QSC PLX, 1602 or 2402?

Discussion in 'Amps and Cabs [BG]' started by slombovia, Oct 9, 2003.

  1. slombovia


    Jul 15, 2003
    I am a determined follower of Jesus Christ and am a Mormon.
    I am planning on getting a QSC PLX - either the 1602 or 2402. I am not sure it is worth the extra $200 to go from 1000 watts to 1500w (in the case of my 4 ohm cabs in stereo) - for just a couple db.

    I have a Zon Sonus Special 6 and Carvin fretless piezo 6. I play numerous styles and venues. So far, 600w from my Crown into my pair of Avatar CB112H cabs has been sufficient. I am looking for a little more headroom, lighter weight (my Crown is 55lbs.), and hopefully better sound. I think I need the subsonic filters too because the sub lows from my basses really make those woofers move more than necessary.

    And what about the 1602 being class AB and the 2402 being class H. What are the differences and should I take them into consideration?

    Many thanks,
    Tom H.
  2. Schwinn


    Dec 4, 2002
    Sarasota, FL
    Wow...I've been wondering the exact same thing all week. I'm moving from the world of RMX to PLX. I'm leaning more toward a 1602 because that is sufficient power for my use.
  3. boogiebass


    Aug 16, 2000
    I own the PLX 1602 and find it works well for most gigs, indoors and out. I do, however, use a Stewart World 2.1 when I want the extra headroom and when I use more than one of my Bergantino or Epifani cabs. The Stewart has the added advantage of being dual mono, with separate power supplies for each channel.
  4. slombovia


    Jul 15, 2003
    I am a determined follower of Jesus Christ and am a Mormon.
    How does the fan noise compare between your PLX 1602 and your World 2.1?
  5. boogiebass


    Aug 16, 2000
    Pretty comparable, I'd say. Haven't noticed a difference either way, really.
  6. Eric Moesle

    Eric Moesle

    Sep 21, 2001
    Columbus OH
    You can never have enough power. Limit yourself, and you'll question your decision later. I use a 3002, and though it is likely overkill, I never have to question whether I need more.
  7. chucko58


    Jan 17, 2002
    Silicon Valley, CA, USA
    I paid for all my gear myself. Well, me and MasterCard.
    The PLX 2402 uses a Class H output stage, so it is more efficient than the 1602, and actually uses less power at idle!
  8. brianrost

    brianrost Gold Supporting Member

    Apr 26, 2000
    Boston, Taxachusetts
    Curious if you ever have any AC power issues with a 3002.

    While the PLX amps are pretty efficient the reality is to put out 2400 watts from a 120VAC source, you need to draw 20 amps...25 to get 3K watts. Sure, the amps don't run flat out but you don't want to be popping circuit breakers left and right when you crank it up.

    On big shows where the PA includes racks of high powered amps they usually tap into 220V.
  9. ColonelZulu

    ColonelZulu Not Impressed By Those Who Flaunt “Authority” Supporting Member

    Apr 14, 2001
    $200 for the extra 500watts...Helllll yes.

    And not for any extra db...you wouldn't even notice. It's like your getting an V-6 instead of a 4-banger in your car. That doesn't mean you have to drive faster, but the engine works harder for the same output the smaller it is.

    I think it's a reasonable analogy. There's more to volume than watts. Much more. But as far as having a robust powerplant that can handle whatever you throw at it...Bigger is Better.
  10. gfab333


    Mar 22, 2000
    Honolulu, Hawaii
    Hopefully, fellow TBer Adrian Garcia will chime in as I believe he runs a 2402 with his cabs. I recently heard him at a few of his gigs in Vegas, and his amp really kicks! Great tone, clarity, volume, and projection!

    My vote goes for the 2402; I'm in the "it never hurts to have more power" camp. To put it another way, how many gigs would it take to make the extra $200?
  11. bben


    Feb 28, 2002
    Santa Fe, NM
    I had a 1602 for a while - if I were to buy another PLX I would go for the 2402 for the Class H headroom.

    brianrost: I have a PDF file of the QSC owners manual, which I downloaded from their website.

