Estimating Speaker Power Rating

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.

Reply to
Blake
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You're going to have to forget it.

DC measurements are useless since the voice coil uses its movement under actual working conditions to help air cool it.

I've come across 12 inch speakers with as diverse power rating ( continuous ) as

15 Watts at the low end to 400 Watts at the very high end.

The voice coil diameter, materials and adhesives all play alarge part in determining the power rating. Some speakers can actually work with the voice coil hundreds of degrees C over ambient.

Graham

Reply to
Pooh Bear

You can register at

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and ask the tech folks there, for an accurate answer.

My educated guess is the speaker is rated for 50 W RMS, based on the "50" at the end of the letter/number sequence you listed. That is a "normal" power rating for a 12" guitar-amp speaker.

Reply to
tlbs

I've written a couple programs that graph rms and avg of music, and the rms always seems to track the avg about 3dB hotter. So a nice S L O W avg would track voice coil heat pretty close.. just assume the rms voltage is 3dB hotter than what you are measuring with the avgerager.

Reply to
BobG

Doesn't that read "Line 6 t5263 8Ohm 50" ?

--DF

Reply to
Deefoo

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