unearthing the mysteries of the leslie cabinet
Contents
1. Pe Steel Bearing Washer Rubber Bearing Washer ATT Sound From Driver Bearing Plate Figure 1 Plan view of the Leslie Treble Rotor UNEARTHING THE MYSTERIES OF THE LESLIE CABINET by Clifford A Henricksen Community Light amp Sound First published in Recording Engineer Producer magazine April 1981 The Leslie Rotating Tremolo Speaker System has produced the same unmistakable sound for so many musicians that it has become an international institution for the recording and performing musical arts Everything from the venerable Hammond B 3 organ to human voices and electric guitars have been processed by the Leslie Sound and have ended up on countless hit records This article is an attempt to unearth the mysteries of its operating principles and includes a discussion of the Leslie Cabinet s practical use in both stage and studio situations My love hate relationship with Leslie Speaker began with the purchase of a Hammond organ during the mid Sixties The salesman told me would probably end up buying a Leslie for it a statement that dismissed as the usual sales banter Besides at the time had no idea what a Leslie was anyway The Hammond was purchased because that s what the Animals organist Alan Price used on all the group s early hits especially The House of the Rising Sun saw the band live in Schenectady New Youk where they put a Hammond M 102 direct into a Fender Bandma2. all around and goes through multiple reflections If you want a real treat of all kinds of bizarre whirling horns and things order copies of Don Leslie s original U S Patents RE 23 323 and 2 622 693 available from The United States Patent Office Washington D C 20231 for a fee of 50 cents per copy These patent specifications are incredibly entertaining documents and a must for any Leslie fan The Real Life Leslie A practical and commercial manifestation of the Leslie principle may take on many forms Indeed the manufacturer of Leslie Speakers Electro Music Inc now a division of Hammond Organ produces a wide variety These include models with reverberation triple channels and rotating cone speakers However any Leslie afficionado will tell you that the Leslie Models 145 147 and 122 are the ones with The Sound All three Models share the same basic innards a 40 watt monophonic tube amplifier an 800 Hz 16 ohm passive crossover a rotating treble horn anda rotating bass speaker Both rotating speakers are available with slow and fast A C induction motors Older Models 45 47 and 22 are identical except for having single speed rotors Furthermore these Leslie models are similar in that they all have components mounted in a three compartment cabinet The top compartment houses the rotating high frequency horn the middle box the high and low frequency drivers and crossover and which also acts as a vented box for the
3. a Hammond Organ to a Model 122 22 or 122RV never connect a Hammond via a Leslie Cord to a Model 147 ot 145 Leslie It will basically blow up Inside the organ a very simple connection can be made via the RCA phono jack fitted to the expression control box This jack can be located by taking the back off the organ and merely plugging in It is a line level input that will accept most relatively high impedance signals A recent welcome accessory to the Leslie line is the Leslie Combo Preamp These little beauties actually booost the signal of an instrument to the required level provide A C power for Leslie s amplifier and motors and have foot switches to change speeds It also plugs into the wall via a real A C cord connects easily to most instruments a real 1 4 inch phone jack and attaches the preamp to the Leslie via the standard Leslie Cord You may want to build a customized system for your own special use from a stock Leslie 147 or 145 You ll probably want to modify it this comes later Any modifications that involve poking around within the power amplifier should be carried out with extreme caution Remember that the Leslie speaker is fitted with a tube amplifier which has a power supply voltage of over 400 VDC I ve heard that if you re a player such a shock can improve 128th note runs but wouldn t recommend it Watch where you put your fingers Engineering your own system is actually a simple matter once you can l
