Compression = Headroom???

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by jamison162, Feb 6, 2012.

  1. jamison162

    jamison162 Supporting Member

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    Is this an accurate statement?

    From the Groove Tubes website:

    "The rise time of the V1 and V2 tubes will increase the compression in your amp's front end, while at the same time reducing background noise. A larger percentage of your distortion will be generated by the output section rather than the preamp section. You will have increased clean headroom as another benefit."
     
  2. guitarcapo

    guitarcapo Senior Member

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    I usually associate tube compression with clipping. As clipping occurs, you don't hear much volume change between large and soft.

    For example, listen to the guitar lead on "American Woman" by the Guess Who. Extreme compression and sustain to the point where the guitar sounds like a keyboard.

    Aspen Pittman has a bit of PT Barnum in him.
     
  3. '58Bassman

    '58Bassman Member

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    Compression occurs before clipping but it's easier to see than to hear it. Technically, lowering the noise floor does mean the dynamic range has increased but in a lot of cases, the level of the signal is too low to be useful at that point. It does make for better recordings and live gigs when the amp is mic'd, though. Not having to use noise gates and other filters can really mess up the overall sound.
     
  4. jamison162

    jamison162 Supporting Member

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    But does increased compression = increased headroom. I thought a decrease in compression would equate to more headroom.
     
  5. Blue Strat

    Blue Strat Member

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    It would, as long as you don't run into clipping instead.
     
  6. diagrammatiks

    diagrammatiks Member

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    compression = the end of headroom.
     
  7. analogsystem

    analogsystem Member

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    This is how I hear it as well
     
  8. diagrammatiks

    diagrammatiks Member

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    that's pretty much the dictionary definition.
     
  9. chervokas

    chervokas Member

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    Well, headroom is a measure of how much clean, undistorted power an amp can put out for a short burst over and above some steady state signal level. So, say you're playing along at X level and you hit a big chord really hard -- the level of that which the amp can deliver that without clipping is the amp's headroom.

    Theoretically, I suppose, compression at the preamp level -- and certainly applied before the preamp stage -- might be able to give you more apparent headroom by limiting the peaks and therefore not asking as much of output section when you're hitting those hard loud parts, but it's not really increasing the headroom of the circuit, just limiting the peaks going it. And I would think that any compression you're getting in the preamp stage of the amp itself = distortion, right? I mean, if the preamp stage is compressing haven't you already run out of headroom?
     
  10. donnyjaguar

    donnyjaguar Member

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    I dunno 'bout you guys, but when I use my compression stomper on my bass the background noise goes up. ;)

    Aspen Pittman never let electronics theory get in the way of good techno-babble.
     
  11. diagrammatiks

    diagrammatiks Member

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    Aspen Pittman never let electronics theory get in the way of selling books and selling tubes.
     
  12. Timbre Wolf

    Timbre Wolf GoldMember Supporter Gold Supporting Member

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    No. Compression means less headroom - that's what it does (compressed amplitude). It may allow you to have the illusion of "more headroom" if it prevents your circuit from clipping your signal, but that is different.

    - Thom
     
  13. '58Bassman

    '58Bassman Member

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    Think of the lowest volume signal as the bedroom floor and the ceiling as the limit of how height someone can jump, whether it's jumping on the bed or from the floor. If the limit of height is lowered, the range has been compressed. The same would occur if the floor is raised. Compress means to squeeze together and the only things that compression can do is limit dynamic range. Usually, it will have a low threshold, which is to raise the minimum volume- this is particularly helpful when someone wants a chord to continue without dying out or keeping the sound from changing as the chord continues, possibly at the end of a song. Limiting the loudest parts keeps the dynamic peaks within a narrower range, which can be used to avoid clipping the input of a mixer or recording rig. A guitar part can be made to sound really loud if compression is used- emphasizing the frequencies humans are most sensitive to adds to the music "sounding loud, even though it never exceeds 0VU. Leslie West's 'Guitarded' CD is probably the loudest CD I have ever heard and as we know, a CD or other digital recording can't exceed a specific maximum level, unlike analog recording gear.
     

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