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Compressor before preamp?

Discussion in 'Preamps & Processing' started by yodermr, Dec 21, 2003.

  1. yodermr

    yodermr Guest

    I have a Aardvark I/O and it has 4 inserts. I need to add another compressor but I have run out of inserts.

    Is there any problem in going from the mic to the compressor and then to the mic input? My best guess is that it puts the compressor before the preamp, just not sure of this is a problem.

    Thanks
    Mark
     
  2. Kurt Foster

    Kurt Foster Distinguished Member

    Joined:
    Jul 2, 2002
    Location:
    77 Sunset Lane.
    You could try it and if it works, ok but it's not how it is usually done. It is doubtful that the comp will even work well on a mic level signal. Comps usually require a line level source. I think the best solution is to get an outboard mic pre, go through that into the compressor and then into a line input on the Aardvark.. You can also try not compressing at alll and then applying compression and gain make up in the DAW.
     
  3. yodermr

    yodermr Guest

    Kurt
    Thanks for responding, maybe I could prod a little further.

    I would rather record without a compressor but I just want to protect my self from that nasty digital clip(recording drums). Maybe a limiter is more appropriate.

    I may merely need a quick lesson on how to set the input level for digital recording. It all seemed easier and more forgiving with tape. Hell I never owned a compressor or a limiter through 15 years and 3 analog recorders. My stuff sounded decent then.

    Maybe I'm just used to pushing the max and not worrying too much about clips. I used to run away from low signal with lots of hiss. Now that I have a clean digital system, I still have the same habbit but clipping is not forgiving.

    Thanks
    Mark
     
  4. Duardo

    Duardo Guest

    If you'd rather not record with a compressor, then don't. You've got enough dynamic range with the Aardvark converters that you can safely peak at -10dBFS or lower without worry. That should leave you plenty of headroom for the occasional errant peak. No need to push to the max, especially with even half-decent 24-bit converters.

    -Duardo
     
  5. jdier

    jdier Active Member

    Joined:
    Mar 20, 2003
    Location:
    Milwaukee
    Home Page:
    yod,

    You should just do some dry runs. I have been OK on drums with no clipping on my Q10 for some time now. Just run some tests, tell the drummer to play a little louder for the tests... You should be OK. Another choice you have is to run the mic into the Q10, then assign and out in the routing menu, take that out of the back into the compressor and then back into the front on another track... This method burns two tracks, but the nice thing is you get a clean (uncompressed) version as well as the compressed version. It works just fine. I did it in a pinch before I had the right cabling to use the inserts.

    Hope this helps.

    Jim
     
  6. yodermr

    yodermr Guest

    Thanks for all the input. I do need spend some time with my drummer to hammer this out. We always play more than figure out how to setup correctly.

    Curious about what 0db represented on the Q10 versus analog, I contacted their tech support. The response;

    ******
    0 dB is technically where our converters clip. Unlike most converters, however, we utilize components that allow a certain amount of saturation past 0dB before you’ll encounter any audible digital clipping. The saturation is not as warm as tape, but far nicer than what you’d encounter with inputs on other A/D interfaces. It’s best to record with the inputs as close to 0dB as possible, and the occasional spike isn’t much of a problem.

    *******

    Thanks again
    Merry Xmas to all.
    Mark
     
  7. Duardo

    Duardo Guest

    The statement that "it's best to record with the inputs as close to zero as possible" isn't necessarily true. I'm surprised someone from Aardvark would say something like that without qualifying his or her statement.

    -Duardo
     
  8. yodermr

    yodermr Guest

    That was a direct quote, nothing left out - cut and paste.

    Mark
     
  9. realdynamix

    realdynamix Well-Known Member

    Joined:
    Feb 23, 2001
    :) You could test that, take a 1k tone signal and drive it up until you see clipping on the wave. Though it is not the same as dynamic sounds, it will give you an idea where the absolute max is with respect to their metering. They must be using some kind of limiting up there, somewhere??? Interesting, esp. if your want some form of accuracy.

    Just a suggestion,

    --Rick
     
  10. Duardo

    Duardo Guest

    Oh, I believe you...I'm just surpised that someone from Aardvark would make such a generalization. Unless he's speaking specifically of their converters...but if that were the case that would mean there was something wrong with the design of their converter, and from what I've heard of them that's not the case.

