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When is a 'compressor' working

Discussion in 'Effects [BG]' started by vince a, Mar 13, 2014.

  1. vince a

    vince a

    Jun 13, 2006
    Modesto, CA
    I have three compressors: one built into an Eden WT-550 amp, one built into an Eden WTDI, and an EBS Multi-Comp.

    When I use any of the above, I "do not hear" the slightest bit of difference. I've used just about every possible setting of the compressor control knob, right along with all the other knobs (gain, volume, etc). Even turning the compressor to off - nothing!

    I've read that "if you don't hear the compressor - it's working!" I can't fathom that.

    Anyone have good answers that would help me out?
  2. vbchaos


    Sep 5, 2011
    Groningen, The Netherlands
    Uncompensated endorsing user: fEARful
    I know that in a slightly different way:

    A well set up compressor is in-audible

    But even that is only half of the truth, because you can use a compressor as sound-shaping unit - often done on snare-drums. An overloaded compressor would be audible; sounds like your amp is pumping the sound.

    Have a look at ovnilabs or contact bongomania - he is the compressor expert around
  3. bongomania

    bongomania Gold Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    It's a volume control, mostly. There can be other tone/shape effects, but the reason people say you can't hear it when it's working correctly is because at root it is just adjusting your volume.
  4. SirMjac28

    SirMjac28 Patiently Waiting For The Next British Invasion

    Aug 25, 2010
    The Great Midwest
    ^^^ perfect
  5. vince a

    vince a

    Jun 13, 2006
    Modesto, CA
    Awesome . . . I think I finally understand what a compressor is/does . . . thanks so much!
  6. vince a

    vince a

    Jun 13, 2006
    Modesto, CA
    Sorry, one last question . . . when someone says, 4:1 or 3:1 (etc) ratio . . . 4:1 what to what? I use the compressor in an Eden WTDI - one compressor knob. So what is 4, what is 1?
  7. Input level to output level in dB, if the input is over the threshold.
  8. ok, I'm old and hardheaded....


    So for every 4db the signal goes over the threshold it reduces it 1db????
  9. In a compressor, you have a threshold, like a volume limit. Everything under that threshold is unaffected. Once you go over that threshold, the compressor starts to reduce the volume of the signal. The ratio is how extremely the signal is compressed back down to the threshold level. The higher the ratio, the more extreme the compression. 1:1 would mean no compression at all. 4:1 is moderate compression. My MXR bass comp has 20:1 as it's maximum setting, that's pretty extreme. A limiter with an infinity:1 ratio would mean that no signal is ever allowed to go over the threshold.
  10. No, it would mean that if a signal is 4 dBs over the threshold, it would compress it down to 1 dB over the threshold. If the signal was 8dBs over the threshold, it would compress it down to 2 dBs over the threshold, etc.
  11. No.

    For every 4db over threshold at input, 1db comes out.

    That's why it's better to look at it as dynamic range control (because that's what it is) and not a "volume" control.

    It is VERY hard to use a compressor well - I say that after making my living for a period of time as a live engineer, also spending time in studios. I took years to learn how to use, not abuse, a compressor.

    That's why most amps with on board compressors make them somewhat idiot proof by limiting the controls.
  12. vince a

    vince a

    Jun 13, 2006
    Modesto, CA
    I think I'm even more hard-headed . . .

    On the Eden WTDI, I have a gain knob, a volume knob, and a compressor knob

    Gain knob - 0 to 10 . . . set at 11:00
    Volume knob - 0 to 10 . . . set at 1:00
    Compressor knob - 0 to 10 . . . set to where? Or is it a matter of listening? Guessing? Off permanently?
  13. bongomania

    bongomania Gold Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    Listening mainly. Consider it like adding salt to food.
  14. depalm

    depalm Gold Supporting Member

    Apr 22, 2004
    best advice
  15. I HATE built in compressors. This bit on the Eden WTDI THAT I found on the Interweb does a fairly good job of illustrating why:

    "The compressor has only one knob, and just like most other one-knob comps that are found in a typical amp head, there is no way for a user to tell exactly what the knob does. Yes it increases the compression, but so does turning up the input gain knob. You might reasonably expect the comp knob to control the ratio, since input gain can control the threshold, but even with the comp knob at maximum it seems to have a fairly low ratio. It's really best at unobtrusive light-to-medium smoothing. If you want hard peak limiting or a fattening effect, this is not the one for you. It will certainly provide more extreme squish if you turn up the gain and comp knobs, but the tone and action become dark and muddy at that point. The hotter your instrument signal, the more it gets squashed and muddied, and of course the noise floor gets boosted some as well. But at the light-medium range, it does a really good job of evening out your signal without harming the tone at all."