Classical Organists Dislike Most Hammonds

Yes, it's true. Classical organists who are used to playing on pipe organs generally hate the Hammonds. Why? Well here are ten reasons (in no particular order)~:

1. The flat 25-pedal clavier is nonstandard and limiting.

   Classical organs have 32 concave radiating pedals that are far easier to play,
   and that are in a standard layout (though U.S. and European standards are different).
   The concave design makes it easier to reach pedals at the ends of the pedalboard,
   especially for organists of smaller build.
   Some classical literature requires the additional pedals, which extend the top of the pedalboard
   range from C to G.
   The pedalboard is probably the biggest practical problem for classical organists playing Hammonds.
   If Hammond would have extended the pedalboard up to D, instead of C, the entire organ literature,
   up to the 19th Century, could be played on the Hammond organ.

   Several Hammond models (including the RT-3 and D-100) are equipped with a full 32-note, concave radiating
   AGO-standard pedal clavier.
   In general, these models are somewhat rare, however (due to their larger size and weight) they are not
   especially sought after, and can often be had relatively cheaply.

1. Most Hammonds have the unique reverse-color preset keys or theatre organ-like flip tab stops. To a classical organist, the preset keys are an unnatural abomination. Pipe organs have push-buttons between the manuals and toe studs for presets, and have drawknobs or tabs for individual stops. On pipe organs, the presets can be adjusted by the organist to activate and retire different stops; on a Hammond, they can only be adjusted from inside the rear panel.
2. Hammonds have drawbars to mix the organs harmonics together.

   Pipe organs have ranks of pipes of different sizes, shapes, materials, etc. each with its own tone.
   A Hammond has nine sets of sounds that, to a classical organist, sound like boring flute pipes.  A classical organist who is familiar with Hammonds can achieve reasonably good approximations of flute pipes and mixtures, but they lack the "chiff" -- the opening transients -- of pipes.  Reed voices can't be adequately emulated on a Hammond because the buzzy square-wave tone would require many more upper drawbars to achieve.

1. Most Hammonds have WaterfallKeys stepped above each other like stairs. Spacing between manuals is relatively large to make room for busbars.

   Pipe organs have DivingBoardKeys that may overhang each other slightly.  Spacing is narrow, and standarized, to allow more than two manuals.  Also, a classical organist sometimes needs to "thumb down" -- that is, play with a thumb playing one manual and the other fingers on the same hand playing on another manual (though the number of situations that actually require this is small).

1. The expression pedal on a Hammond changes the volume of both manuals and the pedals.

   On a pipe organ, Swell refers to pipes enclosed in a chamber with shutters that are opened and closed with the Swell pedal.  These pipes are assigned to the Swell manual (of course...).  The Great pipes and the pedal pipes are almost never inside a swell chamber.  The Swell manual is the "only" manual whose volume should change with the Swell pedal.
   Classical organists expect to be able to change the volume of the swell without affecting the volume of the great or the pedal division.  Certain Hammonds directed specifically at Classical organists (Model E, Grand 100) did split the manuals into two expression circuits.

1. The attack on a Hammond is much too abrupt. Hammond engineers tried all sorts of manual tapering, busbar greasing, speaker fiddling, amplifier filtering, etc. to hide the KeyClick.

   Organ pipes lag a hair behind the keypress as the pipe begins to valve under the opens and air flows into the mouth.  More importantly, the column of air in the pipe takes some time to begin vibrating, and can produce opening transients (chiff) that are different than the continuous tone it produces.  The bigger the pipe, the more pronounced these effects are.

1. The Hammond is too "pure". Pipes in a organ, not matter how carefully tuned do not stay tuned to each other for long. The position of the pipes in the building, temperature changes and humidity changes can all affect pipe tuning. Subtle differences in pipe tuning give the organ a rich complex tone. The synchronous motor, gears and tonewheels "lock" the Hammond in tune. Hammond tried to imitate this effect first with tremolo and then with the chorus generator and the scanner vibrato.
2. A weak pedal division. In a finer pipe organ, the pedal division is as strong as the manuals, having not only bass stops but foundations, reeds, and color stops as well. Hammond never gave the pedal division its proper importance, probably because amateur church organists who served in churches in the Hammond target market lacked the training to use it -- many amateur organists only use the bottom octave of pedals, or do not use pedals at all. Pipe organs in smaller churches often lack a proper pedal divison, but make up for it (to a degree) through use of couplers that allow the stops on a manual to be played with the pedals. The Hammond does not provide this, and with only two drawbars for the pedals, it is impossible to get a big sound. Also, there are no 32' tones available except on certain models that were synthesized with tube oscillators.
3. The harmonics are all wrong... Now, try to remain calm, it's true. Hammonds use harmonics from the equal tempered scale but these (while close) are not the same frequencies as the natural harmonics. Stike a key on the piano, the fundamental is tuned to the tempered scale (let's not bring spread tuning into this) but the natural harmonics of vibrating strings are not equal tempered. Case in point; the 7th harmonic is included in very few Hammond models because the equal tempered equivalent on the tone generator to the 7th harmonic is way off pitch. Models with the 7th either put up with the error or had another tone generator to provide a true 7th.
4. The keybed (action) is all wrong... Again, try to remain calm, this is also true. While the Hammond does feel a lot like an electric action pipe organ, a real honest-to-God tracker pipe organ couples the key manuals directly and mechanically to the valves under the pipes. When you press a key, you can actually feel a tactile pluck as the valve is opened against the wind pressure and then suddenly releases as the air rushes into the pipe. Pipe organs with electric or electropneumatic action simulate this action with a little magnet under each key. When the key is pressed, the magnet is pulled away from a steel rail that adds just a touch of heaviness to the spring tension. After about 4mm of travel, the magnet would suddenly break it's attraction to the steel and the key released against only the spring tension to the keybed. Electronic organs made by Rodgers and Allen often have a similar touch.

On the other hand, most B-3 session players have at least some classical organ training.