Does anyone think the rotary should be in the cab block? Are there any rotary cab IR’s or IR’s that come close?

Greg Ferguson said:
From what I can tell it’s impractical to create an IR of a spinning Leslie speaker.

Starting with https://wiki.fractalaudio.com/wiki/index.php?title=Impulse_responses_(IR)#IR_length and https://en.wikipedia.org/wiki/Leslie_speaker …

The drum and rotor spin at different speeds whether they’re running fast or slow, so an IR would have to capture up to the point where both speakers crossed their original starting points at the same time otherwise the resulting IR would have a weird artifact. So there’s probably two different versions of the IR…

But it gets even worse because an Impulse Response is a tiny burst of sound that is supposed to occur before echoes in the room can bounce back and be captured. With sound traveling at 1100 feet/second, it’s going to take a big room.

During that process all outside/extraneous sounds need to be ignored by the capturing microphones, because, remember, two spinning speakers need to be captured and they’re driven by two motors, pulleys and belts that can make noise.

And then there’s the differing speeds that other versions and different company’s versions rotate at, and their different cabinet types, and the different ways their amplifiers distort…

And then there’s the needed IRs used to accommodate standard rotations plus speeding up, slowing down, and braking….

I’m not going to do the math because it doesn’t mix well with the couple glasses of wine I had with dinner, but my preliminary checks put it firmly in the nuh-uh range.
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You could just shoot an IR of the stationary speaker and apply whatever modulation etc over that. The only difference to running a normal factory cab sim is that you'd be using an IR of the actual speakers that are in a Leslie Cabinet. Thus, tht would help you to better nail the tonal character of the Leslie cabinet. You could even have a separate IR for the drum speaker and the horn speakers if you wanted to get super precise.
 
Piing said:
I don't like the idea of having the Rotary embedded at the CAB Block. If I want a CAB at the Rotary, I set it independent of the main CAB

View attachment 84999
The CAB for the rotary uses two IR in stereo (panned Left and Right)
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Which cabs are you using for the Rotary signal?

I'd be happier if the rotary itself hand maybe 5 -10 IR slots available. Maybe 5 factory ones and 5 user slots. Just an idea.
 
MisterE said:
If you have enough CPU left, you can use two Rotary blocks one for the Left channel and one for the Right channel and set both parameters the same.
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Yeah I'm hearing you. Could do that. My main jamming improv preset is maxed out for CPU but other song specific presets would have some extra headroom for that to work.
 
NaturalScience said:
Nope, how else would you get rotary if you play thru a poweramp and cab with the cab sims off.
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NaturalScience said:
Nope, how else would you get rotary if you play thru a poweramp and cab with the cab sims off?
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If I'm reading you right, you're asking why would I run a leslie IR into a Power Amp and Cab. Well ideally you'd be able to use a NULL cab or switch off the Leslie IR if you wanted so it would be no different than how it is currently if that was how you prefer it. Exactly the same as you can do with the Cab block currently.

But to clarify, I run cab sims to the desk and I also send a feed with no cab sims into my power amp and cabinet simultaneously.
 
Ant Music said:
If I'm reading you right, you're asking why would I run a leslie IR into a Power Amp and Cab.
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Nah, I'm saying if you embed the effect into the cab block but play through a poweramp and real cabinet, you may not want a cab block in your preset at all. Maybe you're advocating to keep the rotary effect as well, but to also add it to the cab block; however, I didn't read it that way.
 
I think IK did a good job with their officially sponsored Leslie sim in Amplitube, though the control parameters are way less than what Fractal has in their rotary block - using this approach in Axefx would mean that you'd have separate rotary amp and cab block type selections with rotary effects parameters in the Cab as suggested in the OP. I would not expect this to happen as I don't think it fits in well with current Axefx cab block design (it's also a little strange in Amplitube as you have effect type controls in the cab block which is not really standard to the rest of the Amplitube cab types) - my own fantasy would be to have some rotary amp types in the amp block (122, 147...), a rotary effect block for the drum / horn parameters the same as we have now, and then some Leslie specific cab ir choices for horn and drum. Not sure Cliff's back will be up to the task of lugging 10 Leslie Cabs out of the amp barn every time there's a major fw update - lol! - but maybe some 3rd party IR builders could come up with a few static Leslie IRs as this seems to be an untapped space - the amp types could perhaps be done from schematic if there are some available somewhere (a quick search reveals a whole whack of them here ).
 
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Greg Ferguson said:
I'm not going to do the math because it doesn’t mix well with the couple glasses of wine I had with dinner, but my preliminary checks put it firmly in the nuh-uh range.
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MEME2021-06-19-03-56-27.jpg
Yeah, you perty much nailed it. The math of it all kills the idea.

Too many different rotational states, and transitions between states, and too much time needed to capture them without the room influencing it, even in a bloody sports arena....

I think a straight-on IR of the stopped horn's output and, separately, of the stopped rotor's output, would help to capture their frequency response, which could then be fed to the algo that rotates each.

The horn probably doesn't go all the way up to 20kHz, and that would affect how 'zizzy' the thing gets when the amp is screaming.

The frequency response of the woofer probably starts to die at 4kHz on top, and in the 30-40Hz range on the low end, (if it even gets down that low), and that is before the simple passive crossover splits them up into highs and lows from the single amp driving it.

