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High CPU affecting Midi timing???

May be really obvious - but I'm still new to hardware use in my setup.

When my CPU use gets high, I've noticed it starts losing the midi timing from my Virus B. Does this sound normal? Anyone else had this problem?

Some things to bear in mind:

1. I am using manual delay compensation (pre) to time all other VST's / FX to the delay of the Virus. This is because FL doesn't have Auto PDC.

2. When CPU use is low, this midi timing issue doesn't occur - which is why I think high CPU is causing the issue

3. If high CPU is causing the issue - it would seem logical that the CPU cannot accurately maintain the delay compensation - so why would it ONLY affect midi from an external source and not the midi to/from the VST's?

I don't think it's the Virus going wrong - I have a Nord Rack too but a mate is borrowing it so I can't test to see if this does it too.

Kit Involved:
- FL 9.0.3 - using 'Midi Out' plugin to route midi to / from Virus to / from FL
- Audiophile 2496 soundcard
- Basic midi cables

Thanks for your help (again!)

Nick

Have you tried monitoring the Virus using its headphone output (i.e., before the analog outputs get routed back into your DAW)? If you do that and the Virus is still out of time, then that would likely be a MIDI timing issue. If the Virus headphone outputs show that it is playing in sync with your DAW, then you've probably got a delay compensation issue. I'm betting on the latter.

quote:

Originally posted by cryophonik Have you tried monitoring the Virus using its headphone output (i.e., before the analog outputs get routed back into your DAW)? If you do that and the Virus is still out of time, then that would likely be a MIDI timing issue. If the Virus headphone outputs show that it is playing in sync with your DAW, then you've probably got a delay compensation issue. I'm betting on the latter.

It's not a delay compensation problem - I sorted this out.

If I cue up just a kick and a bassline from the virus - set the delay compensation to account for the Virus delay, they time perfectly.

If I keep this same Kick / Bass combination, then add a load of VST's & FX into the sequencer to increase the CPU load, the timing of the notes from the Virus starts to go off - but randomly. Some strike true, others are late, others early.

Not a massive problem - just not ideal, as it means I'll have to overdub the Virus onto a bounced wav of the track to keep the CPU down.

I've tried shortening the buffers on my soundcard, doesn't cure it. And I've got FL running as ASIO, so it uses the buffer settings straight from the soundcard.

if it was a cpu issue the shortening the buffers would make it worse. try increasing the buffer and see if that helps.

quote:

Originally posted by Sonic_c if it was a cpu issue the shortening the buffers would make it worse. try increasing the buffer and see if that helps.

Good point! Doh!

Sadly the problem occurred when the buffers were at max at 2048 samples. Thanks for the suggestion though.

I'm going to wait until I get my Nord Rack back and see if the problem is repeated on it.

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