Note: This article is adapted from first-hand conversations with organist Bob Mitchell and with Don Leslie, inventor of the organ speaker bearing his name.

ONE OF MY FRIENDS is a man of fairly advanced age....... well, let's face it — he's OLD! At least a hundred and fifty! (Actually, he is 97 but LOOKS about 150!!) His name is Bob Mitchell.

Once upon a time Mr. Mitchell was a very noted, if in some quarters controversial, figure in the Los Angeles choral and organ music scene, and also played at several Los Angeles radio stations in the 1930s and ’40s. He had a very well-known choir, the Mitchell Singing Boys, who went on several European tours and also appeared in a number of films in the 1930s including The Bells of St. Mary’s.

One of the stories Bob has told me several times over the years involves a good friend of his named Don Leslie, who was a radio repairman employed by the Barker Brothers Department Store in Los Angeles. Don was also an amateur musician, playing, as Bob put it, “for his own amazement.” In his home he had a Hammond Organ. (It must have been one of the first, as we are talking the mid 1930s here).

Mr. Leslie liked his Hammond but did not like the sterile, dry tone quality of it. There was no life, or movement — no sense of chorus or ensemble, as there was with the sound of even the smallest pipe organ. He wished there was some way to overcome the lifeless sound.

One fine day in 1937 or ’38, somewhere thereabouts, Mr. Leslie was standing in his front yard when a pickup truck drove by with a large radio speaker mounted on the flatbed, you know, one of those big horn-type speakers, which was broadcasting musical advertising announcements for a political candidate. He noticed as the truck drove by and down the road that the sound trailed off in pitch, his first observation of the well-known doppler effect.

And that got him to thinking. He had always thought the sound of the Hammond Organ was so dry, one of its greatest detriments and making it sound the most unlike a pipe organ. Hearing this dramatic demonstration of the Doppler Effect gave him the idea to experiment with a doppler type of effect for the Hammond tone cabinet, in order to smooth out the flat, dry sound.

So he went out to a radio store and bought a “one-dollar” speaker to begin experimenting with. He originally was just thinking about using a slow-turning baffle to produce a chorus effect, but then he found that a faster speed also produced a very warm tremulant — which sounded far richer than the electronic Tremulant (this was pre-vibrato days) on the Hammond.

At the same time, Bob Mitchell was the studio organist for radio station KHJ, following Gaylord Carter. He then went to KFI Radio in 1939. While he was working at KFI, playing on the Hammond Organ in the studio, Mr. Leslie's wife Carolyn also worked at the station. Mr. Mitchell happened to mention something to her one day about not liking the dry sound of the Hammond and that he would like to buy some other type of organ, really wishing there was room for a Wurlitzer pipe organ. Mrs. Leslie told him, “Well, don't buy ANY organ until you hear what my husband has done!”

So one Sunday morning, Mr. Mitchell went over to the Leslies’ home in Altadena, California (where Mr. Leslie and his wife still live). Mr. Leslie took Mr. Mitchell into his living room where he saw a Hammond organ sitting there, and he noticed that there was a small hole cut in one of the doors in the living room that was covered with a screen-type of curtain [grille-cloth].

Mr. Mitchell wondered, “What in the world...?” Then Mr. Leslie invited him to sit at the console and play. As he did, he noticed that the sound was coming from the grille-covered hole in the wall — the tone cabinet was in a large closet off the living room.

Then Mr. Leslie flipped a switch on the console and, as Mr. Mitchell puts it, the sound of the Hammond just “spun into life!” He said it had the most glorious full and rich tremolo he had ever heard on an electronic organ!

He asked Mr. Leslie how he did that. Mr. Leslie went over to the closet door, opened it, and showed Mr. Mitchell the rotating apparatus inside.

This first Leslie consisted of an 18-inch-in-diameter metal horn (like the kind used on gramophones) mounted onto a revolving turntable. Attached inside the wide, belled end of horn was a speaker. As the turntable spun, the speaker spun around creating the doppler effect.

And that was the humble beginning of the Leslie Speaker.

