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Power Amp Question

Discussion in 'Amps and Cabs [BG]' started by CLJMB, Aug 26, 2005.


  1. CLJMB

    CLJMB Supporting Member

    Jan 4, 2005
    North Alabama
    I have seen several posts regarding people using "half" of a QSC PLX power amp. I have read the QSC manual online and didn't see anything saying it was OK to run a load on one side of the amp and none on the other. Is the amp OK with doing that? :confused: I have a Schroeder 1210 and am thinking of getting a QSC PLX2402, but am not sure whether I should run the amp bridged (because of its much higher power than the Schroders' rating) or "halfed".
     
  2. Lex P.

    Lex P. You've got it awful loud -Kathy P. Gold Supporting Member

    Mar 19, 2003
    MSP
    I would run the 2402 bridged and not worry about overpowering the 1210. Within reason of course. I have a 2402 that I run bridged with my 1210 and the extra head room just gives it more booty. The difference between running a single channel and running it bridged is remarkable.

    Since I got my Eden WT550 my 2402 is being used for vocal monitioring. I run the 2402 with just one channel and it is not a problem. I just turn off the input to the second unused channel. Been doing this for years and have not had a problem.

    I guess what it comes down to is you can use it either way. Just experiment and go with what sounds best. You will not hurt the 1210 running the amp bridged, and you will not hurt the 2402 running a single channel. However you should use some common sense for sound levels because either way you could blow a speaker out.
    Lex
     
  3. Stereo amps are 2 completely seperate amplifiers in the same case. Saying you cannot run one channel and leave the other one unused is like saying you cannot run your bass amp unless your guitar player also has his head hooked up to a cab as well. They share a case, and sometimes a power supply. That is all. other than that, they are completely independent.

    Having said that, there may be consequences if you hook your preamp up to channel A and crank it up if you accidentally hook the speaker up to channel B....

    Randy
     
  4. CLJMB

    CLJMB Supporting Member

    Jan 4, 2005
    North Alabama
    Appreciate the input. It is my understanding that, except in the case of a true dual mono amp with independent power switches such as the Stewart World 2.1, that "stereo" amps such as the PLX use the same power supply for both channels. So I don't quite understand the analogy between my amp and the guitar players (since his power supply doesn't turn on when I turn my amp on). The sharing of the power supply is the basis for my question.
     
  5. Gotcha, I thought you were referring to "blowing" the unused channel.

    Since the power supply is designed to support both channels at full output, the effect on only running one channel at full output and the other unused is?

    The same as running both channels at half output.

    If you have a light fixture designed to handle 2 60 watt bulbs, what's the effect if you only screw one bulb in?

    Not being a smartass, just using a clear example to show why its not an issue.

    Randy
     
  6. CLJMB

    CLJMB Supporting Member

    Jan 4, 2005
    North Alabama
    Got it. Thanks. :)

    Lex - why did you switch to the 550? How did it compare in volume?
     
  7. Lex P.

    Lex P. You've got it awful loud -Kathy P. Gold Supporting Member

    Mar 19, 2003
    MSP
    Strictly because I got tired of hauling the weight of a 4 space road ready rack, a preamp and the 2402. For pure volume the bridged 2402 will blow away the 550, however in real world playing situations I'm not even taxing the 550 and I have plenty of power to spare. We play at what I would call moderate volume.
     
  8. Lex P.

    Lex P. You've got it awful loud -Kathy P. Gold Supporting Member

    Mar 19, 2003
    MSP
    I should also add that I am very satisfied with the WT550, The tone options are great and the thing seems to be way underrated as far as power and it even goes to 2 ohms so when I get my 410 or second 1210 I'll really be rocking. I can safely say that the 2402 is now strictly a backup with it's main focus being PA support.
     
  9. Masher88

    Masher88 Believe in absurdities and you commit atrocities

    May 7, 2005
    Cleveland, OH
    Just run it bridged, if you are worried, but turn the volume down on the QSC amp. ;)