Need helps setting up a F-1X and PLX 1602

Discussion in 'Amps and Cabs [BG]' started by rojo412, Aug 13, 2003.

  1. rojo412

    rojo412 MARK IT ZERO! Supporting Member

    Feb 26, 2000
    Cleveland, OH.
    I just received my QSC and now have a rig. But since I'm used to a regular head, I'm not 100% sure on what I should set what to.

    The QSC has filter switches in back... any suggestions on how to set them? Also, I'm bridging the amp to run 1100w into 8 ohms. I am using speakon (it came from my GK) and I disconnected 2 leads (black and yellow) so it would run the amp bridged. Is this correct?

    Any suggestions on settings for the F-1X? I am going for modern tone with a Status and haven't monkeyed with it too much yet. (I guess I need more monkey time)
  2. rojo412

    rojo412 MARK IT ZERO! Supporting Member

    Feb 26, 2000
    Cleveland, OH.
    Oh, almost forgot:

    Volume settings on the preamp and amp. Where should I be keeping them for optimum headroom, performance, etc?
  3. I've got an Alembic/QSC as well. Since the PLX does not have as much gain as other amps, you might need to crank up the Alembic volume and EQ a bit more than usual. The passive instrument input on the Alembic (on the left) will provide a few extra decibels.

    Here's what I suggest: set the EQ flat (9/3/9 o'clock bass/mid/treble, i.e. "<- -> <-"); set the PLX gain very low; play your bass with it's volume cranked. Turn up the volume on the Alembic until you hear distortion. Back it off a bit and keep it there FOREVER. Make volume adjustments on the bass and QSC/PLX only. This will maximize signal-to-noise ratio and give the QSC/PLX the strong signal it needs.

    Then adjust the EQ to suit your tastes, but do not roll off the mid EQ very much (again, the QSC/PLX needs a strong signal).

    Sorry about the long winded response...
  4. bben


    Feb 28, 2002
    Santa Fe, NM
    I thought my 1602 sounded better without any of the filter stuff on. Not world-shaking better, but some.

    Dunno about the colors on the GK cable, but probably not unless you have also moved one of the remaining two wires at the amp end.

    This is the one downside I see to Speakons - you can't tell when you have a specially configured cable for the QSC bridged mode.

    My advice: leave the GK cable alone, use it with GK amp/cab setups only. (The new GK manuals now say not to use that cable with anything but GK cabs, and to get a two-wire cable for other cabs. The last two GK cables I got (one with a 700 last year, one with a new-model 1001) are kind of cheesy anyway, with a not-very-good imitation Speakon instead of the real thing and with some of the wire clamps loose.)

    Get or make a two-connector Speakon cable, wired the way it says on page 11 of your QSC PLX owner's manual:

    1+ and 1- at the speaker end;

    1+ and 2+ at the amp end.

    Label the cable with a tag that says "QSC BRIDGED" and also clearly label the AMP and SPEAKER ends. Make damn sure you don't use that cable for anything else. Make damn sure you hook the speaker end to the speaker and the amp end to the amp.

    Alternatively, you can make a cable with a banana plug at the amp end and a normally wired (1+ 1-) Speakon at the amp end. Then there's no doubt which end is which, and you can see that you have properly plugged the banana plug into the amp in bridged mode. That's what I used to do.
  5. IvanMike

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

    Nov 10, 2002
    Middletown CT, USA
    biggest deal with the fix is it only has 1 full range output
    i use a high quality "y" cord to connect it to my stewart
    don't be scared to experiment a lot with the tone controls and the deep and bright switch
    the eq has lots of range and every time you turn a knob it affects the way the other ones work (hence passive/interactive)
    this setup will take you a lot longer to get used to than the typical active eq sections on a lot of amps, but in the end it's well worth it
  6. rojo412

    rojo412 MARK IT ZERO! Supporting Member

    Feb 26, 2000
    Cleveland, OH.
    Is anyone using a super-high output bass on their setup? I have a Status Graphite Empathy and it has monster output levels that usually require padding or rolling off the bass volume (which kills that tone, too). I'm not sure if this will drive the tube a bit hard or not. I'm also not even sure that the tube is still working well, I got this pre used. Any way to check? I get a lot of hiss when I switch the BRIGHT or DEEP switch on. Is it related?

    As for the cable, it's got 4 leads:
    Red, white, yellow, black.
    Yellow and black were in the "side" holes and white and red are in the "central" holes. This appeared to be what the online manual said to do. Is there a way to tell if the amp is working properly or not in this situation?

    And should the "Parallel" light be on on the amp?
    Oh... and is it okay to run these 2 things into a Furman and use the switch on that to turn on everything or does it need to be switched on 1 at a time?

    (edit) Reading deeper, I see that you meant that I should "Y" the high and low pass from the pre to power ch. 1? Or is it possible to send the high and low to the 1 and 2 then bridge the amp? Forgive the ignorance, I'm quite green on this bridging/ohm load/parallel/etc. stuff.
  7. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    The Republic of Texas
    I have a PLX1602 I run bridged into 4 ohms and I think mine sounds better with the filters and clip limiter both off. Keep an eye on your level lights, if you blip the clip light very often, turn the clip limiter back on (probably won't happen unless you're driving a very inefficient speaker really loud).

    The PLX's have a relatively high input sensitivity so I don't know if this will work or not, but if your bass has a really high output, try running it straight into your power amp. You might not need the preamp at all. If your bass has a good sound, you might like it better this way.

