Hi, please listen to this audio I recorded from using a Tetra I just purchased second-hand.
https://soundcloud.com/sonic-sand-castles/tetra-chirpingI'm not sure what can cause this distinct high frequency "chirping" like noise. I know I've heard it before when using vintage synthesizers, or when something else in the audio signal chain introduces it (a mixer perhaps, or recording device of some kind). But this noise coming out of the Tetra sounds wrong, as if it shouldn't be there and as if there's a fault with something inside the unit. Maybe it's something to do with gain-staging? I also don't hear it on every patch, which makes me thing it's something defective with some component that doesn't get used in every patch (a filter, oscillator, etc).
Can anyone help me identify what this noise is and if there's realistically anything that can be done to fix it?
Thank you!