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interface and guitar re-amp issue

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I have an electric guitar track recorded dry and direct, line in into the mac via a unity gain tube buffer, with the intention of re-amping. It's fine, sounds as expected.

Directing it to a channel in my Behringer UMC404HD interface, via the Logic I/O plugin, to then send out to the guitar rig for overdrive and tone control, yields exactly the sound expected. Everything along the way is unity gain, the guitar amp (just monitored through it's speakers) sounds identical to the guitar plugged in.... except for massive noise, certainly more than the rig alone, with or without instrument plugged in.

The noise (not hum, noise) is immediately apparent when plugging the interface into the guitar rig, from any available output on the interface.

As a test, I took the Behringer out of the setup, solo'd the direct guitar track, set the channel and output at unity, and connected straight out of the Mac line out to the guitar rig. Also sounded fine, as expected, but- no noise, or, very little, and consistent with the guitar rig.

Obviously I have not brought the re-amped sound back into the interface/daw yet, to record it, seems to me I need to solve this first.

Unless I am doing something wrong with the setup, being a novice with the interface, is it a simple matter of unusable noise levels in the Behringer?

There's a lot of gain in an overdriven guitar rig, other uses of the interface with outboard gear may not bring out this noise. But the fact that the track, direct out of the Mac, works fine with no noise, seems to me to point to the Behringer.

I could be doing this all wrong, so any input is greatly appreciated.


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The output of an audio interface is line level. That means you use either a TRS or XLR cable (balanced).

The input of a guitar amp is instrument level. That means you use a TS cable, which is unbalanced.


You cannot go out from an interface into a guitar amp without a Re-amp box, which accepts XLR and then converts to TS or instrument cable.

Are you using a re-amp DI box?

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*heathen* here but I always reamp directly interface to amp, never had any real issues.




to clarify, Line-Level is usually hotter than instrument level, meaning you just need to pull it down before feeding to an amp.


The other way around is problematic (instrument to line in) because instrument is usually in the vicinity of -20dBv while line is +4dBu.


But yes, just pull the lineout ~15dB down and you're good to go.


The other phase of the balanced connection is just wired to the ground and discarded when feeding a TS/mono input.

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to clarify, Line-Level is usually hotter than instrument level, meaning you just need to pull it down before feeding to an amp.

This generally works but you have to watch out for potential issues:

• Impedance mismatch: line and instrument audio signals vary not only in level but also in impedance. The low impedance of a line output does not match the high impedance of an instrument input. This can affect the way the amp sounds, its frequency response, and you'll typically get more hiss from your amp.

• Level mismatch: guitar amps don't sound the same depending on the strength of the audio signal present at their inputs. A hotter level will create more gain and distortion in the preamp stage of the guitar amp. That one's easy to deal with though, just turn down the line output until the amp sounds the way you want.

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I've been very careful to keep all levels at unity throughout these tests. Further indication this is as it should be is indicated by a saturation LED on the Fryette GP/DI coming on at the exact times and intensities during re-amp as when I played into it directly, as well as simple tone and overdrive sounding the same. I am aware of line vs instrument levels and impedances. The interface does have RCA outputs as well as TRS, thought I was using the TRS with only a normal 1/4" chord out of it into the Fryette. I'll play around more with connectivity issues, I was not aware impedance could have such an effect on electronic noise (not hum) independent of audio levels. This vid seems to indicate it does, skip to 8:42-


I'm still suspicious of the Behringer, I'm seeing other complaints of noise on line, and the fact that results are perfect (thought not useful) right out of the Mac into the Fryette seems to support that. As usual the price was probably too good to be true. I'd like to avoid spending more, either on a better interface, and/or a re-amp box, but I may have to. A lot of great input here, thank you all. I'll report back how things go, any further comments very helpful.

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HI, thanks. Sorry, my wording is wrong. By all indications and what control I can exert, the level going back to the amp, from the recorded dry guitar track, is the same, or very much so, as the guitar hitting the rig. In my case, perhaps the impedance issues are more relevant... or, again, just the noise performance of the Behringer.


let me add, right now the only reason some evaluation of levels throughout the chain is important to me is to get a handle on the noise situation.

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  • 1 month later...
Just to close this out in case anyone else searches with the same issue- the problem was solved with a new interface. Since it has impedance matching specifically for reamping, and much better noise performance than my previous interface, it's hard to state specifically which was the problem. Thanks for the input here.
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