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What will a compressor do to my sound?

Discussion in 'Effects [BG]' started by bas_anton, Jun 30, 2002.


  1. Please answer my question. By the way if I go for a compressor is the EBS Multicomp a good choice?
     
  2. slam

    slam Guest

    Mar 22, 2000
    Virginia
    Ive got an EBS MultiComp for sale. Let me know if you are interested.
     
  3. Bruce Lindfield

    Bruce Lindfield Unprofessional TalkBass Contributor Gold Supporting Member

    Suck all the life and dynamics out of it!! ;)
     
  4. A compressor is basically a variable gain device, where the amount of gain used depends on the level of the input. In this case, the gain will be reduced when the signal level is high which makes louder passages softer, reducing the dynamic range. A compressor's input/output relationship is often described by a simple graph (graphic compressors are barely made). The horizontal axis corresponds to the input signal level, and the vertical axis is the output level (both measured in decibels). A line at 45 degrees corresponds to a gain of one - any input level is mapped to exactly the same output level. The compressor changes the slope (makes it more horizontal) of that line above some value called the threshold (which is most often adjustable). The height of the line defines the dynamic range of the output, and the slope of that line is the same as the compressor's gain. The compressor weakens the input signal only when it is above the threshold value. Above that threshold, a change in the input level produces a smaller change in the output level. The compressor setting is usually stated as a ratio, such as 2:1, which means that the input level would have to increase by two decibels to create a one decibel increase in the output. With a 4:1 setting, the input would need to change by 4 dB for a 1 dB change in the output level, and so on. Limiting is simply an extreme form of compression where the input/output relationship become very flat (10:1 or higher). This places a hard limit on the signal level. the compressor makes loud signals quieter, but it does not make quiet sounds louder (although it may be perceived that way). However most compressors do have a secondary gain stage for adjusting the output level so that if you turn the compressor on while playing, the extra gain will prevent your instrument's volume level from dropping. You can make a case that this extra gain stage is or isn't really part of a compressor, but in any case, that is what makes the softer sounds louder. Now discussing exactly how the level detector in the compressor operates. It is usually some sort of time average of the input (often a root-mean-square (RMS) calculation). Alternatively, the instantaneous peak voltage or sample value can be used, in which case, the compressor becomes a hard limiter.

    When the level sensing function is a short time average, the compressor will take a little time before the gain is adjusted to meet the new input level. The amount of time the compressor takes to respond when the input level rises above the threshold is called the attack time, and is usually fairly short (under 100 ms.). When the input level is above the threshold and then drops below it, the compressor will take some time to increase the gain as well. This is the release time of the compressor, which is generally larger than the attack time (possibly up to a second or two). The effects of a compressor on a signal. Only the middle portion of the input is above the compressor's threshold. Note the overshoot when the signal level increases (it takes some time for the gain to decrease), and the attenuation when the input signal returns to the first level (and the gain increases). The release time is generally longer than the attack time.

    How is this useful for bass? You ask... As well as increasing clarity and response over the dynamic range of your playing and taking care of nasty peaks and valleys in a normal signal. This is very useful when it comes to protecting your gear from extreme peaks or lows that may lead to either clipping or cab damage. Used moderately they can also be useful for reducing feedback in rooms with poor acoustics. There are downsides to compression though, when you compress a signal you experience a loss in certian frequencies that are somewhat fundamental to the bass. Most common you'll experience a loss of highs and a genlte roll-off of extreme lowend, but is only notice when harsher limiting takes place... This can usually be fixed by adding an eq after the compressor, some compressors feature an enhancement circuit that recovers (or boosts) highs.
     



  5. Good advice, but do you have any skin left on your fingers after typing it? :D
     
  6. Callaces; another great part of being a bass player.:rolleyes:
     
  7. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    Smash it, squash it. Stuff like that.
     
  8. old_skool

    old_skool

    Aug 17, 2000
    Milwaukee, WI
    Ooooh...musnt...gah...IT WILL COMPRESS IT!

    Sorry, Im leaving, I promi...stop looking at me like that, BF.

    :D
     
  9. Bruce Lindfield

    Bruce Lindfield Unprofessional TalkBass Contributor Gold Supporting Member

    What I said - it sucks all the life out of your bass sound - especially if is a cheap pedal!! *


    (*Not necessarily applicable if we are talking subtle application of studio-quality gear - i.e. rack-mounted units costing 10s of thousands of $ and a huge mixing desk!)
     
  10. :rolleyes: ;) :p :D
    are you trying to wear out the ;) emoticon, Bruce?


    FWIW (ie. either a good or bad thing, depending on which way you see it) Billy Sheehan uses compression a lot.

