Scope Signal Not Showing - Though It Is In The Mixer

Thought I was/am going crazy, probably something really simple that I’m not seeing or set up wrong, but can’t get a rhodes sound showing up in the scopes though it is clearly playing and giving a signal in the mixer. Also, when the rhodes track is soloed, in the ‘master spectrum’ it is only giving visualization of the low frequencies even though the signal contains a fuller spectrum.

http://www.megaupload.com/?d=7GPKIS2U

Adding a gainer and/or raising the volume doesn’t help anything, though changing the panning slider does create a signal visualization in the scopes leading me to think the phase content of the stereo sample cancels out the scope?

Strange…

In the gainer, try inverting one of the stereo channels.

It sounds like your stereo sample is actually mono, but has been converted to ‘stereo’ and had one of its channels inverted to give some kind of fake stereo effect. You should be able to see in the sample editor if the right channel is simply an inverted duplicate of the left channel, for example. This would result in the track scope cancelling out, since it’s just a mono-mixed representation of the track output, but you will still hear the sound coming through since the separate left and right channels do not cancel each out in the same way during playback. You should still be able to see activity in the master scope, however, since this shows both left and right channels separately.

Megaupload is blocking me at the moment, so I can’t test your upload yet.

Nah, it’s really more like a ‘quirk’, I’d say.

Imagine if you have a mono sample which contains the following values:
1, 0, -1

Now we convert this into a stereo sample and invert the right channel, so we have the following values:
Left: 1, 0, -1
Right: -1, 0, 1

Since the individual track scopes are showing a mono signal with left and right mixed together, the output of the scope is:
1 + -1 = 0
0 + 0 = 0
-1 + 1 = 0

But the audio is still being played back in stereo, so we still hear the separate left and right channels, and they do not cancel each out here.

If we were to make a duplicate copy of the ‘stereo’ sample now, and then invert both left and right channels of this duplicate copy, and finally play both versions together, THEN the result would be total silence, since we have now the left channel of sample 1 cancelling the left channel of sample 2, and the right channel of sample 1 cancelling the right channel of sample 2.

Left: 1 + -1 = 0
Left: 0 + 0 = 0
Left: -1 + 1 = 0

Right: -1 + 1 = 0
Right: 0 + 0 = 0
Right: 1 + -1 = 0

Fun stuff :)

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Yep, gives visualization in the scopes (though also ugli-monofies the sound ;) ).

Thanks for the info, funny this inversion business also influences the master spectrum. Don’t think this is a bug, but can be confusing when not expected :)

To be honest, this kind of inverted phase ‘stereo’ sample can be considered broken, and I would personally avoid using it in that state. It could quite easily ruin your mix, and you can also forget about putting it on vinyl as the needle simply won’t handle it, not to mention this can also damage certain types of speakers.

It can be an interesting phenomena to hear over headphones and stuff, but I would avoid it myself.

Edit: You should also consider that some club sound systems have been known to output mono, so you may find that even if someone were playing your music from CD (where the vinyl needle thing is obviously not an issue), you might have entire instruments that literally disappear because they have been cancelled out during the mono mix. Freaky shit!

Dunno if I ever end up with a track on this pattern, but will keep in mind. Maybe some additional effects on top can ‘fix’ it.

Do you know if it is the same technique as used in Renoises ‘width’ parameter? Think I’ve once had a sound disappear live, having the pa go near to silent while I was sure the song was playing. Good times.

Edit: missed your edit :)

What happens in this case is that the original sound is subtracted, leaving only the true stereo results (in the case of a stereo delay or stereo reverb, etc) remaining. This in itself is kinda interesting to play with, and can be a very useful technique to know, but it definitely doesn’t solve the original issue.

I think that was explained on here in an older post, but I can’t remember exactly which method was being used to expand the signal. I think it involved separating the mid and side channel components, and then boosting the side to give the impression of a more wide sound.

Yeah, sorry about that, haha. Bit of a bad habit of mine as I think of new stuff after the fact.

Anyway, regarding that, consider the following example: http://illformed.org/temp/phasephun.xrns
(Really terrible sounding shit using some generic free loops, just for quickness, haha)

Couple of dodgy sounds in there with inverted channel fake stereo, which generally playback ok, but when the master channel is mixed down to mono they suddenly disappear.

There’s also one sound that shows the reverb thing I just mentioned as well.

Nice one! Will experiment with this in coming tracks, putting an lfo to control the stereo expander etc :)