# Speaker Wattage



## RCE (Sep 14, 2009)

I have salvaged several speakers form different things. Some of the speakers are marked with the ohms and wattage on them and some are not marked at all.
I can get the ohms with a VA meter but don't know the wattage.
Is there a way to find out the wattage of a speaker so that I will not ruin the speaker with to large of an amp ?

Thanks
Richard


----------



## Greg Elmassian (Jan 3, 2008)

nope, and an ohmmeter is not very accurate, measures resistance, not impedance.. 

Greg


----------



## JPCaputo (Jul 26, 2009)

The speaker will draw as much as it wants from an amp. Listen for the speaker to clip (sounds like a pop ) then it's too loud. If it sounds distorted, clipping, the amp is overdriven. 

Ive run 1/4 watt speakers from a 200w amp with no problem. The volume knob on the amp is very low and the speaker is full blast. 

I've also blown speakers on a small amp, like 100 watt speakers on a 50 watt amp. I cranked the amp up too far, it clipped hard and blew the speakers. I've also blown amps from trying to drive high power speakers to a loud volume. 

A quasi way to determine impedance and watts is to measure the resistance of known speakers of similar physical size. This will give a very rough idea of the speakers impedance. 

A true way would be to use a frequency generator with a resistor in series. Measuring the voltage over the speaker need a true RMS meter to do this. When you read .707 X the low frequency (as low as the freq generator will go ) will give you the impedance through a formula. Search for RL circuit in wiki.


----------



## Greg Elmassian (Jan 3, 2008)

If you need a rough idea of power handling, you look at the diameter of the voice coil, the excursion of the cone, the type of suspension at the edge of the cone (forgot the terminology). (surround?) 

If you are trying to get bass, then tapping the cone with your finger.... the lower the "thud", normally the lower the resonant frequency of the speaker, the lower freqs it can handle. 

Fake stuff, like oversized or intentionally hidden magnets, or weird treatments of the cone belie a cheap speaker. 

Greg


----------

