Author Topic: Creating a rotary/leslie effect in SpinCAD  (Read 985 times)

ferdinandstrat

Creating a rotary/leslie effect in SpinCAD
« on: September 01, 2021, 01:14:50 PM »
Hey, I've been messing about SpinCAD but I honestly cant seem to get to desirable effects, half of what I try seems to sound distorted or plain doesnt work

Where should I start with this?

Digital Larry

Re: Creating a rotary/leslie effect in SpinCAD
« Reply #1 on: September 01, 2021, 05:08:19 PM »
Well, maybe you can tell me what you think goes into a Leslie.  I haven't built one up and it may not be practical to make a super accurate model but let's try.
Digital Larry
DSP tinkerer and former transistor twister

Ice-9

Re: Creating a rotary/leslie effect in SpinCAD
« Reply #2 on: September 01, 2021, 05:38:41 PM »
I would start with a chorus or similar like a vibrato, make the LFO quite deep and wide.
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ferdinandstrat

Re: Creating a rotary/leslie effect in SpinCAD
« Reply #3 on: September 01, 2021, 11:31:01 PM »
Well, maybe you can tell me what you think goes into a Leslie.  I haven't built one up and it may not be practical to make a super accurate model but let's try.

I tried two flangers in parallel each with a filter but it just gave me a clean sound on the simulation, same for choruses

Then I tried a phaser into a flanger but everything was just extremely distorted

I would start with a chorus or similar like a vibrato, make the LFO quite deep and wide.

Tried that but it sounds like a chorus
« Last Edit: September 01, 2021, 11:46:50 PM by ferdinandstrat »

Ice-9

Re: Creating a rotary/leslie effect in SpinCAD
« Reply #4 on: September 02, 2021, 05:29:24 AM »
Well, maybe you can tell me what you think goes into a Leslie.  I haven't built one up and it may not be practical to make a super accurate model but let's try.

I tried two flangers in parallel each with a filter but it just gave me a clean sound on the simulation, same for choruses

Then I tried a phaser into a flanger but everything was just extremely distorted

I would start with a chorus or similar like a vibrato, make the LFO quite deep and wide.

Tried that but it sounds like a chorus

Yeah ok, but a Leslie is closer to Vibrato so modifying the chorus or vibrato modules to make a Leslie is the way to start, a Leslie is a lot more complex to do than straight chorus or vibrato but it is where I would start to code up.
As the speaker in a Leslie cab is spinning you get a higher and lower pitch effect due to the Doppler effect as the speaker spins toward you and then away from you as well as the volume changes.
www.stanleyfx.co.uk

Sanity: doing the same thing over and over again and expecting the same result. Mick Taylor

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potul

Re: Creating a rotary/leslie effect in SpinCAD
« Reply #5 on: September 02, 2021, 05:32:37 AM »
I went through this journey some time ago (not with SpinCAD), and I found a couple of documents useful to understand the rotary speaker and how to simulate:

https://ses.library.usyd.edu.au/bitstream/handle/2123/8431/MCroteau_310303923_InitialTechReview.pdf

http://www.willpirkle.com/Downloads/Rotary%20Speaker%20Sim%20App%20Note.pdf

Enjoy the reading.

Digital Larry

Re: Creating a rotary/leslie effect in SpinCAD
« Reply #6 on: September 02, 2021, 09:31:42 AM »
It would probably help me for you to include screenshots of your layout along with the control panels of any blocks that you think are misbehaving. 

If you are getting distortion, try lowering the input level and/or some setting of the block itself.  The phaser block operates internally on very low level signals and I believe that there is a large attenuation initially followed by boosting it back up later after the phase shifting itself.  Also check the waveforms by looking at the Simulator->Scope view.  I'm sure if something sounds distorted it will look distorted, so this might help you identify which things are causing the distortion.  It's simple enough to temporarily connect some internal signal of your patch to one of the output block's connection pins so you can see it on the scope and hear it directly.

It's probably helpful for you to know that all of the modulation blocks are WET output only, except for the phaser block, which also offers a "Mix" output.  In order for you to hear real flanging you have to mix the block's output together with the dry signal using a 2:1 mixer block, or if you are looking for a through-zero flanger, mix the flanger block's wet out with the fixed tap out.  Also experiment with phase inversion of either the dry or delayed signal with flanging, it makes a HUGE difference.

Here's what I would do.

Start with a Servo Flanger block and a Sin/Cos LFO block.  Adjust everything so that you are getting a vibrato.  Now you can use the Sin/Cos outputs to do other things such as filtering or tremolo synchronized with the pitch LFO.  Try to imagine what is happening physically to correlate it with the various LFO phases.  Also consider that some interesting sounds may occur if you do things which do NOT directly correlate to the physical motions of a real device. 

If you want to split the signal high/low so the bands can have individual processing, use the two pole SVF (State-Variable Filter) and use the high and low pass outputs.  This acts like a low budget crossover.  Regarding strategy on this, however, I would advise trying to build a single modulatable delay/filter/tremolo chain by itself first.  Once you get that under control you can copy/paste and modify the blocks.  Note that when you do this, you'll need to change the LFO assignments in one set of the Sin/Cos LFO and Servo Flanger blocks to avoid a conflict.

