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tube distortion/replacement question (on a hybrid amp)

Discussion in 'Amps and Cabs [BG]' started by Bill Brasky, Jul 18, 2003.

  1. Jul 18, 2003 #1
    Bill Brasky

    Bill Brasky

    Jul 23, 2000
    Columbia, Missouri
    I've got a carvin R600 head that is 4, maybe almost 5 years old. It's a hybrid and has a single 12AX7 preamp tube in it which I have just recently noticed a little distortion in. It pretty much only happens if I have the volume on the bass and the gain turned up pretty high, but it has kind of a decent overdrive sound, and if I want to get rid of it I can just turn the knob over to solid state. My question is, does that mean it needs to be replaced soon? i.e. will the distortion rapidly get worse and worse or is there any possibility of hurting the amp by leaving a bad tube in? I suppose it won't hurt anything as long as I use only the solid state part, but since I haven't had to change a tube before I thought I'd ask about it.

    This is more a question of opinion, but how should I go about choosing a replacement tube? Should I just get another Carvin tube or would it be worthwile to experiment with some other type? I know there is a lot of personal preference when it comes to tube amps, but personally, I couldn't tell much difference between the tube sound and solid state sound until now (since it started distorting). That might be because of the hybrid preamp though, or the type of tube it had, or maybe I just haven't listened to it that closely.
     
  2. Jul 18, 2003 #2
    DryWater'Bass

    DryWater'Bass

    Nov 6, 2001
    Johnson City,Tennesee
    If you're turning the gain up and getting overdrive, it sounds like you're just overdriving the tube...microphonics and shutdown are the big reasons for replacing the preamp tubes...I went with a GT12AX7A, I got it from suggestion of my dealer...If you like the distortion, and I'm not familiar with the hybrid carvins, didn't they have a gain and a mix knob?If they did then I'd get a low gain tube that's replacable with a 12AX7(check http://www.tubestore.com/gainfactor.html) It's a gain chart for the preamp tubes..Low gain preamp tube(it'll distort easier), blend in some tubey distortion and up the gain...You'll have a sweet amount of OD.If you're not looking for OD, then get a good 12AX7 and stick it in there...I like the GT and The sounds I heard from JAN/Phillips tubes....

    If it's hard to understand...I don't know what to say:D

    DWB
     
  3. Jul 18, 2003 #3
    Bill Brasky

    Bill Brasky

    Jul 23, 2000
    Columbia, Missouri
    Yeah, the carvin has a gain knob and a mix knob. It seems like it is distorting on a lower gain setting now than I ever noticed it doing before though. Like it will even distort some with the gain set at 0 (on a scale of -12 to +12) so that is what made me start to wonder about the tube in it.