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Something is wrong with my amp

Discussion in 'Recording' started by Guitarfreak, Sep 17, 2009.

  1. Guitarfreak

    Guitarfreak Well-Known Member

    There has got to be something wrong with it. I recorded my guitar DI a few nights ago and finally got around to reamping it today. Just out of curiosity I put an amp sim on the files before I reamped. Sounded great, excellent even, so I know it's not the guitar signal.

    I have narrowed it down to two possibilities:

    1. Bad tube - My amp has a single 12ax7 tube that has never been replaced, I got it from a friend so it's bound to need replacement. However, I don't know the first thing about tubes, you know brands and reliable suppliers and all that. I know power amp tubes need to be biased but do preamp tubes need to be biased as well?

    2. Impedance mismatch between the amp and cab - Back of the head reads (4ohm min combined impedance) and the back of the cab reads 8 ohms.

    The sound is what got me. It sounds anemic X5. I have files, if you'd like to hear them I'll post them.
  2. Boswell

    Boswell Moderator Distinguished Member

    If you get a sound you are happy with when playing guitar normally through the amp-cab combination, your re-amping problem has nothing to do with the tube or the matching of the amp to the cab. It's more likely you are overdriving the amp input when replaying the recorded track. Try a 30-40dB attenuator in the input lead, or putting the replayed signal through a passive volume pedal before feeding it into the amp.
  3. jg49

    jg49 Well-Known Member

    If you bought the radial reamp box which I thought you did, no need for an attentuator or pedal as the box has variable attenuation via the adjustment knob.
  4. Guitarfreak

    Guitarfreak Well-Known Member

    You guys really think it's too loud a signal going in? I was about to say to make it hotter going in because I can't get enough gain from it. Here, have a listen to this file, you'd know better than I.

    Recorded with SM57 dead center of the upper right hand speaker.

    Bass: 4
    Mid: 5
    Treb: 8
    Gain: 7
    Volume: 6


    The second one is the sim which you can listen to for comparison.
  5. Kapt.Krunch

    Kapt.Krunch Well-Known Member

    More info?
    Interface out to amp?
    Settings and physical output used from interface?
    Cable used from interface to amp? (TS guitar cord? TRS signal cable? Speaker cord? :shock: )
    And what Boswell said. Does your guitar play fine just through amp/cab?
    (Some amps are more forgiving of speaker impedance mismatch than others. be careful, and be sure). Preamp tubes don't get "biased" in the vast majority of tube amps...as in biasing the output tubes...but we don't know if yours is a tube amp, hybrid...whatever?

  6. Guitarfreak

    Guitarfreak Well-Known Member

    The amp is a B. K. Butler designed amp called 'Tube Driver'. The amp is a hybrid amp with a single 12ax7 in the preamp section and the rest is SS. Preamp is wired in a fashion that is referred to as "MosValve" which is similar to MosFet except that it includes the aforementioned 12ax7. The cab is a Crate 4x10, I am not sure of any other details on the cab, other than that it is rated at 8 ohm and the two inputs are wired in parallel. Amp and cab are connected through speaker cable.

    Interface out to amp is a PreSonus FireBox going TRS > XLR to a Radial ProRmp Box. Then from there it is going through TS guitar cable to the input of the amp. The output of the FB is at 0dB attenuation.

    According to my ears the sound coming from the amp is 95% the same as when I play my guitar straight through the amp except with a bit less treble response. This is most likely because I did not use a DI box, I plugged straight into the FB's' Neutrik connector to record the DI.

    Thanks for the response
  7. Boswell

    Boswell Moderator Distinguished Member

    Does this mean that for your re-amping you don't now have a problem, or you still have the original problem, or you have 5% of the problem?
  8. Guitarfreak

    Guitarfreak Well-Known Member

    There is no problem with my reamping at this time, it works as well as it should be expected to. The problem I believe lies elsewhere, perhaps in the design of the amp itself. It could also be because I am using a 4x10 instead of the industry standard 4x12 and striving for the sound produced by these standards.
  9. jg49

    jg49 Well-Known Member

    Mr Freak, when you opened the cab to check the wiring did notice if the speakers were the no-name black speakers or were they celestions? The reason I am asking is I was reading that Crate for a period of time was producing their own Asian speakers and the sound quality was poor, however during the period they used the Celestions they got big thumbs up. Just curious.
  10. Guitarfreak

    Guitarfreak Well-Known Member

    If it is between those two then I am going to guess that it's the cheap asian ones. I couldn't really make out the name but it definitely didn't look like Celestion.
  11. Guitarfreak

    Guitarfreak Well-Known Member

    I could be pulling this out of my ass, but I think the name on the speakers was 'Mefisto' or something. I've got to go to work now, but I can check when I get home.

    Thanks jg :D
  12. Guitarfreak

    Guitarfreak Well-Known Member

    OK it's official, I pulled 'mefisto' out of my ass. (wow, that sounds even worse) The speakers are by SLM Electronics, acoustics lab.
  13. Guitarfreak

    Guitarfreak Well-Known Member

    I recorded something today and to tell you the truth it isn't all that bad. In the past I have recorded at extremely high levels and the tone has just been thin and full of feedback. I guess you just can't overload these cheap speakers like you would a Celestion or something. Today I recorded at a level that would be considered bedroom level and actually it's not half bad once you run it through some post-processing.

    Straight distorted tone through SM57 then EQ'd the bass peaks down -10dB or so at 150Hz and made a little inverted pimple at 750Hz at -2dB. Next I put a high pass at 80 Hz, Low shelf at 250Hz at -1.5dB and a low pass at 10 kHz. Then I put it through an 'overdrive' plug to warm it up a little and then duped the tracks and applied parallel compression. Finally, I bounced the tracks and opened them up in a new project in order to raise the overall level to the highest that it can possibly be without clipping or compressing the overall dynamic range. *Catches breath* And that's all she wrote.

    Not bad, but if you listen to the pick attacks very closely it sounds a bit plastic I'd call it. Let me know your thoughts on the situation.


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