Hi all, I purchased 3 Casio keyboards in the last few years and all developed the same intermittent problem after a few months. Occasionally, the notes from each key have a slightly out of tune overtone, which makes for a quivering overtone sound, maybe 10 beats per second at the middle notes. All keys, all tones, as far as I can tell. From the start up - at the default settings, and have not been able to eliminate it by changing tone, split or layer settings. It makes the note sound sour, but not really off pitch. Its heard from the on board sound system only. The headphone and line out signal is clear, without this problem. After a day or so, it goes away and sounds normal. I can't find any similar reports on line. We live where the air is clean. The boards are a Privia PX-400R, CTK-900 and CTK-5000. I have not yet contacted Casio about it. Anyone else encountering this?
Eureka !!! I found the cause of the problem. This is incredible. There is nothing wrong with the keyboards. The problem only happens in the small sunroom where I have two of the Casio keyboards set up. Never through the headphones, but it does happen when the on-board speakers or amplifier is on. And, it is intermittent, so the problem is there some days and gone other days The problem goes away if I move the equipment to another room. Take a guess...
It's the ceiling fan. The blades reflect the sound, and when it is spinning, there must be a doppler effect. Tile floor probably makes it worse.
