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Our New York office’s sound system was, frankly, awful. It had a persistent background buzz, a loud hum, which we could not get rid of until we re-engineered our audio cabling.
We switched to shielded cabling and professional-grade connectors, and when we finished we no longer heard the buzz. And we are able to drive our sound system with an iPhone.
In our original setup, we had pulled a 50 foot cable over an air-conditioning duct and lighting fixtures. Even though it was a thick gauge wire, it was not shielded.
[Unshielded wires are susceptible to ground loops and electrical interference. In audio cables, this usually results in a background hum or buzz.]
The cable had a 1/4″ phono plug on both ends. This is a 1950s connector which was used on large headphones and electric guitars. Numerous adapters were cobbled together to connect the sound source to the audio system. The results were uniformly dismal: no matter what we played, no matter how it was connected, it always sounded terrible.
After some research, we settled on the following:
A direct-in or (DI) box. In our setup, we used a Radial ProAV2 Passive Stereo DI with RCA 3.5mm XLR and 1/4in Inputs.
We also have a Sescom SES-IPOD-RCA03 3.5mm Mini Stereo Plug to Dual RCA Male Plugs. These are used when we need to connect an iPhone or another 3.5 mm jack device. This allows us to play an audio source from the back of the room.