The Hammond Homepage -------------------------------------------------------------------------------Hi, my name is Sean Jewett. I attend Middle Tennessee State University. I am cur rently majoring in Recording Industry, with an emphasis in Production and Techno logy. In the Fall of 1996, I enrolled in Physics 160, Physics of Music, a course designed for Recording Industry majors. Part of the course requirements is to d o a research paper or design a musical instrument. Upon some deep thoughts, I hi t upon the idea of designing a very simple model of a Hammond B3, to show the pr iciples upon which it works. Our school happens to own one, and many theories of electronic music are taught using the Hammond B3 as a model. With help of Dr. J im Piekarski, I became convinced that my model could work. Dr. Piekarski suggest ed using the guitar pickup and pointed me in the direction of the excellent main tainance staff that works for the Recording Industry Department. They supplied m e with the info I needed to get the ball rolling (with one of the best written s ervice manuals to be found). -------------------------------------------------------------------------------The results presented here is my research and my model. Also included are sample s taken from the Recording Industries' own Hammond B3 with the Leslie Speaker (m ore about that later). -------------------------------------------------------------------------------I would like to thank the following people for helping with the research and mak ing this project a semi-reality: Dr. Jim Piekarski Alton Dellinger Dale Brown Recording Industry Maintanance Dept. Shane Smith (for the studio time). Dr. William Robertson(my professor...for letting me do this project) Matt "The Prod Man" Lane Jay Bodiford That being said, lets dive into the Hammond B3! -------------------------------------------------------------------------------The principle behind the Hammond B3 -------------------------------------------------------------------------------Sound generation in the Hammond B3 comes from within what is known as the main g enerator. 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, wi th 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 mo unted to that same shaft is the tone wheel. There are 12 different sizes of bake lite gears. These gear ratios provide the proper speed (pitch) for the tone whee l to be in tune with one another. The tone wheels are steel discs about 2 inches in diameter. These discs are mach ined with high and low points known as teeth. The number of teeth vary in relati on to the tone trying to be produced. The basis of the tone is the equal tempere d 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. A t 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 playe d, 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 f or each of the upper or lower (grand) registers. These preset keys are the "oppo site" (black instead of white) keys below the lowest of the "regular keys" on th e organ. -------------------------------------------------------------------------------The principle behind my project 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 unwieldl y and hardly the contraption I would want to carry into class, I settled on a "T ee nut". These things are used when a person wants to secure a threaded rod or b olt 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 construc tion began. The guitar pickup was mounted to a piece of plywood. A pulley was secured to a s mall 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. Th e tee nut was carefully aligned and is held into place with a nut/ lock washer c ombination. The axel and tee nut were suspended above the guitar pickup using an gle irons. The axel is held into place and is kept in a relative position by mor e 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" (ra dio 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 fac ilitate 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 cou ld possibly be generated could only be two, there is just not enough room above the guitar pickup. -------------------------------------------------------------------------------The Results -------------------------------------------------------------------------------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 start ed 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 conjuncti on with the angle iron... The threads wanted to track in the angle irons. This t racking cause the rubberband to move very freely in its path, resulting in an un constant 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 lou d racket.) The next problem involved the mounting of the pickup. (From a '66 Fen der). I mounted the pickup in open air, and by doing so, introduced all of the p roblems associated with pickups, noise. Noise from electicity, noise from the mo
tor. These problems aside, the project did generate a tone, albiet very unconstant an d very low in volume. I plan to further work on the project. First and formost w ill 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. -------------------------------------------------------------------------------The Leslie Speaker Cabinet -------------------------------------------------------------------------------Perhaps the success of the Hammond B3 would not be without the trusty Leslie Spe aker Cabinet. Invented by Don Leslie, it just goes to show what a little America n ingeniuty can do for the musical world. The idea is this; create a speaker cab inet that spins, or spins the speakers to provide a very non directioal sound th at when coupled with the B3, sounds very much like a church organ, without all o f 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 ta ke 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 t rain that blows it horn has several factor involved, one of which is the speed i t 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, whi ch ivariably is traveling faster that the speed the train is traveling at must p ass through this negative speed. The speed works against the horn, and low and b ehold pushes the sound waves closer together. This causes an increase in the pit ch because sound wave is pushed together. When the train is nearly upon you (I hope you are standing on the side of the tr acks, otherwise you will not recieve the full doppler effect, even if you surviv e) the pitch lowers, almost or to the tone the horn is trying to produce (yes, t rain horns are tuned... older trains might have three or even one, the newer tra ins have at least 5, this is to help prevent the chance of someone being tone de af 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...therefor e lowering the pitch. How Sean, does this relate to the Leslie? I thought you would never ask, my dear Watson! The spinning of the horn (althoug h 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. Ma ny recordings are done with 1, 2 or even 3 micrphones to try to simulate that Le slie effect in home stereo. It really depends on the producer and or engineer, I have heard many arguments as to which is the best.
Also, Leslie cabinet contains a woofer, and rather than try to get a woofer to s pin, a drum with a slot cut out spins around the woofer. The helps create a non directional sound (a wash if you will) in a room. The Leslie Cabinet has two modes, fast and slow. The fast mode is know as tremel o, 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 l ike a church organ.
-------------------------------------------------------------------------------Samples from the REAL Hammond B3 -------------------------------------------------------------------------------I would like to thank Shane Smith for letting me use his studio time to sample t he 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 p art) D. Any other questions, refer to the FYI at the bottom for the sampling informat ion. -------------------------------------------------------------------------------Discography The Wallflowers Album BRINGING DOWN THE HORSE The Wallflowers' use of the Hammond is incredible...It adds a much needed dimens ion to their sound. Both "6th Ave. Heartache" and "One Headlight" feature the Ha mmond. Incidently, I saw them in concert at the Ryman Auditorium w/ Sheryl Crow. ..Their Hammond player does one thing that I would not recommend, played the Ham mond standing on the keys and sitting on the keys... He is wild, check him out. 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 demo nstrate 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 a nd "quiet" sections. This is a great use of the B3 given the title of the song a nd 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. -------------------------------------------------------------------------------Trivia Fun Fact Your are visitor # to play a chord on the Hammond B3! -------------------------------------------------------------------------------FYI 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 J ohn 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 cons ole, they were patched back out into the studio where I has set up my Optimus Di gital 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 roommate s Acer Penitium computer. Using Sound Blaster Soundo'LE, I sampled the DCC throu gh the line input. Sampling rate used was 44.1 kHz, no compression, 16 bit stere o. 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 bi t file to make the file smaller. I then resaved and uploaded to my account the a udio samples you have here. Whew. To make things easy, here is you A/D flow char t! 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!
