Microphoic cables.

Discussion in 'Effects, Pedals, Strings & Things' started by raj, Jul 6, 2006.


  1. raj

    raj Member

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    I am unsure as to what you mean when you say the cables are "microphonic".

    When I use the Canare 10ft, I can hear distinct noises when the cables hit the ground, like a "thup". Is that, microphonic?

    Thanks!
     
  2. jony2

    jony2 Member

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    Yup it is.. I have the same issue here.. If its an issue..
     
  3. jamison162

    jamison162 Member

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    Canare is supposed to be one of the best cables for low microphonics and handling noise as it is very well shielded. I've never had (or heard for that matter) any of these issues with my Canare/G&H cables.
     
  4. loudboy

    loudboy Member

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    Something's wrong with the cable - I've made my own for years and they're silent.

    Monster, OTOH... I've had to use these a fw times and couldn't believe how much noise they made. Hard to believe that anyone would put up with that, let alone pay a premium for it.

    Loudboy
     
  5. LavaMan

    LavaMan Gold Supporting Member

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    Which Canare is it? GS-6 or L-4E6S? I echo the low microhonics of the GS-6 - it has a 93% braided shield acording to the manufacturer...

    Where did you get the cable from?
     
  6. landru64

    landru64 Member

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    what ought to be asked is... how much gain are you playing with?
     
  7. raj

    raj Member

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    To be honest, a boatload of gain.

    Does gain contribute to the problem? I realise that when I tap my guitar, I can hear loud 'thubs' as well.

    So, the cables are fine? And this is normal even at high-gain?
     
  8. landru64

    landru64 Member

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    you ought to try some other cables that claim to be very unmicrophonic and see if they're any better. when you are using a lot of gain, it's not hard to make a cable transmit noise this way. gain just amplifies! noise and everything else!!!
     
  9. eaudio

    eaudio Member

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    With a coax cable for example:

    When you hit your cable against something -- where you strike the cable changes the distance between the shield and the center conductor.

    Capacitance is a function of the insulation material used around the center conductor and the distance between the shield and center conductor (You can vary capacitance by using thicker or thinner insulation material).

    Anyway when you strike a cable and compress the insulation material you change the distance between the shield and center conductor, and this very fast change in capacitance generates a small voltage.

    This voltage will do one of two things: Dissipate into the center conductor and be heard as a "pop" or; dissipate into a conductive material applied over the insulation material.

    It is a bit of an art form to blend a conductive polymer which extrudes well over the insulation material. The carbon molecules don't always link up with an even-density; or they can break their bonds over time and reduce the conductivity in places... but basically you want it done well, and done in such a way that any spurious voltages generated from cable movement are discharged into that material and NOT the center conductor.

    The amount of shielding has nothing to do with microphonics. Sheilding is just a necessary evil that kills tone. The more shielding a cable has, the more effective it is against external noise; but the worse it sounds. Nothing sounds sweeter than two wires with nothing around them between gear. Put a shield around them and the top end closes down. Put two shields and it gets worse. Three...

    Of course, you need to be playing in the desert off of battery power in order to insure freedom from noise... so I'm just saying for the sake of illustration... Overkill on shielding where it isn't needed just makes things sound worse. If you have a cable with 50% shielding in an evironment where 50% coverage is enough to block any noise in that environment, an equivalent cable with 90% shielding is going to sound worse in that environment. An equivalent cable with 95% shielding and a 100% foil wrap under the braid will sound even worse in that environment, etc and so on.

    Try it.
     
  10. LavaMan

    LavaMan Gold Supporting Member

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    Well put Tony. But I think many of us laymen attribute microphonics to both internal and external noise...for example a microphone amplifies the external noise presented to it (your voice) So, in this sense shieding which protects against external noise such as RFI makes cables in general quieter correct? This why even some of the speaker cable I carry (The Sommer Quadra Blue as an example) is shielded - to make for a quieter cable - both external and internal - the 6 AWG litz wires in this case have the thickest insulation I have seen...

    What I do not understand is that you are saying that the top end closes down with more shielding. If this is the case, why does the van den Hul sound so good? As it has a double spiral shield and the thickest inner PVC/Polymer of any cable I have.
     
