Posts by Todd78

Yes, new Kemper Beta-Firmware 7.5 brings faster SPDIF Latency!

I did a test (44,1kHz) with Constant Latency = ON:

Main Out = 4.9ms (+217 samples)

SPDIF = 4.33ms (+191 samples) -> old release = 8.3ms (366 samples)

So, it’s no longer necessary to use the MainOuts to Audio interface for monitoring while recording SPDIF (Maybe just if you want to record SPDIF DI mono/Wet mono and use stereo effects in the Kemper while monitoring…)

My new Reaper offsets for aligning the recordings/reampings are:

“Use audio reported latency” = Flagged

Output manual offset: -16 samples (-> wet reamp signal arrives a bit faster – I don’t know why… ???) ckemper

Input manual offset: + 191 samples

All measurements with RME Fireface -> this device do not have any calculation errors reported from the driver to Reaper. So the Reaper offset values can be just the Kemper.

Since the testing was done fast, I hope there are no errors… maybe someone can check and confirm what I figured out

Quote from FlyingPig

Todd78 Almost all of them are merged. There's a pdf that comes with the pack that says which ones are merged and which ones aren't.

Thanks! I could download it - nice! I like merged profiles since I like to use Ownhammer impulses (And Lasse knows how to dial in an amp!)

Quote from tooltool

Best i have found are stl lasse lamert pack

All are merged and he really knows how to dial in the amps.

Are you sure the STL Lasse Lammert profiles are merged? I don't find any info about that on the STL homepage...

Maybe it could be implemented via control flag like this for "Monitor Cab Off" ?? There is already room on the same screen! Please do it - cannot be too dificult to get a "SPDIF Cab OFF"

Please, I would pay extra for that feature (or of course also for the other way I mentioned in the thread opener post)

If I record, I use Spdif, mostly both channels - DI and Wet. From what I‘ve noticed, there must be something like a limiter in the digital output of the KPA, probably to prevent clipping. Am I right?

You can check it, just watch the di or wet signal in your DAW, maybe it‘s on -6db when hitting hard, increase rig volume (and/or clean sense) by maybe 8db, hit hard, your DAW shows under 0db - and this, no matter how much you increase the rig volume... so there must be a limiter before the digital outs, I think?

So, probably it’s better to stay below -6 to -7db in your DAW from the KPA inputs , since I have the feeling, that the KPA Limiter starts to take action at about these values.

Dear Kemper-Team,

it would be extremly useful to have an option for SPDIF Output -> 'Git / Amplifier', in the way that the left channel is the DI-signal (like in 'Git / Stack') and the right channel is the signal pre Cabinet, just the Amplifier - yes I know this terrible distorted sound in high gain rigs

The use case is in recording for later use/change of Impulse Responses. Works this way:

- record DI signal (left SPDIF) for later reamping

- record Amp (pre-Cab) signal (right SPDIF), especially with merged profiles for use with IR loaders

- monitoring via Main Out - since no one wants to listen without cab when recording

I think it's no big thing, just a routing and would help so much!

Thanks,

Torsten

Quote from johnnypig

Just using the RTL utility from http://www.oblique-audio.com/free/rtlutility

Since USB itself is a dynamic latency RTL utility should be fine for Focusrite interfaces. I didn't bother adjusting sample offsets in Reaper since I wouldn't likely use software monitoring with the Kemper. It's also handy for figuring out hidden buffers which mess up Reaper's latency calculation.

The Apollo being thunderbolt 3 doesn't have the same problems with dynamic latency since it's basically external PCIe and you can also disable it's default 64 sample hidden buffer. Of course for the cost of this dang thing it better not have all those little annoyances.

I think we have a misunderstanding. The sample offset adjustments I do in Reaper are mainly for compensating the KPA-SPDIF-latency in the RECORDED items (375-13 In for the 1st recording + additonal 58 Out for a possible reamping loop, if needed). I also do not monitor through software, but through the KPA-Main Outs.

