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recommend qsc plx power amp

Discussion in 'Amps and Cabs [BG]' started by paz, Aug 16, 2005.

  1. paz

    paz Banned

    Jun 26, 2001
    Seaton, Devon, England
    say ive got a 1000w RMS (2400w Peak) cab and a 400w RMS (1200w Peak) cab, both are 8 ohms. what sort of plx power amp should i get, i would be running it on bridged mono mode, how much power would be the best out of a 1200 watt amp, 1600 watt amp, 2400 watt amp, 3000 watt amp or a 3400 watt amp.
    a few days ago i would of gone for the most powerful one but now im not so sure, apparently too much power can damage the cabs.
    any help would be greatly appreciated
  2. All that matters here is how much volume you need. The most powerful one won't damage your speakers any more than the weakest one if you set them both to produce the same volume.

    I would get the biggest one you can afford. More is better than less :D
  3. Funky Doctor

    Funky Doctor

    Aug 28, 2003
    Hmmm... 1000 watts rms... 2400 peak... Sounds like an epifani 410!!! If it is, in fact, even if it isn't, get the biggest power amp you can find. You won't regrett it, especially if you are getting/have a cab like that. And I should know!!!
  4. shanmag


    Jul 27, 2005
    are the qsc plx power amps "better" than the qsc rmx power amps?

    i read a few threads about these power amps and everyone seems to recommend trying to get the plx over the rmx
  5. afroman

    afroman Supporting Member

    Aug 31, 2000
    Austin, TX
    I really love my QSC PLX3002. I'd say at least a PLX1602; 1000watts bridged at 8 ohms and 1600watts at 4 ohms for if you use your 2 cabs. I use my PLX3002 with a GS410 and 2 GS112s each on one channel, and they sound better the more power you give them (without going nuts of course). Having that extra power as headroom is great cause you'll never have to encounter the dreaded CLippining issues that destry speakers; at least it happened to me.

    Take care man...
  6. Eric Moesle

    Eric Moesle

    Sep 21, 2001
    Columbus OH
    I use a PLX 3002 running a 410 in each channel. Loud freakin' band, too loud. I have yet to turn the power amp's gain knobs above 2 o'clock. Plenty of power in reserve.
  7. r379


    Jul 28, 2004
    Dallas, Texas
    Actually, not everyone here recommends the PLX series over the RMX. While the RMX series may have better specs vis-a-vis distortion figures or some such you may not be able to hear those differences in a band setting and maybe not even playing by yourself. Depends on what sort of tone your going for. Ampeg? Maybe not. Demeter? Maybe.

    Not long ago there was a lengthy (and occasionally acrimonious) thread about light-weight switching amps versus the older, heavier transformer amps. No less a personage than Jim Bergantino argued that switching amps did not have the oomph to properly reproduce low frequencies. As it happens I, and others, agree with Jim. Older-style amps weigh more but cost less per watt so that's a consideration. Some folks I know say that if you want a switching-style amp you'd best buy a bigger amp (more watts) than you would if you were buying a transformer amp. YMMV.
  8. Geoff St. Germaine

    Geoff St. Germaine Commercial User

    I'm powering an Epifani T410 with a PLX1602. I can't really complain about anything with it. If you can afford to get one of the bigger ones, you might as well. They're the same weight and more power than you need is never bad (unless you can't control yourself).
  9. inazone


    Apr 20, 2003
    I have a epifani 410, 212 (and others) and a plx 3402. I wouldnt rcomend a plx amp for a bass rig. jmo.
  10. brooklynbassguy

    brooklynbassguy Supporting Member

    Feb 8, 2004
    maplewood, nj, usa
    I think the PLX is one of the best as far as switching power supplies goes. Pretty good damping factor and slew rate figures. My ideal is Trace, tons of booty, and the worst would be a Walter Woods, no booty. The PLX has got some snap to it...
  11. Funky Doctor

    Funky Doctor

    Aug 28, 2003
    Out of pure curiosity why do you say that?
  12. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    PLX amps clip at the same voltage at 20 Hz, 1 kHz, or 20 kHz.

