a bad crossover?

[mcshaggy]

a friend of mine purchased some very large PA speakers from a trusted source. they were homebuilt, and (for some reason) have 8 tweeters 4 mids and an 18" bass driver. after looking at the specs for similar models of the bass driver, we guessed it to take around 600 watts. he got his hands on an amp to test them with he found that everything worked but the tweeters. he took a tweeter out and tested it seperately and it worked, so now im assuming the crossover is bad. but how can one go about testing that, and if so fixing it?

and as a seperate note, whats beneficial of having so many tweeters?

last note; im new here still learning (i have a lot to learn)

[jjdche]

I don't know much about pro audio stuff, but that just doesn't sound right to me. Usually the tweeter has a way higher sensitivity than the bass driver, there is no way an 18" woofer can keep up with 8 reasonably efficient tweeters unless the tweets have miniscule power handling.

[Bill Fitzpatrick]

If all the tweeters were wired in series and only one was dead, the tweeters wouldn't work. Maybe he tested a good one.

Or, the tweets are wired series/parallel and one is dead in each series branch.

On the other hand, the tweeter section of the crossover could be kaput.

[aaroncgi]

jjdche,

Actually, if this is a pro 18" woofer, it could have quite high efficiency (as most 18" do anyway, but ones with accordian surrounds usually even more so - easily in the mid to upper 90's at 1W). If all the tweeters were wired in series, or series parallel for the same net impedance, there's no reason to assume a huge mismatch in overall efficiency between those two sections.

Bill,

Yep, all good points. My personal guess would be a kaput crossover, but it could be any of the above. Usually , if a crossover has lost one or more of it's outputs, the damage will be easily visible. In the case of a tweeter section out, most likely would be a burnt resistor or blown capacitor. There's always a small possibility that a wire has simply become disconnected, or there's a bad solder joint on the crossover. Troubleshooting is not difficult, just a process of elimination. Usually it's a lot quicker when you only have one tweeter. Good luck!


Aaron Gilbert

[mcshaggy]

the idea of one tweeter being out in the series seems logical. ill also note that the 18"ers do indeed have the accordian thingy on them. one thing i gotta say though is this; both speakers suffer from the same problem. is it safe to assume the same problem could have happened to both speakers at the same time? or perhaps maybe one of the components used in the crossover at the time has since gone bad in both circuits. the speakers have been laying in storage for some time now according to the guy we bought it from, so who knows.. anyways thanks for the tips, ill be looking at each tweeter before i poke my head in at the crossover.. they glued it to the enclosure so i cant easily take it out

also, any guesses as to what we should power these with? i was thinking of maybe building my own amp to go with this as its a lot cheaper than buying a pro audio amp. any suggestions would be helpful (but first i gotta make the speakers work )