This month begins a series on electronic keyboards ranging from the1930's to the present
and how each keyboard's development was tied closely to the technology of its time.

HAMMOND ORGAN

In my opinion, the first commercially available electronic keyboard was the Hammond Organ. At the time of the first manufacturing of the Hammond Model A in 1935, the only keyboard alternatives were pianos and pipe organs. Hammond's marketing strategy was to replace the pipe organ in churches with a Hammond Organ at a much lower cost and they were successful at this. Also, weighing in at 400-500 pounds the church environment, where it didn't have to be moved, was perfect for it.

As time went on the Hammond Organ gained popularity with other musical genres, making its way into big band, and smaller jazz combos where the bass lines were played on its bass pedals, the lower manual used for chording and the upper manual for soloing. Using the Hammond in this way allowed a small group of musician's to simulate the sound of a much larger band. Of course as time went on the Hammond found its way also into R and B and Rock.

At one time I owned a model A from 1935 serial # 1912. It was a wonderful sounding instrument. Unfortunately it met with an accidental demise. I was playing in a disco band at the time and we were secretly making the transition to rock intending on also firing the singer of the band. We had the organ stored in our truck and after setting up our the equipment at a gig the singer in the band, who had no idea there was an organ sitting by itself in the back of an empty truck (he didn't help unload- one of the reasons he was fired), decided to use the truck to go get some pizza. He heard a loud crash while making a turn and stopped to look in the back of the truck. When he came back he asked why there was a now destroyed Hammond in the truck and was told "we're going Rock and you're fired"

HAMMOND OPERATION

The Hammond organ is an electro-mechanical instrument and operates much the same way as an electric guitar. Both use a vibrating piece of metal inside the magnetic field of a pickup On a guitar, the string's vibration causes a change in the pickup's magnetic field resulting in a voltage being output from the pickup coil at the frequency of the string's vibration, On the Hammond a rotating metal tonewheel sits in the magnetic field of the pickup inducing a voltage from the pickup at the frequency the tonewheel is spinning at. This is the basis for the sound generation from a Hammond, but one tone wheel per note is not enough to create the Hammond sound. The actual tone generator contains nine tonewheels per note on the keyboard. Each tonewheel creates a different harmonic that can be mixed together.

Looking at this concept more closely it is best to explain that each harmonic output from the tone generator is a pure note with no harmonics called a sine wave. The sine wave is the most basic element of sound and every sound we hear is a combination of sine waves mixed together. The balance of harmonics mixed together create the sound or timbre. The mixture of harmonics includes s a fundamental frequency which we hear as the notes pitch mixed with its higher harmonics of thirds, fifths,sevenths, octaves etc. Obviously there is more to sound such as envelope (attack, sustain decay), but for purposes of the Hammond we are looking at harmonics. Therefore the nine tonewheels per note are each able to controlled in level by the drawbars. The Hammond has two sets of nine drawbars, one for each manual. As you slide each drawbar towards you it increases the volume of its associated harmonic. The output of the same harmonic for each key goes to its drawbar, so sliding a drawbar sets the level of that harmonic for every key on the manual. at the same time The overall combination of the level of all the drawbars is called a registration. One interesting thing that the Hammond could do that is commonly available on digital keyboards today is it could actually store different registrations. Although it took a lot more effort than pushing the store button on today's keyboards the result was the same. Suppose you were an organist desiring different drawbar registrations, maybe even within the same song. All you needed to do is play with the drawbar combinations and write down your preferred registrations and then set them up using the Hammond's preset capability.

The lowest octave of the keyboard contains reversed colored keys. These keys are actually switches to call up different registrations. Each preset key has nine wires(one for each harmonic) that can be attached to a panel inside the keyboard where it can be screwed to a busbar on one of eight positions corresponding to the eight levels available when drawbars are pulled out. When set up, pushing the reversed colored keys brings up the registration each key is wired to, or you can bypass the presets and use the drawbars to set the sound manually. This latter is useful to make subtle changes on the fly. So here was an ingenious low tech way of providing a multitude of different sounds available to the player instantly in a time period long before it was a common thing to have.

