Old Kimball model 285

[StevenW]

I found a Kimball 285 and its a tube model. The only tubes I could see by looking down after lifting the top were 6BQ5 and 5Y3GT but there must be others in there.

The thing is huge - full pedal board and two manuals (I believe 66 note manuals, not sure). Makes my Hammond M-111 look tiny.

This organ was given to me, free for the taking (I already committed to taking it off their hands, hope that wasn't a big mistake). Any information on it would be appreciated. I can't find anything on the net about it.

[Jan Girardot]

Hey, Steven, you have a real collectors item, there! Here is the listing from my Mother List:
KIMBALL 285 1960 PC A32 2 photocell AGO console

Deep inside the organ, there are 12 "tubes", actually photoelectric cells that "read" the waveforms on discs that revolve in front of them. I have an original Kimball-published service manual covering that model for sale from my collection.

For more information, send me a PM (Private Message).

. . . Jan
the OrganGrinder

[StevenW]

Collector's item?

[jbird604]

Interesting. I wasn't aware that anyone had marketed such an organ so long ago. Must have been quite a tour de force on the technical side. That would definitely make it a collector's item, Steven!

Jan, do you know how this thing worked? Did the photocells create a top octave of square waves and then they got divided down to the necessary pitches? That would be a unique solution to the problem of keeping an organ in tune!

[indianajo]

Optical Read only Memory, I'm impressed. Even more so if the generators produced sawtooth waves, 82 or 96 of them. Stable pitch like a hammond, no tonewheels. I wouldn't drive very far to hear one, though.

[StevenW]

Well thanks guys. I have the organ in my posession but its in kinda bad shape. The bottom has rot and possibly termite damage, probably due to being stored in a garage for a long time. The insides have a lot of mouse leavings. But the amp has a pair of Amperex Bugle Boy 6BQ5/EL84. :D

Jan, I got the service manual and owner's manual, plus the key to lock the cover inside the bench, but thank you.

[Admin]

Interesting. I wasn't aware that anyone had marketed such an organ so long ago. Must have been quite a tour de force on the technical side.

In the second edition of Richard Dorf's Electronic Musical Instruments published in 1958, he mentions the German manufacturer Welte and Baldwin having produced organs with optical tone generation. In the third edition, published ten years later, he elaborates a bit mentioning that Baldwin first produced the optical models in the 1950's and Welte prior to World War II(!) but they did not revive them afterward.

He includes this representation of the Welte disk:



Quoting from the third edition:

"While this system conforms with the dictum requiring a total of at least 12 discs, one for each note of the scale, each running at a different speed, each single disc can provide not only the various octave reptitions of its note but also different waveforms....you can see that of the first three bands, the innermost has the longest and thus fewest waveforms and this produces the lowest frequency. The second has twice as many and thirds again twice as many, so that the first three bands produce three octaves, all of about the same tone color.

The fourth and fifth bands produce the same frequencies as the second and third, in a different voice, possibly a diapason because of the strong second harmonic content."

He goes on to explain the difficulties of producing a such a disk with the necessity of hand drawing the patterns and bending them to fit the circular band.

He states that Kimball keyed their optical organs by using a separate lamp for each band and turning it on or off with the corresponding key. Baldwin on the other hand used a single light source and key activated mechanical shutters. Rather than a disc Baldwin put their waveforms on an optical drum.

According to Dorf, Kimball did not produce optical organs for very long before switching to electronic generation. Baldwin apparently stopped making optical based instruments in the '50's, but I believe they revived the technique for models produced after the third edition of Dorf's book was published.

[Jan Girardot]

Here is information from my Mother List:

KIMBALL 225 1960 PC 13 2s photocell spinet
KIMBALL 250 1964 PC 25 2 photocell console
KIMBALL 260 1964 PC 25 2 photocell console
KIMBALL 265 1960 PC 25 2 photocell console
KIMBALL 270 1960 PC 25 2 photocell console
KIMBALL 275 1960 PC 25 2 photocell console
KIMBALL 280 1960 PC A32 2 photocell AGO console
KIMBALL 285 1860 PC A32 2 photocell AGO console

All the Kimball photocell models were developed by the original W. W. Kimball firm in Chicago, along with a cute little transistor divider spinet. Maybe StevenW will describe the vibrato system: what a hoot!

When the Habig family bought W. W. Kimball, they hired a European engineer to develop a hybrid electronic, employing twelve vacuum tube master oscillators driving transistor dividers.

The first Baldwin p'cell, the Model 20 was under development before WWII but wasn't produced until after the war. They had lots of problems and were withdrawn by the factory, being replaced by the Model 5 (vacuum tube divider). In 1974, Baldwin took another stab at it with the Multi-Waveform organs: "still no joy".

As well as the above, similar photocell organs were produced by Compton, Dereux and Electro-Voice (on Dereux patents).

(Sorry, John, no "dividers" in these babies!

. . . Jan
MITA Historian

[Admin]

As well as the above, similar photocell organs were produced by Compton, Dereux and Electro-Voice (on Dereux patents).

According to my sources, the aforementioned Dorf editions and Alan Douglas' The Electronic Musical Instrument Manual, 5th edition, 1968, Compton, Dereux, and Electro-Voice used electrostatic tone generation, not photo-electric. They are similar in that they use spinning disks with waveforms. Douglas describes the Dereux organ as follows:

"This has the unique feature that the waveforms are...fully preformed pipe organ tonecolours produced from cathode ray tube photographs of the actual sounds required. The rotors and stators are made from plastic material which is silver plated, and the wavforms are etched thereon. Polarizing potentials are fed through the stators to the appropriate rings, and the rotors are driven by an endless belt".



Photos of Dereux electrostatic disks, showing both rotors and stators, and a Compton electrostatic generator unit from Douglas book.

[Jan Girardot]

Hello, Admin & all;

At this point, perhaps we should develop a glossary, defining and contrasting electro-static, photoelectric, tonewheel, unless someone has already done so.

Any volunteers?

. . . . Jan