"Eeyore" wrote in message
...
Trevor Wilson wrote:
"jakdedert" wrote in message
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....
**Just whack a 070 PolyswitchT in place of the lamp you'll be sweet.
There
might be a slightly noticeable increase in HF, but I doubt it. The
Polyswitch will last a very long time.
The Polyswitch guys actually do/did an app note on tweeter/driver
protection
inluding using bulbs as well ! Polyswitches on their own tend not to
'reset'
very well you see, whereas bulbs do.
**Incorrect. PolyswitchesT 'reset' just fine. They simply require the user
to reduce levels going to the driver/s. Best of all, is that if the
PolyswitchT is used within it's specs, it will not readily fail. Lamps WILL
fail. One needs to understand how PolyswitchesT work, before using them.
For the record: I've used PolyswitchesT in *A LOT* of speaker systems, since
1985. I've never had to replace a PolyswitchT, or a tweeter in a system
which has been so modified. OTOH, I have seen failed PolyswitchesT in some
equipment. They can be destroyed by over-Voltage. It's a pretty rare event
though.
--
Trevor Wilson
www.rageaudio.com.au