Stereo or Mono that is the Question...

Discussion in 'Amps and Cabs [BG]' started by Kurt M., Apr 26, 2002.

  1. Kurt M.

    Kurt M.

    Dec 11, 2001
    Reading, PA
    I've always used purpose built bass amps. Now I'm pretty sure I'll be moving to a preamp/power amp setup. I've been talking to people and getting conflicting info.

    I'm pretty sure I'm going with the Ampeg SVP Pro preamp/QSC PLX combination. I'm pretty sure I'll be running a Golliath III (2/10 already have) and a Son of Bertha (1/15 or BagEnd S15BD). Let's say both cabs are 8 ohms. Originally I thought the QSC 1602 PLX which puts 350W into each of the cabs would be plenty. Some feel I need to upgrade to the 2402. Anyway, I've also been told by some to bridge the amp. Now if I do that I basically have one big amp and one bigger speaker. Correct? I loose the ability to adjust the level of the 2/10 box and the 1/15 box independently. Correct? I'm not going to add a crossover and the Ampeg pre doesn't have one built it.

    What is the best way to run such a setup?


  2. coyoteboy

    coyoteboy easy there, Ned Supporting Member

    Mar 29, 2000
    Sactomato, CA
    Running the amp at 4 ohms in bridged mode will get you the most output from the amp. You are correct that in this mode, you do not have individual adjustments for the 2x10/1x15 cabs. I wouldn't worry about a crossover, both cabs will do full range just fine.
  3. Lovin Bass

    Lovin Bass

    Feb 8, 2002
    Los Angeles
    To start off with, I have no experience with the Preamp/Poweramp rack setup and have only used an integrated bass head but when I was shopping to upgrade my setup, I did do alot of research to see what would be best for me. That research included the preamp/poweramp route.

    The QSC PLX series is supposed to be some good quality stuff.

    I have the PDF Manual for the QSC PLX series and the QSC PLX 1602 that you mentioned will put out 325watts RMS into each cabinet(8 ohms) in the stereo mode and you will have the ability to fine tune the individual gain/volume of each cab. When you bridge the amp, you will be putting out 1600watts RMS into both cabs since they are in parallel(4 ohm total load) and will lose the ability to adjust the volume of each cab. That means that you will be putting approximately 1600watts/2 (or 800 watts RMS) into each cab since they have the same nominal impedance and therefore the power will be split 50/50 into each cab. The power balance may vary slightly though as the impedance of the cabs will vary as they are used and the 8ohm spec is only the average impedance for the cab. That is alot of power into each cab that are rated at 350 watts/8 ohms each.

    Without any hands-on experience, I would think that the stereo output of the QSC PLX 1602 should be fine. If you need more than that, then you will probably only use your rig as a stage monitor and run a line thru the main sound system to cover the audience requirements and therefore in reality, you won't really need more than that.

    My ignorant opinion is to go with the QSC PLX 1602.
  4. Kurt M.

    Kurt M.

    Dec 11, 2001
    Reading, PA
    Thanks all. Depending on how you look at it it starts to sound like alot of power doesn't it. I almost always run direct in addition to my rig. But my current SVT3 Pro into Genz Benz 4/10 is having trouble keeping up on stage with 2 very loud guitar players. I'm all the way up on the volume and the gain is cranked pretty good too. So, I'm looking for more power among other things. Personally I thougt the 1602, a 2/10 and a 1/15 would be a good way to go. It has been suggested that I won't be happy and should run the 2402 into (2) 4/10 cabinets. That's alot to carry and alot of money! So, I'm thinking on trying the first approach.