New PWM

[k brown]

I noticed this produces pretty severe distortion/aliasing on higher notes - any way to smooth that out?

Does this maybe only work best in blue?

[BobF]

BobsAllWaveformPWM_1a Antialiased and white.fsm

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Hi Kevin,

Try this one!

Good luck, BobF.....

[k brown]

Thanks for that - however I would describe the results as a mild improvement at the expense of noticeably duller sound.

[BobF]

Hi again Kevin,

Unfortunately aliasing is common in many distortion and wave shaping devices. If you missed this post read it over for possibly a little more help.

Reducing aliasing of waveshaping using convolution.

Try the conv tanh.fsm and see if it helps any better than the anti-aliasing filter I added.

conv tanh.fsm

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And last, you could also remove some of the 1 pole low pass filters from the 36db anti-aliasing filter, they are each 6db. This could add a LITTLE punch back in.

Good luck and please let me know how you make out.

Take care, BobF.....

[k brown]

A 'convoluted' answer! - I'll give it a try.

[adamszabo]

Bob, unfortunately the 36 dB filter is just a simple filter its not anti-aliasing at all. You cannot remove aliasing by simply filtering the signal with a low pass filter, its not how it works.

[martinvicanek]

A simple antialiasing technique consists in synthesizing the time integrated waveform and then numetically differentiate it. Example: a square wave is obtained by differentiating a triangle wave. The method is called DPW (differentiated polynomial waveform).

[k brown]

Easy for you to say!

[BobF]

My bad on the antialiasing filter, just found it in another schematic and well used it. Sorry!!!

Later then BobF.....

[BobF]

Bobs3Freq_PWM.fsm

(836.92 KiB) Downloaded 968 times

Hello all,

Had this laying around, so just thought I would add it for completeness.

Later then, BobF.....

@ Adam, it's fixed, very sorry!