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Author Topic: A bit LessLee  (Read 1806 times)

phatt

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A bit LessLee
« on: January 04, 2012, 08:10:46 AM »
Is it a Tremolo, a Vibrato, or Rotary speaker? ???

Most Phaser systems use an LFO to work the phaser setup which is nice but most can't replicate the rotary effect like a Leslie Speaker. In this case the signal is the LFO tremolo effect which is then passed through a phaser circuit.

My guess is a real rotating speaker has phase modulation as well as level modulation which delivers a much closer resemblance to the real thing.

Please don't ask me how it works as this was just one of those days when I stumbled upon something.
Every now and then even a novice like me does something really cool.
So glad I tried it. :)


Notes;
It will likely distort too much on a 9 Volt supply,, I'm using 18 Volts.

The separate bias for the XR2206 is definitely needed just fine tune the trim pot it until the hash disappears and it's then very quite.

XR2206 is a function generator IC and I'm told it is fairly common chip though I had to spend  $15 to get one.


I also tested the phase circuit used in the *ROGphozer2* which works well but adds to the part count and circuit complexity.

In Use;
       This Schematic is on the breadboard and I have another slightly altered unit being used live.
The speed should be obvious. The Tremolo and Vibrato are mixed separately allowing for many combinations. Some may wish to simplify it with one dual pot.

This can go from straight Tremolo (Volume up, down) to full on modulated head spin phase modulation.
(Depending how you mix the levels) Turn the *Dry mix* full off and it will go back to straight Tremolo no matter where the other knobs are set.
The rotary trick relies on a dry mix always being present in the mix.

As I'm sure you can appreciate I don't have a warehouse full of every efx unit made to compare this to but I DO Own a real rotating speaker so I've got a fairly good example of what constitutes a Leslie effect.

This is still not as good as a real spinning speaker but I'm very happy with what I've stumbled upon and it's a lot smaller than a speaker. Winky. 

Any interest and I'll get some samples recorded.
hope you all have a happy 2012. Cheers, Phil.

 

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