Cheapest solution for fixed delay ?

Many years ago, I was answering a customer's questions about a sound system install in a gymnasium. Among them was a concern for how to properly store the excess wiring to one of the the 2 speaker enclosures, which was about 75' closer to the equipment rack than the other. "If this is a permanent install, it'd be better to just trim it to the correct length," I explained. "Well, you can't do that, the sound will come out sooner!" he declared with a note of contempt.

I took a deep breath and attempted to explain the difference between the speed of sound, and electrical current flow (which is somewhat faster I'm told), but he wasn't having it. "I guess I'll just coil it up behind the rack," he decided.

The thing that stuck in my craw was: The guy was technically correct. :rolleyes:
 
Make that 1000 km for 5 ms, assuming a dielectric constant of about 2.25. That won't be cheap...

Whoops my bad, i somehow misplaced these 3 zeroes in my calculations :)

It's possible to delay the signal with a simple low-pass filter... Technically...

Lipsync ICs, a-la TPA5050/1. One of these could be programmed with resistors (no need for mcu/i2c).