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GRRRRR.....Pre to Compressor to Power to Cab troubles!

Discussion in 'Amps and Cabs [BG]' started by James reeve5, Apr 11, 2003.


  1. I am running a Demeter Hbp1 into a DBX 160a into a QSC RMX 850 parralled into two Accugroove 110's (8 ohms each). The sound is the most amazing thing I have heard, but since it starts farting at such low levels, I think I am going to be the only one to ever hear it! I like alot of bass in my sound, but I don't think that it should be farting that quickly, and I am afraid for my two accugrooves. Do I need a higher output amp? Should I change the compressor setup? Should I run the speakers bridged mono? Is there a way of setting this up better so I can get a good bass sound without destroying my equipment?

    help!!!
     
  2. Although I wouldn't trust me to be the final authority on this subject, by my experience you might have better results using the DBX in the effects loop of your Demeter. It sounds as if you are overloading the inputs with signal from your preamp. Give that a shot!
     
  3. BruceWane

    BruceWane

    Oct 31, 2002
    Houston, TX
    Hold on there...........

    A compressor is not an effect; don't run it in the effects loop.

    You should run the compressor in front of the preamp, like this..........

    bass > compressor > preamp

    What you want to do is smooth the transient spikes out of your signal before you hit the preamp, thus allowing more headroom before clipping. What you're doing is BOOSTING the spikes, then trying to compress them.
     
  4. BruceWane

    BruceWane

    Oct 31, 2002
    Houston, TX
    Also, you'll get more out of that rig if you'll bridge the QSC and hook up the cabinets in parallel (daisy-chain) for a 4 ohm load.

    The QSC in stereo is 200 watts per channel at 8 ohms, versus 830 bridged into a 4 ohm load.
     
  5. ThunderStik

    ThunderStik Guest

    Jun 25, 2001
    Claremore OK.
    I agree with Bruce Wayne. I use the 160a and this is my chain. Bass-160a-Svp pro-Carvin dcm1500- Cabs. Also, you may want to brige the amp if possible and us the gain on the 160a to make sure your signal is up enough ( press the bypass and check signal level between comp and no comp).
     
  6. Hehe... like I said, I'm not the final authority on DBX. The DBXs I've used in the studio were all "line level" type that ran in conjunction with the console. Thanks for the correction.

    At least I got the "overloaded input" part of the equation correct. :rolleyes:
     
  7. Could you guys possible explain how you would go about plugging my bass into the 160a... and then getting that to the hbp1 then to the power amp...I am a bit confused.
     
  8. BruceWane

    BruceWane

    Oct 31, 2002
    Houston, TX
    Pretty simple.......

    Plug the cable from your bass into the 160's 1\4 inch input, then hook a cable from the 160's output to the input of your preamp, then preamp output to power amp input...........
     
  9. Flight Time

    Flight Time

    Aug 29, 2002
    Why shouldn't you go thru the effects loop?
     
  10. rockindoc

    rockindoc Daily Lama

    Jan 26, 2002
    Bonham, Tx
    I'm also wondering why not. Here's a quote from a Rane publication regarding their DC24 compressor.

    "If it's used as a comp/limiter for the input signal, it would go after the bass (if the bass has a line level output) and before the preamp. If it's to function as a limiter to protect the speakers, it would go after the preamp. Another method is to insert the compressor into the effects loop. This allows the signal to be affected by the preamp first, then by the comp/limiter, and then sent to the power amp. This can be desirable with tube preamps."

    I'm using my Rane in the effects loop, and it seems OK. I'm new to this compression thing, however, so I haven't explored the other options. Maybe someone can explain a few pros & cons of each method.
     
  11. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    James, I'm going to against the grain of this thread and suggest that maybe a total of 2 ten inch speakers may not be enough. It has been my experience that even high end cabs with 2 ten inch drivers can only get as loud as a drum kit if you wind off the bottom end. If you don't, they fart.

    Add a more speakers and that's when they start to sing. But you could only add speakers if the RMX go down to 2 ohms.

    My 2 cents.
     
  12. Schwinn

    Schwinn

    Dec 4, 2002
    Sarasota, FL
    It looks like there are 3 ways to run a compressor. I use mine AFTER the preamp and that works fine for me. This way, the noise gate on the compressor silences noise from the preamp, and the compressor works on my total signal output. I don't think this is a wrong way to use it, but I don't think your way is wrong either, just different.

    As for your problem James, I think Petebass is right on target, add more speakers. You might try running the 2 you have in one channel and running a 4x10 or a 2X12 in the other channel (stereo mode).
     
  13. Rack compressors usually should be behind the preamp, since they are made for line level signals and NOT mic/instrument levels, believe me.

    (If you have ever seen a channel strip you will notice that internally the compressor is always after the preamp, and btw putting it in the effects loop should be the same)
     
  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
    The effects loop is a good place to put the compressor. I think you probably need significantly more speaker surface area.
     
  15. I gave up folks...the thing is for sale...250$ shipped.
     
  16. 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
    What, the whole rig? Are you serious?
     
  17. haha...you wish...the compressor
     
  18. 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
    Why are you giving up on it? It's a good product.
     
  19. g4string

    g4string Supporting Member

    Sep 19, 2002
    Melissa, TX
    James,

    Way to go! I personaly feel that you do net need the compressor. I too have the Demeter HBP-1. However, I run mine through a QSC PLX-1602 and two Aggie GS112's. I don't think that the Demeter and QSC setup warrants a compressor. IMO it is just more "junk" that gets in the way of your bass and amp's true sound. I think maybe 12" speakers or a slightly more powerfull amp might help you on your quest for thump, not a compressor. Just my $.02.
     
  20. g4string

    g4string Supporting Member

    Sep 19, 2002
    Melissa, TX
    BTW, I run my QSC PLX-1602 bridged at 4 ohms and daisy chain the two Aggie 12" cabs. With my rig configured this way, I feel that I have plenty-o-thump.