    P.S. A lot of hiss may indicate a microphonic tube in your pre.
  8. IvanMike

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

    Nov 10, 2002
    Middletown CT, USA
    1st i use the y to take the single output of the alembic to put it into both channels of my power amp
    never put 2 different signals into a y and put them into a power amp......bad deal
    the brite will cause hiss, so will the deep if the treble is over 6 (1 o clock)
    the amp should be able to handle the hi output, just put in in the right output
  9. rojo412

    rojo412 MARK IT ZERO! Supporting Member

    Feb 26, 2000
    Cleveland, OH.
    Wow... this is great insight and I truly, honestly appreciate it.

    I'm going to get a new tube asap. This one may not be that bad, but a new one will be new and I can afford it. I didn't know if maybe there is some sort of routine maintainence to do while I have the pre open... other than an air dust. I have pro gold too, should I spray out the pots and switches?

    I re-did the speakon to 1+2+ on the amp end, 1+1- on the speaker end and it works well. I am very eager to crank this thing, but I get home from work too late for the neighbors to NOT hate me for doing so.
  10. This is not really pertaining to the original question but something I found out. If you closely read the PLX Manual while Bridging or and single channel operation like Stereo you should have #4-5-6 selectors on the Stereo (to the left) for the best operation. That changes the input impedence. This does include Bridge Mode because even though the amp is combing both sides of the amp it is still utilizing only Channel One for input. So, if your in Bridge mode and want to use channel two for the signal to another amp then you would switch 4-5-6 be on the parallel side (to the right). I hope I explained that good enough. It will work either way for Bridge. I think QSC does not state it that way for confusion reasons, but it is supposed to be a better way to run the amp.

    I usually run mine in Paralled with two 8ohm cabs which on of the correct ways to run. When I bridge my bigger 4ohm cab I now run 4-5-6 in stereo and the number 7 of course in bridge. Channel two gain is off and the speaker wire from the back of the amp is Red=channel one + and Black= channel two +. I know this has been gone over a lot but I thought I put it all down anyway. If you use a Neutrik-Speakon connector in bridge make sure the amp end is wired like the Bananna, it would be using both positive + 1 and 2 connection inside that end.

    Bob-did I miss anything ?
  11. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    The Republic of Texas
    OK. I'm bridged with no filters and no CL, so here's my switch settings:
    01 left
    02 left
    03 right (position shouldn't matter?)
    04 left
    05 left
    06 left
    07 right
    08 right (position shouldn't matter?)
    09 left
    10 left

    Thanks, BS; I'll give that a go this weekend and see how it works.
  12. Hi Lo
    I didn't detect any difference in sound let me know if you do. Also it was recommmend that at least the clip limiters are left ON. Be Careful..
  13. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    The Republic of Texas
    OK. Thanks.

    When I get really loud, which is not very often, I keep an eye on the clip indicator lights, haven't seen them even flicker yet (those oodles of headroom watts doing their job).

  14. I keep hearing that from you and maybe a few others. I've got the 2402 and weather I bridge or go parallel I can usually always make the RED clip light flicker. True you get more head room with bridging, but I can still easily make the red blink if I slap or pop a low note. I only have my Demeter set on 9:00 never any higher than 11:00 depending on which bass I'm using. Now my PLX gain/gains are always all the way up, is that how you run yours? Maybe our loudness needs are different or what is loud to us may be different...

    I even set the internal trim on the Dem up to 3/4 so it would be cleaner like turning up a master volume and keeping the pre down...
  15. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    The Republic of Texas
    Probably, the main difference is I don't do slapping & popping live; the largest place I've played with this rig is maybe 200 person capacity; and I'm mostly playing in a Country & little bit of older Rock band (I am blessed with a lead player that I have to tell to turn up). So, the overall volume levels aren't very high and I don't use much bass boost with my SR5.

    Yeah, I run the PLX & my bass maxxed out and control the level with the Dem.
  16. You ARE Blessed my friend.
    My guitar player doesn't really play that loud but he stands next to me and the vocal monitor usually is enought to really hurt me. I think he's deaf. Anyway we have a six piece band with horns and keys too. Lot's of people and instruments going on. It's fairly loud Blues/Rock/RB stuff. It's funny our audiences love us for being not as loud as most bands because they can still talk without screaming (via Pa suppport) but the stage volumnes are usually too loud for me and the guitar player always complains he can't hear himself. :bawl:

    After five years with this group I finally talked him into setting his 15watt amp on a chair so he can hear his geeetar. I think we are just going to put him on one side of the stage all by himself. :D
  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
    That's correct. You're not going to hear any difference in the sound with them on or off, unless you clip the amp, in which case the clip limiter will reduce the amount of distortion (but only if it is engaged). Think of it as a safety backstop helping to protect your sound and your loudspeakers, just in case.
  18. Regarding the Alembic F1-X tube: it is not used for normal operation. The tube is used only for the effects loop and for the direct output.
  19. rojo412

    rojo412 MARK IT ZERO! Supporting Member

    Feb 26, 2000
    Cleveland, OH.
    Really? It's not like the SWR (or all other) tube operation? It plays NO part in the sound?
  20. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    The Republic of Texas
    I believe this is not correct. The F-1X preamp is based on the Fender Showman preamp circuitry (tube) which did not have an effects loop or DI.

    Not sure where you heard this, but you might want to check with a different source.

    Like this one.