cheap battery-operated sine generator?

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Hah, an Italian company. Angelo Farina works on similar but not commercial software, I do only hardware, mostly DSP stuff. I wonder how you come to know that I said it cannot be done, I said it cannot be done with a single speaker IMHO.

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What are you into? Want to promote yourself? Seems more the opposite. A lot of what you say doesn't make sense. You also seem just to operate software, well that doesn't need much of an insight.

Ciao Ban Apricale, IT

Humpty-dumpty made his words mean exactly what wanted, no more and no less. It made for an amusing children's book but isn't conducive to technical communication.

So what do you think the physical origin of the Leslie effect is, then, if it isn't Doppler shift and multiple reflections?

Of course it's possible to simulate the Leslie effect to any accuracy you like--it isn't even especially complicated, it just needs some DSP horsepower because (unlike a true transfer function) it produces a finite bandwidth even with a perfectly sinusoidal input. That means that in frequency space it's a matrix multiplication, not a single multiplication per frequency.

The fact that Ban couldn't do it 30 years ago just shows that it couldn't be done on an 8-MHz 8086, which it still can't.

Cheers,

Phil Hobbs

• Have it your way then - 'The Leslie response' - what you get out for what you put in.

• As I wrote before: 'it must be possible to simulate this in electronics, but no-one has done it yet. So far, everyone that's tried ... has missed out something very important _but I don't know what it is_ - nor do they, so it would seem.'

• Strange that no-one appears to have done it yet then in a commercial product, wouldn't you agree? Add to the list the Digitech 'Expression Factory' and Native Instruments 'B4' plug-in.

I don't think that's strange at all--even the original Leslie is a niche product, and the economic upside is pretty limited, so it probably doesn't justify the level of effort or the quality of people needed.

Lots of things are in that class. The likelihood that there is actual new physics involved in spinning a horn around at low speed is pretty small, wouldn't you say?

Cheers,

Phil Hobbs

In addition to the ideas already presented, you might consider a test CD and CD player, or even an iPod (use a lossless compression scheme, of course).

No one has yet pointed you at a Wein bridge oscillator, but a op amp/FET oscillator can give good performance. See National Semiconductor AN-32 for example schematic, or look for a commercial unit (my HP 204C has builtin batteries, it's "option 02" on that model).

The niche for the Leslie sound may be quite a large one. I've already named seven commercial products whose manufacturers have claimed to provide the sound but don't get very close, add to this most of the multi-effect units sold to date and lots of keyboard instruments, and Hammond Suzuki themselves are still flogging full-size Leslie cabinets with no smaller-but-accurate substitute. If you search for them, there are also several purveyors of rotating horns in (smaller) cabinets - perhaps an acknowledgement of the fact that this is the best that's been achieved so far in the accuracy/size stakes. Hammond Suzuki used to sell a rig (2101) with electronic 'rotation' of bass frequencies and a horn in a box (2102) for treble frequencies.

I agree it seems very unlikely that some new branch physics has yet to be revealed when, eventually, someone cracks it (and patents the simulation, and cleans up on licensing) - but my reason for mentioning it in this thread is that I believe the challenge still exists.

More likely it's an as-yet unforeseen combination of known processing functions. Also, as I mentioned earlier, eventually it may become possible to simulate the sound (by a method like that applied in the Nebula software) without ever knowing how it was made.

Thanks for the chat.

Chris

So the smart engineer figured out how to spin less mass. Look again.