Capacitor Question

[rborder]

I recently picked up some old LaScala's (type K-447). They've lived a very hard life, but I think I can resurrect them []

They have the original type A crossover. When I got them, both tweeters were totally blown. I picked up some replacement K-77 tweeters on ebay, have tested them, and they seem to be working great. My understanding is that the later crossovers (type AA) offered better protection for the fragile tweeters.

In car-audio applications, I've installed capacitors in-line with the tweeter speaker wire to protect them. I am wondering if doing the same on these speakers would:

A) protect the tweeters

degrade the sound quality

And, if I was to do so, wonder what frequency cut-off would be appropriate.

I know that replacing/upgrading the cross-overs would probably be a cleaner way to go, but it would also be a lot more cost effective if I can just add a cap. When I get them done, I plan to treat these speakers with much more care than their previous owner(s)- but I've seen enough speakers with damage to think it might be worth while to add a little protection if it's not too hard.

While I have these torn apart for rebuilding, I may do the bass-bin mod, but I'll save those questions for another thread.

Thanks-

Ryan.

CP-1 (pro cornwalls), Heresy HIP (pro heresy's) 2 sets, Theater LaScala (new toys)

[Guest " "]

adding an addtional value capacitor would change the cross over frequency.

The AA's have 2 5.1 volt zeneer diodes in series to act as a peak voltage limiter.

You could get a poly switch real cheap on parts express. Some folks use fuses. Some even use auto light bulbs. Each has pros and cons.

The newer AL-4 xover also uses a poly switch. If you go the poly switch route, adding a 100ohm resistor parallel to the poly switch, with both the poly switch and resistor in-line with the tweeter works best.

A lot of folks feel fuses, poly switches, diodes, and limter bulbs alters the sound of the tweeter.

[BEC]

Rebuilding the old tweeters with new diaphragms would also help since the original diaphragms were only good for two watts.  The new diaphragms can stand more power and have much better leads (Copper-Beryllium).

Bob Crites

[rborder]

My CP-1's each have 2 fuses at the input panel; a 1.5 amp, and a 3
amp. I've never cracked them open to see what's hooked up to what.

I'm
guessing that the 1.5 amp is in-line with the tweeter, and the 3 amp
fuse is inline with the squaker. Would this be correct?
Would this be an appropriate way to fuse the LaScala's with the type A
crossover?

Thanks-

Ryan.

[BEC]

There is a good chance that no fuse would act fast enough to protect the K-77 tweeter from a sudden overload.  Klipsch has always used either zener diodes and a steeper slope crossover to the tweeter or a 0.5 amp polyswitch and a steeper slope crossover.  Those methods protect against low frequency getting to the tweeter and against high power at higher frequencies.

Bob Crites

[djk]

The time constant on the 0.5A polyswitch is so long it is of no use on the old tweeters, and marginal on the new. A 211-2 automotive lamp works better for protection, but is best in conjunction with the newer steeper slope networks (AA and newer).

"I'm guessing that the 1.5 amp is in-line with the tweeter, and the 3 amp fuse is inline with the squaker. Would this be correct? "

The 1-1/2A fuse is for both the mid and HF driver, the 3A is for the woofer.

It is not possible to fuse the tweeter for protection, even 'fast acting' fuses are not fast enough. A 3/4A fuse takes longer to blow than a 1A (due to the way they are made).

Most K77s die from mechanical damage, not heat. Fuses and such are for heat protection. Zeners and the newer steeper crossovers are for mechanical protection. The replacements from BEC are much better mechanically due to the BeCu lead out wire.