    I use a bit of the dual-band compressor on my Trace Elliot amp to smooth things out a touch.
    the multi-band compression method (splitting the signal into different frequency bands and compressing them separately) is reputed to avoid loss of highs on bass guitar signals.

    I'm getting to grips with using the track compressor in Sonic Foundry Acid and Soundforge for compression in mixdown- the level meters seem to work in advance of the signal for some reason...
     
  11. Flatwound

    Flatwound Supporting Member

    Sep 9, 2000
    San Diego
    Bruce L. (supreme arguer) and I are at opposite poles on this one. A compressor is the single biggest improvement I have made in my sound (other than learning to play fingerstyle). Not only that, but a relatively even level to the board makes sound guys happy. If the sound guy sees big peaks in your levels, he just turns you down so that the peaks don't cause problems. Can you see where I'm going here?

    Also, as Bruce (sort of) pointed out, a compressor will change your sound; whether the change is subtle or dramatic depends on how you set the parameters.

    Bruce L., in my opinion, absolutely does not have to use a compressor if he doesn't want to. He is 100% entitled to his opinion. Realize, though, that many pros (the aforementioned Billy Sheehan, Peter "Mars" Cowling, Tony Senatore and many others) would disagree with his anti-compressor stance.

    I'm still learning to use mine, but I ain't going back- that's for sure.
     
  12. Bruce Lindfield

    Bruce Lindfield Unprofessional TalkBass Contributor Gold Supporting Member

    Well as I was trying to point out (with only 1 emoticon up to now - hardly wearing them out! :rolleyes: ) there is a world of difference between a pro using subtle, studio-quality compression and the sort of cheap pedals that guitarists (!) use!! Don't buy cheap pedals they suck.........all the life out of your sound! ;)
     
  13. TRU

    TRU

    Apr 12, 2002
    Northern Europe
  14. Flatwound

    Flatwound Supporting Member

    Sep 9, 2000
    San Diego
    I find myself in agreement with Bruce's last post. Cheap pedal compressors are generally not so great. The EBS, however, is not cheap, so I'm not saying you shouldn't use it. I haven't tried it, so I don't know if it's good or bad or what.
     
  15. I was pointing out you seem to use that emoticon in every post- is ;) the "patronising emoticon"?

    the "Simon Cowell of Talkbass" now, eh?

    I thought you'd be more the "you don't wanna do that" Harry Enfield character:p


    Steve Harris uses compression a lot too.
    (I think he uses a DBX rack-mount compressor)


    anyway, I think no-one should feel that they have to depend on any effect pedal all the time.
    I used to make this mistake when I always used to go through my Trace Elliot SMX dual compressor pedal (not a cheap guitar pedal, though), thinking that it was essential, for gigs, rehearsals, recording, even practice.

    I think that using a compressor when practising can hinder developing an even playing technique.

    what does everyone think about compression when recording?
    compress to tape/hard disk, or compress off tape/hard disk in mixdown?

    my opinion so far is that compression should only be applied on mixdown, so you can monitor the note volume and attack directly and adjust your technique accordingly when recording without any interference from an in-line compressor.

    also the method of compression (level, threshold, ratio etc.) can be judged more accurately in mixdown when you can see how the bass signal sits with the other instruments.
     
  16. Bruce Lindfield

    Bruce Lindfield Unprofessional TalkBass Contributor Gold Supporting Member

    I actually bought one of these things based on what I'd read in magazines etc. I hated it and couldn't sell it fast enough! It made everything muddy and indistinct no matter what settings and always added some noise - horrible!

    Fortunately lots of people buy things based only on reviews and I sold it quite easily for not much less than I paid! ;) (Is that more Simon Cowell?)

    PS I agree entirely that compression should only be added in mix-down when recording and that, to me is the only time you should [ever use it!! ;)
     
  17. CS

    CS

    Dec 11, 1999
    UK
    Where's JimK when you need him? ;) ;) ;) ;) ;)
     
  18. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    I put a dbx 1066 in my rack for a week or two, and it was interesting, but I just don't need it. So I took it back out.

    Not to hijack the thread, but has anybody tried the Aphex 204 and/or the Avalon U5? I know they do different things, but I was just curious.
     
  19. i use a boss limiter/enhancer as a compressor, and set it up pretty high. it compresses the sound a LOT, but makes just about EVERYTHING the same volume level, which works greatf or me. my lows are still deep, but my highs are crisp and clear, too.
    i value my compressor, but then i've modified my bass with a preamp and pickups that tend to push my higher notes a lot harder than my low notes, so i use a compressor to balance it all out. it gives me a much fuller bass sound, IMO.