A big bit of the magic happens in the crossover area, where you are hearing some signal in each, spinning at different rates, and accelerating/decelerating at different rates when you change speeds....
 
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Greg Ferguson said:
From what I can tell it’s impractical to create an IR of a spinning Leslie speaker.

Starting with https://wiki.fractalaudio.com/wiki/index.php?title=Impulse_responses_(IR)#IR_length and https://en.wikipedia.org/wiki/Leslie_speaker …

The drum and rotor spin at different speeds whether they’re running fast or slow, so an IR would have to capture up to the point where both speakers crossed their original starting points at the same time otherwise the resulting IR would have a weird artifact. So there’s probably two different versions of the IR…

But it gets even worse because an Impulse Response is a tiny burst of sound that is supposed to occur before echoes in the room can bounce back and be captured. With sound traveling at 1100 feet/second, it’s going to take a big room.

During that process all outside/extraneous sounds need to be ignored by the capturing microphones, because, remember, two spinning speakers need to be captured and they’re driven by two motors, pulleys and belts that can make noise.

And then there’s the differing speeds that other versions and different company’s versions rotate at, and their different cabinet types, and the different ways their amplifiers distort…

And then there’s the needed IRs used to accommodate standard rotations plus speeding up, slowing down, and braking….

I’m not going to do the math because it doesn’t mix well with the couple glasses of wine I had with dinner, but my preliminary checks put it firmly in the nuh-uh range.
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This is why you don't see Leslie IR files.

Cycling through 4 or 5 files do not even significantly cover the travel of the upper horn, never mind the travel of the lower horn.

The cycling would also need to be tied to the rate parameter and Crossfade between IR files in order to not have a choppiness to the audio.

It would be memory intensive.
 
dr bonkers said:
This is why you don't see Leslie IR files.

Cycling through 4 or 5 files do not even significantly cover the travel of the upper horn, never mind the travel of the lower horn.

The cycling would also need to be tied to the rate parameter and Crossfade between IR files in order to not have a choppiness to the audio.

It would be memory intensive.
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The idea is to apply the dopplers while using a single IR. I've had good success implementing that design.
 
for the OP - in answer to the question - absolutely not. Plenty oy "rotary" pedals out there (which is what the block emulate rather than a true speaker cab) - and how about those of us that dont use cab blocks but still need the effect?
 
paulmapp8306 said:
for the OP - in answer to the question - absolutely not. Plenty oy "rotary" pedals out there (which is what the block emulate rather than a true speaker cab) - and how about those of us that dont use cab blocks but still need the effect?
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Easy.... Select a Null cab so you are not using an IR if you are just wanting to use the doppler shifting of the rotary block. Just the same is if you want to use a Leslie IR or any other IR. You select which one you want to use or simply select a Null cab if you don't want to use one. Simple solution.
 
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Greg Ferguson said:
From what I can tell it’s impractical to create an IR of a spinning Leslie speaker.

Starting with https://wiki.fractalaudio.com/wiki/index.php?title=Impulse_responses_(IR)#IR_length and https://en.wikipedia.org/wiki/Leslie_speaker …

The drum and rotor spin at different speeds whether they’re running fast or slow, so an IR would have to capture up to the point where both speakers crossed their original starting points at the same time otherwise the resulting IR would have a weird artifact. So there’s probably two different versions of the IR…

But it gets even worse because an Impulse Response is a tiny burst of sound that is supposed to occur before echoes in the room can bounce back and be captured. With sound traveling at 1100 feet/second, it’s going to take a big room.

During that process all outside/extraneous sounds need to be ignored by the capturing microphones, because, remember, two spinning speakers need to be captured and they’re driven by two motors, pulleys and belts that can make noise.

And then there’s the differing speeds that other versions and different company’s versions rotate at, and their different cabinet types, and the different ways their amplifiers distort…

And then there’s the needed IRs used to accommodate standard rotations plus speeding up, slowing down, and braking….

I’m not going to do the math because it doesn’t mix well with the couple glasses of wine I had with dinner, but my preliminary checks put it firmly in the nuh-uh range.
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I don't know how anyone got the idea that I was suggesting to shoot an IR of a moving speaker. 🤔 I was suggesting shooting some IRs of a rotary cabinet (Horn & Drum) whilst the cabinet is stationary. Once you have a good IR of the stationary speakers you can then apply the appropriate doppler shifting for a more authentic Leslie tone. Also the Preamp section in the Cab Block could incorporate the Leslie type to get even closer to the real thing.
 
The rotation doesn't just do the Doppler thing. The whole effective response of the horn is different when it's pointed at you vs pointed directly away from you and everywhere in between.

Simulating all of this is non-trivial, and poorly suited to the strengths of IR technology IMO.
 
Dave Merrill said:
The rotation doesn't just do the Doppler thing. The whole effective response of the horn is different when it's pointed at you vs pointed directly away from you and everywhere in between.

Simulating all of this is non-trivial, and poorly suited to the strengths of IR technology IMO.
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Of course I get all that, but I'm just saying that you'd have a better chance of getting a more authentic tone of a real Leslie cabinet by at least using an IR from an actual Leslie cabinet instead of applying rotary simulation to any other random Cab IR.
 
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