4. con nected ta the treble hom while a JBL D120 12 inch speaker handles the lower frequencies custom Leslie unit It enhances the Leslie action by putting full range sound into the bass unit and only high frequencies to the treble unit This customized unit was designed for use with electric guitars Motor Speed Change A really effective means of changing the rotor speed is to reach into the treble motors and move the belt from one of the three drive pulleys to another Tricky eh Actually that s what they are there for you are supposed to do it My own preference is the middle pulley There have been a variety of speed change controls made available for Leslie motors None have been very successful however since they just lower motor voltage with the result that the motor will usually draw more current and possibly burn out Watch out for these things Leslie motors are A C induction types and since they have no brushes will last practically forever However their speed is determined by the 60 Hz frequency input which is the same problem as varying tape drive speed The only solution that makes any sense is to hook up a 115 Volt variable speed oscillator This can be constructed from a generator and tube amplifier that has a 115 Volt output tap Just like the old days Sonny am told it is really not worth the trouble though the intermediate speed doesn t really sound very good STUDIO PRACTICE As with just about an
5. for Procol Harum to play Whiter Shade of Pale it was Matthew Fisher The correction has been made here and will be forwarded to the author ed
6. on axis level Figure 4 and 5 show such coverage angles compiled from a series of third octave polar response curves Note how the beamwidth gets smaller and smaller without the deflector This means that if the deflectors are removed the sound will be much hotter on axis but much softer off axis Therefore the AM portion of the Leslie Sound will be much more severe and choppy as many a rock and roller will tell you Many Leslies played in clubs are faced backwards with the top and bottom rear panels and deflectors removed because the sound cuts better an effect that translates as You can hear it better over the guitar player This beaming process will actually raise the on axis sensitivity of any driver as can be seen from the frequency response curves of a University ID 40 driver a respectable but typical 3 4 inch throat PA unit mounted on a Leslie horn with and without deflectors Figures 6 and 7 Itis interesting to note the extra sensitivity above 1 5 kHz available without the reflectors in place Note also that the low end 800 Hz to 1 5 kHz response isn t affected by removing the reflector and that the response is 5 dB from 400 Hz to 10 kHz This latter range could be made even flatter with a real time analyzer and an third octave equalizer in the studio Now this entire discourse is based on the treble horn measured in an anechoic or non reflecting highly absorbent room In real life t
7. rotors and spaced 10 feet apart The mikes are panned left and right and recorded on two separate tracks Allen prefers the U67 s natural roll off on the high end for de emphasizing the high frequency distortion on top He told me of recording Billy Preston who played a Fender Rhodes electric piano with stereo vibrato and sent each channel to two separate Leslies Joe McSorely Veritable Recording Ardmore Pennsylvania likes to use a pair of U87s mounted relatively close in top and bottom cabinets For a tight organ sound he rolls of the lows from the bottom rotor but records the top flat Joe echoes a repeating problem wind noise up close and he always uses windscreens on the mikes He says that most organ Leslie recordings done at Veritable are on one track but a great fake stereo mixdown effect can be achieved by panning the dry track to one side and using a Harmonizer in the doubling mode on a second track panned full opposite Joe describes the resultant sound as monstrous Several Odd Things To Try An interesting sound results from running a full range 15 inch speaker with a full range signal into just the bottom rotor It should be obvious how to do this The slow acceleration and deceleration of this massive rotor is quite different from the top unit as is the frequency content Try it There s one other item Iknow for a fact that certain old Leslie Cabinets have a structural resonance in the wood and probably in th
8. 00 watts RMS and is made from aircore coils and Mylar capacitors Besides being a true hi fi crossover it would make an excellent choice for a super power system It is also possible to design and build your own crossover network from drawings and circuits published in any of the audio textbooks and cook books The best most versatile and most adjustable solution would be to biamplify the Leslie Again it s art right A Crown VFX 2 and stereo power amp would be a great setup with which to experiment Lastly a crossover network consisting of a single series capacitor is a possibility 20 microfarad for 8 ohm units and 10 microfarad for 16 ohm It allows full range sound to pass to the bass speaker and high frequencies above 1 kHz to the treble speaker with a 6 dB per octave rolloff Such a crossover network has been used successfully and produces a very interesting and pleasing sound Microphone Prepared Stock Leslie This technique has been used very successfully in a live music situation A pair of small electret lavalier microphoes are permanently fastened to opposite corners of the treble horn compartment Output from these mikes is connected to an external stereo mixer equipped with equalization hopefully by a permanent connector fitted to the back of the Leslie cabinet and hence to a stereo power amp and a pair of speakers located on either side of the stage If a stereo PA rig is being used the mikes can be fed into two chann
