Kemper REAMP with SPDIF

REAMPING PROCESS

(this guide is tested and builded for MBOX Audio Interface but can be easily used for any sound card that have at least 2 analog in, 2 SPDIF in, 2 analog out and 2 SPDIF out)

STEP 1 – Direct Signal Recording (using SPDIF Output for the Dry recording and Main Analog Out for monitoring)
DAW
1)      Arm 1st track (Input 1+2) for recording the full processed signal from the KPA Analog Main Out
2)      Arm 2nd track (Input 3+4) for recording the dry signal from the KPA Digital SPDIF Out
Kemper
1)      Output Page on “Reamp” with Main Out = Master Stereo and SPDIF Out = Studio Git or any other with Git on the Left channel (only the left channel of the SPDIF Input will be taken for the Reamping)
2)      Input Page with Input = Front Input and, if possible, CleanSense=0 and DistortionSense=0 (it simplify the 2nd step of the reamp process)

STEP 2 – Reamped Signal Recording (using Main Out for Analog Reamp recording or SPDIF Output for Digital Recording)
DAW
1)      Arm 3rd track (Input 1+2) for recording the full processed reamped signal from the KPA Analog Main Out
2)      Route the DAW Output (from Mixer) of the SPDIF Dry Track previously recorded to Out 3+4 (=Software Returns 3+4 or Digital OUT)
Kemper
1)      Output Page on “Reamp” with Main Out = Master Stereo (for Analog out recording) or Page on “Default OUT” with SPDIF Out = Master Stereo (for Digital out recording)
2)      Input Page with Input = SPDIF Input (only the left channel of the SPDIF Input will be taken for the Reamping) and, if possible, CleanSense=0, DistortionSense=0 and ReampSense=0 (it simplify the process)

HARDWARE and Audio CONFIGURATION
This configuration is for the MBOX Pro Control Panel but can be used for any Sound Card
1) Outputs 1/2 = Stereo Mix   with Input 1+2 Active = 0db, all the others Input on Mute (including SPDIF Input 7+8 to avoid to listen to Direct Signal of the guitar in the recording monitoring); Main Output 1+2=0db

Outputs 3/4 or SoftWare Return 3+4 Active = 0db (all the others Software Return Output on Mute);
2)  SPDIF Out Mixer = Stereo Mix with active only the Software Return Output 3+4 and all the rest (Input and Output) on Mute
3) CLOCK     In the MBOX Control Panel Setup Menù put Clock Source = SPDIF and
BufferSize (latency) lower or equal to 256 (5,8 ms) [128 –> (2,9 ms)]; Sample Frequency 44,1 KHz
Hardware Wiring
1)      Connect the SPDIF In from the MBXOX to the SPDIF Out of the Kemper
2)      Connect the SPDIF Out from the MBXOX to the SPDIF In of the Kemper
3)      Connect the Main Analog Out Left+Right from the Kemper to the Analog In 1+2 of the MBOX

TIPs & TRICKs
·         To Reamp more times the same track and avoid phase issues it’s needed to use a constant latency (Output Menù – Page 5) that will be of 4,5 ms
·         Latency additional is introduced when Reamping respect to the original Analog Direct Recording, with MBOX Pro the additional latency is a delay of around 55-65 samples (1,2-1,5 ms)
·         When Reamping (but also when recording directly) it’s good to compensate the latency with a negative delay of samples in the track: each 128 samples are approximately 3 ms of delay, so considering the latency of 256 samples introduced by the DAW two times (first step and second step of reamping) plus the latency of the KPA of others 3 ms, a good value should be between 768 and 1024 samples.
NOTE: A good Sound Card + Good ASIO Driver should automatically compensate the DAW Latency –> Test on Mbox Pro shows that it do!
·         Using both the Digital SPDIF In/Out; leaving the same levels on the various mixer all to 0db; leaving CleanSense, DistortionSense and  ReampSense all to 0db the Reamp process is very simple and the levels are perfectly matched.
·         The CleanSense doesn’t work in Reamp Mode with SPDIF Input selected, so it has to be compensated with the appropriate ReampSense.
·         The CleanSense for Dry SPDIF Signal Recording acts exactly as a pure Booster from -12db to +12db indipendently from the Gain level of the Amp while for the Amp sound it acts as a pure booster variable with the gain knob position;
this means that for a simplest process it’s better to leave CleanSense to 0db (to avoid further leveling) but to have maximum Signal-to-Noise ratio it’s better to put CleanSense at +12 before record the dry signal and then leveling the dry signal before the reamping putting ReampSense to -12.
•    Before start the reamping process take note on the track (i.e. in the name of the recorded file) of which level of CleanSense has been recorded the dry track to be sure to have the information in the future for correct leveling of the track before reamp. For an optimal leveling before reamping it has to be compensated the CleanSense value with the same opposite amount of the ReampSense value.
The level of DistortionSense instead is perfectly replicated before and after the Reamping in the Step1&2, so it is possible to leave as it is without taking particular notes on that.
•      If the SPDIF Dry Signal is recorded with CleanSense at +12db (with Gain of original Profile between 3 and 4) to compensate and obtain the same sound and level on reamping you can use one of these options
a)      Put Reamp Sense to -12 db before reamping, leaving the dry recorded track to the same volume originally recorded
b)      Lower the track from Sequoia (DAW) to reamp at -12db of the original recording and after reamping rase the volume of the reamped track of 6 db
•     If the SPDIF Dry Signal is recorded with DistortionSense at -12db to compensate and obtain the same sound and level on reamping you can use one of these options
a)    Put DistortionSense again to -12 db before reamping, leaving the dry recorded track to the same volume originally recorded
b)    Put Reamp Sense to -12 db before reamping, leaving the dry recorded track to the same volume originally recorded
•     Pickup FEEDBACK from AUDIO Speakers: in the pickup the speakers sound of the room enter of about 60 db under the clean signal (on a vintage pickup). The problem of backing is more audible when the gain of the amp is very high because of compression.
The Noise Gate on the Input section and the Noise Gate Stomps helps a lot to reduce such problem. With Noise Gate Stomps higher than 3 in the first position the feedback is almost completely cancelled.