie cables in knots is essential, as that just destroys the 'lay' of the cable, as well as trying to get the distorted shape back out of the cables is enough to really piss you off. I also like the cloth-covered instrument cables, but also agree with how much of a PITA they are to re-terminate ends on.

One of these days, I'll set up some of the cable tests to measure AC Mains field pickup, including adding transient noise spikes on the AC mains line to see what the results are. And, check them on my network analyzer along with other cables to see what the differences are like in the phase domain.

[Enzo]

The longer the cable, the more accumulated capacitance. If you use a six foot cable down to your pedal board, it will matter a lot less than if you use a 20 foot, or even a 30 foot cord. COmpare two 20 foot cords and you might hear the difference in capacitance.

it also matters how you test a cord. if you just plug into the amp with it and dial up a tone, then you never notice that cord A and cord B differ in that one has a treble knob at 4 and the other at 5. I never dial in tone by number, I do it by ear. So if I can dial in a tone, then the cord is OK.

Try this experiment. COmpare two cords of the exact same materials, one 6 foot and one 20 foot.

[Helmholtz]

allowing silent disconnect from the amp while changing instruments on stage/rehearsal.

My favorite silent plug is the big Switchcraft #172:

https://www2.mouser.com/ProductDetai...BdlAVtMyIxaKI=

[nevetslab]

My favorite silent plug is the big Switchcraft #172:

https://www2.mouser.com/ProductDetai...BdlAVtMyIxaKI=

Nice. I haven't seen that one. I'll pick some up once California opens back up, as Pacific Radio is right down the street from my shop....major cable and connector supplier for the Entertainment industry.

[olddawg]

I’ve done blind tests with “golden ears” musicians and no one could tell the difference with a range of cables in good repair for the most part. The exception might be “curly” cords. I’ve even wired up pedal boards with cut up “vcr” type RCA cables side by side with Mogami and no one can tell the difference. The biggest problem I see with cables is the cheap ones develop more mechanical noise over time. I have no idea how you can test for that.

[boroman]

The longer the cable, the more accumulated capacitance. If you use a six foot cable down to your pedal board, it will matter a lot less than if you use a 20 foot, or even a 30 foot cord. COmpare two 20 foot cords and you might hear the difference in capacitance.

it also matters how you test a cord. if you just plug into the amp with it and dial up a tone, then you never notice that cord A and cord B differ in that one has a treble knob at 4 and the other at 5. I never dial in tone by number, I do it by ear. So if I can dial in a tone, then the cord is OK.

Try this experiment. COmpare two cords of the exact same materials, one 6 foot and one 20 foot.

This is only valid when you have straight guitar>amp setup. If you have any "active" pedal on, like buffer for example, there is no "capacitance" effect and no difference in the sound between using $10 and $300 cable.
My question was how to test the "passive" quality of the cable. Since you're not able to generate 20hz-20khz noise spectrum just above your pickup....

[Enzo]

I believe my point was to compare a short cable and a long one, not a cheap one and an expensive one.

[boroman]

I believe my point was to compare a short cable and a long one, not a cheap one and an expensive one.

Yes, you're right, but when you have active circuit (e.g. after the buffer) the long/short cable also does not matter here (no loss in the signal).
We talk about lengths up to 20 meters or so (I don't know when another buffer should be put it, but I'm pretty sure it might be huge length for the need of another one)
The passive circuit gets benefits from shorter/longer cables and for cheap/expensive...

[Dave H]

My question was how to test the "passive" quality of the cable. Since you're not able to generate 20hz-20khz noise spectrum just above your pickup....

For a straight guitar to amp connection it should be enough to just measure the cable capacitance as a measure of "quality" as all cables with the same capacitance will sound the same (ignoring handling noise etc) If you want to have an idea of frequency response it could be modeled in LTSpice as below. The plot is for cables of 300p, 600p, 1200p. I disconnected the guitar's vol and tone controls to show the resonant peaks better. With tone and volume connected the peaks are flatter.