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QSC PLX 2402 - Settings - Help

Discussion in 'Amps and Cabs [BG]' started by Big String, Oct 3, 2002.


  1. PLX 2402 owner operators, please send me your setting/applications. I plan to use a Demeter VTBP-201S and one Bergantino HT212 (4ohm) cab most of the time. I may add another 8ohm or 4 ohm cab at times. Hence my set up questions. I read the manual some, but that confused me more. Sorry in advance for some "no brainer" questions, but I'm in a time crunch and trial and error is not an option for me. Anything I forgot please add. Thanks for your expertise.

    Amp settings using one 4ohm cab:
    1. Parallel - Bridge - Stereo ?
    2. Filters on or off ? If on, 50 or 30 hz ?
    3. Limiters on or off ?
    4. From Preamp, which channel input 1 or 2 ? XLR or 1/4 ?
    5. From Amp, which output 1 or 2 ?

    Amp settings using two cabs one 4ohm one 4 or 8 ohm:
    1. Parallel - Bridge - Stero ?
    2. Filters on or off ? If on, 50 or 30 hz ?
    3. Limiters on or off ?
    4. From Preamp, which channel input 1 or 2 ? XLR or 1/4 ?
    5. From Amp, which output 1 and 2 or cab to cab?

    Thanks to Bob Lee and Jerry for my prior questions on this equipment. I would still like additional inputs. Besides one of my loving Children cleaned out my email with some of the pointers I saved. :rolleyes:
     
  2. ganttbos

    ganttbos The Professor Supporting Member

    Dec 18, 2001
    New Orleans area
    Amp settings using one 4ohm cab:
    1. Parallel - Bridge - Stereo ? (With a 4 ohm Berg 212 rated at 700 watts you can use either one channel in stereo mode or mono bridge - bridge will give you about 1500 watts into the cab - that's OK if you're careful).
    2. Filters on or off ? If on, 50 or 30 hz ? (filters on 50 Hz)
    3. Limiters on or off ? (limiters on)
    4. From Preamp, which channel input 1 or 2 ? XLR or 1/4 ? (channel one - if running channel one of the amp in stereo mode, the input switches 4,5, and 6 in the off position: if running mono bridge, switches 4,5, and 6 in the on position to couple the input signal into both channels. XLR or quarter will both work. You probably won't have a hum problem with a short unbalanced cable).
    5. From Amp, which output 1 or 2 ? (output one in either mode, but if using bridge mode with a speakon connector, the connector at the amp end must be wired +1 +2, otherwise in stereo the speakon at the amp end is +1 -1.)

    Amp settings using two cabs one 4ohm one 4 or 8 ohm:
    1. Parallel - Bridge - Stero ? (stereo)
    2. Filters on or off ? If on, 50 or 30 hz ? (as above)
    3. Limiters on or off ? (as above)
    4. From Preamp, which channel input 1 or 2 ? XLR or 1/4 ? (amp inputs 1 and 2, or only input one if you parallel the input signal - see above directions for the three switches).
    5. From Amp, which output 1 and 2 or cab to cab? (both outputs - each to one cab).

    These directions are off the top of my head. It ended up more complicated to explain than I thought when I started. And these are not all of the options and I could have omitted something. I strongly suggest you suck it up and read the manual thoroughly. The 2402 is too powerful and the cabs too pricey to risk. Good luck - it should sound great!
    Gantt
     
  3. Thanks, all noted.
    The manual showed a picture diagram that demonstrated: instrument to preamp to amp (set bridged) into 4ohm cab. I talked to some others prior to this post and one friend said he had his in parallel all the time and switched back and fourth form one speaker to using two speakers. He did say he should read the manual... but after several years of use no problem. No wonder my HAIR hurts... The manual is straight forward on some things but confusing on otheres to me.
     
  4. Welcome to the club. I have two PLX and know you're gonna dig 'em.
     
  5. Phat Ham

    Phat Ham

    Feb 13, 2000
    DC
    Isn't it actually 2400 watts into 4 ohms bridged and 1500 watts into 8 ohms bridged?
     
  6. chucko58

    chucko58

    Jan 17, 2002
    Silicon Valley, CA, USA
    I paid for all my gear myself. Well, me and MasterCard.
    Good info so far. A couple of suggestions:

    Leave the limiter on. Your cabs will thank you for it.

    If your preamp only has a mono out, and you don't have any stereo effects, I'd set the PLX in parallel mode and leave it there. It's one less thing to mess with. Besides, 700 W per channel ought to be plenty!

    If you're playing a 5 string or a dropped tuning, and your cab has a usable response below 50 Hz, you may want to set the filter for 30 Hz instead of 50 Hz.

    Clear as mud, right?
     
  7. I'm sorry to say I don't understand the Speakon connector application that was mentioned. Are you saying you have to have a different connection for stereo than for the bridge/parallel set up? What does the +1-1 etc. mean? Maybe I should just use 1/4" conncections...
     
  8. I just looked at the manual on line and I see what you mean. thanks
     
  9. ganttbos

    ganttbos The Professor Supporting Member

    Dec 18, 2001
    New Orleans area
    This is correct. I was wrong above (thinking of an 8 ohm cab like my WJ).

