Posts by scratch17

    I re-read this entire thread. I also read the latest version (3.0) of the profiling guide. There is still little information there on the technical requirements of the DI required to make Direct Amp Profiles.


    I am considering the Two Notes Torpedo Reload for my studio. It could replace my Radial JDV and X-Amp. I have seen Pete Thorn's video on it and it seems to be a really good solution for re-amping. I like the Match feature that gets the live guitar input level equal to the recorded track you want to re-amp. And the DI quality is top notch.


    The free Wall Of Sound plugin that comes with the Reload can also be used to add cab IRs with the KPA. That's a nice bonus.


    With it's ability to do reactive load attenuation at 4, 8, or 16 ohms, Reload is a no-brainer for me.


    I am also hoping it can be a good load box for Direct Amp profiling. In an earlier post in this thread, Toneclone said that," ... the results are awesome so far". That is encouraging. I have also seen a few others with Torpedo Live models say they do the job. They use the same load box technology.


    CK indicated a "dummy load" box could not be used to create an accurate Direct Profile. The poweramp signal must pass through the chosen DI box to a speaker load to enable the KPA to create a Direct Profile.


    Given that the Reload has a through connection for a speaker, on its face, it should work just fine. However, I wonder if the amp / cab interaction might be cut when using the Reload's Load Box output. Having read the Reload owner's manual, it indicates that it makes no difference to operation of the Reload whether you connect or do not connect a speaker. This directly implies that there is no interaction between the amp and speaker when Reload is connected between them.


    So I fear that this amp / speaker interaction would be lost when creating a DAP. Anyone here have any thoughts on this?


    I may need to spend more to get the Kemper DI. Bummer.

    I'm also interested in creating a quality acoustic guitar emulation for the KPA.


    I own a Fishman Aura Spectrum pedal. I also own Logic Pro, which has an input response utility that can be used to create IR's.


    If I understand how this works I must follow these steps to get a good acoustic guitar emulation on the KPA:
    1. create an IR of the Aura with Logic's utility. Save the IR as a .wav file.
    2. import and convert it with Cabmaker 2
    3. Select a clean amp profile


    Will this work, or am I missing something?


    Also, while I plan to start with free cab IRs on the web, I'm interested in some of the Fractal Cab Packs.


    you'll have to convert the IR with Cabmaker 2.0 first


    Are the Fractal packs directly convertible via Cab Maker 2? I read the manual for CM V1.010. It says the IR must be in .wav format.


    Scratch17

    Pilotltd quoted the Mesa CabClone manual as saying:


    Quote

    it's acceptable to use a lesser impedance. eg the 16 ohm version is OK at 16 or 8 ohms, the 8 ohm version at 8 or 4 ohms. Not the other way though!


    It may be "acceptable" from a "you won't blow anything up" standpoint. It doesn't necessarily mean you will get a good profile if you cut this corner.


    Consider that if it doesn't change the interaction between the amp and cabinet, why not just make one Cabclone with 16 or 8 ohm specs, and a second with 8 or 4 ohm specs. Why bother making a 4 ohm unit? Somehow, it seems that there must be a difference. Or is the end user supposed to expect that using a 16 ohm Cabclone with an 8 ohm cab will give the exact same result as using an 8 ohm Cabclone with an 8 ohm cabinet?


    My Mesa 20/20 amp comes with outputs for all three standard nominal impedance specs. I know that I can plug a 4 ohm cab into an 8 ohm output. It will not sound the same as using the 4 ohm output with the 4 ohm cab.


    If I'm going to the trouble of doing Direct Amp profiling, I don't want to chance altering the result by cutting corners. I'm no expert. This is just my take on the subject of this form of profiling.


    Scratch17

    After reading as much as I've been able to find online in this forum, as well as from Kemper's press releases, I think that the following sums up what will be needed in a DI box to do Direct Amp profiling.


    For a DI box to work in creating a Direct Amp profile it must:

    • be able to take speaker level input from a power amp or head
    • have no tonal adjustment to its output (i.e. no speaker compensation)
    • split the signal. One output is a through bus to a guitar speaker cab so that it can still interact with the amp. This interaction is the loading characteristic which will be (hopefully) captured by the Direct Amp profile. The second output is a balanced output which will be connected to the KPA return jack for profiling purposes.

    It is the first and third requirements that seem to have some potential variables associated with them.


    The first requirement involves how much power the DI box can accept at its input. I've seen that some manufacturers sell DI boxes with differing power input ranges. So, for example, the same DI can be ordered with acceptable input levels of 1 to 50 watts, or alternatively 51 to 100 watts.


