Kemper Direct Output/Send - Impedance and Type

    Hey guys!


    Just got a Kemper and I'd like to track the DI as well as the effect into Pro Tools - 3 outputs.


    I understand the Direct Out/Send on the back is used for profiling, which we've already done. So I would guess that it's a Hi-Z output to more closely match the input of a guitar amp etc. How then, can it also be used to plug into a line input of a recording interface? Is there a level difference, will there be an impedance issue, or does it somehow magically sense what it's being plugged into? Does it want to be plugged into a true line input, an instrument input (of, say, an Maudio 2626 or DI of a similar interface), or...?


    Just a little confused on this...thanks for any info!
    Sig

    From the tech specs page:


    http://kemper-amps.com/page/re…ier___Specifications.html


    Direct Output/Send:
    ¼ inch TRS unbalanced
    with ground lift max output level: +16dBu


    Hmmmm...a 1/4" TRS jack that's unbalanced? I'm even further confused...is it a stereo output jack for going to a stereo pedal or pair of amp inputs? I'm guessing this is a HI-Z output, and the people here that have said it's LO-Z are just flat out wrong.


    So, it looks like this is meant to be plugged into an amp, or an instrument input/DI input of an interface...NOT a regular balanced line input, as some have stated. Feel free to correct me if I'm wrong here, but it certainly doesn't look that way.


    EDIT - I noticed the front panel input is also a TRS unbalanced jack. Why is this?


    Analog Input
    Front Input:
    ¼ inch TRS unbalanced, dynamic range >108dB,
    impedance 1 MegOhm

    So I guess here's the official word:


    Dear Sig,


    The Direct Output is a low impedance output. But that is no problem, since high z inputs like amp inputs are capable of taking even low impedances without colouring the sound.
    Active Guitars e.g. have a low output impedance.
    A mismatch would only occur, if the impedances come close, but in our case the ratio is made even higher.
    Sincerely,
    Burkhard Dinnies


    This sounds a little odd to me. The last time I checked, I can't come out of a Digidesign 192 into guitar pedals...it sounds terrible and the impedance/levels are way off. It's the whole reason Reamp boxes were designed in the first place.

    As regards the Outputs, the only TRS jack is the Headphone :)
    The info reported is probably a typo.


    FYI, this is what the wiKPA reads:





    INPUTS
    Returns (XLR and TRS)
    and the Alternative Input are
    balanced. The front Input is
    unbalanced.


    OUTPUTS
    XLR outputs: +10dB
    balanced; max output level 22dBu.
    TS outputs: ¼ inch +4dB
    unbalanced with ground lift. Max output level 22dBu.
    Monitor Out:
    unbalanced, with ground lift. Max output level 16dBu.
    Direct Output/Send: ¼
    inch TS unbalanced, with ground lift. Max output level +16dBu. Low impedance.
    Headphones Out: ¼ inch
    TRS stereo, 33 Ω




    HTH :)

    This is quite weird. So Kemper staff is basically telling us we don't need our reamp boxes for reamping?


    I was trying to figure out what was the best way to "insert" a real stomp box into the signal flow of the KPA when feeding the S/PDIF input with the clean DI track from the DAW. What was confusing is that the manual suggests using the same outputs for feeding everything, like impedance doesn't matter.


    If the KPA's I/O's are somehow "smart" then this needs to be clearly stated and some more technical information needs to be provided to us more technically inclined types.


    I find this story similar to the "Clean sense / distortion sense" story. The manual says what to do and how to use it. But I don't feel comfortable unless I know the signal flow. :)


    Same goes for the I/O's. Sometimes in the studio I cannot trust my ears and do tests to "check that the sound is OK". I need to know what to expect so that I don't have to waste time testing stuff.


    I think that this is one thing that the manual lacks. More technical info.

    Quote from SiegfriedMeier


    This sounds a little odd to me. The last time I checked, I can't come out of a Digidesign 192 into guitar pedals...it sounds terrible and the impedance/levels are way off. It's the whole reason Reamp boxes were designed in the first place.


    Maybe the problem was the level more than the impedance.... I don't use a Reamp box with active pickups :rolleyes:

    Some great info from Christoph himself discussing impedance:


    Maybe the full story hasn't been told yet :)

    Here's our story:

    There is two output and two input situations:

    1. Low Impedance Output (Line Output, active Guitar/Bass, Profiler Direct Output), less than 600 Ohm
    2, High Impedance Output (Passive Guitar, Reamping device), more than 5000 Ohm
    3. Low Impedance Input (Line Input, some guitar effects such as Fuzz Face), less than 20 kOhm
    4. High Impedance Input (Tube Amp, Hi Z Input, regular guitar effects, Profiler Instrument Input), more than 200 kOhm

    The rule of thumb is: if the output impedance is much lower than the input impedance, everything will work fine.
    The input will not draw significant current, and the sound will not be colored.

    All combinations are ok, exept 2. -> 3., that is High Impedance Output into Low Impedance Input.
    This combination especially include: passive Guitar into Fuzz Face and Reamping device into Fuzz face or other low impedance pedals.

    The result is: The guitar pickup is heavily loaded by the low impedance, thus coloring the sound. Different pickups undergo a different coloring, caused by the high dependency between both the pickup and input impedance.
    This is what we are used to, this is how we experience the sound of these pedals in combination with our guitar.

    Manufacturers of Reamp Boxes advertize to match the impedance of a guitar. But how could they? Every pickup is different. Different switched combinations of pickups will have different effects. The passive volume and tone control of the guitar has another dramatical effect to the impedance and thus the sound. This cannot be matched by any other device than the original guitar, unfortunately.

    No interconnected device can perfectly match the sound of a guitar directly connected to a low impedance pedal like the Fuzz Face. The Profiler cannot match it, a Reamping Box can't either.
    Even you insert any kind of regular stomp effect between your guitar and a Fuzz Face, the sound will change dramatically.

    The story is different with the tube amp input. It has a very high impedance and will not color the connected device. You can connect everything to it, the impedance does not matter, only the level has to be adjusted.
    The Profiler provides the right level on the Direct Output. The way from the Instrument Input to the Direct Output is simply a buffer amp. An impedance match is not necessary, a Reamping Box is not required, as it wouldn't add a benefit to the setup.

    I have some hints, that unfortunately the full story about impedances in the guitar and studio world is not told, by whatever reason. Thinks are not logical, or hidden in the dark:
    1. On the web you find numerous recommendations for buffer amps, that will be connected between the guitar and the amp. Same as active guitars. Buffer amps actually create a line signal. No word that a buffer amp will "destroy" the original impedance of the guitar; that same impedance that is "reconstructed" by a Reamping Box. That is a clear contradiction. Some hints can be found, that a buffer amp in front of a Fuzz Face will create a nasty sound, still.
    2. There is no specific list available on the web about those few stomp effects, that have a high impedance input and will cause trouble in many situations, such as interconnecting with other pedals or wireless systems
    3. No manufacturer of Reamping devices had the idea to use the "impedance reconstruction" to reliably drive a Fuzz Face while providing a high impedance input.
    4. No manufacturer has provided a double buffer amp (second with impedance reconstruction) to use long cables on stage, but connecting with a "pickup impedance" to the amp.
    5 Manufacturer of wireless system make no big deal about their output impedances, that go straight to the amp or the pedals. They should actually, because technically a wireless system is like reamping.

    Quick conclusion: Impedances are no problem in most of the cases. Much more cases than people think!
    But in those rare cases where impedances become a problem, there is no perfect solution available.

    Christoph Kemper