[sdiy] Continuously variable waveshaping (was Behringer Neutron)

Ben Bradley ben.pi.bradley at gmail.com
Sun Apr 8 19:10:56 CEST 2018

Yeah, that's the one. I don't recall reading the text, I was just
looking for a schematic for the thing. I saw that one and it clearly
showed how the thing works. I admit I used a TL074, but my ears roll
off at 10-12k so maybe I'd hear no difference.

I stumbled across a datasheet for a NS "programmable" (it has a
bias/operating current input) op-amp from a few decades ago. That
would be perfect for adjusting slew rate. Does anyone still make such
a thing?

On Sun, Apr 8, 2018 at 9:51 AM, Ian Fritz <ijfritz at comcast.net> wrote:
> Another common example is in the Saw - Tri converter.  I use a 741 there to get rid of almost all of the spike that you get.  Filtering doesn’t work there — it mostly just smears the spike out, making it sound worse.
> Ian
>> On Apr 8, 2018, at 4:00 AM, Tom Wiltshire <tom at electricdruid.net> wrote:
>> It’s probably best *because* it’s slowest. There are plenty of examples in the stompbox world where people prefer the rubbish old slow op-amps over more modern “hi fi” options because the limited slew rate reduces the “edginess” of the high frequencies. Effectively, you’re adding a bit of roll-off.
>> For a wave folder, that might be true too - you want the wave folded, but lots of sharp spikes is just making high frequency hash, as you say. A little bit of rounding of some of those points might reduce the hash and still leave the interesting harmonic evolution in place.
>> Tom
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