Can Anyone Help With This Issue?

[AveryWatts]

Hello All,

I wanted to see if anybody had some insight on an issue I’m experiencing.

I have a setup with two signal chains:

#1: Guitar straight into Axe-Fx III front panel (Input 1) > Output 1
#2: Guitar straight into a real high-gain tube amp > load box (X-load) > Input 2 on Axe-Fx > Output 1

Signal chain #1 is obviously just working within the Axe-Fx. Signal chain #2 is using the Axe-Fx merely as an Impulse Response loader for a real tube amp.

My original intention was to put these two signal chains on a switcher, either a loop selector or an A/B box. This was so I could go back and forth between the two inputs (without unplugging the guitar), comparing tones in the real world versus recreating those tones solely within the Axe-Fx.

I setup two parallel block chains inside the Axe-Fx, on two different rows, both joining only at the output (Output 1). They’re basic and look like this:
#1: Input 1 > Amp block > Cab block > Output 1
#2: Input 2 > Cab block > Output 2

Both signal chains have the same IR’s loaded in their respective cab blocks as well.

I tried doing this setup first with a Voodoo Labs HEX switcher (with #1 on Loop 1 and #2 on Loop 2), then also tried this setup using simply an A/B stompbox (#1 on A, #2 on B). Both of these solutions are true-bypass and made of top-quality components.

This is the issue: When switching to #2, the real tube amp produces a deafening squeal. It doesn’t matter if the guitar volume is up or down, it doesn’t matter if you disable either input block inside the Axe-Fx (Input 1 or 2), and it doesn’t even matter if you switch back to #1 on the switcher (you can still hear the squealing at low levels coming from inside the actual physical amp). Also, it seems like no matter if you’re on loop 1 or 2, the Axe-Fx is always receiving some very small amount of input signal from both Input 1 and Input 2 (even if currently deactivated on the switcher) all the time, as indicated by the front panel input LEDs.

The second you pull the Input 1 cable out of the signal chain (whether it’s currently activated on the switcher or not), suddenly the tube amp (loop 2) is a perfect angel and sounds amazing.

I spent hours diagnosing every aspect of every component involved; cables, tubes, volume levels, switchers, pedals, guitar, etc. This is my conclusion: Input 1 and Input 2 simply cannot be plugged into the same circuit, even if the circuit is bypassed or disabled. For whatever reason, with this setup, they absolutely hate each other. Just for fun, I even used the A/B/Y box to play both #1 and #2 at the same time (Y) and it was a phasey, cacophonous, noisey disaster of a sound.

My question is this: Is there some kind of internal crosstalk between the inputs within the Axe-Fx itself? Is there some kind of I/O setting that I’m missing on the Axe-Fx that could be causing this to happen? If I use them separately, it works perfectly; only when trying to use the switcher do I experience a problem. I would think that the A/B switcher was just leaking signal to both Inputs all the time, but I also tried this on the HEX, which I definitively know is not the case, and got the same result. Input 1 and Input 2 can simply not be even plugged into the same component without causing each other problems.

Just to clarify, this is squealing that I’m experiencing. Outside of that, I’m not getting any humming, buzzing, or anything that would indicate a Grounding issue, 60 cycle hum, phase issue, or otherwise. This is more like an oscillation loop that is occurring only on the real amp from the relationship between Input 1 and Input 2 on the Axe-fx, interacting is some unseen way.

Any advice or insight anyone could provide would be greatly appreciated.

 

[bleujazz3]

@AveryWatts,

Your best solution is to read the Axe III manual with the subject 4CM, or 4 cable method, for wiring peripheral amp/combos. What is necessary is that your amp head/combo contains an FX loop for circumventing the preamp section of your amp. The Axe III manual is free to download from the Fractal Audio website.

You should consider purchasing some Fractal Audio Humbuster cables to help mitigate ambient noise. But, first, read the manual.

 

[strabes]

I don’t know about the squealing issue, but a simpler way to do this is to just put the real amp and load box in a loop on the ax3. That way you can use scenes to instantly switch between the real amp and the fractal amp by simultaneously bypassing the In3 block and enabling the fractal amp, and vice versa.

