Settings for Axe Fx II & GT800FX

Maqbrown

Member
What is everyone setting the output level of the Axe Fx 2 and the input levels of the Matrix GT800FX at? Should my Matrix be maxed out and I just control the level with the output on the Axe or what? I'm running stereo to a recto 4x12 cab.

I read the following from the wiki:

"Gain staging a power amp
The gain-staging information and procedure below is provided by forum member s0c9. Source Go here for more info: Gain Staging Explained.
Gain staging: The "knobs" on a power amp are NOT volume levels, they are input signal attenuators. They control how much input signal voltage is allowed to pass to the power stage. The amp can reach its rated output wattage with the input attenuators wide open, or almost closed. Its totally dependent on the strength of the input signal. If the amp knobs are down, but the Axe outputs are cranked, that amp can still produced its full power output. If you have the amp wide open, the noise floor will be much higher and if you mute the input signal you will get "noise/buzz" thru your system. That noise may be quite loud/annoying, especially if you have 50/60 cycle hum added thru bad grounding.
NOTE: The following steps ONLY apply to SOLID-STATE amps. Opening up a tube amp (wide open) with no speakers connected can PERMANENTLY DAMAGE the amp!! They are also not valid for active devices (such as the QSC K12) that have the amp built in.
To properly gain-stage your system, take the following steps: 1. Turn down the output level (assuming OUT1 going to amp) on the Axe-Fx.
2. Turn down the input attenuators on the amp.
3. Disconnect the cab from the amp (only with solid-state amps! Tube amps need a load at all times).
4. Open up the amps input levels all the way.
5. While playing a relatively "loud" preset, SLOWLY turn up the OUT1 level on the Axe until the CLIP lights on the amp light up.
6. Now, (while still playing) back down the input level on the amp just hair - that could be one click of the knob or one measurement - so that the CLIP light goes off.
7. Now play real hard and make sure the CLIP light does not come on. if it does, back down the amps input levels another notch.
8. Turn off power amp, turn off the Axe-Fx.
9. Reconnect speakers.
10. Turn on the Axe-Fx, then turn on amp (amps should ALWAYS be switched on LAST and powered down FIRST!).

You have now gain-staged your setup. Will this be the "loudest" it can be? No. But you will not be in danger of blowing speakers, and you should not be introducing any more "noise" in the system than already existed. You should use the Tuner mute to silence the system or the volume knob on your guitar. You should not need to adjust the OUT1 level on the Axe, nor the knobs on the amp."

But the GT800FX has no clip lights...
 
I dont have the axe2 or a matrix amp but when i got my ultra and art-sla2 i used a global EQ setting i got from Mark Day. Also, I turned my poweramp up at about 3/4s full and just used my output level on the axe to control volume. Input levels just tickle the red now and then. Hope that helps. I've never tried the gain staging of an amp so i have no info for you on that. Maybe someone with your setup will chime in with their settings.
 
http://forum.fractalaudio.com/amps-cabs/48733-matrix-gt800fx-mesa-212-safe.html#post633820

not quiet like the Art. If I recall, it has soft clip - which is quite valve like and not the harsh clip youd normally associate with SS amps and therefore wont cause the same kind of nasty stuff. It doesnt have a clip light though - Matrix went with a signal light which flickers at -9db and remains on at -6db. That equates to 50W when flicking ans 100W when stable into a 4 Ohm load, 30W and 60W into an 8 Ohm load, then 15w and 30w into a 16 Ohm load. While with a 16 Ohm load thats not much use - the Max OP is 130w anyway so should be safe for most 16 Ohm cabs. With 4 and 8 Ohm loads it was deemed more useable as it gives a guide of OP power at or around the powers cabs are more suited for while lesving enough headroom.

Thelight is very useable. Set the AFX up using the gain slider int he global Out menu while both AFX and Matrix are up full so the light on the Matrix flickers when playing your loudest patch hard (with any vol boosts engaged). At that point you know the power the amp is pushing into the speakers. Then raise the gain slider by however many DBs you need to provide the most power your speakers can handle. That way when both hardware vol pots are up full - your at the max volume your cabs will safely handle. from there you control your actual volume from the Matrix gain knob (on the Gen 1 units I used the AFX knob but on the 2 you get that zipper noise doing that so I prefer using the Matrix knob).

for example, if you have a 2x12 cab rated at 8 Ohms loaded with a pair of V30s, you max RMS power handling is 120w. Set the Gain slider of the OP connected to the matrix at its lowest (-12db) set the Matrix knob to its lowest and the AFX knob to its highest. Start playing and raise the Matrix knob to full (you can actually do this with no speaker attached with SS amps - so no danger of damging your cab or blowing your ear drums during the procedure). If the light starts to flicker while raising the Matrix gain to full your patches are too hot - back off the patch gain. Once the Matrix is up full - go back to the global output menu and start raising the gain slider until the Matrix light flickers while playing. At this point your puttong 30w into your cab - if the light goes to permanantly lit quickly (from off) thats fine - it means you putting 60w into the cab - but your better off with the light flicking. So - now you know your at 30w. the cab handles 120w. Each 3db raise doubles the power - so raising the gain slider in the global out by a further 6 db will then push the full 120w into your cab (3 db up from 30w = 60w, then a further 3db up from 60w = 120w). At this point your set. Provided you use the patch as your "comparison" patch and dont make one thats louder - the max you can push with bopth Matrix and AFX front pannel knobs up full is 120w - which matches your cabs handling. If you get the odd spike more than that (possible if you play harder with the adrenaline of a gig) its not an issue - as guitar speakers can handle spikes above their rated power (the manufacturers know for example a 50w tube amp will push up to 80-90w when the power section is pushed hard - so take this into account).
 
Thank you for your help but that is greek to me. I set the global OP1 to -12db and the light is still flickering...how do I "back off the patch gain"?
 
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