USEFUL TIPS ON HAMMOND TONEWHEEL ORGANS

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As far as electronic organs go, in my opinion Hammond Tonewheel Organs are the best The story starts in 1967, when I first saw "The Nice", who became "Emerson, Lake & Palmer" later on.A necessary step I suppose for Keith Emerson's musical developement, but I loved the feel of Lee Jackson's bass playing & vocals ..........The band were late for this gig in Leeds all those years ago, so everyone stood in this packed hall for 4 hours, some even passed out with the heat, but the gig was one of the most memorable ones I've ever seen....... real playing, no sequencers in those days, just raw talent. I was mesmerised by Emerson's awsome playing - I still am! & realised that that was what I wanted to do, play a Hammond ..... so I started piano lessons with an incredible old lady, who's long dead now unfortunately. She could sight read anything at the correct speed, with a minimum of errors. While studying, I used to take her the most difficult pieces of sheet music I could find, Liszt, Bach etc....... she would light a cigarette & Just play them straight off !!!

Thinking about it,in retrospect, I would have been a much better player, if I hadn't kept taking the back off the organ & getting into it with  my soldering iron! ........ but after a while I knew the workings of  Hammond Organs inside out...... Especially the HAMMOND C3 ............       

I spent a lot of time while I was a pro musician repairing & refurbishing all types of Hammond Tonewheel organs, after a while, dismantling & rebuilding of Hammond C3 organs was something I could do in my sleep! as time went by the old tonewheel organs were getting in very bad condition, some having very severe faults (dropping to bits!) 0nce I collected some old Hammonds from a Flooded Warehouse, as I was wading through the water in my wellies, I kicked something........ groping about in the water I found a C3 pre-amp, which had been underwater for six months! after a couple of months on the workshop shelf, out of curiosity, I powered it up after fitting new valves & it worked!!! Once I bought a Hammond B3 organ, which had been used in a pub for the last 12 years at the time, to support a Large tropical fish tank......! with the leaks & grime it was in a bit of a state, but after prising open the lid's rusty hinges, it powered up & worked first time.....try that with digital stuff!!!!

I never fail to admire the genius of Laurens Hammond whenever I find myself inside a Hammond organ. The tonewheel generator is truly a mechanical work of art, as is the synchronous motor, (also invented by  Laurens Hammond!) with cotton threads from the central oil reservoir for lubrication of the plain phosphor bronze bearings, other organ systems have tried to emulate the mechanics of the Hammond, some using electrostatic disks, but none even come close for reliability or sound. The principle (for those of you who don't know) is as follows:

Each iron tonewheel disk has a wavy edge, of varying dimensions, some coarse, (low frequency), some medium, (mid frequency) &  some fine (high frequency). When these disks are rotated at different speeds, (from a central synchronous motor & gear train), in front of a magnet with a coil of wire around it, a current representing the frequency is generated...... (Hence .....  "Tonewheel Generator")     so .......... take 91 or so of these, mount them in a rigid frame, all with coils adjacent, & you get many near sinewaves generated, which via multi-key contacts are switched out to an pre-amplifier. 
 As there are inaccuracies in the system, the tones are not 100%   perfect so then we get the starting point of the Hammond Tonewheel sound. The frequencies generated are a bit rough in fact, so a arrangement of coils & capacitors on the top of the generator, start the process of smoothing out the waveform, further capacitors connected to ground in the pre-amp, filter the harshness & key click even further. The end product routed via the drawbars, is the "pureHammond organ sound we all know & love!

Yes, I know this is an over-simplified explanation, but simple is good!

For live work, I used to modify things, (not the coils & capacitors on the generator though) but I used to put a switch in series the two capacitors on the pre-amp mainboard to act as a treble boost, also I used to make switchable, a capacitor just behind the centre terminal box on the pre-amp. This made the percussion very unruly & the key click, which Hammond used to try to disguise, came right up front....... Great for solos ....... The best compliment I ever got was from the wife of a  pro drummer friend of mine, she said that she had travelled all over with her husband on gigs, & he had worked with many well known accomplished organists, but mine was the most unpleasant Hammond sound she had ever heard!, she said it was like having notes hammered into your ear with a sledgehammer! .....Great ..........my happiness was complete....!!! at the time she said that, she was at the back of the hall !!!!!

