Audio RF Interference & Demo with Sammy

Sammy and I chat and do demos about hum and RF interference

Sammy asks her dad to explain interference and how sound from the outside world gets into a cable. Dad explains that cables can sometimes act like antennas, and shielding is put in place to protect them from outside interference. He mentions that aluminum foil hats might be increasing radio wave exposure rather than preventing it if not grounded correctly. They then put together a test rig to demonstrate how RF interference gets into cables.

Dave Rat demonstrates the impact of grounding on immunity to spurious sounds. When he touches everything to the ground, there's no sound because everything is grounded out. But as he lets them live, they become susceptible to interference. For instance, when he grabs the cable wire, there's no sound. However, he hears a buzzing sound when he separates the extended out clip leads.

He explains that the microphone output is equal and opposite to cancel the buzz on the signal line.

Dave discusses how cell phones can create RF interference and affect audio gear, such as mixing consoles and headphones. He explains that even when on silent mode, cell phones can still produce noise that can be picked up. Additionally, he shares a story about a concert he did in Germany where the entire city's radio station transmissions were coming out of one giant tower, causing interference problems that had to be solved by grounding the stage. He recounts his experience of dealing with audio RF interference during a stage performance. The aluminum stage was acting as a giant antenna. To resolve the issue, he had the crew dump salt on the grass around the stage posts to create a good ground using the wet ground and the aluminum downposts. The process eliminated the RF interference temporarily, but the problem came back after a few songs. They repeated the procedure using more salt and water, and it worked again.

For more info on solving RF stage interference with salt, check out

https://www.ratsound.com/cblog/archiv...

00:00 Intro
00:54 Accidental antennas
02:25 Tin foil hats
04:12 Interference and hum demo
06:10 Balanced line hum demo
07:42 Sound of Sam
09:38 Cell phone RF interference
11:07 Samufacturing on Instagram
11:38 More cell RF interference
13:05 Solving large scale RF issues
17:28 Outro


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