Long ago, I was a member of the German Hammond Club, which restores only the Hammond tube organs. Barbara Dennerlein had at that time an honor member ship, same as the late Wild Bill Davis, who played once in our club, and I own a 78rmp record of him. Though she is amongst the best of today's organ players, she plays too "clean " for me. Whereas for the music some black artists perform, I can hear this for hours. Look for Wild Bill Davis in youtube. Here is a great recording of some unknown artist, playing Superstition by Stevie Wonder, in an organ shop. He seems to play in in E-flat, which probably makes the chords come out easier for his right hand, as the chords seem to use a lot of black keys. Look at his feet, not a single mistake. He is a magician! This shows how a B3 can sound. He plays a C3 which doesn't look as nice a B3, but it has the same hardware and the same sound.
The Hammond B3 is a 1950's organ, with mechanical tone generators (so called tone wheels). Some people think this was a Hammond invention, but it the inventor of the tone wheels organ was a man called Charles–Emile Hugoniot, who patented the tone wheel generator build 1919. After his death, some others began to build organs like this, here is a picture of a 1930 magnetone.
There is a whole battery of tone wheels in the Hammond organ, called the "tone generator". There is not one tone wheel for every key, there is one for every frequency, including the bass pedals. A musical instrument tone is build from it's generic frequency, all of it's harmonics and sub harmonics with the right amplitudes of course. Each key tone is composed in that way with one basic frequency, two sub harmonics (-2 and -3), the 2nd, 3rd, 4th 5th,7th and 8th harmonic. The odd harmonics have black slides, the even harmonics have white slides. The amplitudes are regulated with the slides you see on the organ desk. It's a bit of an art to get a particular tone, like for instance the mysterious Deep Purple "Smoke on the water" sound, or the seducing sound of Procul Harum's "Whiter shade of pale". The Santana sounds are made will all draw bars pulled fully out. That gives a heavy rock sound which you distort it by overdriving the Leslie, or leading the organ output into a stack of guitar amplifiers. On the other hand, most combinations sound not bad anyway.
Add to this the "click" noise which depends on how fast you press the keys. This is because each key has 12 contacts. This makes also the click sound different every time. Then the percussion harmonics are added, and there is your Hammond B3 key tone. The organ uses a resistor network, wired from resistance wire, underneath the keyboard, adding up the harmonics in a different way for higher or lower tones. Quite scientific. That makes the Hammond "cry" at the higher end of the keyboard, mellow in the mid range, and the heavy bass at the low keys.
The B3 is made with superb quality in mind. Anything that moves is made to last for ever. The slide contacts are made from Titanium, just to mention something, and the tone wheel generator is oiled by a spider network of several hundred cotton wires, which lead the oil to each single bearing, no matter how small or where it is, deep inside the organ. The vibrato scanner and the volume control are capacitive, so no contacts get bad. I love this piece of machinery, it's so well done.
Hammond B3 Organ
Barbara Dennerlein plays a Hammond B3 stage organ. These don't exist originally, and they are made from a regular B3, and it is put inside a new made stage case. It saves weight, and it looks better. So the case is the only change. The challenge is to get it inside all original and completely restored, and I know from some of the Club Members that her technicians put lots and lots of efforts in her one and only B3.
Barbara Dennerlein plays a virtuous foot pedal. Rhoda Scott who plays just as nice, but she has a more down to earth playing style. Here is a Barbara Dennerlein version of Bach, played in a church. I visited one of her concerts. She is a very nice person to talk to, and signed a record for me :)
These are some pictures of a B3, same as the one I have.
B3 Run Engine (square part) with mechanical Chorus and Vibration Generator (left part)
The chorus generator works really interesting. It speeds up and
down the frequency a tiny bit, making the tone vibrate.
Note the angled position for mains transformer. The square box
is a capacitor operated volume control. So it has no contacts, and also
gives the right sound expression because at lower volume it gains high frequency.
Capacitor board of Chorus Generator