Another Matrix GT800FX query

    Hi all,


    I brought my KPA rack w/ a Matrix GT800FX down to rehearsal yesterday. I'm running it in stereo through two CAE 1x12's, with Celestion G12 Vintage 30s @ 8 ohms.


    First time using it at real volume, however it seemed rather quiet. I had the volumes on the Matrix's channels at ~ 1/4. I adjusted the monitor out volume so it would be louder through the Matrix, then gradually turned up. It didn't seem to get to stage volume until the dials on the Matrix were halfway up. Have others experienced this or am I going about this wrong?


    I read in the manual that this little amp puts out ~ 250 rms per channel, wasn't sure how much the Vintage 30s could take, that is my big concern.

    Before we start, load your loudest rig, whatever boosted lead sound or heavy sound for chugging


    1. Turn the Profiler's Monitor Out down all the way, completely down

    2. Turn up the Matrix amp (both channels) to full power

    3. Slowly start to up the Monitor Out

    4. The LED indicator on the Matrix amp starts to illuminate at about -9dB input signal which equals roughly 30W RMS output @ 8 Ohms

    5. The LED indicator on the Matrix will start to stay lit permanently when the input signal reaches about -6dB which equals roughly 60W RMS output @ 8 Ohms


    Obviously you shouldn't go even higher because the V30s only take 60W but this should already be insanely loud. :)

    Hope this helps. Take care of your ears. ;)

    I should have added the following further steps:


    6. Once you have set the maximum (60W), measure the sound pressure level you get.

    7. Turn down the Matrix amp channels quite a bit.

    8. Turn up the Monitor Out to maximum.

    9. Now level the Matrix amp to the maximum SPL you had measured before.


    Reason for these additional steps:

    If you don't do this, an accidental increase in Monitor Out level can blow your precious cabs.

    By limiting the power amp output, a change in Monitor Out level can't destroy anything. :)

    Awesome - thanks for the advice! :)


    I'll apply this at our next practice.


    I have to say... I was really suprised at how the KPA felt and sounded. Soooo much better than I was expecting. The plexi profile I was using really sounded and felt like a plexi. Can't wait to gig with it.