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Y Cabling in Audio

Discussion in 'Sound, Music, and Intercom' started by Thefoxygranpa, Jun 3, 2009.

  1. Thefoxygranpa

    Thefoxygranpa Active Member

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    So was at the warehouse in my new job organizing a system I will be using...when I find this Y Cable. It allows two microphones to be plugged in and go to one source. Two females to one male.

    What is everyone's suggestion on this cable? The owner said that he uses them on drum mics, as only one tom or such is hit at once. My immediate thought was, "that won't work...".

    Anyway, thoughts?
     
  2. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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  3. jkowtko

    jkowtko Active Member

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    This was just covered in another thread ...

    Some people think they won't work.

    However we used them for a music concert last week -- had four pairs of Behringer C-2s running off Y's. Sounded fine. I imagine you want your two mics running at the same impedance, I don't know if this would work with dynamic mics, and I would be hesitant to try it with powered devices -- but unpowered condensor mic pairs seem to work pretty well for us :) Did it screw up the sound at all? Maybe -- but this was a middle school concert so we had bigger sound problems to deal with ;)
     
  4. Shillyer

    Shillyer Member

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    My understanding this that running two mics with a Y cable is a bad idea no matter if they are dynamic or a condenser. I will bow out and let someone with more knowledge than me tell you why (they will probably do a better job).

    Also there is no such thing as an un-powered condenser microphone. A charged back plate is a key component of any condenser mic. The only other thing I could think of is if you are talking about a condenser with its own power source instead of phantom power (ex. 9V battery) but still that is a powered device.

    Someone else please correct me if I am wrong in any of this.
     
  5. jkowtko

    jkowtko Active Member

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    My understanding is that dynamic mikes generate their own current (like a car generator/alternator) whereas condensors require phantom power in order to provide any signal.

    Our Y's were done with standard small condensors ... no power in the mic, we provided phantom power from the board. (that's what I meant by unpowered mics, i.e. they don't have their own source of power) you're basically running two condensor plates in parallel. So other than half the resistance, I don't see any other electrical behavior to be concerned about.

    Again, I have not tried this with any sort of powered signal source (nor do I intend to) .. that's where the "Why not Y" article seems to address the issue.
     
  6. waynehoskins

    waynehoskins Active Member

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    It works plenty fine. It's impractical to do when impedances and levels of the things wyed together are different, or where the source material is different. A vocal and an acoustic guitar, for example, you don't want to hard-wye because the signal levels are quite different; you need to be able to mix them. For toms, though, there's no reason not to. Great idea, in fact.

    Those things are also useful for other things too.
     
  7. rwhealey

    rwhealey Active Member

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    *Cough*
    Why Not Wye?

    "Here is the rule: Outputs are low impedance and must only be connected to high impedance inputs -- never, never tie two outputs directly together -- never. If you do, then each output tries to drive the very low impedance of the other, forcing both outputs into current-limit and possible damage. As a minimum, severe signal loss results." - Rane Note 109

    derekleffew even posted a link earlier in the thread...
     
  8. waynehoskins

    waynehoskins Active Member

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    Hmm .. I disagree with their reasoning, at least from what I read in this paragraph. If you terminate a low-impedance output with another output circuit of its characteristic impedance, no harm results; it is a summing bus. Sure, it's better if they're resistively connected, but it works plenty fine. Now, if you terminate an output circuit with a phenomenally lower-impedance circuit (be it input, output, whatever), then sure, you do load down the higher-impedance output circuit.

    If wyeing blew things up, our Clear-com and RTS intercom systems would be very dead. Well, CC set the bus impedance a little higher, 1.5K if memory serves, but the principle holds.

    Terminating an AC circuit with another of its characteristic impedance, I hold, is perfectly fine, and I've never heard the "severe signal loss" they claim as the best-case scenario.
     
  9. Chris15

    Chris15 CBMod CB Mods Premium Member

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    I don't see how a battery powered device is any different to phantom powered one or a dynamic one.

    The basic circuit to make an electret element work is - leg and shell of electret to ground, + leg to +ve rail via relevant bias resistor and + leg via cap to output. You won't get DC out of the output on that basis...

    I maintain as I have in other threads that it works, used wrong it will do bad things but used properly (and one must note there are far more wrong ways than right) it it a useful device...
     
  10. mbenonis

    mbenonis Wireless Guy Administrator

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    You'll note that this only applies to ACTIVE output stages, and not passive ones (such as the output of a dynamic mic).

    In this case, it comes down to whether the output stage is designed to work into the bus impedance. A ClearCom system is designed to work into a 200 Ohm load (I believe this is the bus impedance, but don't quote me on it). The active output stage of a console may or may not be able to do it, and the only way is to (a) analyze the circuit, or (b) ask the circuit designer.

    BTW, on busses, they are often terminated with an impedance that is significantly lower than the output impedance of each device on the line, such that the output stages do not load each other - the resistor does. That make any sense?
     
  11. TimmyP1955

    TimmyP1955 Active Member

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    These days most gadgets have an output impedance of between 50 and 150 Ohms, and they are designed to work into an impedance that is at least 10 times the output impedance (most mics are 150, most mic inputs are 2k).
     

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