Compressor Ratio and Threshold

Discussion in 'Compressors / Limiters (analog)' started by Shacke, Feb 22, 2003.

  1. Shacke

    Shacke Guest

    Help! I just bought a Focusrite compressor/preamp and would like to know how to set the compressor ratios, e.g. 2:1, 4:1, etc I keep hearing about, as there's nothing in the manual covering this. I'm new to using a compressor and always assumed that these ratios were all set button/ knobs on a compressor unit.

    Also, is there any rule of thumb as to what level to set the threshold at?
  2. Kingpin

    Kingpin Guest

    Read this if you havent already:
    (Dead Link Removed)
  3. Shacke

    Shacke Guest

    Thanks for the link which was very enlightening. The confusion still is that again the article mentions compressor setting ratios to use, however it doesnt' say how.

    Is it simply a case that when you say you use a 2:1 ratio as opposed to a 5:1, it simply means set your threshold close to the loudest sound in the former as further from it in the latter. Or is it just that the compressor I have bought does not have the 2:1, 3:1, etc which exists on other units?
  4. Kurt Foster

    Kurt Foster Distinguished Member

    77 Sunset Lane.
    It would help if you would tell us what unit you have and what controls it has and what legends are screened on the front?.. I suspect you may have a unit that has the ratio and release and attacks all "pre set" and therefore not adjustable. It may be a preamp with a clip limiter inline to prevent overloading of the digital inputs. If that's the case the ratio is probably preset at 10:1 and the attack and release is probably pretty fast.

    On a compressor with a full set of controls, there is usually a
    (1) Ratio control that goes from 1:1 up to 10:1 or higher,
    (2) Attack control
    (3) Release control
    (4) Gain control to make up any gain that my be lost in compression.

    To set the compressor one would;
    (1) Decide on a compression ratio, 2:1 or 4:1 being a good start.
    (2) Dial in the amount of gain reduction with the threshold control somewhere between 1 or 2 dB to 6dB maximum. Switch the meter selector to “reduction” to view the amount of gain reduction being applied.
    (3)Set the attack and release for fast.
    (4)Adjust the output to match the input before compression (gain make up).

    This is a rule of thumb example and by no means is it set in stone that this is the only way to set up a compressor but in most cases this will work acceptably. It is a very conservative approach to compression. Higher ratios and more gain reduction 8:1 with 8 to 10 dB reduction for example are considered to be a more “radical” or “aggressive” compression setting. Anytime a ratio of more that 10:1 is used, it is generally thought of as limiting rather than compressing. Fats
    Tannoy, Dynaudio, Blue Sky, JBL, Earthworks, Westlake, NS 10's :D , Genelec, Hafler, KRK, and PMC
    Those are good. …………………….. Pick one.
  5. Shacke

    Shacke Guest

    It is a Voicemaster Pro and has an optical compressor with knobs for Threshold, Release, Gain Reduction, Slow Attack, Hard Ratio, Makeup Gain. There is no ratio control that I can see, except maybe one of those other knobs is the ratio control.
  6. Doug Milton

    Doug Milton Active Member

    I went to the focusrite web site and looked at their info on the Voicemaster Pro. It’s pretty disappointing. After opening the PDF, all it had to say about the ratio was “do not use the hard ratio switch if you want to maintain some of the original dynamics.”

    So you’re right it doesn’t allow you to choose your ratio. Rather, the ratios are fixed via soft / hard button. Hopefully the manual is a little more detailed. It should tell you somewhere what those fixed ratios are. If not, email focusrite tech support and ask. My guess is that the “soft” is a 2/1 or 4/1 ratio with hard being an 8/1 or greater “peak limiter” ratio.
  7. Shacke

    Shacke Guest

    The manual say that the ratio is 2.5:1 (without hard ratio button slected) and 6:1 (with hard ratio button selected). I have enailed their tech support yesterday, but guess I have to wait till Monday for a response.

    Does this mean that I only have a choice of 2.5:1 and 6:1? I wasn't intending to record vocals at any higher than 2:1, so I hope i'm not stumped here.
  8. Doug Milton

    Doug Milton Active Member

    It sure sounds like they have selected the ratios and you have no way to change them. It will be interesting to see what tech support says. Please let us know….
  9. millionvalve

    millionvalve Guest


    Wow! With all of the stuff on that Voicemaster, you'd think they'd give you a little more control over your attack and ratio!

    Of the 4 compressors I've used in the very recent past (dbx 286A, Symetrix 501, Joemeek VC1Qcs, RNC (Really Nice Compressor) the RNC is my favorite. In my opinion it sounds the best, and is really versatile with its two compression modes.

    Oh, and it costs $175 including shipping. Leaves a lot for a nice mic pre, huh?

    BTW, did you get the Focusrite in the Baby Bottle Bundle?

  10. Shacke

    Shacke Guest

    I'll keep you posted on the feednack from Tech Support.

    The Focusrite Platinum series (of which the Voicemaster Pro is one)supposedly have very good Class A mic pre-amp built-in, which was the attraction. I have however been doing some checking up and find that they have a unit called the Penta which not only has presets but these are tweakable asper all the parameters. I guess if Tech support can't come back with anything favourable, i'll look into the other ones you mentioned.

    No I didn't get the Baby Bottle Bundle, I think that's only shipping in the US, i'm in London.

    I'll keep you posted.
  11. Kurt Foster

    Kurt Foster Distinguished Member

    77 Sunset Lane.
    OK, Focusrite Platinum. This is an all in one piece aimed at the home studio market. It has a fixed ratio for the compressors as has been stated. The mic pre is supposed to be “class A” but reports have been that there's nothing to write home about. These are reportedly the same pres that are in the 001, 002 and the big mic pre, control surface thing Digi-bastards puts out.

    This is my big gripe. Equipment and marketing plans to appeal to the "novice" that set expectations that their latest piece of budget gear is gonna put them in the ball park with the big boys.

    First, let me say that nothing precedes talent. If there is talent to be recorded, it's the easiest thing to do. Just hit record. Barring any unforeseen disaster, overs or cord shorting you should be fine. That being said …..,

    IMO, there is no way to get a world class sound from cheap gear. Some cheap gear is better and/or sounds better than other cheap gear but in the end it is all cheap gear. If you want it to sound like it came into the DAW through a Neve, get a Neve. No way around it. If you want the best compression, go get a Manley, a LA2a or 1178. There are others but you get the meaning. The Focusrite should be fine. Just don’t expect it to give you a sound like a LA2a. BTW, even a LA2a has a fixed ratio and release. 2 knobs, “reduction” and “gain”. There is not that much difference between 2.5:1 and 2:1. I suspect that the silk screening inaccuracies on many pieces would lead one to set a slightly higher or lower ratio than one would think they were. Try 2.5:1 with just 2dB to 6dB of reduction… This should work fine. ….. Fats
    Tannoy, Dynaudio, Blue Sky, JBL, Earthworks, Westlake, NS 10's :D , Genelec, Hafler, KRK, and PMC
    Those are good. …………………….. Pick one.

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