Discussion in 'Amps and Cabs [BG]' started by Andrew Dunbar, Jan 10, 2002.

  1. I'd like your opion.

    I'm about to purchase a new power amp. I'm going with a QSC PLX and here's the deal.
    I was going to get a 2402 (425@8ohms, 700@4ohms), then realized that for about $100 more I can get a 3002 (550@8ohms, 900@4ohms). Now I'm thinking about (for $200 more than the 3002) a 3402 (700@8ohms, 1100@4ohms).
    So now it's between a 3002 and a 3402, and my thoughts are this:
    Is it worth the the extra money to get the 3402? Yes the power is more but, the 3002 requires 10a and the 3402 requires 12a. With my next band I plan to play EVERYWHERE, so since the average house has 15a circuits, am I better off with the 3002, or should I even worry about it?

    My speakers are still in a state of flux, I'm testing out various configurations, with the possibility of bi-amping.

    Thank you for your thoughts.:cool:
  2. My advice is generally to buy as much power as you can afford. In the real world a 3402 driven hard will trip 15A breakers. The specs on the QSC site are quoted at 1/8 power, 4 ohms, not at full power. In most situations it will probably be fine, but I just thought you should be aware that the 3402 is very capable of tripping 15A breaker. That amp is also capable of blowing a large number bass guitar speakers, even below clipping levels, especially in bridge mode. So be careful. :D If the 3402 is only slightly more expensive, by all means get it. Unless you like to play VERY loud the stuff I jsut mentioned shouldn't be a problem.

    PLX series are great amps!
  3. Jerry J

    Jerry J Supporting Member

    Mar 27, 2000
    P-town, OR
    I can see speaker confetti all over the place!

    I have the PLX 2402 and that amp scares me. I'm running one side into my 8 ohm Aguilar 410 and it rattles the ground. I haven't even bridged it yet.

    Great amp!:D
  4. I also have the 2404. I'm using Acme speakers and can't imagine needing any more power. They are great amps.

  5. I have the MX-3000a and you should get the biggest PLX you can afford. Don't buy anything smaller than the 2402 because the output circuitry is less efficient.

    Mine is capable of breaker tripping and driver blowing also, but it doesn't do either.
  6. Nightbass


    May 1, 2001
    Seattle, WA
    I'd like to point out a misconception that I hear from time to time. A PLX whose specified maximum current draw is 10 or 15 amps does not "require" that current all the time. Continuous maximum current draw only occurs when the amp is delivering continuous maximum power, such as if you were feeding it continuous sine wave test tone in a lab. So don't think that a 3402 can't be plugged into just about any outlet as used as a bass amp - it can.

    Likewise, a 2400 watt amp isn't putting out 2400 watts all the time any more than your car is going at it's maximum speed all the time. In the real world, you are probably using anywhere from 1 to 100 watts in a bass rig. So it doesn't matter from that standpoint whether you get the 1602 or the 3402. In theory. But I agree with Bruce - go no smaller than the 2402, since it is just about right for today's 2x10's and 1x15's. If you have 4x10's, then move up a notch or two to the 3002 or 3402.

    I tried my PLX-2402 bridged into an Epifani 3x10. It was a downright scary experience! The darn cab started scuttling across the hardwood floor. And that was only a couple hundred watts out of 2400....

    Thanks for letting me clear this up. :)

  7. 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
    Full power is with a continuous-level sine wave right at the point of clipping. That has no analog in the real world except on a test bench.

