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PA power amps vs. "Bass power amps"

Discussion in 'Amps and Cabs [BG]' started by mgmadian, Feb 20, 2002.


  1. mgmadian

    mgmadian

    Feb 4, 2002
    Austin, TX
    I've recently acquired a Kern IP-777 pre-amp and am in the market for a power amp to accompany this fine piece of machinery...most likely to drive a pair of 2x10 cabs.

    I'm looking into the usual suspects (QSC, Mackie, Carvin, etc), and am wondering if I should seriously consider the power amps from SWR, Eden, Ashdown, etc...i.e. the ones that are allegedly "made for bass". Is there anything to this? For example, is the SWR power amp better-suited to driving a bass rig than a PA power amp such as the QSC PLX1602?

    I've noticed that the SWR amp (for example) has a minimum impedance of 4-ohms, whereas the QSC and other PA power amps typically can handle a 2-ohm load, and are lighter to boot. But...is there a real (or perceived) difference in sound between the two?

    One plus for the PA power amp is that I could...well...use it to power a PA in addition to my bass rig. A nice extra, considering I've already got a small Mackie mixer, and at least one of the bass cabs I'm considering is allegedly usable as a PA speaker (guess which model this might be...?)

    Thanks!
    Greg
     
  2. chucko58

    chucko58

    Jan 17, 2002
    Silicon Valley, CA, USA
    I paid for all my gear myself. Well, me and MasterCard.
    There's no advantage to "bass-specific" power amps. Any modern pro level PA power amp is perfectly adequate to drive a bass guitar speaker. A power amp is a power amp.

    Some folks think that power amps using a switch mode power supply (the lightweight ones - Stewart World, PLX, etc.) lack low end oomph. This is a judgment call. It may be true; I don't know because I don't own a lightweight power amp. The good news is that if you do buy the wrong PA amp, you can probably find someone who wants it when you upgrade!

    Take those 2 ohm ratings with a grain of salt - think of them as the "afterburner" rating.

    And as for using your bass rig as a part-time PA, I'm right with you. Haven't tried it myself yet, but I hope to at my next jam session.
     
  3. mchildree

    mchildree Supporting Member

    Sep 4, 2000
    AL/GA
    I'd go with the standard PA type power amp. If you already own some other PA gear, then it could serve multiple functions. I have a few Mackie 1400s that usually run our PA, but when I have a gig that requires more volume on the bass rig than my SM400S will generate, I just use one of my Mackies and a preamp, or use my SWR as a preamp.

    If nothing else, think of resale. If you get a "bass-specific" power amp, like an SWR or Eden, you'd be limited at resale time to bass players only.
     
  4. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    I think the bass-specific thing is utter nonsense. Your best bet IMO is just to get a good PA amp.
     
  5. boogiebass

    boogiebass

    Aug 16, 2000
    I agree.
     
  6. VicDamone

    VicDamone

    Jun 25, 2000
    Most all the amplifires your looking at will do the job. I use a QSC PLX2404 because:

    Two channels with front pannel gain control
    Light weight
    Flexable in's and out's
    Frequency and clip limiting
    Light weight
    Durability
    Price (Lord Valve)
    Did I mention they're very light weight?
    And they do low frequencies very well. In a direct comparison with a Pass Labs 350 and recently a Krell 600M, powering a Bag End S18E-D, the little QSC held its own.
     
  7. Jerry J

    Jerry J Supporting Member

    Mar 27, 2000
    P-town, OR
    I whole-heartedly agree with Mr. Damone. I have a PLX2402 also and it is GREAT! No slouch in the low end oomph, at all. If fact the amp is kinda scary having that much power. It could be real easy to confetti a nice set of speakers if one isn't careful.:D
     
  8. I don't think there's anything actually "bass specific" about bass specific power amps. Switchmode technology has progressed to the poit where there aren't low end deficiencies any more. Check out a PLX for confirmation of that. The company I work for just bought some L-Acoustics amps to power a little V-DOSC PA (also amazing). These things are switchmode amps, 2400W per channel at 2 ohms, 22 pounds. I ran them at a rock show in a 10000 seater and they didn't even get warm:eek:. The fronts of the amps actually felt cold! Also no low end deficiencies. Real expensive though.
     
  9. EdenSmith

    EdenSmith Guest

    I sometimes wonder just how bass amplifier manufacturers rate their power amps. For example, I own an Eden WT800 that is supposed to be around 400-425 watts per channel at 4 ohms. I also have the Eden Navigator preamp and currently use a Crest LT1000 power amp with it, but for years I had been using Crest's FA901 amp. The 901 was rated at 375 watts per channel at 4 ohms and let me tell you the 901 would totally smoke the WT800's power section...MUCH louder and cleaner and better low end oomph. I've noticed this with other makers too.

    Go with a "PA" power amp...you'll be much happier. :)
     
  10. lo-end

    lo-end

    Jun 15, 2001
    PA
    Isnt there a difference in input sensitivity? I know that PA power amps aren't necessarily designed to be used with bass preamps...
     
  11. JMX

    JMX Vorsprung durch Technik

    Sep 4, 2000
    Cologne, Germany
    Why that?

    Line level is more or less the same. That's marketing voodoo.
     
  12. mgmadian

    mgmadian

    Feb 4, 2002
    Austin, TX
    1. Thanks all for the advise...sounds like PA-amp is the way to go.

    2. Re: the compatibility issue with bass pre-amps, I did call up and talk with Kern the other day, specifically asking them among other things if they recommended any particular power amps, and their replay was that their bass pre-amp is compatible with any power amp that will accept a line-level input (i.e. a regular ol' power amp)...so this incompatibiliy rumor does appear to be a bit of misinformation that's gone around a bit. hopefully this shoudl clear that up.

    Thanks! :D
     
  13. Jerry J

    Jerry J Supporting Member

    Mar 27, 2000
    P-town, OR
    I've got 3 preamps. An Alembic F-1X, an Eden Navigator and a Demeter 201DBL and I've not found any trouble driving my PLX2402 or my Crown CE-1000 with any of these guys. That's a fairly decent cross-section of preamps.:D