VIBRATO / TREMOLO

Although there is a good range of tones to create, it's still kind of a static sound. Most instruments have a way of imparting some extra expression to their basic sound. A violin player can employ vibrato on the instruments sound and a piano player can play with dynamics or the sustain pedal. The Hammond did not give a way to change its sound outside of moving the drawbars. This is why Vibrato and chorus were developed. It allows for subtle variations of volume and pitch to be imparted on each note. Again we see a very low tech solution for an easily digitally solved modern problem. A second generator called the Chorus Generator was added to the first tone generator. It contained additional tone wheels that spun slightly slower and faster than the main tonewheels adding complexity to the sound. This worked well but certainly added much weight and expense to the unit.

PERCUSSION

One other popular effect added to the Hammond was called percussion. Here a harder attack was added to the beginning of each note changing the feel of the sound. It did require the highest harmonic being removed from the sound as this was used to trigger the percussion generator, but the percussion sound more than made up for its loss. Percussion was also variable in which harmonic its sounded and its level and decay rate.

AMPLIFICATION

One of the beauties of the Hammond sound was the use of tube amplification either in the console itself or thru Hammond tone cabinets. Obviously as the amps were pushed harder they went into a growling overdrive tone further adding life and expression to the tone. And don't forget John Lord of Deep Purple. He took the output of his Hammond and ran it directly into Marshall guitar stacks giving him the overdrive capability of a guitar player.

SYNCHRONOUS MOTOR

One other idea that Hammond employed was the use of a motor called a synchronous motor to spin the tonewheels. Without getting too technical this motor derives its speed from the wall A/C power line frequency which is always a rock solid never varying 60 HZ per second. Had they used a voltage that created it's speed using line voltage the pitch of the tonewheels would vary whenever the line voltage varies which is basically all the time.

Of course this is not without its potential problems. there are times when the line frequency does vary. Certain areas use 55 HZ not 60 Hz and of course portable power generators or cruise ships may not be at 60 HZ. I clearly remember playing an outdoor concert in a park using a portable power generator. We started to play and quickly discovered the Hammond was out of tune with the band. This was not a fun gig. I also remember being at an outdoor show and trying to get the organ to start on stage right before the band was supposed to go on in front of 10,000 people

LESLIE SPEAKER

Probably the most important thing to happen to the Hammond was the invention of the Leslie Speaker. Although not a Hammond invention, it quickly became a must have for amplification of the organ. The Leslie divides the audio coming from the organ into low and high frequency bands sending the lows to a speaker and highs to a horn driver. The speaker points into a rotating drum containing panels to bounce the sound off of and the driver hooks to a rotating horn. As the organ is played into the spinning horn and speaker the sound is projected out of the cabinet in 360 degree fashion. The principle of the Doppler effect is applied here. We all know as a sound is moving relative to us we hear its frequency change. The classic example of this is the horn of a freight train changing in pitch as it passes by you. With the Leslie, the sound being projected 360 degrees it is dopplered enough that you hear its pitch shift one way as the sound moves away from you and the opposite as it spins back toward you. The fact that the lows and highs are being projected separately at two different rates adds to the richness of the sound. The Leslie also employs a switch so the motors can turn the horns at either a very low speed emulating chorus or high speed emulating vibrato.

Overall the sound and even the look of a Hammond B-3 with Leslies spinning on stage is still an icon coveted by musician's. Just ask anyone who has had to participate carrying a 450 lb Hammond B-3 up two flights of stairs and despite that they will probably tell you it was worth the effort.

Steve Weiss is the owner and main technician of Steve Weiss Electronics Inc. He is experienced in the repair of analog and digital musical equipment. This includes everything from Vintage Tube Amps and Pro Audio equipment to Digital Keyboards There is also a guitar repair shop staffed by some of the areas top guitar repair techs. He is authorized for warranty work on most major brands. Steve Weiss Electronics is located inside of Sam Ash Music at 5460 West Sample Road Margate, FL 33073 954-975-3390 Ext 272. Steve has also spent 25 years on the road as a performing guitarist and is the designer of Primal Guitar amps that can be seen at Primal Audio.com Steve can also be reached at stevew@metromusicmayhem.com