  11. eaudio

    eaudio Member

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    Hey Mark,

    Shielding protects against external noise such as RFI but RFI does not manifest as microphonics. RFI is a separate problem that ranges from non-existent (rare) to hearing a discrete radio station from your amp (rare) and everything in between. When you have a passive output on a guitar and given the impedance of the circuit, it is very susceptible to RF interference and some amount of shielding is necessary 99% of the time. If it isn't blocking a discrete radio station (rare) it is likely as you say, keeping the circuit quieter in general. Braided shields (or spiral) are most effective at blocking RFI. EMI has a more narrow wavelength and if it becomes a problem, is best dealt with using a 100% foil shield. Ferrite beads on the outside of a cable are effective at other frequencies. But that's just it all these shields act as filters and while no, they are not filtering the bandwidth of the guitar, I do find an effect of "closing down" in the upper registers and in terms of “air” and “dimensionality” such that where you add a shied when it is not needed, it has a negative on sound quality.

    Again try this at home and develop your own conclusions.

    The van den Hul sounds different (some people think it sounds good) because it is build quite different from what most people are used to listening to. I think the best way to revisit my position is to say it this way:

    "If you think the van den Hul sounds so good, you should hear it when you strip away all that shielding and just listen to the conductors... it sounds much better!"

    Whatever you like, in the absence of noise, I suggest you will like it better if the shield is removed.

    As for speaker cables; I'd suggest shielding is pointless in 99.9% of the time. The impedance and current level between an amplifier and speaker are such that RFI and EMI, hell even AC Hum can not be induced into the signal path.

    Again try this at home and develop your own conclusions. Try REAL hard to induce noise into a unshielded speaker cable. Hell even lamp cord that uses a parallel run. Good luck!

    The reason a company puts a shield in a speaker cable is one of two reasons:

    a) Perceived value
    b) For use in residential or industrial applications, under construction, where long runs (hundreds of feet) will be used often in conduits, potentially alongside AC power, and the expense of ripping out the wire and replacing it due to a freak occurrence of noise will cost $163,000 instead of having used a shielded cable for a few more pennies per foot in the first place. In other words it is an insurance policy.
     
  12. LavaMan

    LavaMan Gold Supporting Member

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    Good explanation! But, as you put it, a shield is neccessary on an instrument cable 99% of the time due to the passive output and impedance of the guitar's circuit to protect primarily against external noise/RFI and EMI...so it really is a game of trade off's...how much shielding is necessary, vice how much clarity/dimension you can achieve with the electrical properties of the conductor and the other parts of the cable...

    So then, as the example you provide in an earlier post, the REAL reason we need robust shielding on instrument cables is what I metioned above combined with the environment in which they are used - lots of possiblities for external noise from power stations, radio stations, and AC line noise etc...

    So for instance, if I was playing a gig in the desert with a generator for power (a large bank of batteries is a little unrealistic) unshielded speaker cable will sound better than a robustly shielded instrument cable for use between my guitar and amp? Although, I must admit I do not know what kind of noise can come from a generator...

    But, bringing this back around I think what you are saying is that the conductive PVC/Polymer directly over the insulation surrounding the conductor and how it is connected to this insulation is what has the most impact on how "microphonic" a cable may or may not be. Correct?
     
  13. eaudio

    eaudio Member

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    Oh yeah totally needed for those reasons you list!

    That is what I'm suggesting. I used the "desert" context only to represent a fantasy-land environment that is free from external noise.

    And I suggest in such an environment a cable will sound better without a shield than it will with a shield.

    Grab two identical cables and run one of them through 20 feet of steel or copper pipe from the hardware store. Switch between the two and have a listen.

    Yes definitely. I'm saying that. I should have just said it like that in the first place :)
     
  14. LavaMan

    LavaMan Gold Supporting Member

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    Thanks for the education Tony. Well done.
     
  15. landru64

    landru64 Member

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    to tony's point, i remember when kimber kable came out with an unshielded audio (hifi) interconnect in the 80s, offered with the proviso that you MIGHT get noise in your home audio system while using it. they also produced a shielded version. i think they still produce this cable. the unshielded one was heralded as a real breakthrough in transparency, whereas the shielded one was considered nothing special.

    all bets are off, as suggested when you actually have to gig with this stuff ;)

    p.s. i think the evidence lyric HG was probably the most immune to handling noise and microphonics of any cable i've tested.
     
  16. eaudio

    eaudio Member

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