Patch cable audio quality testing?

Discussion in 'Effects [BG]' started by Engle, Jan 21, 2018.

  1. I’m going to be using octave and chorus pedals for a gig next weekend, so I set up the entire chain with my tuner last night. While playing, I realized I was getting substantial tone suck. Careful troubleshooting (I’m an electronics tech and structured cabling designer) narrowed it down to my short patch cords. 3 out of 4 noticeably attenuate higher frequencies when tested directly between bass and amp.

    These cables all pass a continuity test and I can’t see any resistance with a meter at its lowest settings. I suspect they must have been crushed at some point. Most surprising is a Digiflex cable with Neutrik ends.

    Does anyone know of a practical way to test for quality besides comparing them by listening?
  2. Alien8


    Jan 29, 2014
    Capacitance is what causes "tone suck", high frequency attenuation in cables.

    Poor buffers also cause sterile sound that could also be tone suck.

    And one last issue could be an impedance mismatch between boxes.

    If you have short cable runs between a few boxes it would be pretty hard to hear the tone difference. If you had 10 pedals in a row, with true bypass or poor buffers, it would be more obvious but still subtle. Using long cable runs is when you notice the issue. Try a couple short cables between boxes, it's worth the investment.
    Last edited: Jan 21, 2018
  3. bongomania

    bongomania Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    There really isn't a good way. I have done a lot of cable testing, and it takes multiple different tools and retests.

    One problem that none of my tests was able to clarify for me is what happens to an audio signal in the "grey area" of conductivity, where there is conduction but it is poor. With wires that are just starting to crystallize (from being crushed or kinked) you can still pass a continuity test. A solder joint that is fractured but not fully broken can also read as continuous. With damaged-but-still-conductive wires, does the degree of damage affect resistance or capacitance, and if so--exactly how?

    To troubleshoot a bum sounding cable, first you have to clean the plugs, then re-flow the solder on both plugs, and see if that helps; so even if you had a special tester box that could measure the signal-conductive quality of the cable, you'd still have to do several minutes of inconvenient physical work first.

    Another thing is that I found handheld capacitance testers were awfully inaccurate and unreliable at the very low range of guitar cables. I had to buy a serious lab unit to get repeatable results.
    Alien8 likes this.
  4. boomertech

    boomertech Frank Appleton Commercial User

    Apr 8, 2009
    Syracuse, NY
    Designer/Owner of FEA Labs
    Your Digiflex cable has a lifetime warranty, so you may want to contact them about their cable issue.

  5. Thanks. That’s what I suspected. I guess I’ll just use my ears - it’s an obvious audible difference, even to my 53 YO ears. In the network cabling industry we have specialized testers that measure quality parameters. But those work at much higher frequencies. (And the testers cost $15-20K)

    I see that the strain relief on the one cable with a Neutrik right angle connector is crushing the cable. I’m going to reinstall the connector more carefully to see if that makes a difference.
  6. gregmon79

    gregmon79 Supporting Member

    Dec 20, 2012
    Chicago IL
    The only way I’ve found to test patch cables is using a cable tester. One of those boxes with all the different ins and outs. I use the one made by behringer. Works really good for me.
  7. Alien8


    Jan 29, 2014
    Maybe you could hack your network tester with adapters and see if it shows a difference. A lot of work, but an interesting experiment.
  8. mac_4ps


    May 14, 2009
    This is an interesting test of patch cables:

    rtav and Basehead like this.