9. a dummy acts as a counterweight or dynamic balancer providing symmetric air drag at high speed The resulting structure rotates smoothly and without eccentric wobble forces Figure 2 Typical polar response patterns of the Leslie Treble Rotor with the deflectors re moved Range of Polar Lobing 10k Frequency Hz Figure 4 Coverage angle of the Leslie treble horn with the deflectors in place Figure 3 Typical polar response patterns af the Leslie Treble Rotor with the deflectors in fe i En OOO S S T S S TTT NA eA ae ea ents aE a Figure 5 Coverage angle of the Leslie treble horn With the deflectors removed At the mouth of the horn is diffuser cone which is supposed to widen the dispersion of the horn and make a more musically pleasing tone Actually it does work Figures 2 and 3 show typical polar response charts of a Leslie Horn with and without the deflector the results are dramatic The without curve of Figure 2 is typical of a beamy straight horn with a lot of sound concentrated on axis and very little sound off axis The with polar response curve of Figure 3 is almost omnidirectional note however the lobing As the horn revolves the sound will actually rise and fall a number of times giving it an even more characteristic sound The horn s so called coverage angle is taken from polar response charts such as these it is the included angle between 6dB points from the horn s
10. atively cheap can easily reproduce up to 5 or 6 kHz and some handle enormous amounts of power They also have a very similar bandwidth to the stock Leslie driver which means that the same sound quality will be maintained Actually replacing the treble driver would make a stock Leslie much more reliable for leaned on use My own personal preference is the Electro Voice 1829 driver a 16 ohm unit ideally suited to the Leslie crossover used one on stage for years at full chat with a Bogan MO 100A 100 watt tube power amp It s still intact and has a pleasing sound I m told by numerous others that the have had similar good luck with an E V 1829 s sturdiness and power handling ability Replacement of the Leslie driver involves first removing the backs from the upper and middle cabinets to provide access to the driver and horn A special adapter is necessary to fit the screw throat PA driver to the stock Leslie horn as shown in Figure 10 Bass Driver Modification The stock Leslie Bass Driver is a 15 inch O E M speaker capable of handling about 50 watts Supply it with 40 watts of a 30 Hz pedal tone and it shakes a lot You may also be getting dangerously close to the driver s excursion limit but it seems to be pretty sturdy I ve certainly heard of them breaking with stock use If only a keyboard is used through the system one without a lot of deep bass and you protect the driver by filtering out the low end the unit may handle lots mor
11. d The result is a clean Leslie sound with no on stage bleed from other instruments In many cases however a performer prefers more direct level from their own instrument The simplest way of enhancing the sound of a Leslie is to disable the built in amplifier pull out all four tubes and or the fuse and use the motors only via a combo preamp or the adapter discussed earlier The speaker system can then be connected to whatever amplifier you plan to use This is achieved by disconnecting the crossover from the standard Leslie amplifier and patching it to a convenient input socket A 1 4 inch phone jack or a much better but less standard banana or GR plug would be the answer A more versatile method would be a 1 4 inch jack which when accessed disconnected the crossover input from the Leslie amp and connected it instead to the jack The only problem remaining is the power handling capablility of the Leslie Speaker System components namely the high and low frequency drivers and the crossover networks I ll discuss these as separate modifications Treble Driver Modifications The stock Leslie high frequency driver is pretty fragile and is easily overloaded with a stock 40 watt amplifier Unless for some exotic reason you want to drive it at low levels planona new driver Choice of drivers is important and the most expensive ones are not necessarily the best answer The most expensive professional drivers from Altec JBL E
