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The Hammond (B-3) Page

There have only been a very small handful of truly new musical instruments invented since the piano forte in the 1720's - certainly up until the electronic synthesisers of the 1960s and 70's there were only two truly successful (and truly new) ones - the electric bass guitar - a truly new instrument brilliantly devised by Leo Fender - and the Hammond organ.

These instruments are not merely adaptions of earlier instruments - they are new creations for which whole new styles of music were created. And in both these cases there have been very few (if any) improvements to these first designs.

A very important point should be made first of all however - the Hammond organ was not invented as a funky, jazz, blues and rock instrument - and the elements that lend themselves perfectly to these styles were purely accidental. The Hammond was intended to be an economical substitute for a pipe organ - and to a point it succeeded - it was 30-50 times cheaper, sounded quite similar and would last a comparable time - this last point has made these instruments unique amongst electronic instruments - most electronics are designed with a definite lifespan in mind - but Hammond was trying to compete with instruments that would last a thousand years or more!

This is why we can still reliably gig with an electo-mechanical instrument invented 75 years ago - my own Hammond was built in 1963 and works flawlessly every gig (whilst P.A's, guitar amps, D.I's and microphones die all around us!).

But, in their intended role as a pipe organ simulator they are flawed in several areas - they aren't loud enough without serious re-wiring to accommodate many more speaker cabinets - their pitch and the phase relationships between their tones and harmonics is too precise, the tones are produced too quickly and there is an audible click (or, as I prefer to describe it - a "fft") at the start of each note...However all these features make them eminently suitable for jazz, blues, soul, funk and rock styles.

I should also say that this whole page pertains only to organs with electro-mechanical tone generators - that is, organs produced by Hammond between 1934 and 1975 - no other brand of keyboard had a mechanical tone generator during this time (or any other time!). Hammond later produced solid state organs like all the other companies - but these share none of the above mentioned features and have never been used for jazz, blues, funk or soul music! Some of them sound great for surf, garage and experimental styles though - but that's scope for another page - personally I have a 1978 Farfisa Professional 110 and a 1966 Farfisa Compact and they are brilliant sounds - but only really usable as an effect (usually a somewhat comedic one at that) but the mechanical Hammond is a genuine musical instrument like a violin or a piano...

There is enough Hammond history elsewhere (an excellent and detailed version can be found here so I will keep this brief - Laurens Hammond (born 1895 in Evanston, Illinois) was a clever engineer and inventor in that exciting age when electricity was revolutionizing the world the same way the steam engine had - it seemed you could make electric versions of any and everything (much like people are trying to do now with digital technology).

A lovely wall clock from the reverse time page

As well as a bridge table that shuffled and dealt cards automatically (with a creepy rubber finger!), an automatic transmission for automobiles and a 3D movie camera and viewing system it was his "tick-less" clock that set him up in business. Many of his early inventions (including the clock) focused on the concept of the synchronous motor - that is a motor that was in phase with the 60 cycle alternating current that had become standard in the U.S.

There is a fascinating "semi-auto" biography of Laurens Hammond here which contains some fascinating insights to the man behind the instrument - like Leo Fender he never learned to play music but had a remarkable insight into the wants and needs of musicians and composers, and a great appreciation and understanding of music - which is rare in anyone - let alone in a gifted mechanical engineer and inventor.

The direct ancestor of the Hammond organ was the "Telharmonium" or "Dynamophone" (perhaps also an ancestor of the saxamaphone?). Patented in 1897 by Thaddeus Cahill, it worked on the principle of using dynamos to generate alternating frequencies relating to musical pitches but the invention was doomed by it's immense size and the lack of suitable playback equipment (this was of course long before the invention of the vacuum tube amplifier).

For people who think a B3 is a drag to move around picture the Telharmonium - it weighed 200 tons, was 60 feet long, took four people to play and could only be listened to over the telephone! (that is it made no noise of itself - except mechanical noise). Adding to these limitations it disrupted other telephone calls, suffered numerous breakdowns and produced an overall listening experience that was described as "highly irritating"!

It proved, however that musical tones could be produced electronically as alternating currents at different frequencies - Laurens Hammond's great innovation was to see that you didn't need a separate motor for each note (once you could amplify the tones with vacuum tubes) but that a single motor with a very constant and regular rotation could drive a shaft from which many tones could be derived.

The most detailed description of the Hammond tone generator you'll ever find is here but briefly, the tones are created by rotating a small metal disc close to an electro-magnet (identical to an electric guitar or Rhodes piano pick-up). The speed of rotation and the number of teeth (or corners) on the disc determined the pitch. It's an immensely complicated machine, there are 48 sub-assemblies geared to rotate at twelve different speeds, these sub-assemblies each contain two tonewheels an octave apart. The are 12 tone wheels with two teeth and twelve wheels each with 4, 8, 16, 32, 64, 128 teeth and seven tone wheels with 192 teeth. Combined with the twelve rotational speeds these provide all the (91) musical tones for the organ.

tonewheel diagrams from the B3 manual

Now comes the really interesting part! A "normal" (or non-electric) instrument produces a fundamental tone overlayed with multiple harmonics which are related notes that add together to make up the particular timbre of the instrument. For example if you picture the tone of a flute, it's relatively free of harmonics, it's a fairly pure sound whereas a violin has many more prominent harmonics, giving that rich textured tone - the individual notes almost sound like chords (what's the difference between intervals and harmonics? My attempted explanation can be found here).

But the tone-wheels of a Hammond organ produce an extremely pure tone that is, in fact, too pure to sound realistic - it sounds like a dial tone. Laurens Hammond realized he would have to combine several tones together to produce the more complex waveform that conventional instruments produce but thankfully for history he decided to combine them in a unique way.

Instead of deciding on the harmonics and hardwiring them in, he built in "drawbars" which control the volume of each harmonic. With all drawbars pushed in the organ will produce no sound but as you pull each one out you can control the volume of that particular harmonic (each drawbar has eight volume levels they can be set to). For example if you play a middle C and pull out the first drawbar (only) the tone produced will actually be an octave below middle C. The next drawbar will produce a G (the dominant harmonic of C) and the next will produce actual middle C and so on.

The 256,000,000 combinations of settings or "registrations" are part of what gives the Hammond it's great potential for individual artistic expression - there are other factors that separate the Hammond from all other electronic instruments however that no other musical instrument has - or can replicate.

For example - in order to tune an instrument to the Western standard of Equal Temperament, each note has to be 1.059463094 times the frequency of it's neighbour - but Hammond's tonewheels had to have a whole number of teeth (half a tooth would still produce a current and be the same as having another whole tooth) so this ratio was impossible. So Hammond had to shuffle the notes around a little and consequently a Hammond has it's own slightly different (and unique) tuning (or temperament).

Another very important factor in the sound is that the keys actually have nine separate contacts underneath them which correspond to the nine drawbars - and because a keyboard key is a lever rather than a switch or button, these nine contacts close sequentially. As you press a Hammond key very slowly you will hear each drawbar sound one after another - while this isn't very noticeable in ordinary playing it becomes a very important part of the sound in fast runs - if you play a very quick run with many drawbars out, the fastest notes will have a different harmonic content to the slower ones because occasionally you haven't closed all the contacts. On a digital version (except for Hammond-Suzuki's "New B-3" - which uses mechanical contacts) all the tones are produced instantaneously.

Perhaps the most important side effect of these nine contacts is the infamous key click - this is a soft "ffft" kind of sound at the start of a note, caused by the nine contacts closing almost simultaneously. This sound was seen as a defect by Hammond but it was never able to be eliminated. To the jazz organist it is a wonderful sound akin to the valve noise of a flute or saxophone.

Another interesting sound is the "generator cross-talk" - electromagnets picking up a little of the sound of their neighbouring tonewheel as well - this is why the tonewheels were paired in octaves, so the cross-talk wouldn't be dissonant but the overall effect is a slight blurring of the tones so that they sound less artificial or electronic.

Another essential ingredient is what has become known as "harmonic foldback". In order to save money (they had to stop somewhere!) and to cut down on the physical size of the organ, some of the tonewheels were re-used for the highest and lowest notes - If you play a descending line near the bottom of the keyboard, the tone from the bottom drawbar will suddenly jump up an octave as you go down - some people find this inconvenient but most organists use it to throw interesting changes into their bass lines - sometimes the leap up or down is not where you would naturally think to put it and that can be an exciting thing, it inspires you to try more interesting lines.

The other essential Hammond ingredient was the chorus/vibrato circuit. "Chorus" is the sound of a regular shifting of phase of an audio signal - sort of a whooshing, underwater type of sound and "Vibrato" is a regular raising and lowering of pitch. Electronically it's very simple to get both of these effects from one circuit because the chorus effect is created by mixing the vibrato signal with the non effected signal (as the pitch of the vibrato signal is raised and lowered the sine waves get closer and further apart, thus moving in and out of phase with the non-pitch shifted signal). This feature was introduced on the B-2 in 1949 and is created by a huge rotating capacitor assembly on the end of the main tone generator shaft.

All these new features ensured the Hammond's immediate and widespread popularity. Henry Ford, George Gershwin and "Fats" Waller were among many famous early customers. Soon Hammond organs were everywhere - in churches, accompanying radio plays and game shows, at ice rinks and baseball games (where some of them still are) and they soon began venturing onto bandstands and recording studios.

Fats Waller had made the first "jazz organ" recordings in 1926 on a pipe organ and was quick to realize the potential of the portable Hammond organ. Count Basie received some organ instruction from Fats Waller and a number of other early (pre-Jimmy Smith!) jazz organists appeared - Milt Buckner, Ethel Smith, Glenn Hardman etc.

It was "Wild" Bill Davis however who is credited with the invention of the "organ trio" - this is a unique and wonderful combination made possible by the fact that an organist can play bass on the pedals or lower manual (or in reality a combination of both) whilst supplying chords and melody on the manuals, supplemented by a guitar (usually, or sometimes tenor sax) and drums.

No other instrument can adequately replace the bass in a band - for example piano trios often did without drums in order to retain two melody instruments and a bass-line. The organ trio undoubtedly produces the biggest sound of any trio in any genre of music - Bill Davis' idea was to replicate the sounds of a big band and pick up a lot of work in clubs that couldn't afford the extra players - it worked!

Bill Davis quit his job as Louis Jordan's piano player to pursue his experiment of the organ trio - so popular was the sound that Louis Jordan hired him back to play organ on selected records - the first really mass exposure the Hammond got (in jazz) - Louis Jordan's piano player at the time of Bill Davis' guest spots was Bill Doggett - noticing that Bill Davis was getting three times the money for playing the organ he decided to have a go and the Hammond trio began to spread.

It may have remained a passing fad however but for two events that were so fortuitous that it's hard to believe they weren't connected! In January 1955 the model B-3 replaced the B-2 and Philadelphian pianist Jimmy Smith switched to organ after hearing Wild Bill Davis.

Outside the world of jazz/blues organ the difference between the B-2 and B-3 is seen as being trivial - indeed many classical organists feel that the B-3 is overrated - in the world of jazz, blues and funk however there is only one model of Hammond organ - the B-3.

The glorius B3

Like its predecessors it has two 61 note manuals (keyboards) with two sets of nine drawbars for each manual, a 25 note bass pedal board controlled by two drawbars, a chorus/vibrato circuit with three levels each of chorus and vibrato. The chorus or vibrato is selectable on or off for each manual independently. There is an overall volume pedal for the entire organ.

It should be said that there are a couple of other models which are very similar to the B-3 and one that is exactly the same - the C-3 is a B-3 built into a "church" style cabinet - contrary to persistent rumours there are no differences between the two except the woodwork - people forget how important the cabinet style was in the 40's and 50's - indeed the Spinet models (I'll get to in a minute) have separate model numbers depending on the style and colour of their woodwork! It seems strange now but it's only because the instruments have lasted so long that the world they were created in has become so drastically different to ours - anyway...

(As well as the identical C-3 there is the A-100 [which is a B-3/C-3 with built in amplifier and speakers] and there were also models with all the B-3 features and more as well, like the RT-3 and D-100.)

front page of the B3 manual

But the ingredient which differentiates the B-3 from the B-2 was the percussion feature. This circuit adds an attack to the notes, giving a sound closer to a piano or vibraphone - in fact the great Shirley Scott could do an incredible vibraphone impression using the percussion feature. There are two harmonic tones selectable, two decay times and two volume levels of percussion selectable. The percussion is only available on the upper manual on the B preset (the second set of drawbars from the left of the organ). The percussion is triggered from the ninth drawbar contact, so that when percussion is switched on there is no sound from the ninth drawbar (the percussion works best in my opinion! when the percussion tone itself is the highest sound so I've never needed the ninth drawbar and percussion at the same time - you can however change this keying source to any of the other drawbars if you wish).

The really cool thing about the percussion is that it allows another degree of expression due to the fact that it is "single triggered" - that is, the percussion effect is triggered by depressing a key but cannot be triggered again until that key is released - if you hold down that first note, all the other notes will sound without percussion. Although this was an accidental feature of the circuitry it allows you (once you're used to it) to add extra attack to certain notes.

I should point out that, while the percussion effect is single triggered, it doesn't make the organ monophonic per se - the percussion effect happens only once, but other notes can be played while the percussion effect is decaying - they'll simply share the decay characteristic of that first note. Once the percussion decays completely, all other notes will sound without percussion until you lift that first key. Also if you lift it briefly the effect will partially recharge, giving you an element of touch sensitivity (although it's time based rather than pressure based) - so for example you can play a series of fast notes (in the pattern of drumming your fingers for example - I don't know the musical term for that technique!) and, with the right timing, you can choose whether to maintain the charge of the percussion effect or allow it to fade out the riff you're playing - you can choose the timing of the fade-out by periodically lengthening or shortening the time you hold down each note - the longer you hold down a single note, the quieter it will get - it's hard to describe but it's one of the greatest features of the instrument...

The percussion feature enabled the Hammond to interpret a whole new repertoire of material. It was no longer merely an "organ" - it was an entirely new musical instrument. The percussion allowed single note lines to stand out which they never had before - where the organ was previously used to simulate a horn section, now it could play single note solos and runs like a saxophone, trumpet or piano - as well as all the previous sounds available.

And, miraculously, at the same time this feature was introduced, Jimmy Smith came along with an artistic vision of the organ that made full use of all these features. Instead of trying to make the sounds of a big band on a budget Jimmy Smith played the B-3 as if it was invented for (or by!) him - no longer an electronic simulation of another instrument, the Hammond was now an instrument that melded the sounds of the electric guitar and vibraphone (both fairly new inventions at the time) with saxophone, flute and the sounds of the Sputnik spacecraft. It's hard to imagine how futuristic and revolutionary the sound must have been then - it's pretty far out even now (listen to Jimmy Smith's "Groovin' At Small's Paradise" from 1957 and compare it to other 1950's music!).

Also throughout the 1940's and 50's both electrical recording (microphones etc) and electric instruments on banstands were creating a revolution in how music could be played - for example a tenor sax could be played with a low, breathy tone into a microphone instead of having to wail to be heard - and singers could lay much more emphasis on particular notes - if a note is played quietly or intimately but is loud enough to be heard it carries a much different feeling to a note that is yelled or blared out - and the Hammond was able to use this new power of expression to probably greater effect than any other instrument.

Indeed the B3 is eminently suited to jazz because it shares many of the qualities of a wind or brass instrument - there is no predetermined decay time like a guitar or piano - and if you've learnt to play on a piano you find this is the biggest change - where you let go of a note makes almost as much difference as where you play it. So you have the facility of a keyboard but with many of the capabilities of a saxophone or trumpet - but you also have some of the tone and distortion characteristics of an electric guitar - combined with the ability to control the groove of the song by also being the bass player - you can see the amount of power a Hammond can command in a band!

Jimmy Smith's popularity and profile - as well as his newly created style and technique of playing the organ - inspired hundreds of other musicians to take up the instrument - it would not be an understatement to say that every organist that followed after Jimmy Smith was either directly inspired to do so or was directly influenced by him.

Among the greatest to follow Jimmy Smith were Jack McDuff, Jimmy McGriff, Richard "Groove" Holmes, Shirley Scott, Doctor Lonnie Smith, Reuben Wilson, Larry Young and many more in no particular order! It is very important to realize that, whilst these people were inspired to take up the organ by Jimmy Smith's example, none of them were copyists or imitators of him - they all had their unique and easily distinguishable sound.

In fact this is what proves the Hammond organ to be a "real" instrument like a piano or guitar - Rudy Van Gelder recorded a great number of Hammond organists for Blue Note records in the 1950's and 60's and they are all instantly recognizable from each other - even though they all played the same B-3 in Rudy's Hackensack and then Englewood Cliffs studios.

And it's important to remember that of all the artists to follow Jimmy Smith, either stylistically or just chronologically, none of them would dispute that Jimmy Smith is still the unrivalled virtuoso of the instrument, and the one who wrote the new language for this new instrument - even if you personally might prefer the style of another organist.

Now the other side of the Hammond equation is the Leslie speaker. It can hardly be over-emphasised how important the Leslie speaker is to the sound of the Hammond organ. The bizarre part of the story is that, even though 99.9% of material recorded on a Hammond organ has been played through a Leslie speaker and the two are thought by many people to be part of the same device - Laurens Hammond seemingly despised the Leslie Speaker and it's inventor and forbade the two devices to be sold together!

diagram of Leslie speaker

There is some excellent information on this strange story here but basically Don Leslie was an organist who thought he could improve the sound of his Hammond organ by adding a rotating speaker - the point was to simulate the way sound from a pipe organ reflects from all around in a church or large hall, and the way the various pipes interact with each other creating phasing and "harmonic beating" sounds. He attempted various means of spinning speakers around or rapid panning between stationary speakers (much like the Fender Rhodes piano would do twenty years later) but settled on a simpler approach.

