A Hammond Chop is a Hammond organ which has been repackaged into some sort of portablized case. Generally, not much weight is saved by chopping, but the resulting organ will fit in e.g. station wagons, and be easier to ship by air.
There are generally two methods of chopping an organ.
The first is for players who do not plan on using the bass pedals: The internal speakers (and internal leslie unit, if applicable) are removed. Any components in the base of the organ - reverb chamber, power amp, power supply, etc - are removed and placed in the upper half of the organ, above the tone generator. The pedals themselves are removed as well. The swell pedal can either be replaced by a volume knob on the front of the console, or placed in its own box with an appropriate plug connecting it to the rest of the organ. Then, the entire lower half of the cabinet is cut off below the tone generator (usually with a circular saw) and a piece of wood is bolted to the underside. A folding stand or folding legs is then added.
The second type is for players who use the bass pedals and care about size more than weight: Again, internal leslie unit and internal speakers are removed. Anything in the "middle" section is moved to the bottom or top. Components in the bottom that stick up rather far can be mounted in a different position or above the tonewheel, i.e. reverb chambers or heatsinks. Then, using appropriate bracing, the middle part of the chamber is cut off above the base and below the tone generator. Boards are bolted to the bottom of the upper part and the top of the lower part. The wires must be cut and soldered/connected to multi-pin plugs for easy removal and assembly. Aluminum or steel tubes are usually used to hold the console section up from the base.
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