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Clipping a SVT-3Pro?

Discussion in 'Amps and Cabs [BG]' started by KeithBMI, Mar 14, 2006.


  1. Does it damage your speakers if you clip the tube pre-amp section of an Ampeg SVT-3Pro?

    I have heard from different people that you can do it without harm to get a nice overdriven sound.

    Others have told me that it's the same as clipping a SS amp. It will form square waves that damage the speakers. I've also heard that it'll damage the tubes.

    So... which is it?

    Thanks in advance! :D
     
  2. Hawkeye

    Hawkeye Canuck Amateur

    I'll weigh in with a qualified no. The whole idea of a tube preamp section is so you can overdrive the tubes to get the tone you want. How do you know you're clipping it? If the "Peak/Mute" light is flashing intermittently because of your input gain, that's not really clipping in the sense that it won't damage your speakers. The light comes on as you reach the limit of the preamp's ability to add gain to the signal. If your loudest playing is causing that light to come on from time to time, that's not a problem.

    Just to be sure, I want you to understand the difference between overdriving a preamp and clipping a power amp. When a tube preamp "clips" it's distorting and compressing the waveform. Most of the time, this is the whole idea of having a tube preamp. The added even order harmonics of the overdriven tube add fullness and warmth to the signal. Hey, it's distortion from the pure signal, but it sounds good in moderation.

    When a power amp clips (the SVT 3Pro has a solid state power section) it means that the waveform is being amplified beyond the power supply's ability to amplify and control it and the top and bottom of the waveform are actually being truncated or "clipped". This is potentially nasty for your speakers as the power amp is in an uncontrolled state and the resulting spikes etc. can damage your speakers. If you are playing your 3Pro so loud that the power amp is clipping, you will hear it as loud, unmusical clicks coincident with the transients.
     
  3. Fuzzbass

    Fuzzbass P5 with overdrive Supporting Member

    No. :)
     
  4. Dr. PhunkyPants

    Dr. PhunkyPants Guest

    Aug 11, 2002
    USA
    Yes. It's really REALLY bad.




    OK, just kidding.
     
  5. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    No, it won't hurt your amp in and of itself; no, it won't hurt your tubes; yes, it's in principle the same process as clipping a SS device, as clipping is clipping; no, SS power amp clipping is not inherently bad for speakers, as square waves are not automatically damaging if they don't exceed the speaker's capacities.
     
  6. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    What Richard Lindsey said....

    Plus, the red light on the input is not a clip light exactly... It is a "level" light.... that will show probable clipping.

    if it does NOT light, you are probably "too low" in level and could turn up.

    If it stays on a lot, you are too high.
     
  7. Herman

    Herman

    Dec 25, 2005
    Lynchburg, VA
    Edit: Jerrold, I didn't notice that you work for Ampeg. To the OP, "what Jerrold said"
     
  8. Dbassmon

    Dbassmon

    Oct 2, 2004
    Rutherford, NJ
    Hi Keith, Richard and Herm,

    I think is was this past Friday night, Richard, Herman and me had a spirited debate about the potential damage a clipping amp can do.

    I don't think we need to revisit that complete dialog only to say that I have a different opinion on the matter than Rich and Herm. A clipping amp will heat up voice coils and can blow them up.

    I sited several sources including JBL and Rane power amp company who also suggest that clipping power amp emit DC-like voltage that damages speakers (DC-like was for you Herm)

    Clipping a preamp is a different matter. Clipping your preamp will give some overdrive in your sound. Doesn't mean your power section is clipping.

    Anyway, another opinion for what it's worth.
     
  9. 8mmOD

    8mmOD

    Mar 20, 2005
    USA
    I endorse & use Tech 21 pedals, Eminence loaded cabs, EMG pickups, Jim Dunlop picks & Ernie Ball Strings, BC Rich Basses.
    The input gain on the 3 pro isnt really intended to be used as an overdrive for the tubes. I think it sounds pretty bad when you hard clip the input. But chew on this. a guy used my amp one night and towards the end of his set I realized that he was SLAMMING the input gain. The red light was constantly on. The result... he smoked both of the brand new driver tubes I had recently installed.
     
  10. How is clipping a preamp different?

    By that I mean what exactly is different between pre and power amp clipping?
     
  11. Herman

    Herman

    Dec 25, 2005
    Lynchburg, VA
    I hope there was never a debate about this (semantics aside):

    "A clipping amp will heat up voice coils and can blow them up."

    I think there are some nuances to that statement which could be debated but, for the most part, I'll go along with it.

    The term "DC-like" wasn't mine and I wouldn't choose to characterize it that way. That term came from one of your sources and I used it as a direct quote from the source only to make a point. Regardless, I don't want to start up that debate again within this thread. If you want to discuss it any more, we can go back to that other thread - I haven't given up yet on getting you to see the light (or the alternating current).
     
  12. Dbassmon

    Dbassmon

    Oct 2, 2004
    Rutherford, NJ
    Your the best Herm!
     
  13. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    Just kind of remarking on that other thread: If you forgot about trying to shoehorn the DC bit in there (it's a bad fit other than what Bob Lee said about amps from way back when), everybody would probably be somewhat in agreement.
     
  14. Dbassmon

    Dbassmon

    Oct 2, 2004
    Rutherford, NJ
    Essentially there is no difference in that the wave form, in both cases has changed shapes (to a square wave) What differs is where in the amplification chain they occur. Preamp clipping is fed to power amp, the out come is repoduction of that square wave, it's naturally compressed shape, it has alot less energy than what comes out of the power amp stage. Feeding a signal into a power amp beyond what it can produce causes power amp clipping. Clipped amp feeds into a speaker which is essentially a coil in a magnetic field. DC-like voltage fed into a coil causes heat, heat can melt copper.
     
  15. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    Why don't analog synths putting out square waves from their ocillators blow up playback systems, keboard amps, and PAs? ; } - Clarinets in much of their range might be causing problems too, if that were the case.

    ...Simply because a [near]square wave is present doesn't say much about how much mix is occupied or what's going on with the voice coil.
     
  16. Herman

    Herman

    Dec 25, 2005
    Lynchburg, VA
    For that matter, an AC-like voltage fed into a coil causes heat. :D
     
  17. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    But... but - there's nothing direct about that statement! ; }
     
  18. Herman

    Herman

    Dec 25, 2005
    Lynchburg, VA
    No, but it was "direct-like".
     
  19. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc