4CM and feedback at high gain.

Rexxyboy

Member
Hey guys, Been using 4CM at times and i find that to get the same amount of “gain” tone that i would normally get just by going straight into my amp (with no AXE FX), i need to slam an extra 25db of level into output 2.

So on the FXL edit page/screen, I’m maxing the Level 2 input knob all the way up to 20db (this SENDS row 2 INTO the FXL block), and I’m adding another 5db with the slider. I’m getting the same “gain tone” but hello undesirable low mid feedback! I can ride the wave to a degree with gates etc.. but its a bit out of control, and yeah its a high gain situation! Just wondering if anyone else using 4CM has a similar issue? My amp is an EVH 5150 III Mini; Blue Channel (which i have to say Cliff did a brilliant model of, in today's latest firmware!)
 
Something is not right. You shouldn't need to add 25 dB. Simply turn Output 2 Level all the way up and you have unity gain.
 
That's the opposite of what I have experienced with my Triaxis rig. I have to drop the gain in output 2 (I use the global EQ level to do this) by about 3.5bd to match the output of my guitar without the Axe. I have both physical knobs on the front all the way up. I do have an original MKI Axe that has not had the output 2 mod done yet. Is this the problem or is there something else to look at. This happens with only the FX loop at default settings in the signal chain.
 
Its a MK2 unit, less than a year old. My Out 2 volume on the front is always up full. At one point I zero'd the FXL input (back down from 20db), and added 12db on Out 2 Global EQ level, but i found the tone was still not as full and 'gainy' on the Blue Channel, so i reverted back to the other way i mentioned above.

I know A/D conversions are happening along the way here, and I'm sure the feedback is caused by overloading the Amp input. I will start over with a blank patch, will change Output 2 cable as well, and remove the Axe from in between my amp and my cab. BTW when in the heat of battle, I tap the side of my AXE FX with my finger i can hear it thru the rig quite loudly!
 
Happy to report i have solved much of the feedback problem, by putting the AXE rack off to the side of the head and cab (instead of in-between). My AXE rack is a frame (doesn't have panels like most other rack cases) so maybe it's more susceptible to sonic interferences than standard cases.

I've reverted to just gaining up Out 2 from the OUT 2 EQ master and not the FXL block. Not sure which is better, either way, i still find the overall tone is compromised with less bottom end and less gain) compared to direct, but i can live with it now that the feedback is sorted.

One question, i'm using unbalance TS cables for SEND and RETURN to the amp, INPUT 2 on the axe is a balanced input, should i get a TRS balanced cable?
 
I'm glad you got it sorted out. But I'm with Cliff: If you're you're adding 20+ dB at your outputs, something isn't configured right. And if you're hearing loudness when you tap the side of your Axe-Fx, that means there's a lot of gain going on in your Axe, and that's probably going to compromise your tone when you're running your amp at high gain.

Sort through the chains in your Axe and find out where that gain weirdness is that you have to compensate for. :)
 
Cheers Rex, the new patch i used to sort it out was a blank patch with nothing but an FXL Block, and i just cranked up 12db OUTPUT 2 EQ Master. Still missing a certain something tho in the tone as i described above. The signal going to the amp seems weaker that when i plug in direct, not quieter really, just 'weaker', hence why i'm boosting up. Is there a nominal amount that an amp front input needs to see, is there a way i can measure this?

My other Settings:
Output 1 mode LEFT ONLY
Output 2 mode LEFT ONLY
Output 1 mode COPY L->R
Output 2 mode COPY L->R
All phases default and zero values for BOOST/PAD parameter
 
Guitar to AXE Front Input 1
AXE Output 2 into EVH Mini 50w Amp Front guitar input
EVH Amp SEND cable plugs into Axe Input 2-Left
AXE Output 1 cable to EVH Amp RETURN..
Output 1 is my master volume as my EVH does not have one.
Using blue channel, all dials at 12 o'clock.

It all works, i just lose a bit of tone (gain, bottom end, oomph) as opposed to going in direct.
 
Cheers Rex, the new patch i used to sort it out was a blank patch with nothing but an FXL Block, and i just cranked up 12db OUTPUT 2 EQ Master. Still missing a certain something tho in the tone as i described above.
If there's nothing in your preset but an FX Loop...and all the internal-to-the-Axe stuff is at 0 dB...and the Output 1 knob is cranked all the way, then Output 1 will send exactly the same signal that Input 1 is getting (your guitar), at the same level.


The signal going to the amp seems weaker that when i plug in direct, not quieter really, just 'weaker', hence why i'm boosting up.
The trick here is figuring out what "weaker" means. Once we do that, we can address the real issue, and all the mucking about with levels can go away. :)
 
Out 1 is master with the axe, but how do you control volume when you are using the amp alone?
 
If there's nothing in your preset but an FX Loop...and all the internal-to-the-Axe stuff is at 0 dB...and the Output 1 knob is cranked all the way, then Output 1 will send exactly the same signal that Input 1 is getting (your guitar), at the same level.

Do you mean Out 2 knob cranked all the way?

I think we are honing in on something...
 
P.S.: Output 2 will act a lot more like a master volume than Output 1 will. Output 1 is acting more like you're guitar's volume knob.
 
He said out 2 is feeding his amp's input, which I believe is correct?

I wonder if you do guitar to axe input, then Out 2 to Amp input (preset with only shunts and a fx loop in there), and then don't plug anything into the Amp Fx Loop, do you get the right amount of sound? Out 2 knob on axe should be all the way up, Graphic EQs in global menu should be flat.
 
Output 1 feeds the return of my amp's fx loop.. so it is acting as a master volume.
Output 2 feeds my amp's front end, and this is always turned up full, and this is what i've been internally gaining up on the axe to get the same tone..
GLobal AXE out Graphics are flat, but I do max this out now at 12db

Another thing, my guitar to amp, amp to cab, no AXE, all controls at noon, its VERY loud..
To get the same overall volume with the AXE in the loop, i have to max out Output 1 as well up 12db.
This example is WAY loud, but i like to make sure it can get there, as i play in rock bands.

I asked before, but should be using TRS balanced cables for 4CM?
 
"..GLobal AXE out Graphics are flat, but I do max this out now at 12db.."
I'm talking just the master level here, not the frequency sliders, EQ's are flat at zero ;)
 
If you turn up out 1 all the way as well, with just shunts and FX loop and the full 4CM, is it just as "very loud"?

Any chance of trying my idea of everything but the Amp Fx Loop?

No, you don't need TRS cables.
 
He said out 2 is feeding his amp's input...
Ah, I missed that bit of the puzzle.

So, if your amp's SEND is feeding Input 2 on the Axe, where does that signal go once it gets into Input 2? It probably goes to the FX Loop block, and from there, it goes...right back to your amp's input via Output 2!. Now there's a feedback loop to melt eardrums.
 
Hey Chris, here is the test as an audio file, its just with my phone, but you get the idea of how i lose something..
First clip, Guitar -> Axe, Out 2 direct to amp's front input, with the Amp's fx loop off .
2nd Clip , Guitar -> Amp, with the Amp's fx loop off.

AXE patch is as you said, an FXL block, all levels zero, and all globals zero..

**Use speakers or headphones to hear the difference in gain, and bottom end. The level is pretty much the same**

i hope this link works: https://dl.dropboxusercontent.com/u/1674896/AXE FX/AXE TEST REXX.m4a
 
Last edited:
Back
Top Bottom