[Eeyore]

Gareth Magennis wrote:

"jakdedert" wrote

I know, I know...but for $9 in good shape at the thrift store, I figured I
couldn't go wrong. No way to test, but the surrounds were in excellent
condition; so I figured at least the woofers alone were worth $4.50 each.

Brought them home, hooked 'em up, they made noise...so far so good, but
where were the highs? AWOL...crap, blown tweets! Not so fast....

Tested the tweeters with 9v battery--fine. Okay, time to open the box.
Pulled the surprisingly flimsy woofer from the 1/2" MDF box In addition
to the minimal x-over components (resister and cap in series with the
tweeter) was a #561 automotive 'festoon' style lamp in series with the
tweet. Shorting that brought back highs.

Now considering this was a series limiter, should I replace it, or just
bypass? The lamp
http://www.bulbtown.com/561_MINIATURE_BULB_RIGID_LOOP_BASE_p/561.htm is
a roughly 12 watt unit with apprx. 1000 hours rated life. Did it 'fuse',
or just wear out?

Strange stuff, this Bose....


I would not bypass the bulb as the crossover is designed for the bulb in
place and you risk blowing the tweeters. The bulb has a significant
resistance compared with that of the tweeter.

Third party replacement is usually trial and error. Peavey speakers around
the 300 to 400 Watt mark use something like 24 volt truck bulbs,

Exactly what I fit too with wattage varying with x'over freq. EV do it too even
for some 12" units.

smaller speakers may be using 12 volt ones, some JBL speakers higher rated
bulbs.

I've seen JBL get it totally wrong in their JRX series. The tweeter protects the
bulbs.

Graham