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Rig setup and Help

Discussion in 'Amps and Cabs [BG]' started by DougP, Jun 10, 2004.

  1. DougP


    Sep 4, 2001
    OK so what am i doing wrong?

    i just tried my new amp rig out at practice and it wasnt as loud as i expected. Here is the setup:

    Bass > Ampeg SVP-CL pre > Behringer 2600 MDX Compressor (Using both channels) > QSC RMX 1450 > Peavey 4x10 8 Ohm cabinet.

    All connections were made using regular guitar cords except the connection to the cabinet whihc was a Speakon to TRS adapter cord.

    By the specs, this should have given me 280 Watts into the 8 Ohm cabinet, which is rated to 350 W. Last night i ran all the volumes and gains maxed out on 10 (including both output knobs on the compressor) and had just enough power to be heard in a two guitar band. Normally when i practice there i use the "house amp" which is an old Crate 200 W head with the same cabinet. When i use the Crate i only need to get the gain to about the 11 oclock position and the volume is only half way before i begin to over power the other players.

    Here are the settings i had on the back of the amp:
    Clip Limiter On
    Filter On set to 30Hz
    Parallel Inputs
    Bridging Off

    I turned the Clip Limiter Off for a bit and barely got any clipping (according to the front light) while playing very hard just to test it.

    I feel that it is obviously me doing something wrong, since this is the first time i have had attempted use a seperate amp and pre-amp style rig. Am i just expecting too much from the ratings of QSC?

    As always Help is gretly appreciated.
  2. DaveDeVille

    DaveDeVille ... you talkin' to me ?? Supporting Member

    i'm new to the pre/power amp set-up myself , but i was wondering if the Peavey cab is rated to 30hz. ?

    my RMX2450 is set the same as yours, except i've got mine set on the 50hz. rating and it sounds great . give it a try...
    Bob Lee could probably help with this problem . :bassist:
  3. DougP


    Sep 4, 2001
    i dont know what the Cab is rated to, its rather old. i play a six string and just didnt want to be limited by the 50hz filter, so i left it at 30 hz (maybe i am in error with this judgement, i dont know).

    Yeah, i am hoping Bob Lee will pop in and provide me with some enlightenment. Otherwise, i will post this on the QSC site, to get some feedback from there.
  4. With one 8 ohm cabinet you should bridge your QSC to get the most power from it.Don't be afraid of overpowering the Peavey,just get it up to the volume you need to blend in and hear yourself.You'll have much more muscle and will be using the QSC closer to what it will really do.
  5. DougP


    Sep 4, 2001
    what kind of cabling do i need for doing that? i had thought about it, but was concerned i would be doing something wrong.

    and all i would need to do with the amp, would be to set it in bridge mode on, right?

    the amp only has the speakon and binding post outputs, and the cabinet only has the 1/4" input.
  6. Eric Moesle

    Eric Moesle

    Sep 21, 2001
    Columbus OH
    I agree, you should bridge the power amp, you're cab will be fine so long as you don't clip the signal. I would also recommend disconnecting the behringer compressor until you have your volume issues solved.

    The back of your QSC shoudl specify the wiring for the speakon connector when bridging. Just open up your speakon connector and rewire the 1- to the the 2+ for bridged operation with the QSC. Leave the other end to the cabinet alone.
  7. DougP


    Sep 4, 2001
    unfortunately, its not my cable to be modifying. i was borrowing it. i am currently saving to get some cabinets with speak on connections.

    i had the compressor turned off at one point, but not entirely removed out of the signal path.

    but going back to my original line of thinking, shouldnt the one channel of the 1450 be as loud, if not louder than the head that i had been using previously?

    Please excuse any ignorance which i may be exhibiting here.
  8. GrooveSlave


    Mar 20, 2003
    Dallas, TX
    Have you tried it without the compressor?

    Personally, I just removed mine from my rack to use in my studio and I like my sound a lot better. Granted, you have to be careful when digging in, but all in all, it sounds better to me.

    Depending on where you have the threshold and ratio settings, you could be squashing your volume before it even gets to the power amp. FWIW.
  9. Eric Moesle

    Eric Moesle

    Sep 21, 2001
    Columbus OH
    1. An internal speakon connection can be switched back and forth in a matter of minutes, its easy as it gets, and causes no damage to the cable or the connector. Switch it, then switch it back before you return it to your friend.

    2. Whether you are getting the full power from the QSC depends on whether your preamp is outputting enough voltage. Remember, these things are designed as PA power amps, and some bass preamps simply don't have enough output voltage to run the QSC at full power. There is a simple and cheap mod you can get done to the QSC to remedy this, at any authorized repair center.
  10. DougP


    Sep 4, 2001
    1. Ok, i will look into it.

    2. VERY INTERESTING...i will look into that also. I have looked around on Ampegs site for the output specs, but didnt see anything for the SVP-CL. Do you have a ballpark price figure that i could expect this to cost?

    Thanks for all the input...
  11. Just one thing you should do...

