KORG Vintage Analog Organ CX-3 with dedicated stand and hard case included

This is the original KORG CX-3 analog organ model. It comes with its dedicated stand and hard case.

It is believed to have been manufactured around 1979-1980.

All keys and switches have been tested for operation and sound output.

There is a volume difference when the rotary effect is turned on and off.

Regarding this, the AI's response is as follows:
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The phenomenon where the volume increases when the rotary effect is turned off on the Korg CX-3 (First analog model) is likely a design specification rather than a malfunction. This is thought to be a change in perceived volume due to the tremolo effect applied by the rotary speaker, or an intentional design to replicate the combination of a genuine Hammond organ and Leslie speaker.
Countermeasures
If the volume difference is too large to be practically problematic, you can consider the following methods:
- Volume balance adjustment: Use external effects such as a volume pedal or compressor/limiter in front of an external mixer or amplifier to adjust the volume difference when the rotary effect is on/off.
- Internal adjustment (not recommended): Based on the service manual for the First CX-3, it is possible to increase the volume when the rotary is on by adjusting the amplitude modulation gain with internal semi-fixed resistors (presets), but this requires specialized knowledge and may void the warranty.
- Upgrade to Version 2: For the early models of the First CX-3, there was an option to upgrade to Version 2, which included overall sound quality improvements and noise reduction. This may also improve the operation related to the rotary effect.

In conclusion, as this phenomenon is likely part of the character of a vintage organ, we recommend trying to adjust the volume with external equipment first.
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*However, as this is an old model, we cannot definitively say that it is not due to some malfunction caused by aging, so please understand this point.