Power Amp Mode & pre-amp source?

Discussion in 'Amps and Cabs [BG]' started by Sammy Camden, Oct 23, 2006.

  1. :cool: OK! I currently own two bass heads: a Genz-Benz GBE-600 and an Ashdown MAG-600R. I own enough cabs to outfit an army. However, I'm thinking of getting a power amp that will run around 600 to 700W per channel at 4-ohms. I've also thought about getting a 1200W Bass head.

    Now! Here're my questions.

    1. What is the advantage or disadvantage, sound wise, of running two 600W, 4-ohm cabs with": a. A 1200W bass head putting 600W into each cab; or b. A 600W/channel @ 4-ohms stereo head putting 600W into each cab.

    It seems that I can buy a 600W @ 4-ohms stereo amp for a lot less than the 1200W bass head.

    Yes, I know, the stereo amp doesn't have a preamp in it. However, I have two very good heads that do have preamps in them.

    2. So, next question. Why couldn't I use the preamp out from either of the bass heads to run into the stereo head? It seems at first blush that it would work just fine.

    If this works, I could save myself a lot money and just supplement my existing grear with the poweramp head.

    3. I've also considered running the Genz at a 2-ohm load and tapping the preamp out to run into the MAG running into a 4-ohm load. That way they would both be capable of running at 600W. I wouldn't plan on running either one that high as I don't normally run at over about 80% (7 or 8 on the output dial).

    I'm looking for some advice and exerience from those that really know about these things.

    OK TB experts! Let's hear the pros and cons of these two ideas.

  2. Anthrax


    Oct 1, 2006
    Theres only one bad thing i can think of. You have to carry a power amp(probly in a rackmount case to keep it safe) and an amp to gigs.

    other then that, provided your amps have the outputs suitible for a power amp(maybe DI might work ?) then it should sound basicly the same, but your headroom and volume will be amazing...
  3. MacGroove

    MacGroove Brother of the Groove with a 'Pocket Full of Funk'

    Oct 5, 2005
    Hope I'm not confused here, but isn't (a) and (b) in question 1the same thing. You'll usually get a power amp that'll be able to go sterio and bridged, if it's at 1200 watt bridged @ 4 ohms it most likely will not be 600 watts @ 4 ohms sterio more like 350 to 450 watts. Seems all your cabs are 4 ohms so bridging into a 2 ohm load would work.

    To keep the weight issue down and to get the power you want a Stewart 2.1 would be nice, 650 watts @ 4 ohms sterio, 2100 watts bridged @ 4 ohms, 17 lbs.

    Now you need to see if your current amps (using the pre only) has a pre amp out.
  4. :cool: (Quote: Hope I'm not confused here, but isn't (a) and (b) in question 1 the same thing.) MacGrove: Not quite. a. is in reference to a 1200W @ 2 ohm monoblock bass head. b. is in reference to a stereo 600W/channel @ 4-ohm poweramp. Both would be able to power two 4 ohm cabs with 600W into each cab. I'm trying to figure out the advantages vs disadvantages of each.

    Anthrax: Both of my current heads have a DI output, which I'm assuming (ouch) will be suitable to go to a poweramp. The manuals for both alude to that. If it works, I only have to spend the money for a poweramp. If it doesn't, then I'll have to buy a preamp. The poweramp and preamp will probably cost more than the monoblock bass head.

    So, I could forget the poweramp and buy the monoblock bass head, which will set me back a few more coins than the straight poweramp, but not as much as the poweramp plus preamp.

    Or, I could just use both heads to power my cabs, slaving one to the other. Since the Genz puts out its full power at 2 ohms, I'd hook two 4 ohm cabs to it. The MAG puts out its full power at 4 ohms, so one 4 ohm cab should do it there. I have some 8 ohm cabs as well, but that just involves more equipment. I've never slaved heads together before so I'm not familiar with any attendant problems with this type of operation.

    I guess the way I laid it out is confusing, huh? Sorry. I hope I've cleared things up a little.

    I'm trying not to break the bank on this little expansion. I'd like to get good sound, no problems, and spend as little as possible. The whole reason for this little exercise is next Spring and Summer we're going to be doing quite a few outdoor gigs and I think I might need some additional OOMPH to carry them since I can't go through the FOH. Our system just isn't big enough to handle the vocals, the guitars, and me!

    Thanks again.
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