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What does a compressor do?

Discussion in 'Effects [BG]' started by LazyGecko, Nov 24, 2013.

  1. LazyGecko


    Nov 19, 2013
    I have been looking for effects to improve the quality of my bass tone and I find that the compressor seems like it might help but I'm not exactly sure how it works. All the videos I've seen are crappy demos with bad sound quality. So what would it do to my bass's tone??? I have a Fender P bass and a pretty good Peavey bass amp. How would a compressor help? I like to play anything from gospel to rock to lots of slap heavy music. Would a compressor improve my tone? The p bass leaves a lot to be desired when playing gospel and other genres like it. If a compressor won't help then does anyone know what will? I'm looking forward to blowing some cash this weekend
  2. The most basic thing a compressor does is to quiet down any input that is above a certain "threshold" level. I use mine very minimally to just control the volume and make my playing sound more even. Or you can go more extreme to shape your sound in different ways. I am by no means an expert, but this website has a lot of really good info that I read a couple of months ago when I was looking for a compressor.


    Read his FAQ
  3. enjoi1018

    enjoi1018 Supporting Member

    Apr 18, 2011
    Auburn, AL
  4. JimmyM


    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Best way to improve the quality of your tone is not through buying effects, but by working on what your hands are putting out. And my rule of effects is if I don't know what it does, I don't need it.
  5. Baird6869

    Baird6869 RIP Gord Downey. A True Canadian Icon. Supporting Member


    I use a compressor, but generally only need it for slap as I have a super heavy technique. I do leave it on for other songs, but just being lazy as I can control my peaks by changing my style/attack.
  6. It will do nothing to affect/effect you bass' tone. A really good compressor will be inaudible. They are automatic volume controls designed to control the loudest peaks of your playing. A polishing tool.

    Compressors are also used on entire mixes of records - especially for airplay. If you can make sure that the volume never exceeds the point of distortion (0db kids), you can turn up everything else. the overall sound gets louder = more exciting.

    The downside is that all of your finger noise and fret buzzing gets louder too. Also (I have found that) if you get excited and try to play louder, nothing happens. So you play like an idiot and break things.
  7. BFunk

    BFunk Moderator Staff Member Supporting Member

    A compressor will help with tone in some sense. Properly used a comp will provide a certain cohesiveness to your sound that works very well in the mix. But as others have already stated it will not make up for sloppy technique.
  8. therhodeo


    Feb 28, 2011
    Owasso OK
    Some comps do affect your tone and are intended to do so.
  9. Portphilia


    Jun 8, 2012
    Amen! "the sound is in my hands" - Jaco
  10. The comp I'm using combined with my heavy finger technique gives a good punch to my sound which I couldn't do without the comp.
  11. I'll buck the trend here...

    Technically, in reality, a compressor reduces the "dynamic range" of your basses signal. This means it decreases the difference in volume between the loudest and quietest parts.

    In practice, a nice compressor, set in a transparent fashion, though appears to add some pleasing, although subtle tonal qualities to your bass's sound: a slight fattening, a bit of warmth, and a more pliant note envelope, more apparent low end. It's subtle, but a good compressor is an amazing tone enhancing device.
  12. BFunk

    BFunk Moderator Staff Member Supporting Member

    Right, this is because compression reacts to the dynamic range of the signal. Since not all parts of the signal is equal in amplitude, some parts of the signal are more compressed than others. By then raising the overall signal the lower volume parts are louder relative to the loudest parts. Thus the signal sounds richer in harmonics.
  13. Violen

    Violen Instructor in the Vance/Rabbath Method Banned

    Apr 19, 2004
    Kansas City Metro Area
    Endorsing Artist: Conklin Guitars (Basses)
    So you get on a trampoline and you bounce and bounce and bounce and its fun.

    You take the trampoline inside and you do the same thing in your living room. You keep hitting your head on the ceiling. So you jump less and still hit it. Then less and you barely hit it but then you die from a concussion.

    You are the dynamic range of your bass, the ceiling is what a hard limit compressor does. A soft one would be more like a ceiling made out of jello.
  14. BFunk

    BFunk Moderator Staff Member Supporting Member

    I started to think more about what I posted above, and I think I may have a misconception here. A comp has a threshold detector. This detector receives a signal that exceeds the threshold. Once the detector trips, the compression is applied to the signal after a short delay defined by the attack time and stays on for a period of time defined by the release time. Compression is applied to the entire signal once it is above the threshold. i guess part of the misconception comes from not understanding how threshold detectors work. Do they work on instantaneous peaks or RMS? In other words how short is the signal duration before the threshold detector goes "Aha!!" I imagine this would have a pretty significant effect on how it detects bass input since the attack signal from bass can be 30 dB louder than the average and the fundamental and 1st harmonic can be so much louder than higher order harmonics. These differences are less apparent as the wave sustains and decays. Any thoughts on this?
  15. Baer


    Jul 8, 2008
    There is no delay associated with the attack time. The attack time is the interval over which compression is applied. At the start of the attack interval, there is no compression. By the end of the attack interval, compression is fully applied. Similarly, the release time is the interval over which compression is released.

    Compressors could trigger on instantaneous or RMS values. Depends on the design.

    To better understand the effect of a compressor on a signal, look at the following from the Reaper forum.


    If you search that forum for “compressor threshold release” you’ll actually find a lot of good info.
  16. BFunk

    BFunk Moderator Staff Member Supporting Member

    Ah, right, release time is how long it takes for the compression engine takes to stop compressing signals after the signal falls below the threshhold. Still, the images in the post looks like a look-ahead comp. That particular article talks about a particular software comp, where look ahead is possible. But analog comps, at least RMS triggered types need time to determine that the average signal is over the threshhold. I suppose that you could delete the detection time from the attack time settings. Say, for example the detection engine takes 4ms to to detect that the signal has crossed the threshhold. So setting the attack to 20ms actually sets the attack time to 20-4=16ms. I suppose that is why RMS detectors have a minimum attack time. Peak detectors must just have a really short detection time. So, again, how does the detector work? Is is some type of relay circuit?
  17. I'm wondering if a compressor will help balance the output on my 3-band Stingray 4. I have that annoying "dead string" syndrome on my D and G strings. If a compressor can help even out the sound, I might just invest in one...immediately.
  18. Basshappi


    Feb 12, 2007
    What does a compressor do?

    IMHO ruin your dynamics.
  19. shenanigans


    Sep 9, 2013
    From a Rane MC22 manual:

    I used to really not like compressors, and for most of my playing I still don't. But I have noticed that there are dynamic qualities to compressors that I can't replicates with my hands.

    I disagree with people that say it has no effect on your tone. Technically that is correct, but effectively they can have a great deal of effect on your tonal package, with varying results.
  20. Smooth_bass88

    Smooth_bass88 Groove it Supporting Member

    Oct 31, 2006