Profiling non master volume JTM-45 (and other questions)

    I'm going to try and profile my amps at the end of August
    after a non satisfactory first attempt a few years ago.
    I'll be using my friend's house since he has a large walk in closet and
    I can put the cabinet inside with the door shut while monitoring in another room.



    1) For my NON master volume amp, I don't have a power attenuator.
    Has anybody profiled with the volume *full up* for the brief amount of time it takes to profile?
    Is that OK? It's an original JTM-45 and I don't want to blow it up.


    I have also noticed this comment from Mr. C. Kemper:


    Quote from ckemper

    It (the manual) says a combination of pre and power amp distortion should be avoided.
    The amps you mention do not have a preamp distortion, so no problem.

    He was referencing a Vox AC30. The JTM-45 has no master volume, so is he saying
    it's not possible to achieve preamp distortion on non master volume amps?
    Am I wasting my time (and risking possible damage) trying to profile the JTM full up?



    2) Any difference in profiling sound with the amp/cab up and off the floor as opposed to having it on the floor?



    3) Best microphone position in reference to the speaker cone? I'll be using a Shure SM57. I'm guessing
    where the cap meets the cone.



    Thanks everyone. :)

    The key to everything is patience.
    You get the chicken by hatching the egg, not by smashing it.
    -- Arnold H. Glasow


    If it doesn't produce results, don't do it.

    -- Me

    You can obviously profile your JTM 45. Just be aware, that there are a number of free of charge factory Rigs available, which are based on that amp model for example created by commercial PROFILE providers like Michael Britt and The Amp Factory. These guys use a combination of microphones and know exactly what they are doing in terms of microphone positioning. If you search for "45" in the Rig Reference List on our website you will find the Rigs in question and be able to download those.

    you should check this great thread from Don (

    with pics about mic placement. )




    I used an SM57 angled and between two 10" speakers from my JTM30 , standing on the floor with excellent results ( more basses on the floor )


    experiment with a stand also , you'll get brighter results


    About the amp, let it warm up a bit and profile a few times without cranking the volume , then check the results, it might be OK then, and no need to blow up the closet ;)

    Thanks Burkhard and waraba! Much appreciated. :)

    The key to everything is patience.
    You get the chicken by hatching the egg, not by smashing it.
    -- Arnold H. Glasow


    If it doesn't produce results, don't do it.

    -- Me