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Using Rear Input(s) for Guitar


Hi All,

I am putting together a rack and have 1U free for wireless, I was looking at Relay G90 but it only has outputs on the back and the Axe input I've been using "Instr" is on the front. Since my rack will be full (2U drawer, power condition, Axe and Wireless) there really isn't a great way to get the feed from the wireless into the Axe. Has anyone had any experience with using the back panel inputs? I realize they are balanced so my assumption is it won't work the same and may have undesirable side effects but I figured it doesn't hurt to ask.




People here use the back and are happy. I've seen some cool ingenuity for running a cable through to the front port too. Have a search and you should find the threads. If I was in your shoes I would just try them both and see what you think... Ear is the ultimate judge :)

Sent from my Nexus 4 using Tapatalk


I guess I was looking for a way to get the secret sauce on another input :-( I did test and wasn't thrilled with using the back inputs. Can't have it all I guess. I saw one person put their cable through a rack hole, but I don't have an open space and don't want to drill through some gear. I will probably stick with a G50 instead of the 90 and then use a sliding rack shelf (if I can find a very thin one since space is tight) or just front mount the antenna's and put the receiver on the back side of the rack.

Thanks for the suggestions.



Fractal Fanatic
My rack has a small gap at the top that I run my cord thru from my G90. My old rack didn't so I just moved everything down and left space at the top for running my cord to the front input.


i really do not hear or feel any difference between the front and rear on the axe-fx 2. i'm using the rear these days with instrument cables direct.

what exactly did you not like about the rear vs the front? can you describe the secret sauce you're hearing?

wondering if you may just be expecting to hear a difference, thus creating it.


The difference to me is the sensitivity. I have one particular preset that is a little more responsive to my playing, breaking up more than the others. I use it on a lot of in-between type tones a little clean, a little dirty. It is based on the USA Sub Blues. When I switch to the rear inputs I can't seem to dial it in in the same way I do on the front. The patch is either too sensitive or not sensitive enough.

This could be down to gain settings, I spent about 15 minutes playing with it and gave up and moved back to the front. I was making very small changes to the gain but it seemed like it was almost there or just past where I wanted.

Granted this could also be my ears, and possibly something that could be overcome if not, but would take some re-working of my patches (if of course I'm not just crazy). Maybe I'll try to get them a bit closer and have one of my band mates shift them back and forth at rehearsal to see if I can tell the difference when not looking.


Everyone's ears are different, but the tonal difference (if any) between front and rear inputs should be even less obvious to your audience in a live setting then it would be when recording. I have a G90 and use the rear input for gigs - all the cables are out of the way and "permanently" connected in the rear so I don't have to fuss with anything. Then when I rehearse at home, to save my batteries I use a cord and switch to the front input . . . I honestly can't tell the difference (but then again, I'm no tone connoisseur).

EDIT: I should add that I play through a real guitar cabinet - sometimes mic'ed, sometimes using the XLR outputs of my cabinet's mic eliminator; either way I suppose that could help to mask the tonal differences between front and rear.


Don't use your ears it try to tell the difference. Use your fingers. There is definitely a pretty big difference, especially with how clean the G90 is - but it doesn't manifest in tone so much as in feel, noise floor, and dynamic range. For me, this extra dynamic range feels like enhanced sensitivity - which makes me play differently, which comes out sounding like better tone. If you were to record your guitar direct, and play it back into the front and back, it might sound the same. You might not also notice much difference through studio monitors or at low volume - but at live gigging volume, the difference is huge.

My racks have aluminum rails, so I bend the top corner of the right hand rack with pliers and thread the cord through. The little right angled jacks with the hexagonal heads that you usually see on pedal boards work perfectly for this.


The "secret sauce" on the front input is a form of noise reduction, not a tonal difference. Even without the noise reduction, the Axe's rear input has more dynamic range than your guitar. I have my wireless permanently jacked into the rear input, and I use that interchangeably with a hard wire to the front input. It works great, and I can't hear any difference.


I have a line 6 relay 55 and have it plugged in to the rear of the axe fx using standard 1/4" cable and I have no issues whatsoever


Fractal Fanatic
I hear no difference, feel no difference. Been using the rear inputs for ages. It is crucial for me, since I'm feeding the beast from a mixer, and will clip on the front input anyway.


I also run the G90 into the back input with no noticeable difference in tone. I tried both ways and seen several posts on this forum about the difference in the 2 inputs but I can't tell any difference in either. The wireless probably sucks more tone away than the difference in the inputs anyway.


I use the front input, but have also used the rear input. I play metal music and mainly run high gaing amps from AFXII and i haven't notice any difference between the two. Altough i guess axe wiki says, that there is some difference and that the front input is instrument input and rear is line level. If i remember right.


So after some more playing around. There is obviously a difference in the amount of noise when just flipping back and forth between front and back (don't even need an input plugged in to hear it). I won't say this a reason not to use the back, but I can definitely hear the difference in the hiss/noise when not playing.
The back also has a different response to my touch, not something that couldn't be overcome - just different.
Since I use IEM's only - no amps, no cabs (other than what the Axe is doing internally) and going straight to an ears rack I may be more sensitive to the difference. Generally none of the differences I noticed would be very noticeable when playing in a band setting.

What I decided to do was just to mount a G50 that I already have in the 1U I have free towards the back. I'll put a panel on the front with the antenna's attached there and a cable snaking through that panel to go to the front input. The parts in total will cost me about $25 from amazon and I'll just use some of the cash I saved on not buying a new G90 to buy an extra transmitter. I won't have direct access to the receiver without going behind the rack, but honestly the only thing I will ever do is change the channel, which I have rarely ever had to do so it's not really a big deal. I would have bought a sliding rack shelf and put it on that, but I couldn't find one that wasn't wasting a bunch of space with a shelf that is 1/4" - 1/2" thick.

So either way, for me I noticed the difference, could have lived with it, but chose to go a different direction.

Thanks everyone for your input, I do appreciate it!



I finally got all of the stuff in to get my rack finished and some time to get it setup at the practice space. Here is what I ended up doing in case it helps anyone in the future. I stuck with the G50 and mounted on the back side of the rack via Velcro. I bought a rack blank and put the antennas on the front with F/F couplers and a couple of cables. I also drilled a hole in the blank panel and put the signal cable through that. I used a rubber grommet to protect the cable. Here's what it looks like:

This allows me to get to the wireless unit if I have to, but keeps everything nice and clean still. I still need to put in a few things to secure the cabling, but I think this will work well for me. Parts from amazon in case it saves someone 30 seconds of searching:
Amazon.com: BNC Panel Mount Coupler - F/F: Computers & Accessories
Amazon.com : RG58 / AU Stranded BNC Cable, Braided, 3 ft BNC Male to BNC male 1HA : Audio Cables And Video Cables : Electronics
Rack Blank
Amazon.com: Odyssey APB01 1 Space Blank Rack Panel Accessory: Musical Instruments
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