    The pin connections in a speakon are easy to understand if you view it this way: The banana connectors are red and black for each channel, right. Think of channel 1 red and black as +1 -1, and channel 2 red and black as +2 -2. If you were connecting one cab in mono bridge mode using a banana jack, you'd connect to the two red binding plugs, right - that's what the speakon connector is doing when it is wired +1 +2. For the polarity to be "correct" with a banana jack in mono bridge (which means the speaker cone moves "out" first, not "in" first upon responding to the signal from the amp) I think it's always channel 1 red + and channel 2 red - (the banana jack tab is on channel 2 red). Someone correct me if I'm wrong again.
     
  10. ganttbos

    ganttbos The Professor Supporting Member

    Dec 18, 2001
    New Orleans area
    I just read the other thread about the QSC RMX 1450 and an Acme 410 cab and Chuco58 and Bob Lee were just now addressing the same speakon issue there.
     
  11. bben

    bben

    Feb 28, 2002
    Santa Fe, NM
    FWIW, I much preferred the sound of my QSCPLX1602 with the clip limiters and low-frequency filters switched off.

    I also used banana plugs for hooking speaker cables to the amp. I think there is too much potential for trouble using Speakons, where you need different cables for bridged and non-bridged and the only way you can tell which is which is by the label. Too easy to grab the wrong cable when you're in a hurry or if the label falls off. With banana plugs you can see exactly how things are hooked up.
     
  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
    Hi Big,

    I wrote and illustrated the PLX manual, so its strengths and weaknesses are my doing. ;)

    1. Stereo if you want to put up to 700W into your cabinet. Parallel if you also want to be able to easily add another cabinet on the other channel. Bridged mono if you feel safe putting up to 2400W into your cabinet, but I think that might be a bit much.

    2. If you play a 5- or 6-string, turn the filter off (low B is 30.8 Hz). If you play a 4-string, either 30 Hz or turn the filter off.

    3. On.

    4. If you're running the amp in stereo or parallel, pick a channel. In bridged mono, use channel 1. Use either XLR or 1/4"--whatever is convenient.

    5. In stereo: whatever you chose in #4. In parallel: pick a channel. In bridged mono, use the outputs that are labeled for bridged: the two red binding posts, or pins 1+ and 2+ of the upper Speakon output.

    1. Parallel, unless your preamp has stereo outputs for some sort of effects.

    2. Same as #2 above.

    3. On.

    4. With the inputs in parallel, it doesn't matter which one you use. Use XLR or 1/4".

    5. One cabinet on channel 1, the other on 2.

    That should do you well. Enjoy! E-mail me or post another message if you have any questions or concerns.

    Later today I'm heading to the Audio Engineering Society convention, which runs through Tuesday, so I might not get to my e-mail or this Web site during that time.
     
  13. Thanks Mr. Lee.
    You are a fine gentleman. QSC is lucky to have you. A credit to your profession. (not sucking up here, just tellin' it like it is)

    And BTW, your manual is pretty clear. I'm one of those people who have to read things over many times to get a real understanding. I also have a phobia about pluggin' stuff in wrong :eek: I shutter to think of actually blowing something up or getting knocked on my aging rear end. Not to mention having to replace some expensive equipment for lack of understanding it. I really should take some elementary classes on electronics. Recommend and entry level books?
     
  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
    You can call me Bob; I tend to think of "Mr. Lee" as my dad. ;)

    Here are a couple good books for getting through the newbie stage (don't fret; even the experts were newbies at one time):

    Audio Made Easy by Ira White

    Live Sound for Musicians by Rudy Trubitt (former sound reinforcement editor for Mix magazine)

    Both are published by Hal Leonard Publishing (www.halleonard.com), and are available in bookstores, music stores, Amazon, etc.
     
  15. Cheers
    I'll put them on my Christmas list.

    HAGW

    :D
     
  16. chucko58

    chucko58

    Jan 17, 2002
    Silicon Valley, CA, USA
    I paid for all my gear myself. Well, me and MasterCard.
    Just curious, why do you suggest leaving the high-pass filter switched off for 5 string?

    I leave mine set to 30 Hz for use with my Acme Low B-2 cabs. Most ported cabs suffer a huge increase in cone travel below the cabinet resonance, so wouldn't the filter help prevent such abuse?

    Have a good time at AES!
     
  17. bikeplate

    bikeplate Supporting Member

    Jun 7, 2001
    Upstate NY
    Hi!

    Bob, how about one 8 ohm cab? I have the same exact setup as the person who started the thread. I sometimes use and additional 8 ohm cab. Should I just chain them together in this case? Thanx for all the good advice

    Rob
     
  18. Does anybody else get "buzzing" sound from their PLX amp while it's sitting on top of their cabs? It only happens when certain frequencies or tones are going on with fairly high volumne.

    I know top of a cab is not ideal due the obvious vibration at certain times. My questioning is based on maybe something is lose inside and I should have it checked....or this is normal for such a light amp etc....

    THanks
     
  19. Yes. When I first got my 2402, I noticed the same problem. Upon cracking it open, what I found was that the main circuit board was vibrating on the plastic standoffs attached to the case, but just on one side. I remedied this by inserting some standoffs between the side of the circuit board and the case.

    I didn't notice this problem when I got my 1602. But now the 1602 is my bass rig amp and the 2402 is our PA sub amp, so the 2402's not being vibrated.

    I would think QSC could take care of this at the factory.
     
  20. Help me out here.
    What are stand offs and were do I get them?

    Bob Lee - any comments on this??
    Maybe QSC can send me some. I just got it I hate to send it in already....thanks.