[Paul G.]

On Tue, 18 May 2010 16:25:08 -0400, Dick Pierce
wrote:

guy25 wrote:
Thanks Peter,

I talk to digikey on the phone but they do not carried 7W only 10W in
stock. Don't you think it works?

Like others have said several times, YES, it will work.

Increasing the wattage for 7 to 10 watts, or from 7 to
15 watts, or to 20 or 50 or 100 watts WILL WORK FINE.

The wattage of the resistor WILL NOT MAKE A DIFFERENCE:

1. If everytging else in the speaker is working fine,
a 10 watts resistor will sound identical to a 7
watt speaker.

2. If, in the process of blowing up the 7 watt resistor,
you blew up something else (which is possible, maybe
even likely), then replacing the 7 watt with a 10 watt
will ALSO make the speaker sound identical, becasue
it's just as broken with a 7 watt resistor as with a
10 watt.

there also some on ebay but I'm not so
sure about quality. Please give me your opinion.

My opinion is that you're WAY overthinking this.

Just buy the damned 10 watt resistors and be done
with it.


There is a remote chance it is a "fusible resistor", I've replaced
these things on older TV sets. They are used extensively in the
electronics industry, especially where temporary large surge currents
are tolerated. If that were the case, you would be required to replace
it with a similiar resistor of the same power rating. 0.47 ohms is a
popular value for a fusible resistor.
They DO have a compartively long time to blow compared to a fuse,
since the resistor must heat up to the point where the fusible element
breaks. In that respect they would be useful in a speaker, since you
could allow large transients, and the resistor would open up before
the voice coil would be damaged.
They were not meant as a consumer replacable item, since the trauma
that caused the resistor to blow usually indicated some circuit
problem or gross abuse.
My guess is that such a low value of resistance would not have much
effect on the audio performance (being swamped out by the voice coil
resistance), and might give more credence to its function as a slow
fuse.
If it is a fusible resistor, it is probably chosen for a specific
thermal time constant. It would not be wise to replace it with an
ordinary resistor, or fusible one of unknown characteristic.

Paul G.