Use control smoothing on the LFO Rate control signal to give you that "smooth acceleration and braking" sound.
« Last Edit: September 02, 2021, 10:32:11 AM by Digital Larry »
Digital Larry
DSP tinkerer and former transistor twister

ferdinandstrat

Re: Creating a rotary/leslie effect in SpinCAD
« Reply #7 on: September 02, 2021, 10:39:38 AM »
Me and the servo flanger aint getting along, it just sounds wrong like it just glitches randomly like lasers are shooting in the background or something, this is my setup so far


Digital Larry

Re: Creating a rotary/leslie effect in SpinCAD
« Reply #8 on: September 02, 2021, 11:18:28 AM »
LFO Output wants to be 0 -> 1 for use with the Servo Flanger.
Turn the servo gain down a bit.

Also:

You probably don't want the smoother between the LFO and the Servo Flanger.  Put it between the Pot and the LFO rate input.  There is a valid reason to put the smoother directly in the LFO signal itself, which is turn automatically decrease the sweep width as the speed goes up.  However there's an easier way to do that with a Scale/Offset.  Anyway, the Leslie acceleration simulation is created with the smoother between the pot and the LFO's rate input.

Another thing to try with the servo flanger (or any block in general) is to connect the pot directly to its control input.  Now you can sweep the pot and see what effect it has.  In that case I probably WOULD use a smoother because the pot output might be jumpier than the Sin LFO.  Try it both ways.

« Last Edit: September 02, 2021, 11:38:28 AM by Digital Larry »
Digital Larry
DSP tinkerer and former transistor twister

Ice-9

Re: Creating a rotary/leslie effect in SpinCAD
« Reply #9 on: September 02, 2021, 02:13:02 PM »
ferdinandstrat, I just wondered, do you have a real FV-1 effect to test with or are you using the only the Spincad sound though the Larry's program and the computer?
www.stanleyfx.co.uk

Sanity: doing the same thing over and over again and expecting the same result. Mick Taylor

Please at least have 1 forum post before sending me a PM demanding something.

ferdinandstrat

Re: Creating a rotary/leslie effect in SpinCAD
« Reply #10 on: September 02, 2021, 02:39:37 PM »
I actually do have a real one to test with

vigilante397

Re: Creating a rotary/leslie effect in SpinCAD
« Reply #11 on: September 02, 2021, 03:30:15 PM »
I'm partially interested in FV-1 leslie effect, but mostly just here because anytime Larry is talking about SpinCAD I feel like I should pay attention ;D
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Ice-9

Re: Creating a rotary/leslie effect in SpinCAD
« Reply #12 on: September 02, 2021, 04:08:07 PM »
I actually do have a real one to test with

Great to hear you have a real FV-1 circuit as well to test with. I have a few different Leslie effects I can share. I have no idea where they came from but i do know they are not one's i have written myself. I will search them out.
« Last Edit: September 02, 2021, 04:20:35 PM by Ice-9 »
www.stanleyfx.co.uk

Sanity: doing the same thing over and over again and expecting the same result. Mick Taylor

Please at least have 1 forum post before sending me a PM demanding something.

ferdinandstrat

Re: Creating a rotary/leslie effect in SpinCAD
« Reply #13 on: September 03, 2021, 12:26:14 AM »
I actually do have a real one to test with

Great to hear you have a real FV-1 circuit as well to test with. I have a few different Leslie effects I can share. I have no idea where they came from but i do know they are not one's i have written myself. I will search them out.

If you couldd that would be awesome

Ice-9

Re: Creating a rotary/leslie effect in SpinCAD
« Reply #14 on: September 03, 2021, 10:44:01 AM »
I actually do have a real one to test with

Great to hear you have a real FV-1 circuit as well to test with. I have a few different Leslie effects I can share. I have no idea where they came from but i do know they are not one's i have written myself. I will search them out.

If you couldd that would be awesome

PM sent
www.stanleyfx.co.uk

Sanity: doing the same thing over and over again and expecting the same result. Mick Taylor

Please at least have 1 forum post before sending me a PM demanding something.

niektb

Re: Creating a rotary/leslie effect in SpinCAD
« Reply #15 on: September 05, 2021, 04:35:30 AM »
I went through this journey some time ago (not with SpinCAD), and I found a couple of documents useful to understand the rotary speaker and how to simulate:

https://ses.library.usyd.edu.au/bitstream/handle/2123/8431/MCroteau_310303923_InitialTechReview.pdf

http://www.willpirkle.com/Downloads/Rotary%20Speaker%20Sim%20App%20Note.pdf

Enjoy the reading.

Very nice documents! I've been trying to reproduce the papers and it sounds very nice so far. Only thing I can't figure out so far is the delay line. What is a suggested delay line length and depth of the sweep?
I've tried up to 50ms (and then full depth), longer delay line lengths give me a wider stereo image but not sure what's realistic.

ferdinandstrat

Re: Creating a rotary/leslie effect in SpinCAD
« Reply #16 on: September 05, 2021, 10:16:37 AM »
From what I understand the delay time needs to be much much shorter....I think....closer to typical chorus delay times

PRR

Re: Creating a rotary/leslie effect in SpinCAD
« Reply #17 on: September 05, 2021, 06:32:37 PM »
The delay in Leslie can be the size of the cabinet, under 2 feet or 2mS. First it comes out the front. Then it comes out the back.
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niektb

Re: Creating a rotary/leslie effect in SpinCAD
« Reply #18 on: September 06, 2021, 02:50:45 AM »
The delay in Leslie can be the size of the cabinet, under 2 feet or 2mS. First it comes out the front. Then it comes out the back.

Really that short? Will you get enough pitch shifting to emulate the doppler effect that way?