    (IOW, they put out the same power over the entire audio spectrum).
  13. jerry

    jerry Doesn't know BDO Gold Supporting Member

    Dec 13, 1999
    I've been using the QSCPLX series for years! Powering all my rigs including my Bergantinos.......sound great to me :cool:
  14. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    Better in some ways, but the difference will not be really noticeable except in an extremely controlled listening environment. Both are designed to put out a very accurate replica of the input signal (below the amp's clipping point, of course); the PLX is measurably cleaner (more linear) in this regard, but like most well-designed power amps, the differences are in the "too small to really matter" end of the linearity spectrum. The PLX has a lower noise floor than the RMX, but this type of difference would not matter much in live situations, though it might be detectable in a quiet studio.

    The fan in the RMX amps is noisier than in the PLX. We used to have a quieter alternative fan, but then we learned that UL (Underwriters' Laboratories) would require us to re-qualify the whole line with the different fan to keep them listed. UL testing is a pretty expensive undertaking, so it was decided that the demand for the quieter fan wasn't strong enough to justify the expense. :meh:

    Both series are neutral over the audio spectrum--good for bass, midrange, highs, whatever--and not weaker or stronger at any frequency range.

    The PLX clip limiter is smoother and faster-acting than the RMX's, but if you don't run your amp into clipping much that shouldn't be much of a concern. ;) The PLX is simpler to bridge. Both of these are made possible by the PLX's having more circuitry in each audio channel. But more circuitry = more $.

    All the RMX models weigh more than the PLX amps.

    You can look at it as a business decision. If you gig a lot, the lower weight of the PLX may be worth the extra money; if you don't gig much, the lower price of the RMX may be more worthwhile than lower weight because you could recoup your investment faster.
  15. I've owned the MX-3000a (Godzilla, at 69 pounds), still own an RMX-850, two PLX3002 and one PLX1202. Currently bidding on a PLX1202 and RMX1850HD.

    Weight is a deciding factor for my needs, hence the sale of the very robust MX-3000a. Reliability is the other factor, and I think both lines are very good at this. I buy on price, and when I can score a deal.

    A minor nit with QSC is making sure your premap has sufficient voltage to drive the amp to full output. This means as much as 1.9 volts in the case of the PLX3402. My SWR IOD only puts out a maximum of 0.775v, so I use signal processing gear between it and the PLX to boost the output voltage.
  16. Chef

    Chef Moderator Staff Member Supporting Member

    May 23, 2004
    Columbia MO
    Staff Reviewer; Bass Gear Magazine
    I run a qsc/plx 1602 bridged mono into a Schroeder 410 (which is rated for 1600 watts). It's light, powerful, sounds great, and if it's missing low end response I can't hear it. I am a former owner of "heavier amps of several brands alleged to work better."
    Bob Lee is a good guy to talk to off line, and was helpful in guiding me in making that decision. I do not miss the weight of the heavier old school amps I used to carry. I can't hear any lack of bass response with all my pre-amps and basses set the same, thru the same cabs.
    I'm sure some folks maybe can hear some difference, YMMV.
    My personal experience says that qsc is a good decision with either rmx or plx series. I've beat many of them up and down the road, and not had problems with either.
  17. hmjuice


    May 20, 2000
    Austin, TX USA
    I've had my PLX-2402 for more than 4 years and I've never had a problem with it. In fact I've tried other power amps and I keep coming back to this one. As for the volume I only use it in stereo going to a Berg 3x10 and it rocks.
  18. Steve


    Aug 10, 2001
    I have a 2402 with every bit of 4,000 giging hours on it with all kinds of cabinets. It's given me ZERO problems.

    And anyone that thinks it doesn't have good low end..has a cabinet problem.

    Plug one into an Epifani, AccuGroove or Acme cabinet and tell me it doesn't have any low end...
  19. I'd be tempted to run the amp in stereo mode, same input to both channels, with the gain on the 400W RMS speaker cut down about 3-4dB. That way both speakers are maxing out about the same time. Running bridged, they'll get the same power, and you'll have to back off when the 400w speaker starts croaking, but could have pumped more power into the 1000w speaker. Couple hundred watts difference between the cabs, I would go ahead and run bridged mono. But with over 2x the power handling on one cab vs the other, I'd feel safer sending them different amts of power.

    So I'd shoot for a 1500-2000w@8 ohms /channel power amp. The amp will run much cooler at 8 ohm stereo compared to 4 ohm bridged load also.

  20. shanmag


    Jul 27, 2005
    THANX bob lee and everyone else that answered my question.. i will defentely be looking into qsc power amps!!