M4 + AxeFX 4-cable method... The right way?

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Ahess86

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Guys, I finally got my m4 and AxeFX and they're both great.... by themselves. I'm looking for the proper way to hook them up 4CM without sending the rig to a pro. I can do a decent job of making all the cables, etc, I was just hoping to hook it all up myself.

The rig:
AxeFX
M4
VHT 2/50/2

Objective:
4CM AxeFX front end - M4 - AxeFX back end - VHTpower, mono. I'm looking to eliminate ground loops and fix signal level issues between AxeFX and M4.

I was hoping this would be a fairly simple rig, I'm not an electronics wizz but I thought I could handle this one. When hooked up, I have ground loop hum and there is some major signal and tone loss. I'm guessing the primary problem is the loop output of the AxeFX being mismatched to the input of the M4? I think if I can get the solution for the signal mismatch and tone loss, I can figure out the ground loops.

I've read countless threads on the matter but I still can't figure it out. Ebtech Line Level shifter both ways between AxeFX and M4? Or, Radial X-amp re-amping from AxeFX loop send to M4 input? Something else??
 
Ahess86":z9ixmlvx said:
Guys, I finally got my m4 and AxeFX and they're both great.... by themselves. I'm looking for the proper way to hook them up 4CM without sending the rig to a pro. I can do a decent job of making all the cables, etc, I was just hoping to hook it all up myself.

The rig:
AxeFX
M4
VHT 2/50/2

Objective:
4CM AxeFX front end - M4 - AxeFX back end - VHTpower, mono. I'm looking to eliminate ground loops and fix signal level issues between AxeFX and M4.

I was hoping this would be a fairly simple rig, I'm not an electronics wizz but I thought I could handle this one. When hooked up, I have ground loop hum and there is some major signal and tone loss. I'm guessing the primary problem is the loop output of the AxeFX being mismatched to the input of the M4? I think if I can get the solution for the signal mismatch and tone loss, I can figure out the ground loops.

I've read countless threads on the matter but I still can't figure it out. Ebtech Line Level shifter both ways between AxeFX and M4? Or, Radial X-amp re-amping from AxeFX loop send to M4 input? Something else??
Click to expand...

The axe-fx in 4cm seems to be really hit or miss. I used to do it with my mod 50, but then just went the route of axe-fx into the Randall RT2-50 because I could almost match the sounds from my mod 50.

Output 2 of the axe-fx is line level, so using that into the instrument level input of the M4 is most likely causing some issues. The output of the M4 is line and so is the input 2 on the axe. That should be fine. Then output 1 into the VHT should be fine. So, I'd say see if you can find a used Radial unit or anything that takes line level down to instrument level. Also if you haven't read the 4cm thread over at the fractal forums I'd do so. I think some guys figured out how to get rid of a lot of hum. Also, the front level controls on the Axe-fx have a very large range. Try messing with those some if you can with a/b boxes hooked up in various locations to maintain unity gain.
 
I never got it to work properly. I only use the Axe after the M4 now. I have the EbTech and it didn't help much.
 
I couldn't get it to work either without ground hum. The culprit seems to be the M4 more than the Axe as I've had other ground loop issues with the M4, moreso than other units.
 
What are your MASTER settings on the modules? What MASTER setting are you using on the M4?

Try getting your modules MASTERs set so that your quietest module's MASTER ends up fairly cranked (maybe 70% to 90%), and then adjust the other modules' MASTERs accordingly so that the output levels match between all the modules. Then try setting the M4's MASTER to somewhere between 8:30 and 1:00 (start at 8:30, and see if you can find the sweet spot between there and about 1:00 - but you may find you have to keep the M4 MASTER pretty low).

Also, are there OUTPUT LEVEL control parameters to tweak in the Axe-FX? Specifically to lower the output level of OUTPUT 2?

I use the 4CM with my G-System and my M4, and I had to go through this too; and I don't even have a 1M input impedance on the FX Return coming from my M4 like you do on the Axe-FX (G-System is only 24K unbalanced, 35K balanced), so it doesn't look like you have any impedance mis-matching issues to worry about.

Are you using the Cabinet Simulator? This blurb in the Axe-FX manual caught my attention:

  • A more complicated approach would be to send the fully processed sound to the mixing board but tap off before the cabinet simulation and send that to a guitar amp or separate power amp and guitar cabinet. To do this you can use the auxiliary outputs of your Axe-Fx. Simply place the Effects Loop block as the second to last block in your signal chain and the Cabinet Simulator as the last block. The signal appearing at the OUTPUT 2 jacks will be perfectly suitable for driving a guitar amp whereas the signal at the OUTPUT 1 jacks will be perfect for sending to the P.A. system.

I don't know whether the difference between OUTPUT 1 and OUTPUT 2 in the above case would be tonal- or level-related; but aren't there LEVEL and DRIVE parameters that go with the Cab Sim?
 
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