Noise from Rear Input 1...

thehydeout

thehydeout

Experienced
Hey all,

I just bought a new mixer (Presonus 16.0.4) and in trying to set up cabling a patching to still be able to re-amp without using the Axe USB, I was getting quite a bit of hiss noise.

After troubleshooting a while, it comes down to switching between the front and rear inputs in the I/O menu (going into the rear input for re-amping).

I eventually unplugged everything - no cables at all except going to my power amp from Out 1. Setup a simple amp (6505 at default) and cab. Just switching between the front and rear input there is considerably more hiss with the rear input selected. Is this expected?

I can record an example if needed.
 
And here's an example. Same connections and patch as mentioned above, Matrix amp at 12:00, Axe out at 12:00

 
The default Noise Gate on the Input Section only works for Front Input

You'll be needing to put a specific Gate Block in the chain and point it to Input 2
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Still sounds like it's something along those lines, wouldn't you say Sean..?

I was going from memory of seeing similar comments and completely blind with no AxeFX anywhere near
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When you switch the front and rear input select you turn on/off the digital processing that compensates for front input analog processing that lowers the noise floor.

I imagine you are hearing that.
 
Thanks for the replies. That makes sense. I just don't like noise gates and usually don't use them or it's very lightly if I do. When there's already that much noise going into a higher gain amp, it's just unusable to me. I just didn't have this issue reamping through USB so I assume the USB return runs through the same circuit as the front input? And I suppose I can run my dry signal to reamp through the front input instead.
 
hyderipper said:
Thanks for the replies. That makes sense. I just don't like noise gates and usually don't use them or it's very lightly if I do. When there's already that much noise going into a higher gain amp, it's just unusable to me. I just didn't have this issue reamping through USB so I assume the USB return runs through the same circuit as the front input? And I suppose I can run my dry signal to reamp through the front input instead.
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No, the USB doesn't run through any of that.

I think I may be misunderstanding you. Are you plugging in to front and setting to front and plugging into rear left and selecting rear; or are you plugging into one and selecting front rear?

Also what is your input 1 mode set to?
 
What I was trying to setup is using both. The front input for guitar, then the rear left input for the dry reamp track from my DAW, so I can just switch the input in the I/O menu from front to rear when I want to reamp. The example I posted has nothing plugged in either input and just switching between front and rear in the I/O menu. It just seems like quite a difference in noise level.
 
hyderipper said:
What I was trying to setup is using both. The front input for guitar, then the rear left input for the dry reamp track from my DAW, so I can just switch the input in the I/O menu from front to rear when I want to reamp. The example I posted has nothing plugged in either input and just switching between front and rear in the I/O menu. It just seems like quite a difference in noise level.
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That's because you are not getting the full effect. That noise won't happen in a real world situation where you have something plugged into the front and rear and switch. There is an analog compenent to this as well. Test it with something in the front input, input select to front, then plugged into the rear with input select to rear.
 
That's exactly how all this started. I had everything hooked up, guitar in the front input and return from the DAW in the rear input. I at first thought it was noise coming from the mixer due to just not having some level set properly or a cable. That's why I narrowed it down to just the Axe but it was no better or worse. Not to disagree with you, but with nothing plugged into either input, are they both not essentially grounded? That's my experience with guitar input jacks.
 
hyderipper said:
That's exactly how all this started. I had everything hooked up, guitar in the front input and return from the DAW in the rear input. I at first thought it was noise coming from the mixer due to just not having some level set properly or a cable. That's why I narrowed it down to just the Axe but it was no better or worse. Not to disagree with you, but with nothing plugged into either input, are they both not essentially grounded? That's my experience with guitar input jacks.
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I'm not talking about the grounding; I'm talking about the "special sauce" at the front input. When you switch front to rear, you turn off the analog processing that compensates for that. The processing boosts the highs in the analog domain the compensates by inverting that boost digitally. This is similar to how dolby noise reduction works. So when you have the front selected and are not sending a signal through it(just listening to the self-noise - which you have to really boost to clearly hear clearly), you are listening to the signal w/ the highs cut. When you switch to the rear, that processing is removed so you hear more high frequency noise.

That being said, the front IS designed to:
A. Be optimized for a guitar level signal
B. Have processing to make the inputs somewhat quieter
C. Has a soft limiter to make it much less susceptible to digital clipping
 
Very well explained, thanks Sean. So would it make sense with my current setup that the best way to reamp would be just plugging the return from the DAW into the front input? That would be no more of an issue than switching the input.
 
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