 

[AveryWatts]

@AveryWatts,

Your best solution is to read the Axe III manual with the subject 4CM, or 4 cable method, for wiring peripheral amp/combos. What is necessary is that your amp head/combo contains an FX loop for circumventing the preamp section of your amp. The Axe III manual is free to download from the Fractal Audio website.

You should consider purchasing some Fractal Audio Humbuster cables to help mitigate ambient noise. But, first, read the manual.

Hello,
Maybe you misunderstood. I don't want to circumvent the preamp section of my real amp. I'm using the real amp (preamp + power amp) as a complete sound. The amp is then going into the Axe-Fx (Input 2) as an Impulse Response loader, since it's not going into a real Cabinet in real life. In between that, it's going into a load box.

 

[bleujazz3]

Hello,
Maybe you misunderstood. I don't want to circumvent the preamp section of my real amp. I'm using the real amp (preamp + power amp) as a complete sound. The amp is then going into the Axe-Fx (Input 2) as an Impulse Response loader, since it's not going into a real Cabinet in real life. In between that, it's going into a load box.

Perhaps I did. You'll still need to read the manual to even begin to approach where you need to be. You might tag some of the more experienced folks on this forum as well regards your question, which, I must say, is complex.

 

[AveryWatts]

I don’t know about the squealing issue, but a simpler way to do this is to just put the real amp and load box in a loop on the ax3. That way you can use scenes to instantly switch between the real amp and the fractal amp by simultaneously bypassing the In3 block and enabling the fractal amp, and vice versa.

That's a solid solution. The ony reason I wouldn't do that is I would like to select more than one real amp in the real world (one at a time), while still routing it into one Input on the Axe-Fx (as an Impulse Response Loader). For example, I have one tube amp (preamp + power amp) and two additional guitar preamps (no power). With an amp-selector/loop selector, I could choose either Tube Amp #1, Preamp #1, or Preamp #2, which all would share going into Input 2 on the Axe-fx for the Impulse Response, seeing as I would only use one at a time. Otherwise, I would need to occupy all the inputs on the Axe-fx as loops (Inputs/Outputs 2, 3, and 4) in order to do the same thing.

 

[edwinstar]

Isn‘t this a ground loop problem? Have you tried an A/B box the switches everything, including the ground signal (don‘t know if it exists), or have you tried a transformer isolating device between either A or B? Check LEHLE for such devices.

 

[AveryWatts]

Isn‘t this a ground loop problem? Have you tried an A/B box the switches everything, including the ground signal (don‘t know if it exists), or have you tried a transformer isolating device between either A or B? Check LEHLE for such devices.

As previously stated, it doesn't seem to present like a grounding issue, which typically manifests as a humming, buzzing, or general noise. It still is strange that the signals effect one another, even when one is totally disabled in the signal chain (loop turned off). It should be bypassing that path entirely when it isn't switched on.

I don't have an isolated transformer A/B device (closest would be a Radial J48 and JDI Direct box with a Thru Out), but that would be the next test. Thank you for the info on Lehle devices. I just checked out their site and they have all kinds of great looking components. I'll have to dig in more thoroughly for future upgrades.

 

[AveryWatts]

Problem solved. I went to the back of the X-Load and pushed in the Ground Lift. Squealing is now gone. Turns out it was a ground loop that presented as squealing because the gain stage of the amp was so high it turned a hum into a scream. Thank you to everyone who chimed in. I appreciate the feedback (no pun intended).

 

[bleujazz3]

Isn‘t this a ground loop problem? Have you tried an A/B box the switches everything, including the ground signal (don‘t know if it exists), or have you tried a transformer isolating device between either A or B? Check LEHLE for such devices.

Problem solved. I went to the back of the X-Load and pushed in the Ground Lift. Squealing is now gone. Turns out it was a ground loop that presented as squealing because the gain stage of the amp was so high it turned a hum into a scream. Thank you to everyone who chimed in. I appreciate the feedback (no pun intended).

 

[edwinstar]

Problem solved. I went to the back of the X-Load and pushed in the Ground Lift. Squealing is now gone. Turns out it was a ground loop that presented as squealing because the gain stage of the amp was so high it turned a hum into a scream. Thank you to everyone who chimed in. I appreciate the feedback (no pun intended).

Great to hear!