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Bob Lee (QSC): Whats the difference between QSC RMX and PLX amps

Discussion in 'Amps and Cabs [BG]' started by Joe Boom, Mar 31, 2005.


  1. Joe Boom

    Joe Boom

    Jun 25, 2004
    Chicago, IL
    What are the differnces that would effect the use of these two power amps for bass rigs? Are the PLX amps better for bass rigs than the RMX amps?
     
  2. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    I'll take a shot until Bob gets here. I don't think either one is really "better" than the other for bass amps, unless you're old, like me. Then the PLX wins, hands down, because it weighs only 21 pounds. Either one will work just fine, but consider your power needs, financial position and spinal column.
     
  3. Joe Boom

    Joe Boom

    Jun 25, 2004
    Chicago, IL
    Thanks for the info, Munjibunga. I can deal with the weight difference. I just did not want to give up headroom.
     
  4. jerry

    jerry Doesn't know BDO Gold Supporting Member

    Dec 13, 1999
    Hawaii
    I've used QSC power amps for almost twenty years, believe me, the PLX series are a godsend for us olders guys ;)
     
  5. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    Well, your headroom is going to depend mostly on how many watts you buy. Some people carp about the PLX's switching power supply and question its ability to handle bass, but I'm running a PLX 2402 into each of my PA's two EAW SB-220s, and it's mind-blowing. Talk about bottom. I've played the last two gigs direct through my ToneBone to the board, and those subs were sounding really punchy and tight, with no flab (hey, YOU figure out what the heck that means).
     
  6. Joe Boom

    Joe Boom

    Jun 25, 2004
    Chicago, IL
    I had not heard the gripes about the PLX power supply. What is the aleged issue?
     
  7. Big D

    Big D

    May 26, 2004
    Orlando, FL
    I replaced a SWR 750x going into a SWR 4x10 and 1x15 (Goliath and Son of Bertha) with an Ampeg SVP-Pro going into a PLX 3402 into 2 Ampeg Classic 8x10's. There simply is no comparison. The PLX 3402 puts out a ridiculus amount of bass power. When I stomp on my EBS Octabass, with some reverb on top of that, to get a really really big sound for one song that needs it, the PLX doesn't care, it just steps up to the plate and delivers. The light weight of the PLX's is really nice, especially once you stick them in a rack.
     
  8. MJ5150

    MJ5150 Terrific Twister

    Apr 12, 2001
    Lacey, WA
    With all the guys using the PLX series around here, the bass response issue is not really valid. The PLX series are great for bass.

    -Mike
     
  9. IvanMike

    IvanMike Player Characters fear me... Staff Member Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    OK i'll ask and wait for bob to show up too

    years ago the QSC "powerlight" series was the lightweight poweramp that was around (or at least i hadnt heard of stewart prior to 1997)

    anyhow, when i called QSC, the tech and salesmen I talked to told me that the powerlight series was better for program material, and if i was going to be using a poweramp for bass, i should stick to the heavier series for better bass. (i dont think it was the rmx, but another amp which i forget).

    anyhow, from what i was told by gc guys, the plx is the "cheaper poor man's version" or the powerlight. but now all of a sudden that's the amp to get for bass. now don't get me wrong, i think the PLX amps are great and if my stewart died and i couldnt get another one i'd be shelling out green for a plx tomorrow. i'm just wondering what happened to get qsc to change their tune?
     
  10. 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
    I've been here since before the PowerLight amps came out, and we haven't changed our tune. Who did you speak with? Was it someone who actually works for QSC?
     
  11. Fuzzbass

    Fuzzbass P5 with overdrive Supporting Member

    I believe the gripe involves all lightweight amps, not just QSC... it's with the "switching" design or the transformers or something. I'm no techie, all I know is that I use a lightweight Stewart and it has all the bottom I need. IMO the key to any SS amp is having plenty of headroom. I'm amazed at how huge a 3x10 cabinet can sound with plenty of "lightweight" watts behind it... sounds fantastic even with 5 string bass.

    Is it possible that heavy "lead sleds" sound better than lightweight amps? Sure. I've heard anecdotally of double-blind listening tests that show otherwise, but I've yet to see any scientific evidence either way. Bottom line for me is that the lightweight amps sound great to my ears.
     
