Few basic questions regarding my Kemper connecting to the audio interface..

  • Hi fellow kemper pro users just few conceptual questions...


    I have always used the TS main outs from kemper to connect the main outs (L/R) in my audio interface (I use Pro FX8 if this matters), my guitar tone has always been great but I could never raise my volume further through the faders in the mixer but through my kemper only, so out of curiosity I switched to connecting one of the track's line-in L/Rs from the interface instead.


    However my tone became all fuzzy and weak, even tho I could use the fader to increase the volume, Is it because of the built-in EQs that messed up my tone?


    So does that mean we should always (or mostly) connect our kemper to our audio interface's main outs when recording or playing?


    If so how could I raise my guitar volume through the audio interface instead of raising through the kemper (because I don't want to make the guitar output signal too hot) ? Or am I not using my kemper properly?


    Not sure if its a technical question on digital recording but would really appreciate if someone could clear the concepts for me, cheers and stay safe!<3

  • Hi, I'll try and work through step-by-step for you:

    "I have always used the TS main outs from kemper to connect the main outs (L/R) in my audio interface"

    I have always used the TS main outs from kemper to connect the main outs (L/R) in my audio interface (I use Pro FX8)

    Ok so you've taken the TS outs of the Kemper into the ST (stereo) RETURN channel on the Mackie ProFX8 as I understand it, so if it's not working, it's sensible to move to the more flexible inputs.

    I'm just using bold just to denote the actual labelling on the desk btw - I know this is sometimes used to sound condescending instead - not my intention! Also if I've got the wrong desk/interface, you can disregard the rest of this! :D


    The ST RETURN inputs are line level that will accept either balanced signals (TRS) or unbalanced (TS), but TS will be 6dB lower than the equivalent balanced signal level (half the signal) so if there is no input gain control I can see how you're having to push the fader into the bump stops, especially if the output of the Kemper is not all the way up.


    If you connect to the Line L and R inputs on channels 7/8 you have a line input trim of +/- 20dB to help set the input GAIN correctly. Unfortunately, none of the channels have both a Line input gain trim AND an input level LED, so I think you'll need to use the OL (overload LED) as an indication of where a sensible operating level is instead, by doing the following:

    1. Bring the main output level fader all the way down to minus infinity to mute the output
    2. Set the Ch 7/8 fader to U (unity gain, which is 0dB)
    3. Turn the Kemper up to just above where you think'll you have it set usually and switch in all your boosts etc.
    4. Set the desk EQ to 'flat' on the channel; HI, MID and LOW all in the 12 o'clock position
    5. Adjust the GAIN knob at the top of ch 7/8 until you see the OL red LED by the fader flickering a little, then back it off a little (a few dB).
    6. Carefully bring up the MAIN fader.

    This should optimise the gain structure through the desk, for the best signal to noise performance etc. and put your fader controls in a sensible range. They are for level balancing and have the most resolution around the unity gain point (U).

    However my tone became all fuzzy and weak, even tho I could use the fader to increase the volume, Is it because of the built-in EQs that messed up my tone?

    It sounds like this was either the input being overloaded, or the channel OL was lighting up, which appears to be driven post fader and therefore post-EQ. You shouldn't require much EQ on the desk if you're happy with your Kemper tone already. If the EQ controls were already at 12 o'clock, they weren't the culprit.

    Quote

    Not sure if its a technical question on digital recording but would really appreciate if someone could clear the concepts for me, cheers and stay safe!

    The desk's built-in USB interface will take a line level input and convert it. If what you were hearing was from the desk analogue outputs before this stage, or in addition to it, then the problems were all in the analogue domain as described above. If it was ONLY the digital output via USB that was clipping or distorted, I'd be surprised, as the converter should be configured to take the same signal levels as the desk can handle cleanly. That USB interface is 16 bit, rather than 24 bit (common on smaller desks like this). This is fine, but you will find the limitations of a 16bit interface before a 24 interface. The reason is the bits describe the dynamic variation of the signal, so the maximum dynamic range for 16 it is 96 dB between the quietest and loudest signals. By comparison, 24 bit is 144 dB, which is a huge increase in range, and much greater than the range of our hearing system.


