Latency between digital D.I. and Amp Signal via SPDIF. Does the Kemper have any delay compensation?

Hey there,

maybe an old issue, but couldn't find anything here specifically related to this:

I am using a Profiler Stage and going out digitally via SPDIF, left channel D.I., right channel Kemper amp-signal. After converting to optical they go straight into an RME Babyface into my DAW.

The signals sound great on their own, but I figured re-amping the D.I. signal in the DAW isn't such a joy cause there is quite a lot of latency between the D.I. and the Kemper Amp signal, thus resulting in phasing.

I know, that this is apparently due to the digital signal processing of the Kemper Amp signal in comparison to the non-processed D.I., but isn't there anything like delay compensation for this in the Kemper?

I am afraid, there is not, right?

Thank you!

Hey Alan,

Thank you for responding so quickly! This is helpful to know. I think I am doing 44.1k, but I will double check again.

As far as latency compensation in the DAW goes, I know that it's possible to compensate for the DAW-internal Plug-In's etc, but that won't do much for signals having phase issues before even entering the DAW itself, as I'd suppose.

There are some phase allign plug-ins, I know, and they can help to some extend. The thing is, however, the phase difference isn't always the same, depending on the Kemper-sound used, as far as I am concerned. Sometimes it is more, sometimes less.

Thus, a Kemper-internal-phase compensation would have been quite handy.

But anyway, you've already answered my question!
Thank you again!

Hello Musicmad,

Thank you for your advice! Yes, I tried to to sample-nudge it in Logic, it ends up being around 20 samples. But it is not too accurate that way. The best way to deal with it in the DAW I found is to take a alignment plugin, I just took the Waves one. But still, it is phasing sometimes during some periods, and on other recordings the alignemt needs to be of a different value. So it can be quite a drag...

However, I don't really undestand what you mean by Kemper as an outboard effect. You mean sending the DI out of the DAW to the Kemper and sending the amp-processed signal back to the DAW? I think that would just add a round trip you are talking about. So, if the DAW compensate for the round trip dealy, I am still left with the delay of the Kemper processing itself compared to the DI signal I would like to process with Plug-Ins in the DAW, or am I getting something wrong here?

Thank you again : )

Hello Christian,

Thank you for your answer!
I think it goes the same direction Musicmad has suggested.

So you both are talking about just sending the DI out of the DAW -> Kemper-Amp-Processing -> DAW, right?

I am not sure, however if Logic even has hardware latency compensation, I think it is only internal plug-in latency compensation.

Quote from christianbad

in Pro Tools you can put in a value for latency caused by external gear used as an insert, and than the compensation works (hardware insert delay)

Maybe the RME driver has a similar setting?

that´s what "constant latency" in the profiler settings is for.

I've read about 'constant latency' somewhere in the manual, but it sounded like it would only be recommended for scenarios in which the Kemper is connected to another Kemper and their signals are gonna be mixed? Sounds like a good hint, though!

Thanks so much, Alan, I will try this, that sounds good!

Quote from Wheresthedug

This looks like a good explanation of how to use it.

Hey Alan,
That is great! Thank you so much! I will dive deep in this tomorrow, and let you know if that worked for me. Great, Thanks again!

Quote from christianbad

no, that´s not what i meant. if your daw can´t adjust the the latency, you´d have to measure the roundtrip latency (daw-into kamper- back into daw) and that depends on how you connect the kemper (spdif(analog/usb) .

For normal playing the latency depends on how much fx you use in the kemper, (to minimize latency ).

fot reamping, with constant latency enabled, you get excatly that, always the same latency

Oh, I see. This very helpful! I will try this roundtrip, that makes sense, indeed.

As you can see, I am not too familiar with the whole latency issue.

Thanks so much guys, great forum here!

Alright guys,

I was able to accomplish this round trip setup. And the more I get into it the more I understand that my previous questions from my most current post where not too reasonable...
Neither did I know that Logic would create a ping/peak signal on its own nor that the different kind of Kemper-Amp-sims you'd use would cause different latencies, regardless if you're using FX or not.

So, I just put the I/O plug-in on a Logic channel aux/bus and used the usb connection to the Kemper to create a round trip on input/output channels 3-4, having to choose the Profiler as input and output in the preferences first of course. The spdif I usually use as the connection from the Kemper into my DAW and wanted to test in the first place wouldn't work, since once you are using reamping in Kemper to send back the stereo or stack signal via USB it would not let you take spdif as an Input source anymore.

Anyway, this worked eventually at least with USB, and it all took me a while to figure it out.

So, then I ping-ed and it eventually showed me a latency offset.

Depending on which buffer size I would choose in the preferences, I'd get latency offsets of 1434 samples (1024 samples buffer size) or 343 (for a 32 samples buffer size) - both regarding the same Kemper profile of a distortion sound. So, if I do the math, that leaves me with around 7,7 ms (343/44100 x 1000) for the smaller value, which seems to be in the ballpark of what I was expecting. I usually have the buffer size on 1024 samples for mixing, though.

However, what actually is it about the buffer size in this scenario? I would have to subtract the buffer size samples from the latency offset to do it accurately, cause I only care about the offset between the amp and DI signal within the Kemper, correct? So, for the smaller value, it would be 311 samples latency offset, right?

OK, but even if I do all this (with having set the Kemper to constant latency) and delay the DI track region by this value (converting it to ticks), the phasing varies a lot depending again on which amp sim I use on the DI in logic. I mean, of course, I would suppose so it differs, cause different amp sims have different algorithms, but I would have thought that this is what the latency compensation in Logic is for, and that it wouldn't differ so much.

So, long story short: Once I know the latency offset of the Kemper for a certain sound, is there a smart way to have it all in phase in Logic with different Logic-internal amp sims? Is it - again - about the buffer size? Am I not getting something here completely? Aside from the latency while recording, buffer size doesn't affect the actual latency of the recording itself, right? Sorry, for being such a greenhorn, I just want to exclude any potential failures...