Axe fx3 into front of tube amp causing squealing at high volumes on gain channel

J

jackal.like.the.animal

Member
Running my axe into a synergy syn2 (tube), going into a fryette lxii power amp (tube). On all the gain modules i have for the synergy (basically swappable preamps if you're not familiar), once I bring the master to around noon on the fryette I'll hear some type of high pitch squeal (different depending on the preamp).

My axe patch is completely clean / true bypass. I even hear squeal with input and output block turned off and the output knob rolled all the way back. No squeal if I connect the axe in between the preamp and poweramp (where the fx loop would be).

I've tried various cables, swapped out the poweramp and preamp for an identical working pair (i have 2 of each). Swapped out the cabs.

Was even having the same problem when I used my FM3. I believe it may have to do with the output level of the axe/fm3. I tried it with outputs 3 and 4 of the axe which are supposed to be for 4cm. I've never quite understood this because as far as i have read, outs 3 and 4 are line level. Wouldn't the front of a tube amp only receive instrument level?

Anything you can help with is very appreciated. Thank you!
 
Outputs 3 and 4 are set up for unity gain, not line level. With the front panel OUT knobs turned up all the way, the output signal will be the same level as the input signal unless it's boosted or cut on the grid.

If you are still getting squeal with the OUT knobs turned all the way down, it sounds more like a physical microphonic or routing issue that's causing a feedback loop somewhere. There's no output signal at all when the OUT knobs are all the way down.

If you're using high gain preamp modules, the input circuit is incredibly sensitive and can pick up and magnify subtle microphonics or signal bleed/crosstalk and can create a self oscillating feedback loop (the high pitched squeal).

How exactly do you have everything connected and what does your preset grid routing look like?
 
Thank you for the response. My chain is just input 1 -> output 4. All shunts, levels all at default / no boost. As simple as can be. Even with input and output blocks deactivated and the knob all the way down there's squeal (as i said), when I unplug the cable from output 4 the squeal goes away. If having the output 4 knob all the way back makes it such that there is no current whatsoever coming from the axe, then in theory unplugging it wouldn't do anything. Makes me think there's some kind of grounding issue or something?
 
mr_fender said:
Outputs 3 and 4 are set up for unity gain, not line level. With the front panel OUT knobs turned up all the way, the output signal will be the same level as the input signal unless it's boosted or cut on the grid.

If you are still getting squeal with the OUT knobs turned all the way down, it sounds more like a physical microphonic or routing issue that's causing a feedback loop somewhere. There's no output signal at all when the OUT knobs are all the way down.

If you're using high gain preamp modules, the input circuit is incredibly sensitive and can pick up and magnify subtle microphonics or signal bleed/crosstalk and can create a self oscillating feedback loop (the high pitched squeal).

How exactly do you have everything connected and what does your preset grid routing look like?
Click to expand...
See my above response, but might humbuster cables help with this? Currently everything is plugged into a power conditioner
 
Ground loops typically involve low frequency hum (mains induced 50 or 60 Hz usually), but depending on your environment it could be picking up something that's higher frequency. It's worth a shot to try Humbusters on the outputs. Also, if the Axe III and Synergy are in the same rack, maybe try connecting one of them out of the rack to see if maybe you're getting a ground loop through the rack rails as well. If your power conditioner has any isolated outlets available you could try moving things around there as well.
 
I'd switch to output 3 and see if that makes a difference. Also, swap to another cable to confirm it's not the issue. Plug your
guitar directly into the synergy to confirm this issue is not in the synergy somehow.
 
I will try a few more things but its weird.

Plugging the guitar straight into the synergy makes no issue. Tried various cables, in all inputs/outputs. Tried outputs 1, 3, and 4, all the same issue.

Can anyone confirm that the axe doesn't output any signal if the output knob is all the way down / the output block is turned off?

It appears that it does.
 
jackal.like.the.animal said:
I will try a few more things but its weird.

Plugging the guitar straight into the synergy makes no issue. Tried various cables, in all inputs/outputs. Tried outputs 1, 3, and 4, all the same issue.

Can anyone confirm that the axe doesn't output any signal if the output knob is all the way down / the output block is turned off?

It appears that it does.
Click to expand...
I can confirm that it's unity gain from Input 1-> output 3 at the correct settings with the output 3 knob fully clockwise.

