Re: [QLab] Audio Distortion when file played through QLab

[ra byn taylor]

what is the file format?
Sample rate?
Bit depth?
What does the console say?

On Sat, Feb 9, 2013 at 11:29 AM, Bennie Netzley <bennie....@gmail.com> wrote:

I had something happen that has never happened before - audio distortion when a file is played through QLab.  The tracks were "crunchy."

I am using a Macbook Pro, running OSX 10.8.2
The audio interface is a Presonus FireStudio Mobile
Qlab version 2.3.8

The Presonus is the new addition to this setup.  I have used the Firebox with success in the past.

The weird thing is that the file itself is not corrupt.  Playing it through iTunes or even just Preview produces a clear sound through the Presonus.  I'm certainly perplexed.

I even tried tossing files into a new workspace, wondering if somehow the QLab sequence had become corrupt, but still had the same issue. 

Is there something unique in how QLab processes the track?  Or a setting that I'm missing?

[Charles Coes]

What are your levels going out of QLab?  

Is it possible you're boosting the levels to digital distortion in Qlab (you'd see red in the track meters, and should keep an eye on positive values on your faders, either the master or individual outputs.

Are you hearing the distortion in headphones, or in a mixer?

It is possible that the fireStudio has a hotter maximum output than the firebox and is clipping the input of your console.  The Dynamic range of the DAC is 8dB lager on the firestudio.  I'm not sure how that translates to analog signal level (maximum or minimum voltage changing?)

On Feb 9, 2013, at 12:29 PM, Bennie Netzley <bennie....@gmail.com> wrote:

I had something happen that has never happened before - audio distortion when a file is played through QLab.  The tracks were "crunchy."

I am using a Macbook Pro, running OSX 10.8.2
The audio interface is a Presonus FireStudio Mobile
Qlab version 2.3.8

The Presonus is the new addition to this setup.  I have used the Firebox with success in the past.

The weird thing is that the file itself is not corrupt.  Playing it through iTunes or even just Preview produces a clear sound through the Presonus.  I'm certainly perplexed.

I even tried tossing files into a new workspace, wondering if somehow the QLab sequence had become corrupt, but still had the same issue. 

Is there something unique in how QLab processes the track?  Or a setting that I'm missing?

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[ra byn taylor]

While you're troubleshooting, repatch to use the built in audio option in Qlab workspace preferences & check your audio at the headphone jack.

Is it clean there?

Divide & conquer...

*

[Bennie Netzley]

I didn't do anything to fix it (except unplug and replug), but the issue seems to be gone today.  Frustrating, since I like knowing how things go wrong so that I can fix it if it goes wrong again...

File format is .aif on all tracks.  Levels out of QLab are -6 on the master, and 0 on each of the stereo outs.  No red in QLab.  I repatched to the headphone out and it was clear - that's actually how I ran the show last night.

Adjusting the gain on the FireStudio did nothing for the distortion.  In fact, when I ended up running through the headphone jack, I matched the line level to the output of the FireStudio so that I didn't have to adjust every scene on the sound board.

[ra byn taylor]

Heat issue?
Bad FW cable?
updated driver?
Can you go back to the Firebox & it works with the same cable?

What I like about the Firebox is that is doesn't require any drivers to work. It also doesn't require any software to be loaded.

The rest sounds like you've got it all right.

Check the log under console. If you see entries when you had issues, let's see those...

If you see anything related to dropped samples & such in reference to Qlab, that would be a start. Also, if you have issues again, open up the console & watch what is happening. I keep the console on my dock.

ra byn

On Sat, Feb 9, 2013 at 5:09 PM, Bennie Netzley <bennie....@gmail.com> wrote:

I didn't do anything to fix it (except unplug and replug), but the issue seems to be gone today.  Frustrating, since I like knowing how things go wrong so that I can fix it if it goes wrong again...

File format is .aif on all tracks.  Levels out of QLab are -6 on the master, and 0 on each of the stereo outs.  No red in QLab.  I repatched to the headphone out and it was clear - that's actually how I ran the show last night.

Adjusting the gain on the FireStudio did nothing for the distortion.  In fact, when I ended up running through the headphone jack, I matched the line level to the output of the FireStudio so that I didn't have to adjust every scene on the sound board. e your preferences or unsubscribe here: