Conn Theatre Organ 643

Conn 643 Theatre Organ- the latest extension of the Noise Organ modification sound equipment. A good friend happened upon this pristine Conn 643 organ while working a local estate sale. With much angst, 4 strong backs, 1 long trip to my rear entrance (yes I said that) and a few hrs later and the organ was home. Luckily we had installed french doors in previous years allowing for a large enough opening to get it in. I’d like to thank the Malloy brothers with out them this would not be possible. Cost was free minus 3- 12 packs beer ūüėČ Here is a few links to the modifications and below is a full run down of the Conn 643 Organ with tons of pictures.¬†


conn organ circuitry

Conn 643 Organ Modification | Dual Input Insertion | Noise

Conn 643 organ modification, dual input insertion. Noise Organ. We started by exploring some of the many signal lines tangled through ...
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conn organ 643 noise organ


The 643 features a solid state 190 watt Amplifier, analog reverb, stereo play internal and external, built in Leslie cabinet, tibia repeater with oscillation controls. In addition the multitude of switch options allow for hundreds of organ noises played between the 4 internal speaker and outside connections. Let us not forget the hot key drum synth on the side.

conn organ 643

In searching for my first modification point on the organ I removed the rear panel. This gives access to the amplifier, speaker cabinet and tuning adjustments for the 643. I had hoped to find a way to line in thru this area with no avail. With out schematics or pin outs this was a dead end as it appears the pedal volume adjustment is post amplifier. It did however reveal the name plate “Made in Indiana” just a few hrs away from our location in Ohio.

conn organ 643 label plate

The speakers consist of a custom 15 inch custom ¬†alnico, 12 inch custom alnico and a voiced 6×9 (ish) and the Leslie Tremolo 2 with built in 8″ Jensen c8r custom loud speaker.

conn organ speakers

conn organ 643 leslie speaker

conn organ leslie label

In addition to amp, speakers and tune controls it also features a bank of what looks like transformers (they are not transformers) that have a nut and bolt adjust for shifting the pitch of all the played notes.

conn organ pitch adjustment

Undaunted by the lack of luck in my first attempt to add a line in (first priority) I was happy the electronics side of the organ-the top was easily accessible and with each circuit board labeled I knew I was on the right track. Each board was also designed to be variable and has pot adjustments that are all clearly marked. Once the initial hacks are made my intention is to add bent circuitry adjustments that will be harnessed into a separate main controller. Via the Reed Ghazala methods of thinking.

conn organ circuit boards

conn organ decay bias and sustain

conn organ circuitry

conn organ sustain control

conn organ keyboard

conn organ schematic