Reamping - Latency / phasing with Apollo twin (spdif into interface, analog return back to kemper)

    This one is giving me a bit of a headache so figured I would ask for help - did a lot of googling but couldn't find anything about my specific situation, please let me know if I've left out any details / variables


    So I'm connecting the kemper to my apollo twin x via S/PDIF (using one of these) - so far so good.


    Because the twin x only has optical/spdif in and not out, I'm sending the kemper DI back to the kemper through an analog output (Maybe this is breaking/deviating from the interface clock source?), and then I'm getting the reamped track back into the DAW through the spdif input on the interface.


    So when I go to reamp, the reamped track always ends up in the wrong place inside the DAW, layering that reamped track directly on top of the original wet recording and it's never right, no matter what I change; clock source on the apollo, the clock option on kemper output, enabling constant latency, etc.


    This has me pretty confused and questioning whether or not any of the DAW recordings, reamp or not are ending up in the right place - might just be overthinking it, but I am really shooting for precision.



    Anyone who has their head wrapped around this better than me, I would appreciate your input!

    Quote from washedburn

    So when I go to reamp, the reamped track always ends up in the wrong place inside the DAW

    Wrong place means here at the wrong moment "in time", i.e. a bit delayed by some msec which are actually the sum of what you describe above, right?


    I can only speak here for my case and I am using Cubase as my DAW: Cubase takes care of this delay perfectly when the setup is correctly made. And actually all (analog) outboard gear creates this kind of delay so it is a standard functionality which was already needed way before the Kemper or re-amping with it kicked in.


    In my Cubase setup there is a function to detect the exact delay (that's by the way the reason why you need to put the constant latency on in the Kemper, otherwise it would vary depending on the profile / rig). Once detected the Kemper can be used as outboard gear and Cubase positions the re-amped track at the exact right point in time...


    Depending on your DAW that function might have different names but in principle all DAWs should have something like it. Alternatively you can add a reference point to each recorded track, e.g. make a chug at the beginning so you can later position it manually as close as possible...


    Hope that helps for your case as well 8)

    Quote from deadman42

    Wrong place means here at the wrong moment "in time", i.e. a bit delayed by some msec which are actually the sum of what you describe above, right?


    Depending on your DAW that function might have different names but in principle all DAWs should have something like it. Alternatively you can add a reference point to each recorded track, e.g. make a chug at the beginning so you can later position it manually as close as possible...


    Hope that helps for your case as well 8)

    Yeah, looks to be off ~4ms. I will look for that. I'm currently using reaper since I know it the best. I'm not super hip to all the recording nomenclature, but using the term "outboard gear" will hopefully lead me to the right place. Reaper does have options for "output manual offset", and "input manual offset", just slightly worried about fiddling with those in case it screws up my regular recording, although I think I should be fine adjusting the output, and that would leave my regular non reamp recordings be if I'm not mistaken? Maybe that's the solution


    Thanks for taking to time to reply! Will post my solution if I'm sure I have it figured out

    Ok so - update


    After making sure constant latency is on:


    1. I right clicked the reaper timeline, and had it measure by "Samples" instead of "Measure.Beats",
    2. I then reamped a few seconds and stacked it under the original wet amp track,
    3. turned off snapping (alt+s) and zoomed way in and selected the difference between the tracks
    4. To the left of the tempo box, it told me how many samples I had selected, I inserted this as "Output manual offset" in preferences > recording
    5. Redid the reamp, dragged it under the original wet track and checked the alignment, looked good, I played it back, no phasing.
    6. Fully confirmed by taking two copies of the original wet track and stacked them on top of each other, sounds the same as the pair with the reamp!


    So - assuming setting "Output manual offset" won't affect my live recordings, I think this is the solution.


    Thanks again for the reply deadman42


    And for anyone else using reaper who finds this, I'm going to check if there's a way to do this automatically and will update...

    Cool, glad you got it sorted :thumbup:8)


    After quick search it seems that for the outboard gear the ReaInsert function is the go to place. Lots of info around there, e.g. here where the usage of an external unit is explained in detail.


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