Configuring at Axe-Fx 3 for wireless (e.g., differential line in on Input 2 "left")

kgk

Member
I've spent about an hour trying to configure the unit to take input 2 "left" and use that everywhere as its default. I'm sure that this is very common [because of wireless units that make line level, like mine], but I couldn't find any illustrations about how this part of the system is configured. I found various text that almost looked like the right thing, but it wan't. I suppose that I could read the entire manual and try to draw out an actual illustration of how it is connected, but after this, I'll likely never change it again, so if some kind expert has the recipe, I am most thankful.

Thanks for your help!
 
I'd recommend what @unix-guy said. Just use Line1 on the rear. In a jam, if your wireless goes out, you can plug right into the front and it will automatically override the rear input. I always leave a guitar cable coiled in front for that event. Use the instr/aux out on your ULXD direct to line 1. I'm pretty sure you need to set it for +18db on the ULXD for Unity gain. It should sound identical either wired or wireless when swapping.
 
If I can send differential line-level signals to represent my guitar—and I can, as the Axe FX supports it (somehow)—then that's the second-best thing to send (next to digital). Why would I throw that away?
 
If I can send differential line-level signals to represent my guitar—and I can, as the Axe FX supports it (somehow)—then that's the second-best thing to send (next to digital). Why would I throw that away?
That “second best” gains you nothing. Your guitar itself will always have a lower signal-to-noise ratio than your wireless will, regardless of which output you use. Why not use the instrument out into the rear Input 1 jack, and save yourself a lot of fuss for no audible difference in sound?
 
You can use a balanced input if you desire, but the benefits would be imperceptible at such short distances. In all honesty, your wireless unit is more detrimental to the signal than the use of an unbalanced cable in this scenario.
 
I use Sennheiser wireless, and for the longest time I ran balanced out to the Axe II. Since re-doing my rack for the Axe III, I just use the 1/4" unbalanced output to the Axe rear panel, input 1. For the 6" of cable, there's no perceivable difference. When I take the rack to the studio, I can simply plug in the front panel as that overrides rear input 1. I wouldn't worry about it.
 
Electric Guitars use 1/4” outputs. XLR outputs in wireless units are typically for acoustics straight to the board.

You’re splitting hairs on “quality.” Use the 1/4” output and in 1 rear for wireless as designed. Then if you need to hardwire a guitar use the front input and the rear shuts off, as designed.
 
You can use a balanced input if you desire, but the benefits would be imperceptible at such short distances. In all honesty, your wireless unit is more detrimental to the signal than the use of an unbalanced cable in this scenario.

I doubt that I could tell the difference with my ears in any of theses cases:

1. A/D D/A—(very strong differential signal)—A/D, what I did on my FX 2, and what I want to do now.

2. A/D D/A—(very weak non-differential signal)—A/D, what people seem to suggest here (via input #1).

3. (somewhat weak non-differential signal)—A/D, direct cable.

The problem with #3 is that it involves a cable. The only reason to do #2 would be your argument that I could plug in directly if my wireless went down. The problem there is that the Tx part of the wireless is totally overdriven by my EMG 81 active pickups, so I have to cut the gain WAY back. I suspect that this makes the "instrument" signal coming out the back much weaker than my actual guitar, hence they would not be interchangeable. Now, Shure might have boosted the "instrument" port to match however much I decrease gain before the A/D (to represent the conceptual model that it is a "cable" that goes through the air), and in that case there would be benefits of (a) directly plugging in, and (b) I don't have to learn how to do #1. I don't have an oscilloscope, but it would have been interesting to see what happens on the "instrument" output.
 
Last edited:
What is a "differential signal"? I've never heard that term before.

Bottom line is you can do what you want, but a guitar signal is a "weak" signal. This is what is normally sent in to the front of the Axe Fx or an effect pedal or a guitar amp... Doing something else might work but it's not standard.
 
This is a bit like people recording the dry signal, which is weak, then boosting it in the DAW so it “looks better,” then wondering why it sounds different and has too much gain. A guitar signal is a guitar signal. You don’t usually want more than what it already does.
 
What is a "differential signal"? I've never heard that term before.

You might know the concept under another name, it's just a "balanced" signal.

If you want to send a mono signal you can use a pair of wires, where one is for reference (ground), and the other one moves around.

The other way to send a mono signal is over three wires, where you still have ground, but now you don't really use it for reference; instead, you SUBTRACT the two other wires and then multiply their difference to reconstruct the signal. The nice thing about subtracting is that it removes noise that lands on both wires (providing "common mode rejection"), hence this recipe is extremely popular for handling nearly any signal until it reaches A/D conversion.

As you know the Axe FX already processes these signals.
 
I doubt that I could tell the difference with my ears in any of theses cases:

1. A/D D/A—(very strong differential signal)—A/D, what I did on my FX 2, and what I want to do now.

2. A/D D/A—(very weak non-differential signal)—A/D, what people seem to suggest here (via input #1).

3. (somewhat weak non-differential signal)—A/D, direct cable.
Whether you're using a "very weak signal" or a "very strong signal," the bottom line is that your signal will never be any cleaner than the noisiest device in your chain, and that's always going to be your guitar. That makes the "weakness" of your wireless unit's output irrelevant, and leaves you free to consider other factors, like ease of cable routing or preset creation.
 
I use Sennheiser wireless, and for the longest time I ran balanced out to the Axe II. Since re-doing my rack for the Axe III, I just use the 1/4" unbalanced output to the Axe rear panel, input 1. For the 6" of cable, there's no perceivable difference. When I take the rack to the studio, I can simply plug in the front panel as that overrides rear input 1. I wouldn't worry about it.

The problem that I have with Shure is that I have no idea about what any of the outputs actually do. For example, if I put in 50mV sine wave on the input to the transmitter, what voltage will come out on the receiver? They don't really say, so I just wrote to them and asked. My guitars have active pickups and the signals are not so terrible, and if the Shure can recreate the same levels on the output, it might be worth using Line 1 in order to be able to fall over to a cable. In general I use wireless for everything, including practice, so I never even thought about plugging in directly.
 
The problem that I have with Shure is that I have no idea about what any of the outputs actually do. For example, if I put in 50mV sine wave on the input to the transmitter, what voltage will come out on the receiver? They don't really say, so I just wrote to them and asked. My guitars have active pickups and the signals are not so terrible, and if the Shure can recreate the same levels on the output, it might be worth using Line 1 in order to be able to fall over to a cable. In general I use wireless for everything, including practice, so I never even thought about plugging in directly.
Every guitar-oriented wireless device I've ever used runs at unity gain when its output level is dimed.
 
Every guitar-oriented wireless device I've ever used runs at unity gain when its output level is dimed.

It has two gain settings, if I recall, one in the Tx, and one in the Rx. The Tx drops a huge amount of signal because I have active pickups (otherwise it constantly clips). Are you saying that if I add the gain back on the Rx side you expect that the manufacturer wants the "instrument" jack to have unity gain?

They really don't say anything about this in the manual, although to be honest I've been reading the Rx manual, and not the Tx manual... that might say more. Actually, I can't even seem to find the manual, this is the closest, so far...

https://www.shure.com/en-US/products/wireless-systems/ulx-d_digital_wireless/ulxd1
 
Back
Top Bottom