    -Duardo
     
  11. Kurt Foster

    Kurt Foster Distinguished Member

    Joined:
    Jul 2, 2002
    Location:
    77 Sunset Lane.
    What would be 0dB (VU) on an analog machine usually translates to somewhere between –17dB and –14dB (digital scale). Different manufacturers use different standards. At any rate, recording at –10 dB digital, should give you excellent results while putting plenty of signal down to the recorder..
     
  12. AudioGaff

    AudioGaff Distinguished Member

    Joined:
    Feb 23, 2001
    Location:
    Silicon Valley
    In addition to what Kurt has mentioned, digital zero in not always where you think it is. Some gear is designed so that what is displayed as zero (0dbFS) is really less allowing as much as 6db headroom after you see the 0dbFS or clip/over indicators light up. You may see overs or clip/overload LED's get triggered on some gear and using the same source material it can show no overs (or less of them) on other gear including software. The Aardvark unit likley is of this kind of design as is the Alesis ADAT's.

    And in addition to that, some gear, most of which is the top end professional/broadcast/mastering digital units and high end quality converters, allow you calibrate where 0dbFS is in relation to analog 0VU as well as what specific conditions constitute a digital over. The most common of these conditions is how the user may set exactly how many consecutive samples that exceed 0dbFs equals a displayed digital over indication on that piece of gear.
     
  13. RandomGuest

    RandomGuest Guest

    Joined:
    Feb 10, 2001
    Just a little clarification...there's no such thing as a sample that exceeds 0dBFS, as that is the absolute ceiling for digital. Clip lights go on after a certain number of consecutive 0dBFS samples.

    Oh, and you shouldn't need to use a compressor to protect yourself from clipping...just turn the gains down. Odds are your electronics signal chain has way more dynamic range than your room and instrument do, so you can afford to drop the gain down and retain more headroom. Use a compressor if that's the sound you want...otherwise do proper gain staging.

    Cheers,

    Kris
     
  14. missilanious

    missilanious Guest

    0 dB is technically where our converters clip. Unlike most converters, however, we utilize components that allow a certain amount of saturation past 0dB before you’ll encounter any audible digital clipping. The saturation is not as warm as tape, but far nicer than what you’d encounter with inputs on other A/D interfaces. It’s best to record with the inputs as close to 0dB as possible, and the occasional spike isn’t much of a problem.
    He really only told you it has soft saturation, ask him where 0dbfs on the Ardvark in relation to a dbm scale.
    For instance if its referenced to 0dbfs=+16dbm or -16dbfs=0dbm. So with this calibration level to get a signal at 0dbfs you'll be running your pre at +16dbm which is hot as hell and will risk overloading to preamp and you'll eat up he headroom on the pre too. Most likely the ardvarks ofer some kind of headroom with the digital scale so as DR. said don't run your equipement that hot, this is a problem I had when I first started recording digitally and didn't know alot about gain staging, and took advice from people who record analoque which is a completely different medium that should be handled differently.
     
  15. yodermr

    yodermr Guest

    Thanks for the guidance everyone. I went back and targeted -10 on the meter (what that translates to still looks to be a matter of opinion).

    Anyway it sound just fine and now that I know the technical reasons behind the digital target versus the analog one, I'm comfortable with it as well.

    Thanks
    Mark
     
  16. Rod Gervais

    Rod Gervais Active Member

    Joined:
    Jun 8, 2003
    Location:
    Central Village, CT
    Mark,

    One thing I'm curious about - what exactly do you have plugged into the inserts at this point?


    Rod
     
  17. teleharmonic

    teleharmonic Guest

    Kris,

    if you are replying to AudioGaff's statement about there being up to 6dB clearance 'over' digital 0 i believe that he is referring to the fact that in many programs (protools, logic audio etc.) the 0 that is displayed on the screen mixer is not, in fact, digital 0 but rather is somewhere between -3db and -6db. This is simply a safety measure. In Logic i have hit +3 without clipping. You are correct of course that actual digital 0 is the ceiling, which is why you get clipping.

    That being said, as others have pointed out, with 24bit converters there is no need to record close to 0 (on screen or actual) anyway.

    cheers,
    greg
     
  18. yodermr

    yodermr Guest

    Rod

    A RNC and a DBX 166

    Mark
     
  19. Rod Gervais

    Rod Gervais Active Member

    Joined:
    Jun 8, 2003
    Location:
    Central Village, CT
    Mark,

    Personally - I would try losing the compressors and work with my adjustments until i could record without anything in the signal path.

    You can always compress (or add anything else you want) later.

    I have not had any problem recording drums without compression in the chain, and i tend to work the rims a lot when i play.

    Rod
     

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