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PLX-1804 Parallel

Discussion in 'Amps and Cabs [BG]' started by Growly Lytes, Nov 20, 2010.


  1. Growly Lytes

    Growly Lytes

    Dec 4, 2009
    Downunder Oz
    Bass player
    Just an easy question for a couple of PLX-1804 users....
    Do any of you jumper channels 1 & 2 to get the same signal coming out of both speaker outputs without a Y-Cable ?
    If im correct after you send the mono signal to input 1 you can then use a jumper cable from the unused channel 1 to any of the channel 2 inputs giving a parallel signal out of both speaker outs , is this possible ?
    Thanks TB.
    Growly
     
  2. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Yes. RTFM...:cool:
     
    BassmanPaul likes this.
  3. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    .
     
  4. Growly Lytes

    Growly Lytes

    Dec 4, 2009
    Downunder Oz
    Bass player
    Thanks
     
  5. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Just make sure to use balanced connections for the 1-->2 cable if you used a balanced one for the preamp--> 1 cable and you want to keep everything balanced.
     
  6. Lowtonejoe

    Lowtonejoe Supporting Member

    Jul 3, 2004
    Pasco, WA
    Does this help?


    QSCPLX1804Inputs.



    :D

    Joe.
     
  7. Growly Lytes

    Growly Lytes

    Dec 4, 2009
    Downunder Oz
    Bass player
    For Gods Sake, i should have RTFM.
    Sorry fellas.Well that means only one thing that im going to get that mother of an amp.I havent heard one bad thing about it. I cant test it so ive got my fingers crossed that it goes good with my cabinets because they are rated higher than the amp.
    My two quads are 800watt @ 8ohm & the amp puts out only 600watts @ 8ohm ??
    Are any of you powering cabinets that are rated higher than you amp ?
     
  8. Munjibunga

    Munjibunga Retired Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    600 watts per side = 1,200 watts at 8 ohms. I doubt your cabs would actually handle 800 watts without breaking up. If you're cranking out 600 watts into each of your cabs, I hope you're protecting your hearing. Right now, in my practice room, I'm powering a Berg AE212 (600 watts) and an Eden D-210XST (500 watts) with my little Eden WTX-500, which is giving them a total of 280 watts (due to 8-ohm load ... speakers in series), and it is still very loud at below noon on both gain and volume.

    Trust me. It won't be a problem.
     
  9. David1234

    David1234

    Jun 1, 2004
    Sydney, Australia
    Endorsing Artist: SWR Amplifiers
    ... "only" 600 watts per side.

    I think you'll get by!
     
  10. Munjibunga

    Munjibunga Retired Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    Why don't you want to use a Y cable?
     
  11. Growly Lytes

    Growly Lytes

    Dec 4, 2009
    Downunder Oz
    Bass player
    I actaully would love it if it had a switch just for ease of things & i dont want to pay that much extra for the PLX-3102 just for a switch.Having a jumper cable or a Y-Cable isnt much.I thought maybe that a Y-Cable might degrade the sound by introducing hum or buzz so thats the main reason why i think this i dont know really ?? Ive read that a heap of Tb`ers use Y-Cables into amps that dont have parallel switches & it works fine.
    About the watts i quess QSC when they say 600watts a side they mean the real watts.600watts should be enough to power 800watt cab & as you said Munjibunga i dont think the speakers would go that high even though the cabs have 4 BP102 speakers.
    Thanks again guys for the reply.
    G.L
     
  12. monroe55

    monroe55

    Mar 17, 2009
    What other options are there than doing this, besides the Y cable? Using 2 preamps one for each channel?
     
  13. Lowtonejoe

    Lowtonejoe Supporting Member

    Jul 3, 2004
    Pasco, WA
    Sure,
    you could use 2 preamps but unless you are going stereo or biamping (using x-over) that would be spending way more cash than just using a jumper or y-cable.

    The cable run is so incredibly short that any increase in noise would be totally negligible if not balanced and pretty much nonexistent if balanced.

    :D

    Joe.
     
  14. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    One very valid reason for not wanting to do that is that it'll half the input impedance of the amp. Often times not a big deal, but with something like an Alembic F2B it could be a deal breaker.
     
  15. Lowtonejoe

    Lowtonejoe Supporting Member

    Jul 3, 2004
    Pasco, WA
    Sheesh!

    Smart guys! :rollno:

    :bag:

    :p

    :D

    Joe.
     
  16. Growly Lytes

    Growly Lytes

    Dec 4, 2009
    Downunder Oz
    Bass player

    So if i get a Y-Cable the amp will reduce the input impendence ? I use two 8ohm cabs so what would be the rms be for each channel if im using a Y-Cable ?
    Then if i jumper the inputs doesnt the same thing happen as using a Y-Cable.
    This is getting more complicated now.
    If i use a Y-Cable or jumper the inputs using 8ohm cabs will the amp still put out 600watts a channel @ 8ohm ?
     
  17. mikeddd

    mikeddd

    Nov 12, 2009
    San Antonio, TX
    This is actually a REALLY good question. I pride myself on understanding how all my equipment works. I own two QSC amps; a GX5 which you have to jumper the inputs to use both channels with one signal, and a PLX3602 which has a parallel inputs switch that "jumpers" for you. As far as I know (I have not opened up my QSC amps to look) the XLR and 1/4" inputs on QSC (and any amp for that matter) are hardwired parallel. I.E. the signal you present at either input is present in it's entirety, unbuffered, at the other input. Albiet the XLR input is balanced.

    Going by that logic, it IS THE SAME THING as using a Y-cable.

    BOB, please chime in and explain why using a Y-cable to feed both channels is different than running a jumper from one input to the other in a QSC amp without a parallel input switch. It would be good for everyone to settle this debate once and for all.
     
  18. Growly Lytes

    Growly Lytes

    Dec 4, 2009
    Downunder Oz
    Bass player
    Wow i guess you know where im going with this.God i hope Bob can help here.
    If using a Y-Cable is going to do something no-good like an input impendence mis-match i would rather do as the o/m says & jumper the inputs so nothing would change.
    I think by what you have said above... that maybe when connecting the inputs in parallel via a jumper cable & not a Y-Cable the input impedence will stay the same ?? I hope this is correct !
     
  19. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    The jumper cable from 1-->2 IS a Y-cable in terms of function, first off. Just a more convenient, cheaper one. Sorry if I didn't make that abundantly clear!

    Yes, the input impedance of the amp as seen by the preamp will be halved with either type of cabling. This has nothing to do with your cabs. If your preamp can drive the reduced input impedance of the amp you will still get whatever the power rating of the amp says. If not, you won't. As I mentioned, in some cases like the Alembic F2B and other tube preamps with their outputs fed directly from a common cathode circuit's plate this would matter, in the vast majority of others it will not.

    I guess I should also mention that my 1804 works very well indeed for me in bass applications, as well as in PA duty.;)
     
  20. Munjibunga

    Munjibunga Retired Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    Apparently the kids at QSC don't have any issues with the jumper, which you correctly identified as being topologically identical to a Y cable.
     

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