Anyone created a Direct profile using the direct/slave out of an amplifier?

    Been thinking on Direct/Merged profiling lately, along with the need of a direct box for Direct Amp Profile creation. Some amps, such as a Mesa MkIII, have a direct or slave out. It is basically a tap on the speaker lead that has attenuation and output level control to allow the amp speaker output to be run directly to rack mount equipment or additional amp inputs.


    I can't think of a single reason why this type output cannot be connected directly to the Return jack of a Kemper and used in place of a direct box for the Direct Amp Profile process. Of course the output of the amp must have enough attenuation to be within the Kemper's Return jack signal range.


    Has anyone tried this method for Direct Amp Profiles, if their amp has such an output? There might be some gotcha that I have missed. It might give far better results than say a less expensive direct box.

    Quote from MKB

    Been thinking on Direct/Merged profiling lately, along with the need of a direct box for Direct Amp Profile creation. Some amps, such as a Mesa MkIII, have a direct or slave out. It is basically a tap on the speaker lead that has attenuation and output level control to allow the amp speaker output to be run directly to rack mount equipment or additional amp inputs.


    I can't think of a single reason why this type output cannot be connected directly to the Return jack of a Kemper and used in place of a direct box for the Direct Amp Profile process. Of course the output of the amp must have enough attenuation to be within the Kemper's Return jack signal range.


    Has anyone tried this method for Direct Amp Profiles, if their amp has such an output? There might be some gotcha that I have missed. It might give far better results than say a less expensive direct box.


    Hello MKB,


    What you described is not a "Direct" profile, at least not as the term is used by Kemper. You may be confusing the term "Direct Input", or "Direct", with the KPA terminology "Direct Amp". A "Direct Amp" profile involves a suitable DI box (with a speaker load connected), which makes a complete profile of the reference tube amp at the amp's Speaker Output. In other words, a "Direct Amp" profile includes both the preamp AND poweramp stages of the reference tube amp.


    In your quoted example (M-B MkIII), if you make a profile using the MkIII's direct out, you will only be making a profile of the preamp section. The signal has not passed through the amp's power / output stage. While there is nothing "wrong" with making a profile of just the preamp section, it is not to be confused with making a complete profile of an amp. A lot of interesting dynamics and unique tone occurs in the interaction between the amp's output stage (power section and Output transformer) and the connected speaker load. The poweramp tubes also contribute their own characteristics to the final tone.


    Hope this clarification is helpful.


    Cheers,
    John

    Edited 2 times, last by Tritium ().

    I agree with Tritium.


    What I have done is profiles of amps that include loadbox; plenty of amps like that these days. Some with cab emulation, some where you can turn it off for a "direct" profile too. In these cases power amp works too.


    Just run output from amp to kemper return..


    Profile, done :)

    I think both of these guys understood your question wrong @MKB.


    You can totally use slave out to create a direct profile. Slave out is nothing but an attenuated speaker out, so it is kind of like a DI box built inside the amp. But, remember that you will need a load for the amp still. Be it a load box or a speaker cab.
    I once compared DI profiles I made with a direct box and the Slave out of a Mesa Rectifier. I think I liked direct box version a bit more, but that is of course a personal preference.

    Thanks for all the replies. A few things: first, if you look at the schematic of the Mesa MkIII SimulClass power amp, the Direct out is a resistor/pot/capacitor connected to the 8 ohm speaker terminal of the amp. What I meant in my thread was to place the amp as it is in a space, with the speaker connected, and configure it for the tone to be profiled. But instead of plugging a direct box between the speaker jack and speaker for a Direct profile, take a lead from the amp's Direct out to the Remote in of the Kemper. At first look this should work perfectly, as 1) the Direct out samples the signal to the speaker from the power amp, thus providing the full amp tone, 2) the tube power amp has the proper speaker load, and 3) the high level signal to the speaker is attenuated to the level that can be fed into the Kemper.


    To then create a Merged profile, you could then leave the setup as is and mic the cab, to complete the profile.


    The idea is if you don't need a direct box due to the amp having a Direct out, why use a direct box? The Direct out (at least how it is implemented by Mesa in the MkIII's case) should work OK. I just wonder if I'm missing any technical gotcha I haven't thought of such as requiring galvanic isolation between the amp and Kemper.


    citizengain, thanks for the info on your experience with the Rectifier, the Dual Rectifier's Slave Out is the exact type of output I am referring to. The tonal difference is very interesting, perhaps the direct box is shaping the tone a bit?


    Ah, I see. I had to search for the user manual as well as a schematic for the Mk III (which I found). Indeed, @citizengain and yourself are correct on this matter. My apologies. This is a first, for me. Every other time I have seen a "Direct Out" on a tube amp, it was simply pulling off the signal prior to the poweramp stage, and often having this signal run through a built-in "speaker emulation" filter.


    Indeed, the Mk III "Direct Output" looks like it would be suitable for making a KPA Direct Amp profile. Most importantly, there is no "baked in" speaker emulation being applied to the Direct signal (which would pretty much defeat the purpose of this exercise). The only thing that you will probably have to tweak, is the potentiometer dial on the Direct output, in order to dial in the appropriate signal level you will send to the KPA Return Input, during the profiling process.


    Sorry for my initial misunderstanding of the Mesa Boogie's Mk III Direct Out circuit.


    Cheers,
    John

    The main reason I'm going down this path is that a good proper direct box will be spendy. The Kemper direct box looks extremely nice, but it's kind of a one trick device (only truly good for Direct/Merged profiling of loud amps). But a man could make a very inexpensive device that has a resistor, pot and a pair of 1/4" jacks, plug it directly into a spare speaker out jack of most any tube amp, and plug the other end into the Kemper. That would be one of the most inexpensive projects you could do, you could even repurpose an old effects pedal if you knew what you were doing. And due to the simplicity of the circuit, it could give better results than a less expensive direct box that would color the sound.


    I'm just going to have to build one now and try it out.

    Quote

    But a man could make a very inexpensive device that has a resistor


    If I remember correctly, Kemper says that DAP direct boxes should not have a resistor in the path. Check out the thread that discusses
    DIs for DAPs.

    Quote from scratch17

    If I remember correctly, Kemper says that DAP direct boxes should not have a resistor in the path. Check out the thread that discusses
    DIs for DAPs.

    Thanks for the heads up, I found that information, and it was where one member said CK said in a video that a resistor based direct box would not give accurate results. Subsequent threads refined this to mean a direct box with a resistive load (in place of a speaker) would not give accurate results. I'm in full agreement that using a resistor in place of the speaker would give unnatural sounding results; the Slave Out/ Direct Out circuit in the Mesa amps only use resistors to attenuate the speaker signal, they still use the speaker as a load. This is a different setup than CK was referring to.