Kemper SPDIF and Main Outs sound different (worse) than headphone out

  • Hi guys, I have a problem with my setup. If I listen to my sounds using headphones in the kemper it sounds stellar. If I listen to them going via spdif to my audio card (Motu 828 mk3) in Logic pro x the quality of the sounds decreases drastically (using the same pair of headphones). They are not as round and three-dimensional as listening to them with the headphones directly in the kemper. I matched the volumes but there is a clear difference. Any thoughts?

    Thanks for your help!

    Filippo

  • The general speculation here is that the Kemper HP amp does some magic. You can try feeding your Motu from the HP out to confirm this.

    Kemper PowerRack |Kemper Stage| Rivera 4x12 V30 cab | Yamaha DXR10 pair | UA Apollo Twin Duo | Adam A7X | Cubase DAW
    Fender Telecaster 62 re-issue chambered mahogany | Kramer! (1988 or so...) | Gibson Les Paul R7 | Fender Stratocaster HBS-1 Classic Relic Custom Shop | LTD EC-1000 Evertune | 1988 Desert Yellow JEM

  • I’ll check on that , thanks!

    Remember that you can send SPACE through SPDIF as well. Just deactivate the „Space Headphone only“ option (yes, it‘s a double negative to activate Space for SPDIF). I used to have the same issue as you but with SPACE activated and the higher bit rate both the Kemper headphone out and my Focusrite sound the same now.

  • The bitrate should make no perceptible difference whatsoever, but the Space setting, yes.


    The 96kHz option is simply the standard 44.1kHz output upsampled, the point being one of convenience when running one's DAW at 96kHz.

    I A/B'ed the bitrates several times and to my ears they really made a difference. Not saying I might not have imagined it or played the guitar slightly different each time but I was sure enough to leave it on 99khz. Maybe it has to do with how my Focusrite receives the data, not sure.

  • I A/B'ed the bitrates several times and to my ears they really made a difference. Not saying I might not have imagined it or played the guitar slightly different each time but I was sure enough to leave it on 99khz. Maybe it has to do with how my Focusrite receives the data, not sure.

    It's possible that the interface produces a slightly-better result due to an intentional sweet spot.


    Think about it:

    If you're selling an interface featuring several bitrates, you'd want to make sure that the higher the rate chosen, the better-sounding the result. It'd look like you were selling snake oil otherwise.


    This is a phenomenon I've seen across-the-board for many years now. Comparing rates on the same physical (model and brand) interface is not an apples-to-apples comparison, therefore. So many peeps don't think of this.


    Anyhow, if you used S/PDIF as I think you did, the sweet spot thing shouldn't apply 'cause A/D conversion wouldn't have been taking place. In this case, you'd have been better off playing a loop whilst switching rates or soloing pre-recorded tracks. That way your expectations couldn't influence your playing.


    Better still, toggling the playback of the two tracks with eyes closed until you lose track of which one is solo'd removes the possibility of confirmation bias altogether. In this scenario, I doubt you'd have been able to hear any differences 'cause technically there shouldn't be any. As I said, it's just the 44.1kHz signal upsampled, so it's essentially the same sound-wise.


    You could prove this to yourself by inverting the phase of one of the tracks and seeing if they null to zero, which they should.

  • Remember that you can send SPACE through SPDIF as well. Just deactivate the „Space Headphone only“ option (yes, it‘s a double negative to activate Space for SPDIF). I used to have the same issue as you but with SPACE activated and the higher bit rate both the Kemper headphone out and my Focusrite sound the same now.

    Thank you man, it did the trick I think! I'll check about the higher bit rate now, but I just found out that I cannot go higher than 48 kHz. At 96 kHz I get no sounds anymore. Anyway, getting there. Many thanks!!

  • Thank you man, it did the trick I think! I'll check about the higher bit rate now, but I just found out that I cannot go higher than 48 kHz. At 96 kHz I get no sounds anymore. Anyway, getting there. Many thanks!!

    Awesome! If you still want to try the higher sample rate, you need to change it on your soundcard and the Kemper to the same rate, otherwise there is no sound. The motu audio console can change to 96k, then you should use the Kemper as the master and the motu as slave. On my focusrite I have to snych to SPDIF (not internal) and then change it on the Kemper to internal. It‘s a bit unintuitive but you‘ll figure it out. Basically both devices have a romantic dance and you need to decide which one is leading.

  • Awesome! If you still want to try the higher sample rate, you need to change it on your soundcard and the Kemper to the same rate, otherwise there is no sound. The motu audio console can change to 96k, then you should use the Kemper as the master and the motu as slave. On my focusrite I have to snych to SPDIF (not internal) and then change it on the Kemper to internal. It‘s a bit unintuitive but you‘ll figure it out. Basically both devices have a romantic dance and you need to decide which one is leading.

    yes I’ll mess with the higher sample rate ASAP.
    have a nice day man!

  • yes I’ll mess with the higher sample rate ASAP.

    Honestly man, you'd be looking for a solution to a problem you don't have if you did this... IMHO.


    In addition, you'll be opening cans of worms unnecessarily too, such as "should I run my DAW at 96kHz now?"...

  • ... since he is sure I was talking nonsense.

    And it actually IS nonsense as long as it isn't put into context. A higher sample rate in itself won't result in better audio quality unless one knows how/when it makes sense to work with it.

    Just like it doesn't make sense to run a tuned Scania truck in a GT2 race just because it has more horsepower ... and it doesn't even matter if it's an amateur driver or a pro driver on the steering wheel. More isn't automatically better.