Kemper DI Box review -

    Just received it yesterday, I was very impressed that it made the trip from Germany and shipping was free!
    This is the 9th DI box that I have tested,
    My countrymen type 85 is the best DI box so far in my testings…
    I have not been completely happy as my DI profiling seems to add a little bit of top end and bottom end, Also, my resulting profiles seem to have more gain than the original reference amplifier… and the additional gain sounded synthetic… Not real.


    Until now! the Kemper DI box is the best, better than the countrymen type 85, (which got me about 75-80% close to the original reference amplifier…)


    DI Profiles made with the Kemper DI are 80%+ (tone AND feel) through my Bogner 4×12 cabinets.
    I don’t know why it works so well, maybe because it’s passive?
    Anyways, to any of you who are frustrated with your DI profiling, I would highly recommend the Kemper DI, it seems to be the perfect match, which I should have known from the beginning… But I’m stubborn, LOL…


    Please, remember that DI boxes are not all created equal! Those cheap Behringer units and all the units in between are not the same at all… in fact, most of them are complete garbage if you could only compare with this, you would agree.


    If you are going to do DI profiles, skip all the headaches and just buy the Kemper DI box, period.


    Ps/// Mr CK was right!


    If I have not explained myself very well, feel free to ask any questions...

    It makes sense that the Kemper DI sounds great, much better than most direct boxes, and not only because it was designed by Kemper for the purpose. It seems to me that most direct boxes have a lot of circuitry to perform a few functions completely unnecessary for direct profiling, i.e. the ability to isolate the input from the output, drive a long distance balanced mic cable, and give a ground lift\isolation. Passive direct boxes use transformers for this purpose, and it is difficult to make a great sounding high bandwidth iso transformer for low money (perhaps the more expensive ones costing hundreds of dollars sound good). Active direct boxes have transistors and\or ICs to do this task, but that puts a lot of amplification into the signal chain, increasing the possibility of distortion or change of the tone.


    The simple resistive circuit used by Kemper minimizes any tonal change, it has to attenuate the speaker level signal to a level the Kemper can accept and this can be done passively with resistors. From pics of the inside of the box posted on the net, it appears that there are more resistors in it that does other tasks, but I'm not sure what is being done with them.


    I have gotten wonderful results direct profiling tube amps using a simple two resistor attenuator cable plugged into a spare speaker jack, but you have to know what you are doing as you could hurt the Kemper or amp or both if you get anything wrong. I suspect the circuitry in the Kemper DI minimizes the possibility of such damage happening.


    BTW, any profiling done by tapping a tube amp speaker output MUST have a speaker plugged into the amp, as most direct boxes and the Kemper DI do not provide a proper load for the tube power amp. The speaker is needed also for its load interaction with the tube power amp, this is an important part of the Direct profile process.

    glad you like it, I still haven’t had chance to try mine...

    Hi!


    I have been direct profilling with a Torpedo Captor and I manage to get some very good results. If I profile and go for a walk then come back, I cant tell which is Kemper or the amp. It sounds like the real deal, but not exactly as the reference amp.


    However, when profilling I still cant get to the point when A/Bing I could not tell the difference between the profile created and the reference amp, specially when monitoring with headphones.


    I tried many different approaches like driving less the power amp or even profilling just the preamp, different levels and so on.


    If I get quite good resutls, why am I looking further to improve it?
    Well, I have all my tube gear 4CMed with my Kemper, which is the central nervous system in my rig. Whenever I come up with a tone I like, I want to be able to flip the chickenhead knob to profile mode and capture it, without too much EQing after that (that is the main reason I bought the kemper).


    Now after some background, to my quesiton: If I assume that the kemper DI would deliver a better result, could I put it in between the amp and the load box like: Amp -> Kemper DI -> Torpedo Captor ? (using the DI from the Kemper box and the Captor only as the dummy load of course)

    Hi Troy,
    I can’t believe how fast I got it, I just looked and it was exactly 8 days from when I ordered it…
    There was no shipping fee, no brokerage fee, no duty, no tax, no nothing…
    It was so easy I almost feel like buying a spare …
    :thumbup:

    I just ordered one off Reverb for $70. I've been tempted on just getting rid of my Kemper and grabbing a tube amp. After reading a few post about guys getting rid of their amps after profiling them I've changed my mind. I'm guessing but I imagine profiling an amp with your settings that you would use for your cab would get it much closer than buying a profile off someone else. When you said 90%, what do you think would get you that last 10%?

    Quote from clintn

    Nah just finding out I dont need as much variety as I thought. Now Im just going to profile a couple amps with my settings.

    i find it cool to play around with some profiles of amps I’ve never tried i. The physical world but ultimately the best profiles for me personally are almost always when I stick an SM57 in front of one of my valve amps. I was playing around today with trying to see home many cool sounds I could get from a single profile. Set my Dual Rectifier to a singing vintage lead sound with the guitar volume maxed out and bridge pup in HB mode. But with neck and middle single coils and the volume rolled back to 3 it was pure Nile Rogers :P


    There were about 500 variations in between and all on one profile with no FX 8)

    Quote from MKB

    It makes sense that the Kemper DI sounds great, much better than most direct boxes, and not only because it was designed by Kemper for the purpose.
    The simple resistive circuit used by Kemper minimizes any tonal change, it has to attenuate the speaker level signal to a level the Kemper can accept and this can be done passively with resistors.
    From pics of the inside of the box posted on the net, it appears that there are more resistors in it that does other tasks, but I'm not sure what is being done with them.

    MKB, There are Zero resistors in the Kemper DI (A single black line on the resistor). Typically used as PC board jumpers, rather than creating a double sided board. I agree, a passive DI box greatly reduces any coloring that transformers or active circuits could add.

    The Kemper DI box is a great design and well built specifically for profiling. 8)

    Quote from BobWalters

    MKB, There are Zero resistors in the Kemper DI (A single black line on the resistor). Typically used as PC board jumpers, rather than creating a double sided board. I agree, a passive DI box greatly reduces any coloring that transformers or active circuits could add.

    The Kemper DI box is a great design and well built specifically for profiling. 8)

    The Kemper DI box has 12 resistors and 2 capacitors. 9 of the resistors appear to be 1\4W metal film, and 3 are zero ohm resistors of the same size (and probably wattage). The PCB is clearly double sided construction. Here's the picture I'm referring to:


    https://tonymckenzie.com/Site/…kemper-di-box/inside2.JPG


    BTW, my main job for about 20 years was PCB design, so I'm very familiar with these things.

    MKB, Cool and Thanks. I had seen it before. Yes a simple design but effective. I too had designed circuits and their layouts for switchmode supplies, but haven't used Mentor Graphics in years. I think in their design they split the resistor values into more than one for either wattage dissipation or they may have wanted to keep the design with 1/4W resistors and maybe for using a pick and place machine? Cheers! 8)