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Tube amps

Discussion in 'Amps and Cabs [BG]' started by Erich Zann, Jul 30, 2001.


  1. Erich Zann

    Erich Zann

    Aug 14, 2000
    Well, I finally got myself a good Amp, and SVT3. Now, I know this isn't all tube, but it is my first amp with tubes in it at all, and I have a few questions about them.

    1) Is it bad to overdrive the preamp? I know this is very bad for SS amps, but what about tubes?

    2) Since I'm only useing my PV cab right now (it's not very loud and I have yet to figure out the impendence of my other cab), I'm turning it up almost all the way so I can be heard. is this bad?

    3)Are the speakers suposed to move like that? I never noticed them moving quite so much before.

    Thanks.
     
  2. Erich Zann

    Erich Zann

    Aug 14, 2000
    Oh, come on! Anyone?
     
  3. Good choice. I own this amp too and I think you'll be very happy with it.

    1.) Overdriving the preamp will not hurt it. Guitar distortion is made by overdriving tubes. In fact the Tube Gain knob on the 3PRO is used to adjust the voltage to the driver tubes (the 12AX7 and 12AU7 pair) and when your gain is up you can get some distortion out of it. It is possible to clip the SS power amp but highly unlikely since this preamp is incredible.

    2.) Turning up high to be heard is not bad as long as you aren't hurting the speaker or getting distortion. If your speaker handles too little power you could be driving it too hard and if it handles too much power you could be driving the poweramp too hard.

    3.) The more a speaker moves the more air it's moving. The more air a speaker moves the more volume you get. It depends on how they're moving whether it's a bad thing. Usually when a speaker moves farther than it's supposed to it will sound distorted. Also it's possible to get frequencies that are too low to be heard but will be felt. The 3PRO has a low boost and plenty of bass in the EQ. The cab could be getting signals that you can't hear but are still there and you can see the cone move more because of them.
     
  4. Erich Zann

    Erich Zann

    Aug 14, 2000
    Thank you! :)

    The speakers were just moving an alful lot when I turned the tube gain way up. But, I supose my Peavey MKVIII, which lookes like it's from the 80's probably won't do that. The Cab is 350 watts at 8 ohms, so the amp's putting out 275 (I think), so thats alright. But how can you tell if you're overdriving the poweramp?
     
  5. I think you'll know by the sound if you're overdriving the poweramp... But what can happen is the amp will be running at full and trying to push harder because the speakers need more power to sound right. And you'll get some funny signals through the voice coils, which can ruin the speakers. If your amp's ACTUAL power output is correct and matches the speaker you won't over drive it. If it sounds bad you can cut some lows and boost some mids for more volume without losing some good bass sound too..
     
  6. Overdriving the preamp is fine, but overdriving the poweramp is bad. Which leads to your second question. If you are diming out the master volume, your power amp is probably clipping. This could cause damage to your speaker. The power ratings on the SVT-3 are terribly overrated. I owned one for a week, and I was having to do the same thing simply to hear myself at practice. It may sound better with some cabs with a higher sensitivity rating.

    As far as the cones in your Peavey, I can't answer that one. A good amp with adequate power should produce very minimal cone movement. You may want to run a search for 'damping factor' to learn about this.
     
  7. Erich Zann

    Erich Zann

    Aug 14, 2000
    Well, the master is 2/3 to 3/4 the way up, and the volume on the graphic EQ is up as well. But I would hear it if it was clipping, right? But, in all of their "suggested settings" in the manual, the master volume is up ALL the way. weird. But of course all this makes me want to buy the 410hlf as well. Which I will. just not yet.