12. e as you approach its thermal limit If you want to avoid running the risk of breaking the bass driver the easiest solution is to replace it with another unit capable of handling higher loads Speaker choice is left up to the individual since it s a matter of taste can t really recommend any An 18 inch speaker will fit with the following modifications a spacer ring has to be added between the speaker and the Leslie baffle so that the cone doesn t hit it and part of the back panel may have to be whittled out for certain larger 18 inch speaker frames Crossover Modification The stock Leslie crossover is a 12 dB per octave 800 Hz unit requiring both 16 ohm high and low frequency drivers for correct performance Most mondo power 15 inch woofers have an impedance of 8 ohms which tends to extend the reponse a bit higher than 800 Hz Although this shouldn t cause any difficulties it will make an 8 ohm high frequency driver extend a bit lower which will definitely cause excursion problems The answer is to either buy a 16 ohm replacement driver or perform the following modifications If the Leslie is fitted with both 8 ohm high and low frequency components a stock 800 Hz crossover can be obtained from JBL Altec and other manufacturers Community Light amp Sound makes a very good crossover which requires an 8 ohm bass speaker and a 16 ohm treble speaker if you use it without its attenuation pad The crossover handles well over 2
13. e great artists and many more pioneered holding single notes usually the root of the chord and letting the Leslie provide the dramatics in rotor acceleration Synthesizer players today still haven t found something as exciting Lee Michaels had hits and toured for a long time with only his B3 Leslie and drummer Frosty The right players could make a Leslie talk make it scream and make you want to dance The list goes on forever And Deviant Leslie Use And Abuse Steppenwolf organist Goldie McJohn was able to coax an amazing sound from a stock Leslie He connected the stock bass speaker directly full range to the stock amp and ran the thing flat on 10 actually it sounds like he found a way to get 11 You can hear this very clearly on that classic track Born To Be Wild The organ solo features the glorious distortion of a grossly overdriven Leslie amp and you can hear the big bass rotor slowly speed up and slow down throughout the take saw Steppenwolf live at the now physically non existent Electric Factory in Philadelphia Goldie used the same setup on stage only he stacked a bunch of them up right next to him and miked one through the PA system Jethro Tull s Benefit album is considered by some to be the prototype Leslie processed statement and the hit Teacher from the LP is typical lan Anderson put both his flute and vocal through a Leslie as did guitarist Martin Barre It sounds like the Leslie was kept far away from d
14. e louvres but it s the real thing The old wood is simply more resonant and Hammond percussion notes really set it off It s like these guitar players running around in South Carolina pawn shops looking for the ultimate 56 Fender Strat I ve heard Leslies on records that just have a legendary tone to them and others that just play regular Go around and knock on a few new and used Leslies especially the louvres and see if you think I m crazy Anyway the point to this was why not try putting a FRAP pick up on the louvres Experiment see if you can bring more of the sound out of the wood Specific Examples Of Normal Leslie Use Normal Leslies are surgically attached to Hammond B3 or C3 organs usually the former There are many other brands of organs that have been played through Leslies during recording sessions but The Sound which accompanies this great rock and roll Spirit of America is pure and simple a B3 and a Leslie Steinway piano Fender Amp Gibson Lesl Paul Fender Strat Telecaster precision Bass all in the same breath The Isley Brothers used the fast Leslie all the way through their hit Shout Matthew Fisher combined America Soul European Bach and B3 lower drawbars through a continuous slow chorus Leslie and made millions listen to a Whiter Shade of Pale with its gorgeous organ theme Billy Preston Booker T Jones and Felix Cavaliere made an art of timely speeding up and slowing down of the Leslie rotor Thes
