Cytomic "The Scream" stomp box distortion plugin

[Vertion]

I would love an effect to transform sound into a heavy metal guy screaming.

[jbuonacc]

... I dig this guys youtube stuff:

wow, that was pretty eye-opening. all the talk about op-amps, and there was very little differences between pretty much any of them. i was really surprised to see how much of a difference the LEDs/diodes made though. holy cow.

i guess that's what they really need to work on... emulating how the circuit reacts to using a pink LED or a yellow one. do any pedals/fx actually use LEDs in this fashion? it was cool to see it reacting to the input.

[Ichad.c]

... I dig this guys youtube stuff:

wow, that was pretty eye-opening. all the talk about op-amps, and there was very little differences between pretty much any of them. i was really surprised to see how much of a difference the LEDs/diodes made though. holy cow.

It really depends on the circuit, if you changed the opamp in a Rat pedal, it will sound way different. If I had to guess, that circuit(first part) looks similar to a tube screamer, diodes in the feedback of the opamp to give soft clipping.

i guess that's what they really need to work on... emulating how the circuit reacts to using a pink LED or a yellow one. do any pedals/fx actually use LEDs in this fashion? it was cool to see it reacting to the input.

There are tons of pedals with LED clipping and some amps too, you can even use transistors as diodes too.

[andy-cytomic]

...
how about something more unique

"http://www.acidvoice.com/tsx_303_distortion.php"

That pedals sounds very cool for synths, thanks for letting me know about it!

[andy-cytomic]

Andy, how's latency on this? Would it be possible to get no latency at 1x oversampling?
...
I know "Tube Screamers" went through a ton of revisions and different chips with people arguing over which chips/revisions sound better, so if possible, different chips would be nice. Analog Man covers some of the various chips/differences in the various revisions.

http://www.analogman.com/tshist.htm

There is no latency if you are at x1 oversampling.

I've read every TS-808 mod page and analysis page on the internet I could find

[andy-cytomic]

I've almost completed the core DSP development now, the model is sounding spot on to the pedal (apart from the hiss!), and I've come up with a good cpu usage vs accuracy compromise. I'll get a video done soon, but here are some pics of what I'm up to for now.

My development user interface where I can alter component values in a big table (edit: the % values are maximum, minimum, and average cpu usage going from left to right):


The TS-808 I'm modelling:



Scope and spectrum plots of the ts-808 and the scream. I've overlaid the screenshots using the "exclusion" mode so you can see the differences more clearly:

[resynthesis]

... I dig this guys youtube stuff:

wow, that was pretty eye-opening. all the talk about op-amps, and there was very little differences between pretty much any of them. i was really surprised to see how much of a difference the LEDs/diodes made though. holy cow.

i guess that's what they really need to work on... emulating how the circuit reacts to using a pink LED or a yellow one. do any pedals/fx actually use LEDs in this fashion? it was cool to see it reacting to the input.

Fiddling with the clipping diodes is one quick way to change the character of a pedal (especially in diode to ground circuits rather than feedback loop). If you were unaware, the type of diode determines how much is chopped off the top of the waveform and the "shape" of the clipped edges. That's why you'll see all sorts of diodes used - LEDs, si, ge, Schottky, etc. It's also worth playing with asymmetric clipping for yet another character.

PS Brian Wampler is one of the good guys on the pedal scene and it's well worth tracking down his pedal book if you're DIY inclined.

PPS Steve Vai uses a Keeley modded DS-1 rather than stock. If you want a cheap version look out for the Mooer Ultra Drive which includes the Keeley mods

[Ichad.c]

PS Brian Wampler is one of the good guys on the pedal scene and it's well worth tracking down his pedal book if you're DIY inclined.

Thanks for the heads up on about the book! I'll definitely buy a copy.

PPS Steve Vai uses a Keeley modded DS-1 rather than stock. If you want a cheap version look out for the Mooer Ultra Drive which includes the Keeley mods

All those 'little' pedals are fun and there are tons of brands, I have 6 of them connected to a DIYRE L2A reamplifier, it lives on the top of my rack, really cool to mess around with. Disclaimer: I'm not a guitarist.

As for DIY, I'm hoping to add some bass-mods to most of it, basically wider frequency response and less gain, so that I can use then on more sources.

Cheers

[resynthesis]

PS Brian Wampler is one of the good guys on the pedal scene and it's well worth tracking down his pedal book if you're DIY inclined.

Thanks for the heads up on about the book! I'll definitely buy a copy.

PPS Steve Vai uses a Keeley modded DS-1 rather than stock. If you want a cheap version look out for the Mooer Ultra Drive which includes the Keeley mods

All those 'little' pedals are fun and there are tons of brands, I have 6 of them connected to a DIYRE L2A reamplifier, it lives on the top of my rack, really cool to mess around with. Disclaimer: I'm not a guitarist.

As for DIY, I'm hoping to add some bass-mods to most of it, basically wider frequency response and less gain, so that I can use then on more sources.

Cheers

The book is out of print but he's working on a new version I believe. I think there was a PDF of the old version about which, as I remember, he gave his blessing to on one of the DIY forums.

[sqigls]

Can anyone provide a link to the full PDF please?
Thank you very much!

[andy-cytomic]

News update: I've got the production ready solver finished, it's sounding great I've been having fun doing the GUI, I'm getting much quicker at this stuff. Here is what I've done in 3 days:

Actual photo of the Tube Screamer:


Total rip off:


Totally minimal:


The one I (currently) like best, a little green sparkle to hint at the original colour:


I need to add a few extra non physical controls down the black sides at the bottom: pre, post, mix, starve, and bias, and a header for the normal preset / oversampling.

What does everyone think?

[resynthesis]

That looks very nice. Interesting controls too, never heard a TS with bias or starve

[etherdesign]

I know it's meant to model a pedal and all.. but the bottom 50% of the GUI seems totally superfluous..

[andy-cytomic]

That looks very nice. Interesting controls too, never heard a TS with bias or starve

Thanks! The starve is a potentiometer (variable resistor) in series with the battery to lower the power rail, and the bias is a potentiometer for the bias voltage divider. They are super handy to adjust when the buffer transistor and opamp power rail clipping kicks in, so you can get all sorts of different clipping tones happening easier, which is useful not only for guitar but also for synths and other FSU type applications.

[andy-cytomic]

I know it's meant to model a pedal and all.. but the bottom 50% of the GUI seems totally superfluous..

As I said in the previous post, down the sides at the bottom will be Pre, Post, Mix Knobs on the left, and Starve, and Bias knobs on the right Also the entire UI is scalable, so you can have it half the side and still use all the controls easily.

Edit: And the big silver button at the bottom even when "off", like the original, still puts the signal through the input and output transistor buffers including DC filters, so it will still colour the sound. There will be a total bypass "power" on the top left of the gui (as usual).