    1/8 power is with pink noise, which produces brief peaks at the clipping point on average every couple seconds. That is fairly analogous to regular usage with music or audio signals at a level just below where you'd get audible effects of clipping.
  8. Bob,
    I understand that 1/8 power is a more accurate real world approximation than full power. Agreed on that. But given the right circumstances, an amp that powerful can certainly pop 15A breakers especially old breakers. I've seen MX3000s do it. Now they were being driven pretty hard i.e. well into clipping, but that's another story. The 3402 even at 12A current draw is approaching the limit of what you could reasonably power off a wall socket. I just wanted to make clear that 12A is not the maximum current draw of the amp, which was what the original poster thought. Like I said in an earlier post, plugging the 3402 into a wall outlet shouldn't pose a problem except under extenuating circumstances.
    I certainly didn't say that an amp would always draw its maximum current or that you couldn't plug a 3402 into a wall :D (just in case anyone thought I might be insinuating that)
    Again, great amps, you can't go wrong with QSC. Here's a plug for reliability: The company I work for owns about 100 MX series QSCs. They still own and use the original 1500s they bought in the early 80's. The service records report exactly 2 failures. That's pretty dang good if you ask me.
  9. Nightbass


    May 1, 2001
    Seattle, WA
    No, Spacegoat, I wasn't referring to anything you said. Lord knows you know your stuff. :) I was trying to assure the original poster that he didn't have to worry too much about current draw. And after reading a lot of other posts where guys talk about watts as if they were absolutes, I'm starting to pipe up. :)

  10. Cool. I didn't know if I had sort of unknowingly insinuated that:D. What you're saying is definitely true.
  11. Jeff Corallo

    Jeff Corallo

    May 30, 2000
    Other than weight differences, what are the differences between the PLX and the RMX series?
  12. :( You guys are making me feel bad...I have a 1602! Maybe I should've gone for a 2402 but the 1602 seems to be doing the job. BTW I run either 2 2X15's or a 2X15 and a 4X10 (at 4 Ohms per side) and I still have plenty of headroom.
  13. 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: low-impedance switch-mode power supply
    RMX: conventional (big transformer) power supply

    PLX: 106–108 dB signal-to-noise (depending on model)
    RMX: 100 dB signal-to-noise

    PLX: quieter variable-speed fan
    RMX: somewhat noisier variable-speed fan

    PLX: maximum voltage gain 40×, or 32 dB
    RMX: maximum voltage gain depends on model—RMX 850, 31.6× (30 dB); RMX 1450, 40× (32 dB); RMX 2450, 50× (34 dB)

    PLX: costs a little more
    RMX: costs a little less

    PLX: detented gain controls
    RMX: non-detented

    PLX: signal (-30 dB), -20 dB, -10 dB, clip, plus parallel and bridge mono LED indicators
    RMX: signal and clip LEDs
    Both have power indicators.
  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
    Then you've got the power you need. Don't feel bad! :p
  15. Thanks Bob. I'm starting to feel a little better. :)
  16. Jeff Corallo

    Jeff Corallo

    May 30, 2000
    Thanks Bob
  17. pedro


    Apr 5, 2000
    Madison, WI.
    It all seems like an up surd amount of power for anybody but the few playing large arenas to me. (Pedro still shaking his head in disbelief.)
  18. Josh Ryan

    Josh Ryan - that dog won't hunt, Monsignor. Staff Member Supporting Member

    Mar 24, 2001
    I'm an ignorant jackass, so somebody else can explain this, but it's the SOUND you get by having the power behind you bass. People don't want this for insane volume, they want it more for headroom.
  19. Yes, it's primarily for the headroom.

    But, when I play a steet festival (and I'm the guy with the P.A. or working in conjunction with the sound guys), I want to be able to play so freeeeeeekin' loud and deep that the office buildings downtown start to sway.

    When I start playing arenas, I'll just plug into their P.A. with my direct box.

    It's good to be kind and gentle, but sometimes you've just gotta kick some ***
  20. Well. you are free to have any beliefs you want, but absurd is such a nasty and condescending word...

    I suggest you not diss folks, as it tends to really piss them off. I pack a 3,000 watt amp and being labeled absurd really makes me bristle.

    It appears you need a tutorial on dB Math 101 so you can understand why your SWR 350 + Goliath makes the same loudness as an Acme B-4 with a 3000 watt amp. Your cabs are +10 dB more sensitive than the Acme. Doing the math for you, the Acme requires a 10x increase in required power over the Goliath to achieve the same loudness. This puts the required power right up in the 3,000+ watt range, which is far higher than a single Acme can handle.