Resonance Inside the Box
Not all sound waves can fit inside a 2-foot wide cabinet. Bass and mid sound waves are longer than the cabinet since the cabinet is less than the wave-length long. Therefore, there's no room for any of the middle range waves to bounce around inside a small cabinet.
There's not enough room in the cabinet for middle-range waves to bounce around because the cabinet is less than the wave-length long. There's no room for a wave to bounce.
The waves are delayed inside the cab. when they mix in the air outside the cab, they cancel.
- Some of the very high frequencies could bounce but that's not where the sound of the Leslie comes from.
- The sound of the Leslie really comes from the sound waves bouncing outside the cabinet.
The delays for each face of the cabinet is different as well as the beaming of each delay signal is different. That's why different sounds end up coming from diff directions. Bouncing takes place outside the cabinet with differential delays.
- Delays happen inside the cab and a delay is less than the time of one wave length.
A sound wave that is 3-feet long is a reasonably high wave length for a Hammond organ. Most are much longer.
- A wave length is the time for a wave to complete one cycle.
- For most of these wave lengths, not even half of the wave length will fit inside a traditional rotary cabinet.
Even so, all waves are delayed by some part of a wave length. 1000 Hz is where the horn starts working -- where the horn peaks. A half-wave length is about the width of the cab.
- A full wave length is twice the width of the cabinet.
At higher frequencies, such as 2000 Hz, is where about one wave length starts to fit inside the cabinet. But that is very high frequency.
- There are some harmonics there, but this high frequency is not where the heart of the sound resides.
- The horn starts taking effect about an octave above middle C. When you play the lower keys, and some of the higher drawbars are pulled out, those drawbars affect the lower keys. This is where you have the rich Leslie sound.
- These higher frequencies are affected more than the lower frequencies producing a very complex effect.
The low wave lengths are much longer and only part of these longerwave lengths are delayed inside the cab.
Think of it this way, Middle C, the Unison Tab, is called 8 feet because it takes an 8 foot pipe to accommodate it, which is half a wave length long.
- The wave length of Middle C is 16 ft.
- Just a short part of that wave length of Middle C at 440 Hz is delayed inside the cab, which really has no effect.
In reality, it is the music venue that becomes the sound chamber. Very little goes on inside the cabinet -- only small effects of delays. Each delay signal is beamed out in each face direction and it's in the room that you get the combinations that make up the richness of the ORBITED and traditional rotary cabinets
No matter whether it's poolside, patio, street fair or a room, it is where all the rich, beautiful sounds reflect off surrounding objects, interacting with the sound cancelling and reinforcing while filling the room with a wonderfully moving music.
An interesting and insightful article on how mechanical rotories work can be found at http://www.theatreorgans.com/hammond/faq/mystery/mystery.html
Back to Technology
Why ORBITED?
Rotary Speakers also ORBIT
It's the Doppler Effect... Hmmmm, not so fast.
One More Note
How the ORBITED speaker is different from Electronic Simulators
Mic Placement for a Rotary Cabinet
Mic'ing a Rotary Cabinet on Stage
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