    The third requirement is splitting the signal. The through to the speaker side requires a specific nominal expected speaker load. I've not seen a DI box made for this application that can vary the load to match that of the connected speaker.


    So, for example, the Mesa CabClone meets the above requirements. It can handle power amps up to 150 watts. That takes care of a wide range of requirement one's variation. However, it comes in three models, 4 , 8, and 16 ohm. So to do Direct Amp profiles of amps with multiple cabs of differing nominal resistances you'd need to buy three of them. That's an extra $900. Ouch!


    Scratch17

    paults wrote:


    Quote

    One clarification - the JDX is the right TYPE of direct box (it accepts amplifier level signals), but it is not a good choice for Profiling. It has a Speaker Simulator EQ on tXLR output


    I missed this very important fact about the JDX. I stand corrected. It is not the device we need for Direct Amp Profiling. Thanks for catching this. You saved me $200 on gear I can't use and don't need.

    Thanks for the welcomes! I bought my KPA in the summer and haven't been able to use it much. I'm moving in the next two or three months, so I'm covered up in preparation to sell my house and buy another.


    I have a small guitar oriented Project Studio that is a long term hobby. The KPA is a dream come true for me. I love being able to try (virtual) amps I've dreamed of owning.

    There are two types of Direct Input boxes. One is designed to accept a guitar's output to a console. The other is designed to take a tube amp's speaker level output and send it to a console.


    An example of the first kind of DI is the Radial JDV.


    I'm old school, with an analog heritage. I always use a DI box when recording an analog amp. I never know if I want to re-amp later on. So I always connect my guitar to my JDV in the signal path before my KPA and analog rig. I use the JDV for a few reasons.

    • I may (or may not) want to re-amp. Yes, I know I can use the Kemper to provide my console with the same dry signal. The JDV is a great DI and I trust that I'll get a pristine dry signal when I use it.
    • The JDV has two outputs. In their path is a pot (which Radial calls drag) that compensates for the characteristics of my pickups, guitar cable and analog amp's input load. Since I like to run my analog rig and my Kemper simultaneously, the JDV works for me. I'm effectively using the JDV as an amp splitter this way. And the drag control lets me dial in my guitar's loading when I am playing my Mesa rig.

    If you are planning on doing a Direct Amp Profile, you will need a different kind of DI box. As Don Petersen wrote, you need a "DI box that can work with speaker levels ". A Radial JDX will fit that bill. It is an example of the second type of DI box. It is designed to take a speaker output from your tube amp, and split the signal. One side goes to a guitar speaker cab. Think of it as a "thru" bus for speakers. The other side of the split signal is output at microphone level. It provides the equivalent of a mic'd up guitar cabinet's microphone output to the KPA, so it can create a Direct Amp Profile.


    If you don't plan on creating any Direct Amp Profiles, you can avoid this additional purchase. And you can re-amp with the KPA, so you don't have to buy a guitar level DI. Just plug your guitar into the KPA and go wild.

    Check out the Radial JDX. It is made specifically to take input from a tube head, combo or power amp's speaker outs,. It splits the signal, passing the powered side to a guitar cab and the other side is meant to go to a console (DI) on an XLR at microphone level.


    It exactly fits the bill for a DI box that can do Direct Amp Profiles. If you think about it, it has all of the requirements.

    • You want a box that can accept the high wattage coming from your tube amp's speaker outputs.
    • You want an output that is essentially a thru for the speaker outputs of your amp.
    • You want an XLR output carrying the mic level signal that the DI box would normally send to a console. When Radial designed this box, that was their intended use. In this case, however, this signal will be interpreted by the KPA as the incoming signal from a microphone, just as it would interpret a signal coming from a mic that was placed on a cab while creating a Studio profile.

    I have a Radial JDV, which I love and highly recomend. It's meant to be a DI box that splits the guitar's output so you can send a non-compensated dry signal to your console. It has two outputs that incorporate what Radial calls "drag". The drag control adjusts the load before the signal goes to the outputs on the box, which feed your amp. There's also a -30db pad, so you can insert your JDV after it exits your cab.


    It is important to note that Radial says you will damage your JDV if you insert it into the amp's speaker output path. So I can't use it to do Direct Amp Profiles. So I'll buy a JDX.


    I suspect many technically savvy users here are missing the fine distinction as to what type of DI box they need to do Direct Amp Profiles. I know it took me a while to understand the hardware requirements of the DI box to do this profiling method.


    Scratch17