Meanwhile, Mr. Mitchell went to Willard Brown, the Program Director for KFI, and told him about Don Leslie's new speaker. According to Mr. Mitchell, he convinced KFI to commission one of the special cabinets which could be selected by a switch on the console, and only Mr. Mitchell was ever to use the new speaker — the other organists who played at the station were to use the standard Hammond Tone Cabinet. Mr. Brown wanted to know why Mr. Mitchell did not want other organists to use the special speaker, and he was adamant about it! He said, “That is MY sound and I don't want anyone else copying it!”

(n.b. Mr. Leslie was surprised to hear that Bob Mitchell claimed to have a “Leslie” on the Hammond at KFI. He said it must have been one of their prototypes as it was not one of his speakers.)

Mr. Mitchell also introduced Don Leslie to Willard Brown, who assigned some engineers — from Cal Tech, Mr. Leslie recalled — to work on the idea. They did, but in his words, “screwed up” the idea and their version did not work very well. They didn't really understand the concept, he said. Furthermore, Mr. Brown got scared away from the project when he tried to file a patent on it and discovered he could not. Seems that someone back in the 1920s had filed a patent for a record-player with three horns that rotated slowly on a turntable to enable everyone in a large room to hear the sounds from the phonograph!

So, Mr. Brown threw the ball back to Mr. Leslie, who went back to work on the design. In 1940, after months of development, he made the first cabinet-style Leslie, in substantially the form of the model 30A he said, with a rotary horn and a bass reflector.

Mr. Mitchell did use the new Leslie Speaker on the Mutual Radio network which was heard all over the U.S.

Mr. Leslie made some early records of Mr. Mitchell playing the first Hammond + Leslie combination. Mr. Mitchell said that the very first song that they recorded was “Tea for Two,” and he still has the record "around here someplace."

(By the way, Mr. Mitchell mentioned that the early Leslie cabinets were 'gargantuan' — the size of a refrigerator! But when people started wanting them for their homes, he came up with more compact and streamlined cabinetry.)

Mr. Leslie told me a funny story about demonstrating the speaker for “the Hammond people.” He got a prototype finished and installed it in the Mona Lisa bar, where Bob Mitchell was the house organist. The Mona Lisa was across from the Penny-Owsley Music Store in Los Angeles, at that time the area Hammond representatives. (Those who know their Hammond history will recall the noted theatre organist Jesse Crawford’s affiliation with Penny-Owsley.) Men from the music store would come over to the bar, and when they got an earful of the sound from the Hammond they of course wanted to know how Mr. Mitchell got “that sound.” But Don Leslie had secured the cabinet in such a way that they couldn't see what was inside it!!

Mr. Leslie let the Hammond people “sweat for a couple of days” about the speaker, then called the store and offered to bring a model to the music store to demonstrate it. Penny-Owsley arranged for a group of about 50 organists to come in and here the demonstration. In Mr. Leslie's words, they “just fell apart" at the sound — everyone just went ga-ga over it!”

Mr. Leslie said that Paul Owsley was going around the room whispering to people, “Don't let him know it's any good!” Of course, some of those in the room were friends of his so this got back to him.

After the demonstration, he wheeled the speaker out and loaded it on his Model A pickup truck, and said to Mr. Owsley, “Paul, people think is speaker is wonderful — they have heard it on network radio, and many people want it. I need to hear from Hammond within 30 days about licensing my Leslie Speaker, or I am going to market it on my own.”

“Well,” Mr. Leslie said to me on the phone, wrapping up the story, “The Hammond people did me a HUGE favor — they did NOT call me within 30 days so I DID begin marketing them myself — However, SEVENTEEN YEARS LATER, Hammond contacted me and wanted to buy my speaker! Too late!”

And, as they say, “the rest ... is history.”

He found out later that Laurens Hammond did NOT like the idea of the Leslie speaker at all (perhaps professional jealousy — who knows??), and he most definitely did not want anything to do with it. Well, Hammond's loss was Leslie's gain!

Hammond tried several ways of producing the same chorus and tremolo effects, first introducing the double-generator chorus effect and then the new-style, and much-improved, Vibrato and, eventually, even coming up with their own type of rotary-baffle speaker. But none of these were as good as the sound of the Leslie Speaker.

It's funny, somehow I had always figured the Leslie speaker had come along much later in the life of the Hammond. Maybe because so many of the Hammonds I recall seeing when I was a child still had straight tone cabinets. However, I have now learned that the Leslie came along when the Hammond was no more than, what, 3-4 years old! That's really amazing.