15. els of the front of house board and panned left and right As with anything good taste in EQ and general technique is required to achieve a good sound Actually bad taste might work well too try both Wind noise from the horn is not a problem and minimum mechanical isolation is needed Lack of wind noise is probably because the cabinet corners are stagnation or dead air spaces Wind noise if present can be reduced by using an open cell reticulated Scottfoam wind screen on the mikes An obvious extension of this mike technique is to do the same with the lower rotor and obtain a mixed top and bottom left and right sound Apparently the top only technique works very well in a live situation but might also serve the purpose for a studio Leslie Tandem Rotors Slower acceleration of the lower rotor is occasionally undesirable certainly a matter of personal preference only To give a more dramatic Leslie sound the top and bottom rotors can be PICTURE NOT mechanically linked so that both will turn in sync and the pair of horns face in the same direction Silver Sound Systems 337 South Morris Avenue Crum Lynn Pennsylvania built the little screamer with tandem rotors shown in Figure 11 which is an example of a well prepared AVAILABLE Figure 11 Customized Leslie Cabinet with tan dem bass and treble rotors the stock treble hom is driven from a tandem drive shaft coupled to the lower bass rotor An Atlas P A driver is
16. he horn mounted in a louvred wooden box which means that the picture changes somewhat with resulting internal reflections The diffuser cone does another important thing it shifts the apparent sound BERRA AEs ie PLE ET ALT a RA T A H AA OP TT A Bae Se ee A Lf 200 500 aes E Figure 6 With deflectors 100 200 500 ee aa Figure 7 Without deflectors source position on the horn With the cone in more of the entire range of the horn will appear to come from the mouth of the horn with it out however while lower frequencies still appear to come from the mouth higher and higher frequencies will appear to come from progressively further down the throat They therefore appear to be rotating at a smaller radius which results in less frequency modulation effects If the directional sound source was rotating at dead center there would be no FM effect at all So here you are faced with a choice leave the deflectors in place and the result will be maximum frequency modulation and a relatively lower amplitude modulation because of the very wide directional characteristics of the horn Take the deflectors out though and the FM will be lost but you obtain very strong AM especially at higher frequencies due to the very narrow beam width of the naked horn My own ears tell me that the deflectors should be kept on but you make your choice and you take your chances The Bass Rotor 15 inch Low Frequency In
17. he sound of an instrument not to reproduce it The Leslie Speaker System thoughtfully named after its inventor Don Leslie operates on a simple principle a directional sound source is rotated at constant or variable speed around a fixed pivot point At a listening point some distance from this whirling affair three things happen First because the source is directional the intensity of the sound will be at a maximum when it points at the listener or microphone The sound intensity will increase as the rotating source approaches dead center and decrease as it rotates past this point The resultant effect is called amplitude modulation AM which is no big thing and is a feature on any guitar amp with a vibrato or tremolo feature By moving closer to the rotating speaker the inverse square law will increase the modulation effect However the big deal is the Leslie s ability to create frequency modulation FM As the source rotates toward the listener its relative velocity will increase the pitch of any tone it produces as it rotates away the pitch well be lowered This is exactly the same Doppler effect that causes a train whistle or any other sound on the train such as grunting pigs or shrieking passengers to rise and then fall in pitch as the train approaches and then passes Lastly if you are listening in a room with any significant reverberation a complete spatial modulation of the sound will happen as sound is shot
18. istortion a good example of a clean Leslie processing wish know more about the particulars of this record since it s another classic heavy Guitars Through Leslies Many guitarists have used Leslies to modify the sound of their instrument One unusual and very successful instance was Rusty Young of Poco Rusty achieved some marvelous sounds with Poco by putting his steel guitar through a Leslie producing a very distinctive and attractive effect The instrumental line in Player s recent hit Baby Come Back and J Geils soulful intro to The Usual Place are some more typical but outstanding examples of tasty Leslie guitar I m sure your lists contain a lot of others Personal Madness am arranging and putting together this article using a Norelco Dictating Machine which has a microphone at the end of a coil cord that also acts as a loudspeaker You can push a button on the recorder and the sound will come out of the microphone end By grabbing the microphone by its cord and swinging it in circles this entire article can be played back to me with a very strange and mysterious Leslie like effect It s really okay No I m really allright It s just like a Leslie you see Acknowledgements Thanks to Ralph Brownlowe Robert Rankin and Ed Sciaky WIOQ Philadelphia for some priceless and valuable information used in the compilation of this article This was stated by the author to be Gary Brooker but he was not the organist