    On page 29 is an interesting chart of current draw. None of the PLXs draw more than 20 amps at "full power", which is defined as "1/3 power with pink noise represents severe program with heavy clipping". Under those conditions, both channels driven at 4 ohms, the power draw is 8.9, 13.3, 13.5, 17, and 20 amps for the 1202, 1602, 2402, 3002, and 3402, respectively.
  12. Big String

    Big String Supporting Member

    Apr 22, 2000
    Northwest Indiana
    I have 2402 and if I had to do it over I would get the 3002. You won't reget it.
  13. rok51


    Sep 2, 2002
    Crawfordville, FL
    I have a 1602. It's all that I need. If I were to buy again, I'd probably opt for the 3002. Why? Beats me.
  14. I have a 1202, and two 3002. Answering the question, I would opt for the 2402 due to the superior output circuity. Weight is the same in all cases.

    My three were decided by luck of the draw (great eBay deals).

    Downside to the higher power amps, is the decreased sensitivity of their input circuits. You will need more preamp voltage to drive the big QSC to full power. Sans Amps, SWR IOD, F1-X, will not do it. I use a Rane EQ (plus dbx + crossover) between the preamp and QSC. Each of these provides greater than unity gain, so I have no problem driving the QSC to full power.
  15. I was surprised to find that all amps in the PLX line have the same gain, around 30 dB. This means that the 3402 is no louder than the 1602, all else being equal. The difference is in the amount of headroom available.

    It takes a very hot signal to drive the higher powered models, and you might need a few dB boost after your preamp, depending on its specs.

    I have and Alembic F1X and sometimes use an RNC compressor to add about 6dB of gain.

    (Imagine my surprise when I replaced a Stewart World 600 with a PLX 3002, and it wasn't as loud!)
  16. brianrost

    brianrost Gold Supporting Member

    Apr 26, 2000
    Boston, Taxachusetts
    No, it means if you drive the 3002 with a hotter signal, it will continue to get louder while the 1602 will just clip. This is true of most power amp families, BTW.

    As others have noted, not all preamps can drive the amp hard enough to make use of the extra power. Keep in mind the difference between 1600 watts and 3000 watts is only 3 db, anyway.
  17. weldon


    Jan 3, 2003
    Denver, CO
    This might be a good place to ask if I understand the relationship between watts and db. I've heard elsewhere that a 3db increase requires twice the power, which jives with your statement. I've also heard that it takes about a 10db increase for the audience to feel like it is twice as loud.

    So (assuming you aren't clipping) if you wanted to double the volume you can get at 1600 watts, you would need to double your power 3 times (to get a 9db increase). So 3200, then 6400, then 12800 watts to get a 9db increase and an apparent doubling in volume.

    I suppose there are practical limitations in setting up speaker cabinets to handle the range of 1600 to 12800 to demonstrate the difference, but do I have the basic math right?
  18. Brian: as I said, "all else being equal," the amps have the same volume. Yes, if you increase the signal, the higher-wattage amps get louder, but that's not "equal."
  19. Hey Brian, just curious here, but I have never found a family of amps other than the QSC PLX with the same gain ... can you please share?

    The QSC RMX amps, for example, provide a higher gain in their higher wattage models:

  20. brianrost

    brianrost Gold Supporting Member

    Apr 26, 2000
    Boston, Taxachusetts
    So what's your point?

    You seem to be upset that if driven from the same preamplifier at the exact same setting, both amps would be equal volume.

    So what? You turn up more and then the more powerful amp gets louder. Which is what I would want to have happen :D

    There is an easily done mod to change the sensitivity of the larger PLX amps to get full output power from weaker preamps, BTW.

    Other amps with fixed gain across the family: Crown XLS, Crown CE, Crown MicroTech (has both fixed gain and fixed sensitivity modes, switch selected), Crest CA (also switchable fixed gain or sensitivity).

    Perhaps Bob Lee could explain why some amp families are designed with fixed gain and others designed to have fixed sensitivity.
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