Testing your Apollo with a suitable sample (square wave) playing as source on Track A, sent to Apollo/Line Out->KPA/Front_Input and recording on Track B from KPA/SPDIF_Out->Apollo:SPDIF_In would show what I mean (the pure KPA/SPDIF latency). Parallel recording (maybe on Track C) of the KPA/Output/Guitar_Analog is like bypassing the KPA and possibly shows a possible audio driver latency calculation error. That's the value reported to the DAW to align recorded audio automatically (but of course without considering latency of external devices like the KPA). For my 6i6 it's negligible, -13 samples - but since I have to compensate for the KPA/SPDIF-latency anyway, I include the -13...

I'm not an English native speaker and I wished I could explain better what I mean

Quote from johnnypig

Constant latency adds latency like plugin delay compensation does in most DAWs. So for instance the pitch effects add a latency of a few mS. Enabling constant latency makes it so you don't feel that latency hit.

Just disable it. I get roughly 3mS with constant latency disabled measured with both a Focusrite Clarett 4pre USB via spdif and a UA Apollo x6 spdif.

Since the Kemper's spdif update there's no reason not to use spdif if your interface has it. The only minor annoyance is setting your interface to clock from the Kemper. Sound wise with good preamp/line inputs like the Clarett and Apollo there's no audible difference vs. spdif, but you shave a couple mS off the round trip.

Yes, that's correct, Constant Latency adds latency - but to both SPDIF and Main Out. The value added is dependent from the profile you use. So, if you got a profile that has 3ms, the difference is in this case 1.9ms - for me that's not noticeable. But, what's noticeable to me is the SPDIF-latency of 8.2ms (or 9.5ms for reamping), even if you'd substract the 1.9ms by switching CL off (then 7.6ms for reamping). You're right, there's still NO reason not using SPDIF for recording, because you can define an offset (at least in Reaper) in your DAW-preferences to compensate for that and get your item contents aligned automatically - that was just my tip here ...and I wanted to be sure my test cases where correct

How did you measure? As you can see I recorded parallel 4 destination tracks from one source track (KPA bypassed via Direct Out, Main Out, SPDIF Git & Stack). Imho the type of audio interface makes no difference, because it can never know about the latency an external device adds and automatically compensate for that.

Hi, I recently did some testing with the KPA - similar topic - maybe this helps and you can derive some settings for your interface:

Latency measurements KPA (Constant Latency = ON), Focusrite 6i6, Reaper 44,1kHz

Quote from dahla

Can one hear a delay of 362 samples?...

I like being on time and «tight», but this is midi-level tightness, isn’t it...

Edit: did the math, 362 samples at 44.1 is 8,2 ms...

And reamping is even 9,5ms - don't know why this takes even longer…

Aligning the recordings sounds better and more pro to my ears - but maybe it's a Metal-thing where everything has to be as tight as possible

Btw, I never had any problems with my 6i6 or the 8i6 - happy Focusrite-User here. Buffer setting during the tests was 10ms (you only can set ms in Scarlett Mix Control). But as we can see, the aligning error in Reaper based on the audio driver calculation bypassing the KPA was only -13 samples, just -0,3ms - that's really not noticeable.

Quote from Michael_dk

Interesting - so the SPDIF actually has MORE latency than the main out??

Yes, that's correct - I checked more than a few times - I couldn't believe it, too.

Hi, I did some tests with my KPA, since I had the feeling recordings could be a little tighter aligned to my drum-programmings. So, here are my findings:

(Constant Latency = ON), Focusrite 6i6, Reaper 44,1kHz

1) Recording (equivalent to a standard live recording Guitar->KPA Input connected to my 6i6):

- KPA settings

• KPA Input/Input Source = “Front Input”
• KPA Output/Direct Output = “Guitar Analog” (->Bypass KPA)
• KPA Output/SPDIF Output = “Git/Stack”
• switch off Stomp/Amp/FX-sections (original signal stays unaffected)

- Play Track 1: suitable sample (e.g. square wave or snare hit)

• Send 6i6:LineOut1 -> KPA:FrontInput

- Record on Track 2: KPA:DirectOut -> 6i6:LineIn3

• Recording -13 (minus!) samples (early/in Reaper aligned before source-sample, probably 6i6-driver-calculation-error)

- Record on Track 3: KPA:MainOut -> 6i6:LineIn4

• Recording 203 Samples late (consistent with the 4,9ms latency pronounced by C.Kemper, considering the 6i6-driver-calculation-error of -13 Samples)

- Record on Track 4: KPA:SPDIF_Out -> 6i6:SPDIF Left (Guitar Studio/DI)

