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Simple power amp question

Discussion in 'Amps and Cabs [BG]' started by MascisMan, Feb 12, 2004.

  1. MascisMan

    MascisMan Supporting Member

    Nov 21, 2003
    Dallas, Tx
    What is the difference between running a power amp in stereo and running it in parallel?
  2. When you run an amp in stereo you are feeding 2 different signals into the left and right side of the amp. In parallel you are feeding the same signal into both sides. Some amps (Carvin comes to mind) will have a Stereo/Parallel mono switch. What this does is when Parallel is selected it chains the left and right inputs together so you only need to feed one side both sides see the signal. Parallel should not be confused with bridged mono. That is when both sides are bridged together to make one big mono amp. Hope this helps.
  3. MascisMan

    MascisMan Supporting Member

    Nov 21, 2003
    Dallas, Tx
    I see so correct me if I am wrong.

    I have one cab right now. So since there is only one input and one cab I will run in stereo configuration. However if I add another cab in the future, I will want to switch to parallel so that I can drive two cabs with one input device (the bass) right?

    Stereo is traditionall for running two seperate inputs into two seperate outputs where as parallel is for running one input into two seperate outputs.

    Is my assumption correct?
  4. Running 1 cabinet with a SS amp, it really doesn't make any difference if the switch is stereo or parallel as long as you are getting signal to the poweramp. If you run two cabs with only one input then you'll have to use the parallel switch. Can you bridge you power amp?
  5. In case you find some of the terminology confusing perhaps this will help... on a stereo amp your inputs can be:

    Stereo inputs - seperate left & right channel signals. If you plug into only one channel you feed only one side of your power amp and therefore only one speaker.

    Parallel inputs - with respect to the above, when you plug into one side or the other of your amp, the same signal goes to both the left and right channels (both sides of the poweramp) and both speakers. In other words the inputs are combined.

    Mono input - feeding one side of your stereo amp only, unless it is a parallel mono input (see above).

    For the outputs:

    Stereo outputs: seperate left and right signals to seperate left and right speakers (or perhaps biamped - highs to one speaker and lows to another)

    Bridged outputs: the left and right power sections are combined to produce more power into a single speaker. Driving one cabinet only? If your amp can operate in "bridged mono" mode you won't be wasting the power of a whole amplifier channel.

    Mono outputs: Your amp has only one channel.

    Essentially I am saying the same things that others have said, perhaps explaining a little differently. If I made any mistakes, someone is sure to let us all know in short order (*ducks*).
  6. MascisMan

    MascisMan Supporting Member

    Nov 21, 2003
    Dallas, Tx
    oddio-thats pretty much what I was thinking.

    The power amp in question is the QSC RMX 1850HD. 600x2 watts into 4 ohms (stereo) and 1800 watts bridged mono into 4 ohms. The single cab I currently have is 4 ohms (Ampeg SVT-HLN w/ 500 watts RMS and 1000 watts peak). So I was going to run 600 watts into this cab and then in the future when I add a second cab, throw 600 watts into that as well. Hence, switching from stereo to parallel in the future.

    I think 1800 bridged watts would be too much for the SVT cab, dont you guys?

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