Phase 45 Waveform Study

[Paul Marossy]

I thought it would be interesting to see what happens to a 600Hz sine wave after my Phase 45 clone gets done with it. It was quite fascinating to watch on the scope. Scope was my Tektronix 453 with 1M probe, Time/Div set at 1ms and 1V Volt/Div. Sine wave was set at 20dB attenuation. Speed control on the Phase 45 was set at about 11:00.

Here's a few pics, and I'll try my best to describe what happens at each waveform picture.




This is what it looks like when it sounds least affected. The amplitude dips a little lower than what is shown here, I just didn't click the button fast enough.



Here is the first distinct change in amplitude. Every other peak is rising while the other ones in between are diminishing.



Then the peaks start to fall and the peaks in between are now starting to rise. It's quite fascinating to watch this thing undulate.



Then, there is a second distinct change in amplitude, this one larger than the first. I never noticed this with my ears until I looked at it with a scope, and there is two different amplitudes of "swoosh", and you can really tell when you are looking at it with a scope while listening to it.


I'm not quite an expert with a scope yet, but it sure looks like the signal is being inverted to me. Definitely a phase dance of some sort. I sure wish I could record an MPEG of it, it's trippy to watch.

Just thought I would share this in case anyone finds this to be interesting.
BTW, I really dig this little pedal. Works great for some of the songs we play.

[Fret Wire]

Thanks for sharing that. It's always interesting to see pedals perform on a scope. BTW, did you set the trimpot with the scope also?

[puretube]

yeah, phasers are a beautiful "dance" on the scope - flangers/chorus even more so...

on with vacation, now  

[Paul Marossy]

An addendum to the above: I think there is actually 3 different peaks in the waveform, but it seems that one of those peaks doesn't rise or fall very much. It's kind of hard to tell if all three peaks alternate or not. I really need to get it on video. Is there any way to feed a video tape into your computer to make an MPEG?

Fret Wire-

No, I didn't think to tweak the speed control while I had it hooked up to the scope.

puretube-

Yeah, that's really cool to watch! I'll have to look at my chorus next.

[Hal]

its very easy to feed video to a computer...if you have a capture card :-D

Otherwise, its quite difficult.  Unless of course your video camera is digital...

[Paul Marossy]

Bummer.  :cry:
Maybe it's time to get a digital camcorder...