• Recording 362 Samples late

- Record on Track 5: KPA:SPDIF_Out -> 6i6:SPDIF Right (Stack)

• Recording 362 Samples late

2) Reamping:

- KPA settings

• KPA Input/Input Source = “Front Input”

- Play Track 1: suitable sample (e.g. square wave or snare hit)

• Send to 6i6:SPDIF Out->KPA:SPDIF In (Reamp)

- Record on Track 6: KPA:SPDIF_Out -> 6i6:SPDIF_In Right (Stack)

• Recording 420 Samples late

That means for me and my environment to get all KPA-recorded tracks aligned automatically:

• To be save, Constant Latency always ON
• Monitoring with KPA:MainOutput->available 6i6:LineIns – 4,9ms latency

- Settings in Reaper to align recordings/reampings automatically

• Options/Preferences/Audio/Recording/Use audio driver reported latency = ON

• Output manual offset: 58 samples, compensating for the additional reamping-delay over 6i6:SPDIF Out->KPA:SPDIF In
• Input manual offset: 362 samples

--> Result, no more nudging necessary after Recording

What do you think – I hope this makes sense and there’s no misconception on my side?

Hey Guido, do you have plans to re-profile the Hagen or VH4 - maybe with Mesa 4x12 or Marshall AV Cab?

Quote from Guidorist

Hi, yeah, that's right. Sometimes we changed the mic position a bit to get the best possible results.
That's also the reason why on other amps or ME Boo 4x12 cab sounds different on other amp too because on every single amp we used completely different mic positions.
THX!

Great!!! I really like the micing and the sound of this Mesa cab! I have great DIs and HK Razor #5 is my fav cab for the heavier sounds (with a Dual Recti DI)

Schöne Grüße aus Sachsen-Anhalt!

Hi,

I have a question regarding the merged profiles - there are different cabs/cab-sounds in a merged pack (e.g. HK Razor Blade + Mesa 4x12er). I notice it if I lock the amp and change the cab... Is it because different mic positions were used? So I got variations of the micing of the Mesa 4x12er in the HK Razor Blade pack, if I understand this right?

Thanks
Todd

Do you have a package which includes a Roadking Cab miced with just a SM57?

Quote from Michael_dk

Interesting! Why is this, just out of curiosity?

Yes, that leaves back at least one unknown variable ;-), because we never know, is the LED red because of the 6db higher reamping sensivity or because of a possible signal adaption of the Audio Interface / DAW.

I bypassed my DAW this way - cable from KPA Spdif out straight to Kemper Spdif in.

I tested with hard hitting stuff and pinch harmonics:
Input source = Front Input -> led = green, very seldom yellow
Input source = Reamp Spdif -> led = especially with pinch harmonics orange and red

Does the KPA have something like a Limiter, that's only active when Input source = Front Input?

One of my guitars works perfectly with Clean Sense = 0.0 - Input led with hard strokes max. yellow. When I record the dry signal and play this track back to the KPA via reamping, the Input led lights red - so why is that? Which device changes the level? I mean, it's digital without converting (SPDIF) - 0 and 1 to the PC and back.
I think, in the excerpt from the manual Monkey_man posted, there's what I mean: "...the leveling is made to achieve an optimum signal-to-noise ratio, but does not deal with the preservation of the original instrument level."
--> I just would like to understand where this leveling is done - audio interface or KPA?

Hell_G, Monkey_Man, Navar - thanks for your answers!

@Navar, yes, it's the same I do - I name the DI-tracks in Reaper including the Clean Sense value I've tracked them, for reamping = reamp sense the opposite value - but it's often not the same sound with the same profile and the Input LED hits often red. So I'm interested in the exact difference value to dial in the DAW DI track - but maybe I want to be to exact
But eventually, it's really something that's dependent to the Audio Interface and the Kemper cannot know the difference value. In that case, I know, there is no way to get this feature...

Explained in a simple way I mean this:
Track 1 = DI (for the sake of simplicity Clean Sense = 0) / Track 2 = profile A
-> tracking these 2 tracks in Reaper
-> reamping DI track 1 with profile A on track 3 -> should be the same sound like track 2 - but it doesn't work this way. So the Kemper changes the level of the DI-signal or the Audio Interface does it.