That being said, lets dive into the Hammond B3!
Sound generation in the Hammond B3 comes from within what is known as the main generator. A long drive shaft, driven by an AC synchronous motor, runs the entire length of the main generator. From that shaft is connected 24 driving gears, with 12 different gear sizes total. These 24 driving gears are connected to 2 more gears, made of bakelite. These bakelite gears each have their own shaft, and mounted to that same shaft is the tone wheel. There are 12 different sizes of bakelite gears. These gear ratios provide the proper speed (pitch) for the tone wheel to be in tune with one another.
The tone wheels are steel discs about 2 inches in diameter. These discs are machined with high and low points known as teeth. The number of teeth vary in relation to the tone trying to be produced. The basis of the tone is the equal tempered scale.
A magnetic pickup is employed to generate the tone. (Much like the guitar pickup in my model). Each rod is 1/4 in diameter and has a length of about 4 inches. At the one end of the rod lies a wound coil of wire. Each time a tooth passes the rod, it creates a change in the magnetic field (flux) and induces a voltage in the wound coil. The frequency is determined by the number of teeth and the wheel speed. (See diagram).
By combining various upper wheels (frequencies) with the fundamental being played, the Hammond can create a wide tonal palette. The user may create one by using the drawbars located above the swell (upper) register, or select from presets for each of the upper or lower (grand) registers. These preset keys are the "opposite" (black instead of white) keys below the lowest of the "regular keys" on the organ.
After much consideration for my project, I settled upon a guitar pickup for the coil to generate sound. The big obstacle was trying to find a tone wheel in the Nashville area. Seeing as I could not find one in the area, I went to the local hardware store to do some research. Realizing that a saw blade would be unwieldly and hardly the contraption I would want to carry into class, I settled on a "Tee nut". These things are used when a person wants to secure a threaded rod or bolt to a piece of wood. The key to this nut is the fact that there are already 3 notches cut into it, and it is made of steel. That being the case, the construction began.
The guitar pickup was mounted to a piece of plywood. A pulley was secured to a small Mabuchi motor. Using a threaded rod as an axel, another pulley was attached and secured. The connection between the motor and the axel was a rubberband. The tee nut was carefully aligned and is held into place with a nut/ lock washer combination. The axel and tee nut were suspended above the guitar pickup using angle irons. The axel is held into place and is kept in a relative position by more nut / lock washer combinations. The motor(s) are held into place by a 1/2 inch copper pipe mount. The motor(s) are electrically connected to a "black box" (radio shack experiment box). Mounted in the box is a switch to select between the motors, center off. Also mounted in the box is a 1/4 inch mono audio jack to facilitate a patch cord from the pick up to a guitar amp. The motors are powered by 2 C batteries wired in series. Physically, the maximum number of tones that could possibly be generated could only be two, there is just not enough room above the guitar pickup.
Well...
I learned many things. Hammonds use of the synchronous motor keeps
the tone very stable. (And we learned Electronic Music class that if the
Hammond is not started right, the organ could play flat). My DC motors
are
nowhere near stable, and caused the pitch to wander. The threaded rod
proved to be a problem in conjunction with the angle iron... The threads
wanted to track in the angle irons. This tracking cause the rubberband to
move very freely in its path, resulting in an unconstant speed. The
running of the motor proved to be very noisy from a physical standpoint.
(The noise of the motor coupled with the plywood to make a very loud
racket.) The next problem involved the mounting of the pickup. (From a
'66 Fender). I mounted the pickup in open air, and by doing so,
introduced all of the problems associated with pickups, noise. Noise from
electicity, noise from the motor.
These problems aside, the project did generate a tone, albiet very unconstant and very low in volume. I plan to further work on the project. First and formost will be to mount the pickup in a metal enclosure. I will then work on perfecting the axel. I will keep you posted to further developments.
Perhaps the success of the Hammond B3 would not be without the trusty
Leslie Speaker Cabinet. Invented by Don Leslie, it just goes to show what
a little American ingeniuty can do for the musical world. The idea is
this; create a speaker cabinet that spins, or spins the speakers to
provide a very non directioal sound that when coupled with the B3, sounds
very much like a church organ, without all of the messy tubing. To better
understand how this spinning speaker(s) works, we delve into the doppler
effect and and the ever infamous train example. I will take into account
that you at one time or another have heard a passing train or a car that
has honked on their horn as it passes you by. Anyway...An approaching
train that blows it horn has several factor involved, one of which is the
speed it is traveling at. When the horn blows, it is forced to overcome
the prexisting condition (think of it as negative speed in relation to the
horn) The sound, which ivariably is traveling faster that the speed the
train is traveling at must pass through this negative speed. The speed
works against the horn, and low and behold pushes the sound waves closer
together. This causes an increase in the pitch because sound wave is
pushed together.