At that time, I used only one Leslie 145, which was miked up through one Marshall 100 watt amp & 4 x 12 cab, & the organ straight signal attenuated & plugged into the front of another Marshall 100 watt & 4 x 12 cab. This was my modest portable system, When I was resident anywhere, I could use my main system . . . . . .Along with various keyboards of the period (1970's) Rhodes, Clavinet, Minimoog, Arp Pro-Soloist, Korg 700s & "Logan string machine", I used four Leslie 145 cabinets (Miked up),  reverse horn loaded 2 x 18 inch loudspeakers for bass pedals, 8 x 12 inch speakers for keyboards & organ "straight" channel & 4 x 15 inch speakers for extra low - mid body & 4 ten inch speakers for a bit of cut.......all driven with about 1 kilowatt, a lot of power for a back - line in the 70's ...... The sound was stunning, pure delight to play with, indeed I played a lot then......7 Nights a week & 5 lunchtimes !!!!!!! For successful amplification of a Hammond organ, or any keyboard system, the answer is simple..... Watts & Cabs, & lots of them, but not too much as to not be able to overdrive the valve amplifiers.The distortion curve of a Leslie valve amp is just right, Leslie got it wrong with the transistor Leslies, the input pre-amp/driver has insufficient headroom, & when it is clipped, it sounds awful.Some mis-informed people claim that the B3 sounds better than the C3, but that is wrong.....! on page number 1 of the official Hammond service manual (Bible) it states that the only difference between the C3 & B3 models is the cabinet style, which has no bearing on the sound at all.

Why do C3 Hammonds sound bigger, fatter & better than spinets?

It's the generator coils............ believe me I tried everything!!!! ...........   on the C3 generator there are copper rings on the pickup coils, which are not present on the spinets (except on the old M3 models) They act as a damper to the produced sine wave tone, therefore eliminating any ring, however small, which in practise is definitely very audible to the keen player's ear. It feels like dynamic compression. Then there is the vibrato chorus of the big Hammonds. A truly sensational component of the system. A vibrato scanner  is driven by the same motor that drives the tonewheels, this scanner scans a coil & capacitor delay line & pitch modulation (vibrato) of the generator tone is produced. A rotary helical geared cam-driven multi pole switch controls the amounts & type of vibrato & chorus. To obtain the chorus effect, some straight signal is mixed back in with the vibrato channel & the end result is the famous Hammond vibrato chorus, as used by everybody.

A quote straight from the bible (Hammond Manual):

A vibrato chorus effect, similar to the effect of two or three slightly out-of-tune frequencies mixed together, is obtained when the vibrato output signal is mixed with a portion of signal without vibrato. For vibrato chorus, part of the incoming signal appears across the vibrato line and the rest across a resistor in series with the line. As the vibrato effect is applied to the part of the signal appearing across the line, but not to the part appearing across the resistor, the combination produces a chorus effect. For normal vibrato, this resistor is short-circuited.On the Hammond model M3 spinet, (an old one with a 12 note bass pedalboard) the Vibrato system is very similar to the C3, & also the M3 features the copper ringed generator, so it sounds very much like a C3. But the drawback is, as in all spinet models, that the high frequency footages do not go all the way to the top of the keyboard & the percussion cut-off stops at F#, just over half way up the keyboard. It is a good compromise for gigs, as it doesn't weigh as much as a C3.In fact I have a couple of M3 keyboard units, & the keys & stop tabs are interchangeable with a C3. The model M100 has a watered down version of the scanner vibrato system & has a standard generator, so the sound quality is thinner. L100 organs don't have a scanner, a valve circuit creates the vibrato, & the chorus is weedy ...... not so good.

What went wrong?

Obviously the manufacturing costs of the tonewheel Hammond organ sounded it's death knell a long time ago, but what puzzles me, is why none of the large American & Japanese companies are able to get anywhere near the original sound, even today. Do they consult the wrong people? Are they hard of hearing? It is bizarre that professional have to use an instrument that is thirty odd years old (or older), to get the sound that they want. I feel that I could do it, but with a different approach than the big Electronics companies. i.e.: preserving some of the free-phase elements of the original. A very simple basic design approach to creating a simple instrument, just like the late Laurens Hammond did in the 1930's.

Myths exploded

Hammond A100, B3,C3 & RT3 Hammond organs, all have the same type of generator & keyboard assemblies. The only difference between them being that early type with the squarer cabinet with protruding edges around the top, use rectangular section busbars (contact rails) with palladium wire contact areas, & the later models with no wood overhanging & a rounded lid (which cracks easily) used round section gold-plated busbars. the latter are more prone to bad key contact, but on old Hammonds, the palladium wire often comes unfixed from the bus rail & causes problems. either way the use of silicon grease is definitely not a good idea, as after a while it picks up dust & becomes very grimy.

MISCELLANEOUS HINTS & TIPS FOR HAMMOND ORGAN OWNERS
 
GENERATOR OIL & OILING

DO NOT OVER OIL THE GENERATOR & MOTORIF YOU DO, THE OIL CREEPS INTO THE SCANNER (ON THE END OF THE MOTOR) & CONTAMINATES THE CARBON CONDUCTOR, WHICH CAUSES CRACKLY VIBRATO NOISES. THE CARBON DISC WILL EVENTUALLY DETERIORATE & DISAPPEAR ALTOGETHER INTO BITS IN THE BOTTOM OF THE SCANNER HOUSING. FINDING A REPLACEMENT COULD PROVE DIFFICULT. IT IS A CARBON DISC WITH A HOLE DRILLED IN IT, SO I SUPPOSE IT'S POSSIBLE TO IMPROVISE BY MACHINING A BIT OF AN INDUSTRIAL MOTOR BRUSH & DRILLING IT, BUT I'D RATHER NOT.

TYPE OF OIL TO USE

RECENTLY I WAS ASKED ABOUT THIS PROBLEM, OWING TO "HAMMOND GENERATOR OIL" BEING UNAVAILABLE WHAT I AM ABOUT TO STATE MAY NOT BE AGREEABLE TO EVERYONE, BUT ........ I HAD AN OLD C3 FOR 12 YEARS & I USED TO USE "3 IN ONE" OIL IN IT, ONCE A YEAR. I WORKED WITH THIS ORGAN PROFESSIONALLY, SIX OR SEVEN NIGHTS EVERY WEEK OVER THE 12 YEARS, WITH NO ILL EFFECTS AT ALL. I ONCE BOUGHT A LARGE TIN OF "GENERATOR OIL" FROM HAMMOND, THIS WAS REALLY CRUDE STUFF & SMELT LIKE DIESEL FUEL. IF YOU ARE STUCK, TRY CONTACTING A SPECIALIST OIL SUPPLIER LIKE "HENRY HILL" (BATLEY, WEST YORKSHIRE) & STATE CLEARLY THE APPLICATION THAT YOU NEED IT FOR, INCLUDE DETAILS OF BEARING TYPE ie: PHOSPHOR BRONZEDO NOT USE ANY KIND OF "PENETRATING" OIL - "WD40" IS OUT OF THE QUESTION.DO NOT USE CAR ENGINE MOTOR OIL OR GEAR OIL

KEY CONTACT PROBLEMS

NOT SURPRISINGLY, INTERMITTENT KEY CONTACTS ON MACHINES OF THIS AGE ARE COMMONPLACE ON THE HAMMOND C3 & OTHER HAMMOND TONEWHEEL ORGANS. TO RESOLVE THE PROBLEM, DO NOT JUST HOLD THE KEYS DOWN WITH A PLANK OF WOOD & TURN THE BUSBAR SHIFTER SCREWS. THIS WAS A BRILLIANT INNOVATION AT THE TIME FROM MR. HAMMOND, BUT AFTER ALL THESE YEARS, ALL YOU WILL END UP DOING IS RE-DISTRIBUTING THE DIRT. THE KEY CONTACTS WILL GET WORSE. YOU MAY EVEN DAMAGE THE PALLADIUM WIRE ON THE OLDER TYPE OF ORGAN. (SEE NOTES ABOVE ABOUT CABINET TYPE & AGE) WHAT YOU NEED TO DO IS PHYSICALLY REMOVE THE BUSBARS & CLEAN THEM WITH ISOPROPYL ALCOHOL. IT IS NOT RECOMMENDED FOR THE FAINT HEARTED, BUT HOW YOU DO THIS IS AS FOLLOWS:

BE CAREFUL & THINK

REMOVE THE LARGE BOLTS UNDERNEATH THE CABINET WHICH HOLD THE KEYBOARD UNITS IN PLACE. REMOVE THE MUSIC RACK RAIL & POWER SWITCHES. REMOVE THE LARGE BOLTS EITHER SIDE OF THE MANUALS TO SEPERATE THEM. WITH THE HELP OF AN ASSISTANT CAREFULLY LIFT UP THE MANUALS TO THE RIGHT, UPPER MANUAL FIRST (FROM THE FRONT) UNTIL YOU CAN GET AT THE BUSBAR COVER PLATES. UNDO ANY CABLE STRAPPING TO ALLOW THIS TO HAPPEN, BE CAREFUL OF THE GENERATOR WIRES, THEY ARE SOLID CORED & CAN SNAP EASILY.REMOVE THE SMALL WOOD SCREWS HOLDING THE BUSBAR METAL COVER PLATES. SLACKEN, BUT DO NOT REMOVE THE SCREWS HOLDING THE SLOTTED BUSBAR SECURING PAXOLIN PLATES IN PLACE. CAREFULLY WITHDRAW THE 1st BUSBAR & CLEAN IT. REPLACE 1st BUSBAR CAREFULLY & FEEL YOUR WAY WITH IT ALONG THE GUIDES. A MIDWIFE'S TOUCH IS DEFINITELY REQUIRED HERE, DO NOT UNDER ANY CIRCUMSTANCES FORCE IT. THEN ...........WITHDRAW THE 2nd BUSBAR, INSPECT, CLEAN & REPLACE THEN JUST REPEAT THE SAME PROCESS FOR ALL THE REST. EASYINNIT? WHEN ALL ARE RE-FITTED, POSITION THE BUSBAR SHIFTER IN A CENTRAL POSITION AFTER SLIDING THE SLOTTED PAXOLIN COVER PLATE BACK & RE-TIGHTENING THE SCREWS. I'VE DONE THIS JOB SO MANY TIMES, I CAN DO IT ALMOST BLINDFOLD!RE-ASSEMBLY IS THE REVERSE OF DIS-ASSEMBLY!!

PLEASE NOTE:

DO NOT UNDER ANY CIRCUMSTANCES USE SILICON GREASE SPRAYS, OR ANY PROPRIETARY CLEANER THAT LEAVES A DEPOSIT. ALL THIS GREASE DOES IS ATTRACT MORE DUST! IF YOU OWN AN OLD C3 WITH THE SQUARE TYPE BUSBARS, BE VERY, VERY CAREFUL. IF THE PALLADIUM CONTACT WIRE IS DAMAGED & DETACHED FROM THE BUSBAR THE BEST THING TO DO IS EITHER REPLACE THE BUSBAR IF YOU CAN GET ANY, OR AS A LAST RESORT REMOVE ONLY THE DAMAGED BIT OF PALLADIUM WIRE. THE LATER TYPE USE ROUND GOLD PLATED BUSBARS, THESE ARE NOT AS FRAGILE, BUT SADLY NOT AS GOOD AT THE JOB.

WARNING:

IF YOU ARE IN ANY DOUBT AT ALL, AS TO YOUR ABILITY TO DO THIS JOB, THEN YOU MUST SEEK PROFESSIONAL HELP. IF YOU SCREW UP WITH THE BUSBARS, THEN YOUR BELOVED C3 WILL BE IRREPAIRABLY DAMAGED. BE WARNED!

STOP PRESS:

YES, I KNOW IT'S SACRILEGE, BUT .............THE "EMU B3" ORGAN MIDI MODULE IS PRETTY CLOSE TO THE SOUND WE ALL LOVE TO HEAR. IT IS DEFINITELY WORTH A LOOK & A LISTEN. IT HAS TAKEN ALL THESE YEARS FROM 1935 TO 2001 FOR ANYONE TO GET EVEN CLOSE! THE "LESLIE" SIMULATION IS ALSO VERY GOOD. ON THE PLUS SIDE, YOU CAN SEQUENCE IT & IT'S NOWHERE NEAR AS HEAVY AS A PROPER C3 ........ ! ON THE DOWN SIDE, I MISS THE FEEL OF THE HAMMOND KEYBOARDS & THE SMELL OF WARM GENERATOR OIL ............................. !


 

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