Dismiss Notice

Psst... Ready to join TalkBass and start posting, make new friends, sell your gear, and more?  Register your free account in 30 seconds.

QSC bridged-mono question

Discussion in 'Amps and Cabs [BG]' started by Dan1099, Apr 18, 2005.


  1. Dan1099

    Dan1099 Dumbing My Process Down

    Aug 7, 2004
    Michigan
    One more noob question from yours truly regarding pre/power setups...

    I know that to bridge mono on my just-ordered PLX1602, I need a different connection for a speakon connection. Is it an entirely different cable that I need to purchase, or can I use my existing speakon cable? Do I need to rewire it somehow? Insert it in the amplifier differently? Or will I have to buy a whole new one? What will I have to ask for when buying one? Both ends of my current cable are marked in tiny print as +1.

    Excuse my stupidity on this subject.....
    Thanks again.
     
  2. No special connections.

    +1 is the Primary (first) pair of a two pair connector. This is the standard wiring connection used by the QSC amp. Pair Two (+2) is not used on the QSC, so you will be fine.

    The bridge mode in QSC amps combines the output of both channels, into the Channel 1 output. You can use the Speakon output, or the banana plug outlet for Channel 1.

    One or the other.

    You should have absolutely no less than 4 ohms total load, per QSC. IMO, I won't bridge 4 ohms because it is highly stressful on the amp. Much safer to bridge 8 ohms.

    Pay attention: bridging involves lethal currents and voltages. You can get your butt capped if you are clueless about what you are doing and touching.
     
  3. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    The Republic of Texas
    Here's the safest way to put it (I believe).
    According to the QSC PLX user's manual, the connector for the side of the cable that is connected to the positive side of the speaker(s) should be connected to the 1+ post of the Speakon connector and the connector for the side of the cable that is connected to the negative side of the speaker(s) should be connected to the 2+ post of the Speakon connector.

    In bridge mode the banana connection is across the two red posts for channel one & two -- channel one's positive post to the speaker(s) positive connector and channel two's positive post to the speaker(s) negative connector.


    Correct.

    Dan1099, best you check it out yourself:here's the link to the manual online.
     
  4. Sneaky Pete sent me this and it helped:
    Hang on there before you go. Speakons con in three flavors: 8 pole, 4 pole, and 2 pole. The number of conductors doesn't matter but the connector does. Most common are the 4 pole with only 2 leads attatched: 1+ and 1-.

    How do you tell? If the connector has a grey ring that you pull back and twist to remove the connection that is a 2 pole (NL2FC). If there is a thumb tab that's pulled back to remove the plug then it's a 4 pole. (there are some older versions that you twist a blue ring then pull the plug that way called "twist locks", they have been phased out)

    OK, hopefully you've found you have a 4 pole connector (look for the NL4FC or NL4FCX written somewhere on the end). Open it up and you'll see two wires leading into end, black and white. I wish I had a pic of one to post but bear with me, the set screws they are attached to both face the same direction. Orient them so they face up, away from you. Unscrew the one on the left (1-) and place it into the one directly below the remaining wire (marked 2+). Tighten the screw to make sure the wires don't come loose then reassemble the connector.

    I hope that helps, speakons are a superior way to connect amps to speakers. I hope one day 1/4 connects will be gone but 1/4's are so cheap to manufacture. Oh well...

    I followed his directions and I was set. I have a PLX2402 and run it with an Avalon U5.
    Good Luck
     
  5. Dan1099

    Dan1099 Dumbing My Process Down

    Aug 7, 2004
    Michigan
    Grrr... I'm pretty sure mine is only a two connector jack. Blahhhh. Oh well. One more thing to pick up before it gets here, I guess.
     
  6. Dan1099

    Dan1099 Dumbing My Process Down

    Aug 7, 2004
    Michigan
    So wait....to double-check....

    On one end of the cable, I need it wired +1 +2, to connect to the amplifier. On the cabinet end of the cable, it will need to be wired +1 -1. As far as which is which, +1 on both ends will share the same wire, and -1 and +2 will share the same wire. Is this correct?
     
  7. pbd

    pbd Commercial User

    Jul 17, 2003
    Metro Detroit
    owner Procables N Sound
    Be sure to check the dip switches on the rear of the amp as well. If you look at the top speakon on the amp it will show all four numbers (1+/-, 2+/-). This will be the jack you use for bridged mode. If you already have a speakon cable then just buy one connector and put it at the amp end. Be sure to indicate the end so you plug it in correctly. Depending on the size of your cable you could get the NL4FX which allows a larger gauge wire, these also have a new retention system. Typically the FX will cost less than the FC. Beware of imitation speakon...get the one with the Neutrik name on it.

    Good luck
    PBD
     
  8. huskies90

    huskies90

    May 17, 2004
    I assume it is OK to go from the speakon wired for bridge mode (or a bannana plug) into the amp to a 1/4 inch connection at the speaker. Correct?
     
  9. pbd

    pbd Commercial User

    Jul 17, 2003
    Metro Detroit
    owner Procables N Sound
    Dependant on the amount of power your putting into it. I've heard tell of amazing stories where the 1/4" is "popped" out the back from pressure in the cab. :eek:

    Somewhere else on TB someone put it very nicely, (paraphrased)"put your finger tips together at a 90 degree angle and that is how much contact surface you have for the power to go through."

    A new 'dish' on the back of the speaker cab is not difficult to install and doesn't cost much, especially for the benefits you'll get from changing it to a Speakon.

    :)
    PBD
     
  10. Check the speakon connector on your amp. I have a Mo-Bass, and the speakon bridge connector is a the "2", not the 4. Had to search around for a the older 2 conductor cable. The newer 4 conductor won't fit in the 2, but a 2 will fit in a 4.

    Randy
     
  11. 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
    Everybody else covered it pretty well, so here it is in short:

    1. Use a 4-pole Speakon (NL4FC, for example) plug.
    2. Wire the cable to terminals 1+ and 2+ in the Speakon plug. It's not difficult to do yourself, but you can often order a cable already wired this way. Pro Cables N Sound is a good source for somewhat custom stuff like this because he is very aware of what is necessary.
    3. Use the upper Speakon output on the amp. This one has both channel outputs present; the other doesn't.
    4. Make sure the amp is set up properly for bridged operation. (On a PLX amp, you just have to set switch 7 to "bridged mode on" and put the signal from the pre into channel 1's input.)
     
  12. Make sure you mark which end is the amp end and which end is the speaker end. You get no sound if you reverse them. On a dark stage it's easy to make that mistake and trust me that'll be the last thing you'll check and it makes you feel like a total moron.
     
  13. huskies90

    huskies90

    May 17, 2004
    I guess that is one advantage of going from Speakon on the amp to 1/4 inch on the speaker... ;)
     
  14. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    Yes.
     
  15. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    Yes.
     
  16. Dan1099

    Dan1099 Dumbing My Process Down

    Aug 7, 2004
    Michigan
    Thanks, Munji, but I got this thread sorted out months ago. I don't know why it get ressurected. Anyway, thanks for all the help, everyone.
     
  17. huskies90

    huskies90

    May 17, 2004
    I ressurected it because I had a question that related to this topic which I found after doing a search. Do I get a gold star for following procedure and by using the search function??

    :)
     
  18. pbd

    pbd Commercial User

    Jul 17, 2003
    Metro Detroit
    owner Procables N Sound
  19. boogiebass

    boogiebass

    Aug 16, 2000

    ;)