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Do I need a 2nd bridged speakon cable?

Discussion in 'Amps and Cabs [BG]' started by BassistGod, Sep 25, 2003.


  1. Someone clear me up here.

    If I'm running a bridged speakon cable from a plx to a GS112 cab and want to daisy chain another GS112, will I need the second speakon cable to be converted to bridged also?

    This bridging stuff is driving me bananas.
     
  2. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    No. You can only plug one Speakon cable into the PLX amp when you're running in bridged mono. Don't use the lower Speakon connector.
     
  3. Just the guy to help me out here.

    What I meant was when daisy chaining from the first cab to 2nd, can I use a regular 1/4 inch cable or will I need a cable converted for bridging like the speakon cable from the power amp to the first cab?

    In other words, does the second cable, which will run from the first cab to the second cab's input need to be setup for bridging also in order to take advantage of the mono bridging?

    Heres my diagram:
    POWER AMP--->bridged speakon cable--->First cab----->??cable??--->Second cab


    Hope thats a bit clearer
     
  4. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    No, you use whatever wiring the speakers need. They don't care if the amp is bridged any more than they care if you're using humbuckers or single coil pickups.
     
  5. Bob, you are a valuable asset to this site, period.


    Thanks.
     
  6. KB

    KB

    Jan 13, 2000
    Chapel Hill, NC
    You can link the 2 cabinets together with any cable that fits their outputs.
    My setup:
    SWR SM500 amp in bridged mode---->speakon out to speakon input of my first GS112---->1/4" jack from speaker#1 to speakon of GS112 #2 (But I can also take 1/4" jack of speaker#1 to 1/4" jack of speaker #2 with no problems
     
  7. A little off topic, but anyway I use a speaker cable from my preamp to power amp? Is this okay or should I be using regular instrtument cable. It seems to be working fine for awhile now.
     
  8. jdombrow

    jdombrow Supporting Member

    Jan 16, 2002
    Colorado Springs, CO
    Preamp to power amp should be a shielded instrument cable.

    However, speaker cables (amp-to-speaker) should NEVER be shielded instrument cables.
     
  9. pbd

    pbd Commercial User

    Jul 17, 2003
    Metro Detroit
    owner Procables N Sound
    The shielding will will cut out rf interference. A speaker cable won't hurt anything but it may become noisy in certain situations. On the other hand, as jdombrow states, you should never use a shielded cable as a speaker wire. The shielding creates an EM force that the amp reads as a greater impedance. This makes your amp work harder and sometimes beyond it's capabilities.
     
  10. Droog

    Droog

    Aug 14, 2003
    PDX
    From preamp to amp, shielded yes, but use a balanced cable instead of an unbalanced instrument cable. Most preamps offer balanced outs, not just on the DI. If you can use XLR do so.
     
  11. pbd

    pbd Commercial User

    Jul 17, 2003
    Metro Detroit
    owner Procables N Sound
    there is also available balanced 1/4". a 1/4 doesn't have as much surface contact in the socket as other connectors like an XLR. But if that is your only option use a balanced 1/4. The back of your equipment will say if it can be balanced or not.
     
  12. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    Any signals at instrument level (millivolts) or line level (around a volt, such as the preamp output feeding the power amp input) should be on shielded cable. Unshielded cable may allow more noise and hum in, particularly in settings where there is a lot of electrostatic noise to be picked up. Shielded cables have fairly small conductors, but that's fine because they are used in high-impedance circuits where the current flow is a couple milliamps at most.

    Speaker-level signals (10's of volts; several amperes of current) must be carried on large-gauge unshielded cables, not shielded instrument cables. Using an instrument cable in place of a speaker cable is highly unlikely to damage anything, but it's unwise because the conductors are small (that's not good in a low-impedance, high-power circuit) and because the capacitance between the conductors is relatively high, which may cause some amps to become unstable, leading to oscillation. Nevertheless, neither a type of cable (unless it's shorted) nor a higher load impedance will make an amp work harder.
     
  13. pbd

    pbd Commercial User

    Jul 17, 2003
    Metro Detroit
    owner Procables N Sound
    Bob Lee you are deffinately the man to know what load occurs at the amp. But I was always taught (roadies, speaker designers) that the draw from the amp changes due to an impedance change caused by a shielded cable, this is not so?
     
  14. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    Shunt capacitance between the conductors will create a lower impedance at high frequencies. Depending on how much capacitance there is and how stable the amp is with capacitive loads, that may cause problems with the amp, but it usually takes a pretty long cable to develop enough capacitance to make that happen.
     
  15. pbd

    pbd Commercial User

    Jul 17, 2003
    Metro Detroit
    owner Procables N Sound
    Thanks for the clarification. I'll grill my informants to see if I misunderstood or if they were mislead like myself. The length we referred to was a 20' instrument cable (perhaps they started this as a myth to scare musicians into not using them):D :D
    Thanks for your help!