I've been wanting to build a guitar amp for some time now. When I found an amp case with 12" speaker at the swap meet going for a give-away price, I snapped it up.
The first thing I need to do is to know the speaker power rating, so I can design the amp to make the most of it, without blowing the speaker. The speaker's marked "Line 6 t5263 80km 50", but since I haven't been able to turn up any data on the speaker I'm thinking about ways to estimate it.
My idea is to pass a constant DC current through the voice coil and measure the voltage rise as the copper wire heats up. Based on a tempco of 3.9E-3 for copper, I would expect to see the resistance rise from 16 ohms at 25C to about 19 ohms at 75C. If I take 75C to be the maximum safe temperature for a voice coil (pulled that number out of my ear), then whatever power I need to apply to achieve that resistance increase should be my power rating.
Ok, that sounds ok in theory. But we all know that theory (especially interpreted by those with a only little bit of knowledge) can be very different from reality. So, I ask for your comments. Am I way off base here? Is there a better way?
Your comments are appreciated.