SPDIF Output Levels

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mikeb

Intermediate

Posts: 183

Thursday, April 26th 2012, 5:26am

SPDIF Output Levels

I'm reposting this from the problems forum in case it helps someone else.

Using SPDIF out on the Kemper into my DAW sound card I got clipping with most profiles without changing anything, much much too loud. Here is what I found:

Inserting a Gain control on the SPDIF input (in my soundcard control panel software)allowed me to remove all clipping with all profiles. I had to drop the Gain by -11db(depending on profile). After this the Kemper sounds perfect. Exactly like the XLR outs. I didn't even know you COULD have a gain control on a SPDIF.. I probably don't understand SPDIF. I figured that a device cant send a SPDIF signal passed +0db but in this case I must be wrong about what is happening.

Also, it helps to max the Master Volume even if you use the SPDIF (and the Master has no effect) because you can see if the output levels are clipping via the Clipping light.

PS thank you C.K., your advice about changing gain controls along with statements about dropping overall volume levels by 6db got me on the right track.

This post has been edited 1 times, last edit by "mikeb" (Apr 26th 2012, 5:46am)

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dhodgson

Intermediate

Posts: 210

Location: Silicon Valley, CA

Thursday, April 26th 2012, 8:12am

Sounds like it's time to take some measurements again.

-10dBFS from my DAW -> KPA over S/PDIF with Master Volume at 10.0 (not that it matters) and Volume at 0.0dB with Stomps, Stack and Effects Off should yield -10dBFS when echoed back from the KPA over S/PDIF out.

But it doesn't anymore (It used to, for S/PDIF.) It currently reads -4.1dBFS, and since I'd left my analog calibration intact from the older firmware the analog line outs seem to reflect this as well (i.e., the line outs are running hotter as well.)

Why is this so hard to nail down? C'mon Chris, this is the easy stuff!

-djh

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mikeb

Intermediate

Posts: 183

Thursday, April 26th 2012, 8:45am

I also have to report that profiling a modeling stomp box yielded input being overloaded when profiling, no amount of fussing got the level from the direct output send low enough.

Conclusion: direct output send out is too hot as well, I suppose if i had a mixing board I could compensate, but as is, the direct out does NOT send the same level as what goes into the INPUT.

[edit] playing during profiling is what I mean, when I try the direct out in browser mode, the levels are the same.

This post has been edited 1 times, last edit by "mikeb" (Apr 26th 2012, 9:25am)

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professortweed

Intermediate

Posts: 200

Thursday, April 26th 2012, 12:24pm

I have found this too when profiling amps. A very hot sound is going out of the direct out and I don't like it. I deal with it by altering the input sensitivity settings and inserting 'the pot' pedal between the kemper and the amp. I really would like the sound from my amp via Kemper direct out to be the same as it is when I go direct into it with my guitar.

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ckemper

Moderator

Posts: 890

Saturday, April 28th 2012, 3:39am

Please check again if the level of the direct out changes when switching between Browser mode and Profiler mode. It should not change.

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ckemper

Moderator

Posts: 890

Saturday, April 28th 2012, 3:42am

Quoted from "dhodgson"

Sounds like it's time to take some measurements again.

-10dBFS from my DAW -> KPA over S/PDIF with Master Volume at 10.0 (not that it matters) and Volume at 0.0dB with Stomps, Stack and Effects Off should yield -10dBFS when echoed back from the KPA over S/PDIF out.

But it doesn't anymore (It used to, for S/PDIF.) It currently reads -4.1dBFS, and since I'd left my analog calibration intact from the older firmware the analog line outs seem to reflect this as well (i.e., the line outs are running hotter as well.)

Why is this so hard to nail down? C'mon Chris, this is the easy stuff!

-djh

Yes, it's easy.
Please check the Clean Sense parameter in the input section. It has an impact on the pure input gain, while not changing the gain of distorted sounds.

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ckemper

Moderator

Posts: 890

Saturday, April 28th 2012, 3:44am

RE: SPDIF Output Levels

Quoted from "mikeb"

I'm reposting this from the problems forum in case it helps someone else.

Using SPDIF out on the Kemper into my DAW sound card I got clipping with most profiles without changing anything, much much too loud. Here is what I found:

Inserting a Gain control on the SPDIF input (in my soundcard control panel software)allowed me to remove all clipping with all profiles. I had to drop the Gain by -11db(depending on profile). After this the Kemper sounds perfect. Exactly like the XLR outs. I didn't even know you COULD have a gain control on a SPDIF.. I probably don't understand SPDIF. I figured that a device cant send a SPDIF signal passed +0db but in this case I must be wrong about what is happening.

Also, it helps to max the Master Volume even if you use the SPDIF (and the Master has no effect) because you can see if the output levels are clipping via the Clipping light.

PS thank you C.K., your advice about changing gain controls along with statements about dropping overall volume levels by 6db got me on the right track.

This is a bit confusing.
Where do the profiles clip? In the KPA or on your DAW?
The Master Volume has no effect on the level LED.

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mikeb

Intermediate

Posts: 183

Saturday, April 28th 2012, 4:31pm

RE: RE: SPDIF Output Levels

Quoted from "ckemper"

Quoted from "mikeb"

I'm reposting this from the problems forum in case it helps someone else.

Using SPDIF out on the Kemper into my DAW sound card I got clipping with most profiles without changing anything, much much too loud. Here is what I found:

Inserting a Gain control on the SPDIF input (in my soundcard control panel software)allowed me to remove all clipping with all profiles. I had to drop the Gain by -11db(depending on profile). After this the Kemper sounds perfect. Exactly like the XLR outs. I didn't even know you COULD have a gain control on a SPDIF.. I probably don't understand SPDIF. I figured that a device cant send a SPDIF signal passed +0db but in this case I must be wrong about what is happening.

Also, it helps to max the Master Volume even if you use the SPDIF (and the Master has no effect) because you can see if the output levels are clipping via the Clipping light.

PS thank you C.K., your advice about changing gain controls along with statements about dropping overall volume levels by 6db got me on the right track.

This is a bit confusing.
Where do the profiles clip? In the KPA or on your DAW?
The Master Volume has no effect on the level LED.

Ok I was incorrect about the Clipping Light, my bad.

The clipping is in my DAW which is a EMU 1212M based computer setup. I am running the SPDIF out from the Kemper into the SPDIF in on my soundcard, set to slave. The clipping generally occurs with palm mutes, when the bass tones are the strongest. I have never experienced SPDIF clipping before. Not sure why the Kemper is so loud in this respect.

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ckemper

Moderator

Posts: 890

Saturday, April 28th 2012, 11:11pm

Where is the clipping showing up exactly?
In the DAW?
Monitor speakers?

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ChrisBeaver

Intermediate

Posts: 423

Sunday, April 29th 2012, 2:31am

Quoted from "ckemper"

Where is the clipping showing up exactly?
In the DAW?
Monitor speakers?

For me The spdiff levels are way way too hot with rig volume on no 2 its ok but anything louder and it clips from the kemper thats on every profile without exception i have been able to compensate by lowering the spdif levels on my sound card but not everyone has this choice with their soundcard. Please Christoph put the spdiff volume level on the master volume again i cannot understand why you removed this crucial feature?