How the Hammond Chord Organ Works

The picture above is of an S-100, which was the last generation of the Hammond Chord, and added a few features, like reverb. But most of the basics are the same as the older Chord Organs, such as the S-6.

The main difference between the S-100 and older models is that there is an obvious way to turn it on: an on-off switch. With the older models, there's a wand-like contraption under the keyboard, which is nearly invisible when stowed. The wand may be held in place by a metal clip. Make sure the wand is free of the clip, then rotate the wand downward and to the right (counter-clockwise) to turn the organ on. While playing, the wand rests against your right knee, and serves as the expression pedal. Move the wand to the right to pump up the volume.

The S-100 separated the two functions of the wand into an on-off switch and a standard "gas pedal" expression pedal. (Of course a pipe organ may have a "swell pedal" and perhaps even a "great pedal", while the expression pedal is merely "OK".)

The only other major difference is that the S-100 has reverb, and so there's a fourth knob above the keyboard to control the reverb level.

Rhythm Bar

Your left wrist works the rhythm bar. When you press a chord button, the rhythm bar can be used to "strum" the chord in time with the pedals. When the "sustain cancel" table is on, the chord sounds only when you press the rhythm bar.

Chord Buttons

Lots of buttons here. 96 of 'em to be exact. Eight chords for each note of the scale. Check out the details of chord buttons for a breakdown of each chord.

Each note of the scale has one column of buttons, arranged in "circle of fifths" order from left to right. That is, the tonic or root of the next chord to the right is the fifth note of the scale of the current chord. So the chord to the right of C is G (C-D-E-F-G), the chord to the right of G is D (G-A-B-C-D), and the chord to the right of D is A (D-E-F#-G-A).

Going to the left, you get a "circle of fourths". So F is the next chord to the right of C (C-D-E-F)...and so on.

All of this "circle" stuff makes great sense music theory-wise. But it actually makes practical sense. If your song is the in the key of C, the chords you'll most likely need to need will be flavors of F and G, from the two columns nearest C.

Hammond incorporated this bit of applied music theory into its simplified music system. There's a little plastic slide with numbers from one to six on it that fits over the chord symbol bar. The two is circled, and the idea is to place the two over the key your song is in. Both the tablature and standard versions of chord organ music indicate the column number along with the chord name.

Hammond also provided little numbered caps which fit over the chord buttons. These indicated which row to press. For the key of C, your one button would usually be F (major), your two button would be C (major), and your three button would be G7. The four button would be D7.

Chord buttons, showing numbered chord slide in the "C Major" position, and numbered key caps on the F major, C major, G seventh, and D seventh chords.

Numbering the chords is a great concept, but it assumes you won't be playing songs in "difficult" keys like F#, where chords one and two would be in the rightmost two columns, but chords three and four would be in the leftmost two columns.

Tone Tablets

These are the big rocker-switch type items running all the way across above the chord buttons and the keyboards. In general, the white tablets select a sound (similar to selecting a rank of pipes on a pipe organ), and the black tablets modify the sound in some way. A tablet is "on" when the dot on the top edge is showing.

The exception to the black-white rule is the leftmost white tablet "volume soft", which makes the whole instrument a little quieter to avoid potentially interrupting people's conversations.

The next two white tablets control the "organ section" of the keyboard. Your choices are strings and flutes. The organ section voices sound for every key you press on the keyboard.

The remaining white tablets -- a group of three and a group of five -- control the sound of the "solo section".. These voices sound only for the top key you press on the keyboard.

To engage the solo section, you need to select at least one tablet from the group of three and one tablet from the group of five.

Check out the detailed explanation of each tone tablet with descriptions taken directly from the Owner's Playing Guide.

Reverberation Control

Found only on S-100 chord organs, this knob controls the level of the reverberation effect. Turn clockwise for more, counter-clockwise for less.

Pedal Section Balancer

This knob control the relative volume of the bass pedals. Clockwise for louder, CCW for softer.

Organ Section Balancer

This knob control the relative volume of the organ section. Clockwise for louder, CCW for softer. This control affects the loudness of every note you press on the keyboard, as long as one or both of the organ section tablets are engaged.

Solo Section Balancer

This knob control the relative volume of the solo section. Clockwise for louder, CCW for softer. This control affects only the top note you play on the keyboard, and only if at least one tablet is engaged in both groups of solo section tablets.

On-off Switch

Only found in the S-100. On older models, you turn the organ on by rotating the "expression lever" under the keyboard downward.

Keyboard

Seems simple, but you must have a least one of the white tablets engaged for it to make any sounds. And that white tablet can't be the leftmost "volume soft" tablet. Hammond intended for at least three white tablets to be engaged, one from the "organ section" group of two tablets, and one each from the two "solo section" groups of three and five tablets.

Without an organ section tablet selected, only the top key you press on the keyboard will sound.

Without at least two solo section tablets selected, one from each group, all the notes you press on the keyboard will sound the same.

Despite the imperative inscribed above the tablets, you might actually like the effect of silencing the organ section or the solo section. Nothing bad will happen if you do so.

Speakers

Where the sound comes out. Other intriguing possibilities include hooking up headphones, a Leslie speaker, or even the much-ridiculed Hammond Tone Cabinet.

One caveat: tube amplifiers don't like not having a load hooked up. They interpret this an infinite load, and attempt to drive that load. Unfortunately, amp components are not designed to supply infinite power, so it's a race to see which component will overheat and burn up or blow up first. Smoke and flames may result.

Transistor amps are smarter, I guess, and are happy not driving any load.

Expression Pedal

Another item found only in the S-100. Older models feature the "expression control" wand. After swinging the wand down, moving it to the right increases the volume.

Bass Pedals

When a chord button is pressed, pressing the left bass pedal sounds a bass note that is the root or tonic of that chord. So, C for a C chord, G for a G chord, and so on.

Pressing the right pedal sounds a bass note that is the fifth of the chord button you're pressing. So G for a C chord, D for a G chord and so on. In other words, the right pedal plays the note indicated by the chord button column to the right of the one you're pressing -- this is the "circle of fifths" in action.

A great many songs can be rhythmically reduced to two patterns of pedal and rhythm bar. So it's left pedal - chord bar - right pedal - chord bar for a 4/4 "foxtrot" and left pedal - chord bar - bar for a 3/4 "waltz" (followed by right pedal - chord bar - chord bar for the next measure).

In others words oom - pah - oom - pah or oom - pah - pah, oom - pah - pah.

With a little imagination, this approach can adapted to a 2/4 "march" or a 6/8 "whatever" pretty easily. Latin rhythms are a little trickier, but many are achievable. A "beguine" is not too bad, but a "rhumba" would be pretty difficult.

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