19. lectro Voice and others have usable sound reproduction to within the 10 to 20 kHz octave Such performance probably won t be needed for a Leslie I m told that in fact a very high frequency harmonic content is actually a deterrent Extended band high frequency drivers are also rather fragile a percussion note from a Hammond B3 can easily send a 0 002 inch thick aluminum diaphragm through its full Maunting serew Bear ing plate Fiber Rubber grommets to spacer seal absorb vibration Bearing plate Tap bafle Adaptor plate see below Replacement Driver Adaptor Plate gt 12 inch thick alu minum or plywood These holes mateh O eee On Ihe Bearing x sacement ariel OM OT These holes match those on the outside of the re O placement driver Figure 10 High frequency driver modifications Top standard driver and adaptor plate Center changes necessary to accommodate replacement driver Bottom layout of special adaptor plate excursion and into the driver s phase plug At this point the musician is off the air possibly during a now favorite solo or in the middle of a take Also these drivers have large throats between 1 4 and 2 0 inches in diameter whereas the entrance hole to a Leslie treble horn is about 3 4 inch This makes it ideally suited for the 3 4 inch throat PA drivers fitted with screw mounts such as those made by University Electro Voice Atlas etc Such drivers are rel
20. low frequency driver and the bottom compartment the low frequency rotor and amplifier Louvres located in the top and bottom compartments let out treble and bass sound respectively All the above speaker systems are virtually identical in terms of their use and sound quality The larger Models 147 and 122 allegedly have a better low end Both high and low frequency speakers operate on the same principle a stationary driver loudspeaker and a rotating acoustic projector The Treble Rotor The Leslie s high frequency unit is largely responsible for the Leslie Sound Some organists actually find that the bass rotor s slower response to speed changes is distracting and will actually disconnect the bass rotor drive especially when playing a bass line The treble unit consists of a stationary 3 4 inch throat Jensen compression driver connected to a vertical tube that acts as a thrust bearing Figure 1 A twin bell molded black bakelite horn which starts vertically but flares horizontally sits on this bearing tube and rotates via a two speed A C induction motor fitted with three selectable drive pulleys This motor drives the treble horn at fast or slow speeds via drive belt and belt tension spring Direct current is sometimes applied to the fast motor so that it will slow down more quickly this is called a D C brake The treble horn actually looks like two horn assemblies in fact only one is operable as a horn The other side
21. ocate a 6 pin plug that is compatible with the one fitted to the amplifier or buy a Leslie Cord Pin 1 is signal ground and pin 6 signal hot Any source capable of delivering over 6 V into a load of 2 5 kohm or less will be able to drive the Leslie amp to full power with the console load resistor switch set to open The switch also inserts an 8 ohm 10 watt or 16 ohm 10 watt equivalent resistor across the input which means that a 10 watt power amp could be used to drive the Leslie with the level control at the right setting This is the typical setup for many organs equipped with their own power amps A small guitar amplifier such as a Fender Champ would do fine The speaker should be disconnected and the switch set to 8 ohms Don t try it with a large power amp however your Leslie will sound and smell very bad shortly after the input resistors burn up Input power 115 VAC connects via pins 3 and 4 Pins 2 and 5 connect the 115 Volt A C coil of the tremolo relay which is fast when off and slow when on Therefore a D P S T switch connecting pin 2 and pin 3 and pin 4 to pin 5 will activate the relay if you only want fast forget pins 2 and 5 A simpler approach would be to make a direct connection from pins 4 and 5 and use a simple S P D T switch Modifications To The Leslie Ah yes Audio racing in the streets Imagine thousands hearing a vocal track through a Leslie a Leslie that can be heard over a guitar pla
