Tube info

Discussion in 'Amps and Cabs [BG]' started by PollyBass, Aug 14, 2001.

  1. PollyBass

    PollyBass ******

    Jun 25, 2001
    Shreveport, LA
    I hate them. but as long as i have one. I have some qustions on them. I have a tube pre-amp. If i want a new tube.....How do i find out witch one i need to get? ive heard of tubes with early distorsion, medium dis. and late distorsion. whats up with that? how does it affect your tone? and i heard you have to re-calibrate your amp or somthing to change your Distorsion rating? im so confused.
  2. nil

    nil Guest

    Apr 6, 2000
    Auckland, New Zealand
    Now, i'm not an electronics techy or anything, just a vaguely-informed player, but here's a layman's gist:

    "Re-calibrating" is called biasing. It's only necessary on power tubes (so if your amp has a solid-state power section, it'll never apply). What it is in effect is setting the amount of current that the tubes draw while idle...similar to setting the idle speed on your car.

    Most tube preamps can use a possibility of 3 types of preamp tubes:

    12at7 (ecc81) : lowest gain, lowest distortion
    12au7 (ecc82) : medium gain
    12ax7 (ecc83, the most common in preamps) : highest gain

    Not to say that a 12ax7 will distort more, just that it can be made to distort more easily. It's the most common preamp tube you'll find. All 3 are interchangeable, although some preamps are designed to run certain tubes in certain points in the signal path (so changing to a different tube could affect the sound a bit more, but generally won't screw anything up).

    Different tubes from different manufacturers, countries and age will change the sound, but it is kinda hard to tell the difference unless you've been using tube amps for a while and know what to listen for. And of course the old lesson comes into play - you get what you pay for. Cheap tubes can sound cheap and won't last as long.

    You can change preamp tubes very easily - if you're confident getting into the innards of your amp (remember there are some serious voltages in there).
  3. PollyBass

    PollyBass ******

    Jun 25, 2001
    Shreveport, LA
    Ok, if i wanted to get a new tube for my pre-amp, what one could i get? just any ol pre amp tube? or would i have to find out wich one to get? how would i do that if i do?
  4. LittleHetzel

    LittleHetzel Guest

    Aug 15, 2001

    first off, my bad. i know this isn't on your subject, but i am new here, and i was clueless on how to post a message, and i saw the button that said reply, and i guess that will work. so maybe if someone could tell me how to post a message, taht would be cool, then i wouldn't make people mad by getting off the subject- sorry. so heres my question. i was looking through a catalog, and i see these Crate BFX series amps, and they have like digital effects built in and such. i was wondering if anyone knew any thing about these amps, or owns them, any info would be cool, thanks