Distorted Silicon Ship Theremin

Hi all, I'm looking for some advice on a build so this is my first forum post here.

I've recently built a theremin from a Jaycar Silicon Chip kit but it sounds very distorted. I've wired guitars and built effect pedals before, so I have a basic understanding of what I'm doing, but I can't seem to figure out where this distortion is coming from. It's very frustrating considering some of the very clean samples I've heard and makes it almost unplayable. The distortion exists when using both the internal speaker and the line out, so I can only assume it is something internal.

Any ideas why this might be happening? Have I fried something during construction, or could there be a faulty component?

Hi twebb6778!  Do you have a scope?  If so I'd look down the audio signal chain for signs of distortion.  If not I'd get one, you really need a scope to do Theremin work.

That sounds like a great idea, but I haven't got an oscilloscope. Any recommendations as to how I could get around this without dropping big money on a scope?

I don't know, borrow one?  Decent digital scopes aren't too expensive these days, a Siglent or Hantek can be had off Amazon for $250 to $300.  If you do buy one, don't get anything that's low bandwidth, handheld, an add-on module, or clearly a toy - you'll just be wasting your money.  You pretty much have to have a scope in this biz.

I'll take a look, thanks for the advice.