Hiss problem with dbx 166xl compressor

Discussion in 'Effects [BG]' started by Inseam, Jun 30, 2005.

  1. Inseam


    Jun 17, 2004
    Pittsburgh, PA
    I recently added a dbx 166xl to my setup, and it seems to add a lot of hiss to the signal. Is this normal? I was just using a pedal limiter before, so I'm not savvy on rack compressors. But when I hit the bypass switch on the compressor, everything is nice and quiet. Turn bypass off, and there's the hiss. Not a big deal when I'm playing at volume, but I hate the idea of adding noise to my signal. I love the compressor otherwise.

    I have the gate off, and I have moderate compression settings, nothing radical. Output gain at +8 or 10 to match gain reduction, limiter off (I think, I'm not at home right now), using soft knee compression. Am I doing something wrong?

    My path: bass -> eq pedal -> sansamp psa -> 166xl (in effects loop of sansamp) -> power amp -> cab. No hiss problems before when I had a limiter pedal after the eq pedal and nothing in the sansamp effects loop.
  2. fretlessrock

    fretlessrock Supporting Member

    Aug 8, 2002
    What is happening is that you are boosting the noise level with the make-up volume on the compressor. When the comp isn't compressing (gain reduction) you still have that amplification stage pumping your signal up the 8 or 10dB or whatever you have it at. Depending on how you have the EQ and PSA set you could be boosting some high end and then amplifying it further with the comp.

    I'd start from scratch, backing off of the make up gain, and maybe tweaking the gate a little to knock down the gain when the signal is idling.

    The thing about compressors is that there are no basic settings. It all depends on the incoming levels and what you are driving on the output side. So 8-10dB of make up might just be way too much if you are getting a lot of gain on the input with the EQ and PSA.

    What are you trying to accomplish with the compressor? That would help as a starting point for setting the comp correctly.
  3. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    I have a dbx 266 and it's as quiet as the straight signal. What are your settings on your compressor? I generally set the threshold at -10db, the ratio at 2:1 (sometimes as much as 4:1 but never any more than that), attack at 10 o'clock, and release at 2 o'clock, and I match the output gain to the straight signal. From what you're saying it sounds like you're overcompressing. If you can hear it working, you've got too much on it. Compressors do tend to get noisy if you overcompress (and many of them are just plain noisy no matter what you do).
  4. dadodetres


    Dec 19, 2004
    why dont you use the gate for reducing this problem?

    if even with the gate on you hear the HISS, means that the hiss comes frome after the dbx
  5. Inseam


    Jun 17, 2004
    Pittsburgh, PA
    Thanks for the input. Here's more info to answer the questions you raised.

    I use the compressor mainly to even out the signal, so that occasional loud or soft notes don't stand out so much. A lesser reason is speaker protection, I'm usually running the cab close to its volume limits, but mainly I'm trying to tighten up the sound. I don't use the gate because I use a long decay on certain notes in certain songs and don't want a gate cutting off the note. I could set a low gate threshold to cut hiss between songs, but I don't care about that so much. I'm more concerned about using the compressor properly when I'm playing.

    I'm looking at a pic of the compressor online and going from memory, but my settings are approx.: threshold -15 (maybe a bit lower, not sure), ratio 3:1-ish, attack about 10:00 (slightly fast), release about 2:00 (slightly slow), and output gain at +8 or 10, which I set based on the gain reduction lights.

    Is that threshold too low? I'll have to play with that setting.