22. slow or chorus mode Two speed Harn Ratar Crossover Netvork 15 inch Speaker The Complete Leslie System With all these rotating components Two sp eed Wooden Rotor SS i i lA i lA i l i lA ly lA J i J J i lA lA i lA lA i all i i i 4 i i i 4 i 40 W att Power Amp Figure 9 Schematic diagram of the Model 147 Leslie Speaker System installed in the box the System works as follows an electical signal is sent into the Leslie amplifier driving a 12 dB per octave 16 ohm crossover which feeds the 16 ohm bass and treble drivers with the appropriate frequency bands Figure 9 Input signal motor controls and A C line voltage 115 V 60 Hz are connected to the unit via special plugs and sockets linked with the Leslie cable It is this latter cable that s a major problem for many who would like to use a Leslie Most self contained speaker systems have an A C cord that plugs into the wall and an input jack for the music signal The Leslie however has a Leslie Cord Just one of the things with which we Leslie fans have to live The amplifier chassis contains a 40 watt amp fitted with 6550 tubes a wonderful choice of output tube for instruments and motor control circuitry Each rotor is actually driven by two separate motors fast and slow mounted in one package Therefore there are a total of four rotor motors and four pairs of wires which all pl
23. sound bearing in mind the AM effects of close miking The best way know of recording a Leslie however is in stereo The left and right channels can be recorded with either a top and bottom pair of mixed mikes or with just single mikes panned between left and right The stereo image achieved with two pairs panned full left and right is very exciting Many combinations are possible though the point being that a Leslie is capable of providng a great deal of spatial information spoke with a few engineers know about such recording techniques and here are a few of their preferences Jay Mark Sigma sound New York has been pleased with a tight or direct Leslie sound when recording organ His principle reason for this is because the organ is used as background and not a featured instrument the tight sound is needed so that the organ sound is very clear and unmistakable even when way down in a mix Jay has used the folloing setup with good results an RCA 77DX ribbon at back of the top rotor cabinet about 8 inches from the treble horn with the high end rolled of to suit He also uses at the back of bottom rotor a U87 with the lows rolled off and mixed with the top mike to suit He remembers experimenting with the top and bottom sound panned left and right and not liking the effect Allen Sides Ocean Way Recording Hollywood prefers a pair of tube U67s located about 5 feet away from the Leslie aimed midway between top and bottom
24. ster Amp and had to have this sound soon discovered however that my new musical heroes had better sound It wasn t long before knew that Booker T Jones Felix Cavaliere Gary Brooker and Billy Preston and many others were all using Leslies This was The Sound My first Leslie a single speed Model 45 with a 40 watt tube amplifier sounded great but it literally got lost in the roar of the Boston based rock and roll band in which was then playing Two big Leslie Speakers were cumbersome to move they weren t a big improvement in level plus 3 dB and the high frequency drivers broke From then on it was guerilla speed shop tactics mill the heads oversized pistons etc to the point where could finally be heard over any guitar player As a result became an expert at Leslie repair modification and special use occasionally even letting a few guitar notes into my beloved machines I ve spent the past 15 years in and out of the Music Business both in studios and on stage The significant part of this time was spent in some way dealing with Leslie Soeaker Systems As you might guess this is a rock and roll story might as well show my bias here and now With this in mind here s what have learned over the years PRINCIPLES OF OPERATION First and foremost the Leslie Rotating Speaker is designed as a sound modification device It is not a Hi fi speaker but rather a part of a musical instrument You buy a Leslie to change t
25. the lower compartment of the Leslie box is Loudspeaker a rotating wooden drum mounted ona vertical shaft and covered with a black scrim cloth which provides lower aerodynamic drag on the drum at fast speed Figure 8 It also works At the drum s center is a cylinder R Separated by lower bafle board fitted with a scoop which as in the treble unit starts vertically the bass driver faces downward into its entrance and projects sound horizontally The drum assembly is Rotation driven with a two speed motor and ends up 2D at approximately the same rotational speed as the treble unit The only difference is that Direct sound the drum s inertia makes it approach final Figure 8 The Leslie Bass Rotor speed over a much longer time period A D C braking voltage can also be applied to the fast motor to slow down the speed more quickly when switching from fast to slow This system works somewhat effectively To my ears and powers of reasoning the bass rotor works just as an AM device and only for the upper two octaves or so of the bass section 200 to 800 Hz Frequencies lower than 200 Hz are probably uneffected by a scoop of this size since 200 Hz has a wavelength of approximately 5 5 feet There may be some frequency modulation effects near the 800 Hz xrossover point but it sure sounds like AM to me The result is a low frequency throb which is very pleasant and especially powerful and beautiful when used in
