high frequency intermittent noise

@james1969,

I missed the Big Glass Window directly behind your audio gear when looking at your system pictures before.

Just a test you can try, if you are up to it. Cover the entire window with at least two layers of aluminum foil. Tape the foil in place. Overlap all splices by at least a couple of inches. Overlap the second layer by 1/2 the width of the aluminum foil. If possible wrap the foil over the window inside trim to the adjacent wall, window sill, and above window trim. Ground the aluminum shield to the mains equipment ground with a piece of wire. For the ground connection of the wire to the aluminum foil you could try removing the insulation from the wire several inches and then tape the bare ground wire to the foil the entire bared length.

If by chance it works, fingers crossed, you might then try copper window screening to cover the glass window.

EDIT:
If you do try the experiment,  experiment with the foil shield grounded and un-grounded to the mains equipment ground.

Example of copper screening.
https://www.dkhardware.com/bronze-copper-zinc-60-screen-wire-50-BRZW60-product-49932.html?gclid=EAIa...

almarg and or kosst_amojan, or others,
Would the copper screening work well as a shield and reject RFI from entering through the glass window?

@jea48 

I'm with you man.  Check this out:

https://www.select-fabricators.com/rf-emi-shielding/rf-emi-test-shielding/curtains/

I need to get more aluminum foil...

almarg and or kosst_amojan, or others,
Would the copper screening work well as a shield and reject RFI from entering through the glass window?

Yes, Jim, I would think that a grounded copper screen would be effective against 700 - 800 MHz, since the openings in the mesh are far smaller than the wavelengths of those frequencies (which are about 17 and 15 inches respectively). Although as noted at the FCC link I provided earlier those frequencies can "penetrate buildings and walls easily," so keeping them from getting in via the window might not be all that helpful.

Good suggestions, though, in your previous post.

Best regards,
-- Al

This RF/EM signal must be picked up by the voice coil in the tweeter and it is likely a powerful megaHz signal and would be inaudible if it didnt cause problems for the amplifier(which tries to surpress distortion with negative feedback so as to match input) and the problem manifests itself in the audible range somehow due to signal saturation in the amp section making it a broadband signal.

Try adding a choke across the speaker wires to short out the HF signal.

http://audiosystemsgroup.com/RFI-Ham.pdf

See Fig 4 for an example...

Try adding a choke across the speaker terminals to short out the HF signal.

@shadorne 

What is a choke?  How would you implement this?  I'm not an electronics guy, learning-as-I-go-here.