Distortion With The SPDIF OUTPUT

[truthaddict]

I am trying to output my sound from the Triton Extreme through the SPDIF to a Pro Tools Digi 002 Rack (Pro Tools version 7.1). The Pro Tools Rack has monitors attached to it.

There is a distortion or static sound that happens sometimes. It happens with any of the Triton sounds that I have tried, and mostly when the keys are pressed hard for a loud sound.

If I use the regular outputs of the Triton, it doesn't have the distortion, so I know it is a problem with the SPDIF signal somewhere.

I am using the latest operating system on the Triton 1.0.5. Does anyone know if this is a known issue or how to fix it? I am limited how I can troubleshoot, because I do not have any other keybosrd with a SPDIF output, or another recording device with a SPDIF input that I can attach it to.

[truthaddict]

^ I know it is not just the speakers, because I have tried using several.

[synthjoe]

If I use the regular outputs of the Triton, it doesn't have the distortion, so I know it is a problem with the SPDIF signal somewhere.

Very unlikely. SPDIF would either work or not, distortion - if present - is likely to happen in the synth (in which case you'd hear it on the analogue outputs, too), or in your protools setup. You can loopback the 002R digital output to the digital input (make sure you're careful about record enable and output routing so as to avoid a feedback). Putting a signal generator on the output at 0 dB will show you what is happening on the input.

When your Triton is connected and you get the distortion, does the clip indicator on the input (record ready) channel show any clipping? What is the level on your master fader? Are both L and R channels panned to the center? If there's no clipping on the input channel, inputs are properly panned hard left and right and all faders are at unity, then you should not hear any distortion. The last bit to check is whether the 002R output overdrives the power amplifier of your speakers? maybe you can dial volume down a little on the power amp or use attenuation on an active monitor, if that's what you're using.

[truthaddict]

Thanks for the great ideas.

When your Triton is connected and you get the distortion, does the clip indicator on the input (record ready) channel show any clipping? What is the level on your master fader? Are both L and R channels panned to the center? If there's no clipping on the input channel, inputs are properly panned hard left and right and all faders are at unity, then you should not hear any distortion.

The clip indicator does not show any clipping. It looks like it is well below the threshold. The master fader is set to -6.5. The channel the Triton is on is set to +1.2. The inputs are panned far left and far right.

I will have to try the loopback test, and get back with you. Let me know if you have any other suggestions. Thanks again.

[synthjoe]

You're welcome! +1.2 means that the signal pre-fader (that's what the indicator shows, unless you've changed the setting in 'Options') has to remain below -1.2 dB. 'Far below' is quite relative, I think you should activate peak level metering by CTRL-clicking on the number field below the fader. If it indicates anything above -1.2 throughout your session then you've got your source of distortion. (Ok, by experience I think it has some reserve, but I've got no idea how much - so it is best to keep the nominal level going out of the channel under 0 dBFS, meaning that the sum of the fader attenuation value and peak reading should be less than 0.)

Remember also that 0 dB(FS) on the master bus equals to about +21 dBu on the output of the Digidesign hardware, which drives a lot (if not most) audio inputs (power amplifier input stages) into saturation - so that's another high potential distortion source to check.

[truthaddict]

Thanks again for the help.

I tried to loop the SPDIF back in to the pro tools rack, and I didn't hear any sound, or see anything on the channel level display.

I played with the peak level metering, and there is still some distortion, but it seems to have improved things. I'll keep working on it.