    Guitar cables aren't designed for a pre signal, I don't know exactly but the impedance of a guitar cable is either too high or too low for connecting a pre and a power amp, if the cable is too long it will weaken the signal also, you should get some 1,5/2 meter patch cable suitable for that connection.

    my two cents I hope it helps ;)
  12. DougP


    Sep 4, 2001
    Would XLR work? i will most likely eliminate the compressor altogether, since the pre by itself sounds so good.
  13. I play a SansAmp RBI through a PLX 3402, which has the highest input voltage requirement of the PLX series (1.9 V rms @ 4 ohms). You should be able to drive your RMX with your Ampeg just fine (RMX 1450 is 1.15 V rms). What are your settings on your compressor and where is it in your chain? If it's not in your effects loop of your preamp, it's in the wrong place. If you are really going bass, pre, comp, power amp, then you're compressing the output signal of your preamp before it goes to the power amp, giving the power amp less of a signal.

    1. Unplug your compressor from the chain completely right now, go bass, pre, power amp. See if this helps your volume issues. If yes, continue reading...if No, you've got a preamp problem...possible bad tubes or bad patch cable between pre and power amp.

    2. Put your compressor back in the fx loop...only use one channel for now. Set the comp input gain to clip, then roll it back, then set your output make-up gain fairly loud. You should now be able to crank the output of your pre before the power amp.

    3. Making a bridged speakon cable is pretty easy. If there's two wires (black and white) in the insulation (typical) then you just need to pull the speakon connector apart, put the white into 1+ (which it should already be) and put the black into 2+ (it should be in 1- right now).

    4. If you're running both channels of the compressor into the parallel-set power amp, (with two cables) then you aren't getting both signals. When you run parallel, only input 1 on the power amp is amplified. The signal to input 1 is fed to both sides of the amplifier. Running a stereo signal (both channels of your comp) into a parallel power amp will really mess up your signal.

    5. 30Hz filter is perfect for all basses. David Meisner is rolling off all his notes below about a G. The 50hz filter is perfect when running these power amps for midrange in a modular system.

    final note: If you're using the compressor as a channel 1 comp and a channel 2 limiter, put the comp in the fx loop, and try the limiter channel after the preamp...just make sure your input and output gains on the compressor are up so you're not reducing the preamp signal needlessly.
  14. Not 100% sure but shoul work also if you have xlr outputs in the pre and xlr inputs in the power stage. With all the cable thing just remember this, keep it as short as possible and make sure you are ussing the proper stuff.

    I had no idea of how these factors can get your tone/volume ruined, but sure they do.
  15. DougP


    Sep 4, 2001
    The preamp doesnt have an FX loop, thats why i am running it the way i am. from what i am reading then, by turning the the compressor off and leaving it in the chain it will still hinder the output from the preamp? and i am using the compressor with both channels by running the output of ch1 into the input of ch2.

    at the time that i write this, it seems that the answer is to remove the compressor from the rack and run an XLR cable from the pre to the power amp. If that still isnt enough juice then i need to get a signal booster in between the pre and the power amp and/or consider bridging the power amp.

    further thoughts?
  16. Since a compressor is to tame your bass signal, you could always put it ahead of your preamp. But then you need to be careful of clipping the input of your pre. You don't have to run an xlr if you don't want to. I use mine with a little 1' patch cord I got at Guitar Center. It's a nice braided Dimarzio one ;) . I've never really had a problem running instrument cables in my rack, they're just 'shielded' from external interference. I've never had impedence issues.

    You said you had both output gains cranked on your compressor, and went from Channel 1 to Channel 2 on it, so Channel 2 was getting a super hot input signal. That may be a problem. You may have been really clipping Channel 2.
  17. DougP


    Sep 4, 2001
    when i turned the compressor off, i had to turn off the Pad button on the pre to make up for the loss in volume. so i really wonder if it is the compressor causing all of this.
  18. DaveDeVille

    DaveDeVille ... you talkin' to me ?? Supporting Member

    is that a bad thing ??
    i set my RMX according to QSC manual :
    " match the setting of the low frequency rating of your speakers . the 50hz. filter works well with most compact full-range speakers...the 30hz. filter is intended for subwoofers and large full-range cabinets ".
    { my cabinets are Avatar CB series and are rated down to 50hz.} :confused:
  19. "i am using the compressor with both channels by running the output of ch1 into the input of ch2."

    why?? I would guess this is your problem. Just use one side of the compressor if your going to run it inline.

    I run the same compressor into a QSC RMX 850 (sansamp bddi box into the 2600 then into the 850) and the thing is loud as s**t..... I can't even stand in front of it.
  20. Sorry, I didn't RTFM when it came to the filters. I just wanted to limit the ultra-low subsonic frequencies. This is definitely a speaker protection feature, but it has come up numerous times with QSC users. When the E is around 41 hz, why would you want to filter above that? There's two sides to every argument.

    Personally, I have a 30hz tuned cabinet, so the 30 hz filter works great for me, and satisfies all my issues.