Much like the B-3, the Leslie 122 became the archetypal Leslie speaker and featured two stationary speakers firing into rotating horns. The upper quarter (or so) of the cabinet houses a treble driver that fires upwards into a rotating horn arrangement - it looks like two horns but one of them is blocked and merely serves the purpose of balancing the operational one, reducing wear on the bearing.

The middle of the cabinet serves as a bass enclosure for the 15" woofer (and space for the 800Hz crossover and the motors) which fires downwards into a rotating drum in the bottom of the cabinet. This drum has a kind of ramp in it which directs the sound out horizontally. Both the upper and lower units can rotate at two different speeds, controlled by a switch affixed to the organ itself.

The result of this arrangement is a complex, whooshing, phasing, tremolo, vibrato type sound (?!) which is a major part of the "Hammond sound". The volume rises and drops as the horns point towards and away from you but also the pitch is raised and lowered by the Doppler effect. Along with all the reflections inside the cabinet and in the room itself it imparts a wonderful effect that Leslie described as "sound in motion".

Because of the length of bass frequency sound waves, the Doppler effect isn't very noticeable so the bottom drum mainly imparts amplitude modulation (it gets louder and softer) while the treble rotor produces both amplitude and frequency modulation. One of the coolest effects is due to the fact that the bottom rotor (originally made of plywood but later from stiff foam) is much heavier than the plastic treble rotor - it takes much longer to speed up and slow down - so you have the effect of the treble frequencies almost instantly changing and the bass frequencies gradually catching up - some of the greatest whooshing sounds come from the changing phase relationships as the rotors are moving at different speeds...

Don Leslie never advertised his products and yet he probably sold more Leslie speakers than Hammond sold organs - partly because many organists used two cabinets but also because many other brands of organ were wired to accommodate Leslie speakers as well.

Because the Hammond and Leslie combination were designed in an era when "electrical" musical instruments were brand new, they feature a rather odd (by today's standards) connection. The Hammond and Leslie are connected by a (usually) 6-pin cable which contains, not only a balanced audio signal, but also current for the relay (to change speeds) but also the AC for the Leslie amplifier itself (that is, a Leslie doesn't plug into the mains power itself - it takes it's power from the Hammond).

This means that you can't plug your guitar or other keyboard into a Leslie speaker like an amp - you need some extra hardware or serious re-wiring to do this. Fortunately nowadays you can buy preamp pedals that allow you to connect any 1/4" instrument to a Leslie (famous Leslie'd guitar sounds include Jimi Hendrix's "Little Wing" and the chorus of "Lucy In The Sky With Diamonds").

There are a great number of Leslie models, many of which were designed for use with other brands of organ but the king of Leslies is the 122, designed specifically for the B-3. The 147 is exactly the same cabinet with a different amplifier in it, designed for the Spinet models Hammonds.

The original 122 (and 147) amplifier is a beautiful thing. It is a very simple, clever push-pull design using two cathode biased 6550 power tubes, a solid state rectifier, a vacuum tube voltage regulator and a 12AU7 phase inverter. Because the console Hammonds are line level devices there is no preamp as such in a Leslie 122 amp.

Cathode biasing has two or three major advantages and one major disadvantage - for one thing you don't have to re-bias the amp when you change power tubes (useful for non technical people) also the power tubes last a bit longer and the "correct" bias level adjusts as you play - which, while being not a great technical advantage, gives a very characteristic sound - for example some of the most recorded and sought after guitar amps are cathode biased - many of the "Tweed" Fender amps and the Vox AC15's and AC30's.

The disadvantage of cathode biasing is much less power output (than fixed bias amps) and therefore less headroom and more distortion...Don Leslie probably chose this design for the reliability and ease of service - remember most Leslies were destined to be installed in churches and used week in and week out without constant checking and maintenance - a fact which makes them so ridiculously reliable now - especially compared to modern equipment!

The Leslies intended installation in a church is also the reason for the arrangement where the Leslie draws it's AC power from the Hammond - so you don't have to climb up to the ledge where the Leslie is installed to turn it on - it simply turns on when the Hammond is on - this also makes a Leslie difficult to use as a stand alone amplifier - because there's no mains cord to plug in - the mains, speed switching voltage and audio all travel through the same six connector cable...

More to come soon...

Here's the B3/C3 manual in .zip format -

or in .tar.gz - Hammond-201.pdf.tar.gz