Is there a DSP bug with the 'worn tape' algorithm? <probably user error>

[Orvillain]

I was playing with the worn tape algorithm and I noticed a chirping after playing for a while, with the feedback up at 70% or so. Haven't tweaked anything else.




Now at a very very VERY low level, there is some chirping and noise in the -66dB range. If I add some boosts I can make it a bit clearer, as in this clip:




I've brought up the tail towards the end so you can hear it clearer.


@Fractal Audio
Is this a bug? It doesn't seem desirable to me, even for a worn tape.

 

[sprint]

Clipping maybe? (not the cpu kind) I've noticed that, with my stronger guitars, I can start to clip the input of blocks placed before an amp block while overall patch output level is still in the green. Also check for too hi Input1 Gain level and/or Input1 block level

 

[Orvillain]

Clipping maybe? (not the cpu kind) I've noticed that, with my stronger guitars, I can start to clip the input of blocks placed before an amp block while overall patch output level is still in the green. Also check for too hi Input1 Gain level and/or Input1 block level

This is the tail of the delay, long after I've finished playing. No clipping, but I'm tickling the red a little as per manual guidelines.

 

[FractalAudio]

60dB is the threshold of audibility. If you apply enough gain to anything you're going to hear strange noises.

 

[JTI]

Some serious pew-pew on that \m/

 

[Greg Ferguson]

If you apply enough gain to anything you're going to hear strange noises.

Excellent words to remember!

 

[Orvillain]

60dB is the threshold of audibility. If you apply enough gain to anything you're going to hear strange noises.

Cliff, I heard the sound through my monitors without applying the gain. I applied the gain so that I didn't upload an audio clip that was almost silent, and everyone would then respond with incredulity. It was just to make it more audible. But it is still audible even without doing that.

Pop the worn tape in front of a dirty deluxe reverb.. there you go. Clear as day.

Is it a DSP bug, or is it by design?

 

[FractalAudio]

Cliff, I heard the sound through my monitors without applying the gain. I applied the gain so that I didn't upload an audio clip that was almost silent, and everyone would then respond with incredulity. It was just to make it more audible. But it is still audible even without doing that.

Pop the worn tape in front of a dirty deluxe reverb.. there you go. Clear as day.

Is it a DSP bug, or is it by design?

I can't reproduce it here. I would need to see the preset and detailed instructions on how to recreate.

 

[Orvillain]

I can't reproduce it here. I would need to see the preset and detailed instructions on how to recreate.

Cool, gimme a minute and I'll upload the preset.

 

[Orvillain]

I can't reproduce it here. I would need to see the preset and detailed instructions on how to recreate.

Preset attached. I was playing a series of notes, not too hard or anything. My Les Paul has a Duncan SH-6 in the neck, but I don't believe this is anything to do with clipping. Happy to be shown if I've done something dodgy or wrong.

 

[FractalAudio]

Preset attached. I was playing a series of notes, not too hard or anything. My Les Paul has a Duncan SH-6 in the neck, but I don't believe this is anything to do with clipping. Happy to be shown if I've done something dodgy or wrong.

Doesn't do anything unsavory here. Are you using a wireless, SPDIF, or anything else non-standard in the signal path?

 

[Orvillain]

Doesn't do anything unsavory here. Are you using a wireless, SPDIF, or anything else non-standard in the signal path?

Nothing like that no. Guitar into Axe III, out from there into my Quantum interface.

And sod's law, I've reloaded the preset here and I cannot reproduce it now!!! But I'm thinking something got caught in the delay buffer somewhere along the way. I'll keep trying to reproduce it.

 

[Orvillain]

Bloody hell. I can't feckin' reproduce it now. How annoying! My cables are good. My clipping is good. Everything connection-wise is gravy.

 

[iaresee]

If you're putting the delay block in front of a dirty amp model, the amp model is going to apply gain to any noise in the signal as well. Including repeated noise that's captured in the delay algorithm's feedback loop.

For this to be anything other than a gainy amp block amplifying noise in an environment, you'd want to use just a delay block alone to see what it sounds like on the tail.

 

[Orvillain]

If you're putting the delay block in front of a dirty amp model, the amp model is going to apply gain to any noise in the signal as well. Including repeated noise that's captured in the delay algorithm's feedback loop.

For this to be anything other than a gainy amp block amplifying noise in an environment, you'd want to use just a delay block alone to see what it sounds like on the tail.

Listen to the clip. It isn't environmental noise. It's a chirpy sound, almost like a misfiring capacitor. When I reloaded the preset, it went away and haven't been able to reproduce it since. Possibly some sort of serialization bug, but I honestly don't know.

I understand the principles of DSP and gain staging.

 

[Sauro_on_guitar]

I have strange noise out of my monitor when I'm using "time machine" backup on my Mac (with an external HD). Just disconnect external HD in use

 

[Orvillain]

@FractalAudio This never resurfaced. I don't know why, but considered it a load of old phooey!