When the train is nearly upon you (I hope you are standing on the side
of the tracks, otherwise you will not recieve the full doppler effect,
even if you survive) the pitch lowers,
almost or to the tone the horn is trying to produce (yes, train horns are
tuned... older trains might have three or even one, the newer trains have
at least 5, this is to help prevent the chance of someone being tone deaf
at the frequency of the horn). Back to the subject... As the train passes
the pitch lowers. This is in account of the sound waves being spread
out...therefore lowering the pitch.
I thought you would never ask, my dear Watson! The spinning of the horn (although there are two, only one actually works, the other being for balance) creates a doppler pitch shift, in relation to where a person or microphone is located. Many recordings are done with 1, 2 or even 3 micrphones to try to simulate that Leslie effect in home stereo. It really depends on the producer and or engineer, I have heard many arguments as to which is the best.
The Leslie Cabinet has two modes, fast and slow. The fast mode is know as tremelo, the slow known as chorale. The speed adjustment is controled by a switch and a box mounted on the front of the Hammond (At least at MTSU).
Note, while I do say non directional, the sound indeeds is very locatable in an enclosed space...The Leslie's job is to spread the sound around the room, much like a church organ.
I would like to thank Shane Smith for letting me use his studio time to
sample the Hammond B3.
C chord played in tremelo mode
The infamous Hammond B3 wipe This alone makes
the Hammond B3 what it is.
A. All are wav files
B. All are 8 bit stereo with no compression
C. Yes, it really needs to be in stereo to get the whole effect. (for
the most part)
D. Any other questions, refer to the FYI at the bottom for the
sampling information.
Reo Speedwagon
"Roll With The Changes"
From their Epic release THE HITS
@ 3:15. Some of the most infamous Hammond wipes committed to tape
Harry Connick Jr.
"She"
From his Columbia release SHE
@ 4:00. Harry effectively demonstrates the tremelo mode of the
Leslie.
The Black Crowes
"She Talks To Angels"
From their Def American (Now American) release SHAKE YOUR MONEY MAKER
This whole album is the poster for the Hammond B3 / Leslie combo.The
Crowes demonstrate the difference between the chorale and tremelo
mode. The tremelo mode is used during the chorus of the song and bridge,
the chorale mode in the verses and "quiet" sections. This is a great use
of the B3 given the title of the song and one of the big buyers of the
Hammond, churches.
This list is by no means exhaustive, but is some of the best Hammond B3 / Leslie sound committed to tape.
Questions or comments?
Mail me!
Back to the RIM BOY's homepage.
Your are visitor # to play a chord on the Hammond B3!
My Sources are the Hammond B3 Manual, and the Hammond FAQ, as linked above.
All samples were done at Middle Tennessee State University, at Studio
B in the John Bragg Mass Communication building. Microphones used were
Audio Techinca 4033 (AT4033). Each mic was 180 degrees in relation to
each other. They were placed on either side of the Leslie cabinet, about
4 inches away from the cabinet, near the top (in the horn section of the
cabinet).
Through the Otari Studio 54 console, they were patched back
out into the studio where I has set up my Optimus Digital Compact Cassette
(DCC). The samples were taken at 44.1 kHz, while I played the Hammond
B3's
grand register. I then brought the samples back to my roommates Acer
Penitium computer. Using Sound Blaster Soundo'LE, I sampled the DCC
through the line input. Sampling rate used was 44.1 kHz, no compression,
16 bit stereo. I then used Sound Blaster Wave Studio to double volume of
the sampled wave. I then edited the wave into manageable length. Having
saved the wav, I opened up Midisoft Audio Works. With Audio Works, I
converted the 16 bit file into an 8 bit file to make the file smaller. I
then resaved and uploaded to my account the audio samples you have
here. Whew. To make things easy, here is you A/D flow chart!
A - mics
A - console
A/D - to DCC 44.1 kHz sample
D/A - from DCC
A/D - to computer 44.1 kHz sample, 16 bit stereo
D - editing in the computer, conversion from 16 to 8 bit
D/A - from your computer to your speakers... Enjoy!