26. ug into the amplifier chassis If any of these wires are removed and plugged into a live A C outlet the appropriate motor will turn on safely without any problem since this is essentially what the motor control does Input to the amplifier is via the six pin plug The speaker and crossover are both connected by very odd little two pin connectors that have never seen in use outside of a Leslie Speaker They work however and seem to be very reliable over long periods of time Getting Music In And Out Of A Stock Leslie Picture the scene You have just bought a used Leslie you got a great deal on it just in time for the gig You excitedly load it up set up your Farfisa organ and then stare dubfounded at this ugly black 6 pin Harvey Hubble plug the only connector visible on your Leslie Your 1 4 inch phone plug cord hangs limply in your hand useless impotent Mistress Leslie stares back coldly You can t even plug it in the wall and watch the tubes glow Chorus Interruptus The Horror Well it s a real problem But veehaff vays to do ziss Fraulein Leslie Here s how If your studio has a Hammond B3 or C3 organ with a Leslie attached the latter will probably be a Model 22 or 122 This is a quiet reliable and troublefree system although you still can t plug it into the wall and operate the Leslie independently of the organ Most big Hammonds like the B3 and C3 will have a Leslie plug installed on them Be careful Only connect
27. yer s Marshall Stack a clean Hi Fidelity Leslie These things and more can be yours given the cash outlay in proportion to the desired grandeur and even more cash if you don t build it yourself This country is loaded with local Leslie speed shops and there will probably be 50 more after this article is published Electro Music makes Fenderesque Bi Amp Leslies in vinyl cabinets However they are expensive and are only equipped with amplifiers rated to a maximum of 60 watts Also you may very well want to preserve the present walnut beauty and improve its performance If so here s how External Mono Amplification The stock Leslie Models 145 147 or 122 have a marvelous 40 watt tube amp When you really lean on it it sounds even lovelier with a warm rich distortion like nothing you ve heard The show organist at Circus Circus Las Vegas has the best sound of this kind I ve ever heard He runs his Hammond B3 on 10 and just keeps the hammer down However in a live band situation or a club or worse at a concert even a single 40 watt Leslie just doesn t cut it even for a keyboard only The recent rapid expansion of concert sound techniques allows quiter instruments to be miked and simply turned up at the console I m told that Keith Emerson and others have actually installed and miked a Leslie in an isolated backstage room during their concerts Including Bruce Springsteen s keyboard player Danny Federici R e p February 1981 e
28. ything recording a Leslie is a matter of particular taste and purpose You might want record the best possible recreation of a live Hammond B3 Leslie combination you might also want to make it sound better You migh also want to use it as send and receive device like an echo unit with a high level send to the Leslie Amp and a mono or stereo microphone receive You could put it ina studio in a reverb room or in the bathroom during the mix or you might use it live The possibilities are only limited by your level of creativity and or insanity However the following are some standard techniques and descriptions of behavior Mono Recordings have recorded Leslies with a single microphone mounted as close as 1 foot from the treble horn with very pleasing results If the mike is placed even closer within several inches the severe amplitude modulation effect becomes very annoying and wind noise from the rotor at high speeds sounds like you have a helicopter in teh room Which is a sound you might want The same thing happens on the bass rotor where up close there is also a lot of mechanical noise A loose scrim will be real noisy tighten it up The sound from both rotors is mellower coming out of the louvres By removing the back panels and miking the Leslie from the rear the sound is more direct and defined Stereo And Multi Mike Recording Use of two mikes on the top and bottom of the cabinet is a very effective way of getting a good
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