  12. Most of the gripes seem to be comming from the pro sound guys and they're not aimed at QSC, but switching amps in general. They work fine on monitors and top boxes, but they aren't cutting it on the subs. I imagine these guys are driving their amps a lot harder than we would in a bass rig though.
     
  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
    There's nothing wrong with using an amp with a properly designed switching supply on subs. The amp and its supply should be neutral with respect to the signal frequency, whether it's deep bass or mids or high end. Most of the gripes have died down over the past decade as better amp technology has come out. A lot of PowerLight, PL2, and PLX amps, as well as SMPS amps from Lab Gruppen, Crest, and other brands actually are cutting it on subs.
     
  14. I'm just relaying the scuttlebutt going around the boards. I don't have enough experience on the subject to have an opinion one way or the other. Do a search over on the Harmony Central pro sound board if you care to and you'll find a number of lengthy discussions.
     
  15. This may or may not matter to you, but the PLX is made with US labor where the RMX is assembled in (I believe) China. I assure you the quality of the RMX is top notch, I own an 1850 HD myself and absolutely love it. I've used it for onstage monitoring, running PA subs, and general sound reinforcement in my music room.

    We currently use 2 PLX series amps for our PA, and we are very happy with their performance.

    Oh, regarding the weight... I'm always amused at the people who spend money on monthly charges at 24 hr fitness (or other health clubs) for exercise... but heaven forbid you pack a 50 pound power amp into the club Friday night.

    :D
     
  16. Joe Boom

    Joe Boom

    Jun 25, 2004
    Chicago, IL
    Hey Bob, would you answer my question about the RMX vs the PLX please?
     
  17. 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
    The PLX amps have lower noise and a bit lower distortion. The PLX's more sophisticated clip limiter circuitry is a little quicker-acting and smoother sounding. The difference in noise can be audible, while the difference in distortion almost certainly isn't. The sonic difference in clip limiting might be apparent if you clip the amp hard, but I hope you're more sensible than that! But even so, you're not likely to hear a noticeable difference between them in live situations.

    http://www.talkbass.com/forum/showthread.php?t=167261&highlight=RMX+PLX+difference
    http://www.talkbass.com/forum/showthread.php?t=156269&highlight=RMX+PLX+difference
    http://www.talkbass.com/forum/showthread.php?t=133420&highlight=RMX+PLX+difference
    http://www.talkbass.com/forum/showthread.php?t=129357&highlight=RMX+PLX+difference
    http://www.talkbass.com/forum/showthread.php?t=125343&highlight=RMX+PLX+difference
    http://www.talkbass.com/forum/showthread.php?t=115369&highlight=RMX+PLX+difference
    http://www.talkbass.com/forum/showthread.php?t=96716&highlight=RMX+PLX+difference
    http://www.talkbass.com/forum/showthread.php?t=74959&highlight=RMX+PLX+difference
    http://www.talkbass.com/forum/showthread.php?t=71158&highlight=RMX+PLX+difference
    http://www.talkbass.com/forum/showthread.php?t=68683&highlight=RMX+PLX+difference
    http://www.talkbass.com/forum/showthread.php?t=65111&highlight=RMX+PLX+difference
    http://www.talkbass.com/forum/showthread.php?t=59130&highlight=RMX+PLX+difference
    http://www.talkbass.com/forum/showthread.php?t=27413&highlight=RMX+PLX+difference
     
  18. Joe Boom

    Joe Boom

    Jun 25, 2004
    Chicago, IL
    How did I miss these???

    Thanks for the response and the links!
     
  19. IvanMike

    IvanMike Player Characters fear me... Staff Member Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    i can't recall who i spoke with but it was a tech and at least one salesman at QSC (via the 1-800 mumber circa 1996 or 1997). both told me that i shouldnt use the plx for bass but rather a more "standard" one. the "standard" qsc amp they suggested was the one reviewed by bass player magazine in the poweramps under $1500 shootout in the 1997 "play the blues" issue.
     
  20. 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
    I doubt that anyone technical would give you that advice. It had to have been someone in sales. ;)