Check your output EQs, boost/pads in setup menu and you're using "Copy L/R" instead of stereo to send a mono signal from the fractal to the input of the synergy.

Again, for clarity, your signal chain is Guitar ->AxeFX 3 Input -> Output3 -> Synergy input?
 
RoshRoslin said:
I can confirm that it's unity gain from Input 1-> output 3 at the correct settings with the output 3 knob fully clockwise.

Check your output EQs, boost/pads in setup menu and you're using "Copy L/R" instead of stereo to send a mono signal from the fractal to the input of the synergy.

Again, for clarity, your signal chain is Guitar ->AxeFX 3 Input -> Output3 -> Synergy input?
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yup that is my signal chain. guitar -> axe input1 -> axe output3 -> synergy input

Problem exists even with no guitar/guitar cable into axe input 1.

will check output eq, should be set to flat, yes?

ill reduce the pads to minimum (minus 10 I think?)

I'll make sure to use copy L/R but I believe i am
 
I had a similar issue with my setup. Mine is Guitar -> RJM mini effects gizmo X -> Synergy SYN2 -> AxeFX3 -> Power amp. I had the same high pitched squeal that you are describing when using a high gain module in the synergy. Plugging straight into the synergy, and bypassing the gizmo, removed all noise. The solution was to use a buffer BEFORE the gizmo. The internal buffer of the gizmo was not quite enough to get rid of the squeal, but an external one did the trick. I know it is a different situation (Axe FX post synergy in my case), but if you have a buffer handy, try that before it hits the axe.
 
jackal.like.the.animal said:
yup that is my signal chain. guitar -> axe input1 -> axe output3 -> synergy input

Problem exists even with no guitar/guitar cable into axe input 1.

will check output eq, should be set to flat, yes?

ill reduce the pads to minimum (minus 10 I think?)

I'll make sure to use copy L/R but I believe i am
Click to expand...

For now send flat. You don't need to reduce any pads Leave it at 0 on output 3.

So for clarity, you mentioned something that output 3 --DOESN'T-- have which is a -10db pad. Are you sure you're setting the outputs and input settings correctly?

Feel free to open up axe-edit. Hit setup, go to the audio tab (bottom left) and post a screenshot of the settings.
 
RoshRoslin said:
For now send flat. You don't need to reduce any pads Leave it at 0 on output 3.

So for clarity, you mentioned something that output 3 --DOESN'T-- have which is a -10db pad. Are you sure you're setting the outputs and input settings correctly?

Feel free to open up axe-edit. Hit setup, go to the audio tab (bottom left) and post a screenshot of the settings.
Click to expand...
ah yeah i saw that it doesn't have a -10db. ill post that soon but it is all correct I'm 99% sure. the strangest part is that any output from the axe into the front of the synergy will create this problem even with the patch true bypass / outblock silenced / the knobs rolled all the way back. Seems like the axe itself is creating some kind of noise that it shouldn't be making. I am plugged into a power conditioner and have tried all the ground loop switches on the back. Don't really know. Same problem happens when I use my FM3.
 
you can test the loop function by taking 2 short patch cables and connecting them directly from output 3 L/R to Input 3 L/R - then set up a simple patch with just a loop as shown below: Then listen with headphones into Ax3 to confirm that lowering the physical output 1 or 3 knobs silences the patch as you strum a guitar connected to instrument input. This will either confirm or eliminate the possibility that somethings wrong with Axfx outputs (I'm betting they are ok but would test at this point).
1663125062967.png
 
jackal.like.the.animal said:
ah yeah i saw that it doesn't have a -10db. ill post that soon but it is all correct I'm 99% sure. the strangest part is that any output from the axe into the front of the synergy will create this problem even with the patch true bypass / outblock silenced / the knobs rolled all the way back. Seems like the axe itself is creating some kind of noise that it shouldn't be making. I am plugged into a power conditioner and have tried all the ground loop switches on the back. Don't really know. Same problem happens when I use my FM3.
Click to expand...

Sounds like it may be some type of grounding issue. Have you tried a humbuster cable?
 
That is almost certainly a ground loop. The best remedy for that is something like a Hum Eliminator or a similar iso device.
 
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