High Pitched Noise Oberheim DPX-1

[kirill]

Hi everyone, I just got an Oberheim DPX-1, installed a floppy emulator in it and everything seems to be working well except on many presets I'm getting a high-pitched but faint noise after each MIDI key press as long as I keep a key pressed. Some presets have a release built-in and they roll off the noise but you can still hear it getting rolled off. The pitch of the noise changes with the keys. I was wondering if this is normal or if there might be an issue with my device.

I tried using a power filter and a ground loop breaker, but the noise is still present.

Thank you so much in advance!