    This is important for input signals that are still wildly uncompressed (often) and therefore have a lot of dynamic range. I don't think this necessarily applies to your Kemper signal, which has a considerable amount of processing, but you can more easily drive a 16bit converter too hard. Digital clipping sounds horrible, compared to progressive analogue distortion, so perhaps you were elegantly distorting your desk outputs, but harshly distorting your converter if you didn't hear it in the analogue domain.


    Let me know if I've gone in the right direction here or if I'm off on a tangent...

  • Thanks Edward for the useful info!


    Sorry I didn't make it clear I was not plugging into my audio interface's ST return, but "Main Outs L/R" literally, the ones that's just next to the footswitch and phones ports.


    I followed your instructions plugging into ch 7/8, checking on the OL getting things right however my tone still sounds fuzzy and "broken"... Not sure if the problem is my tone so I tried using different tones including the default ones, regardless of clean and distortions its still fuzzy and crappy like my signal is still too hot but my kemper input output is always green light. To provide more info the fuzzy noise is still there even if I lower the track's fader, for gods sake I start to wonder if it's just my speaker's problem :D


    So you can see why I'm confused because at this moment it seems that I could only plug into the Main Outs, however there's no gain control nor I could use the fader to increase the volume, I just couldn't figure out what went wrong :/:wacko:

  • I feel your frustrations buddy i too am going through a very similar scenario (im using SPDIF) sorry this reply aint a solution for you just letting ya know you are not alone ?? hope we both can get a resolve soon.

  • I’m a little confused too - the MAIN OUTS on your desk are to feed your speakers. There are the XLR outs in the rear of the desk, and a copy of the same outputs on TRS jacks in the top, where you describe. Are you saying you connect the Kemper’s outputs to these? I think the desk would be trying to drive the Kemper, as well as the speakers in parallel. The Kemper would be trying to drive the other way and is managing to get some signal to those XLR outs.

    I guess I need to know where your speakers are connected. If you could draw out a rough diagram of how everything is connected, that would really help.


    However, if the level of fuzz does not go up and down with the actual Kemper audio, or with the fader, in means it is later in the signal chain. You may, for instance, have a ground loop situation between your desk and the speakers, or if the ‘short circuit’ situation described above is actually happening, between the Kemper and the speakers directly.


    You have ground lift switches on the Kemper, so let’s try that and see if it influences things.

  • Are you saying you connect the Kemper’s outputs to these? I think the desk would be trying to drive the Kemper, as well as the speakers in parallel.

    Thats a perfect description for whats going on right now I believe!


    Basically yes, in short I connect speakers through XLR outs (rear of interface), usb to pc to get sound from my computer.


    I connect my kemper with its TS L/R main outs to the TRS outs I mentioned, right above eq panels, next to footswitch port.


    I think first thing I need to know is the difference of whats going on for my guitar signal, by going through the main outs (that sounds great but cannot control volume), or through the line in channels (that I should plug into, but sounds bad now).


    I pressed the ground lift next to the main outs but still no luck :(, thanks for explaining so much to me still, perhaps at one point we can prove that its just sth wrong with my equipment (they are with me for quite some years) and I should start to get a new interface haha..

  • I feel your frustrations buddy i too am going through a very similar scenario (im using SPDIF) sorry this reply aint a solution for you just letting ya know you are not alone ?? hope we both can get a resolve soon.


    Thanks Adam! Before I post this I saw few similar posts regarding how to connect the interface, its been a struggle for many I think because we just never get the concepts right, most of the time when it works then I just let it be and never wonder why. I feel like these are some newbie questions but Im more afraid if I don't ask I will never learn :pinch:


    I will try digging more posts and wish you can figure out the solution too, cheers.