We have a pair of Peavey DTH S4 PA speakers. Recently, the one cabinet has developed a buckling sound in the woofers, and the horn cuts in and out also. The speaker functions fine until it has ran for awhile (warmed up). Have eliminated the drivers as a cause of the problem, and have narrowed it down to the crossover assembly. The assembly has a 4PDT full range/biamped switch, but the rest of the crossover is pretty much standard design. The solder connections are all good. Any suggestions as to which type of component (cap or inductor) would be more likely to have a heat related failure? Or any other suggestions where to look.....?
dougpke said:
First guess is the caps. They can fail two ways: Either a disconnection of circuit(no sound) or a short (full frequency delivered to the tweeter)
The only failure I'm familiar with (not actually seen this) in a coil is the magnet coating somehow becomes worn and creates a short (full frequency delivered to the woofer)
I can't comment on the switch but I would also try by-passing it to test.
Cal
The switch is never used (it's locked in the full range position), but both the low range and the high range circuits pass through the contacts of that switch more than once. There is no noticable damage to any of the components (signs of heat), so perhaps I will jumper over the switches contacts, reassemble and try it again. Due to the size of the cabinets, I hope the switch is the problem. I have to reassemble and transport these cabinets back to the club, and then haul the replacements back home each time I'm wrong
Back to the Drawing Board
Removed the switch and installed buss wire jumpers on the PC board. While there was no distortion from the woofers the horn started cutting out after it had warmed up. Pretty much leaves two caps in series, with a resistor in parallel with one of them, and an open air coil across the leads leading to the high end driver. Whatcha think, the caps next?.....
Removed the switch and installed buss wire jumpers on the PC board. While there was no distortion from the woofers the horn started cutting out after it had warmed up. Pretty much leaves two caps in series, with a resistor in parallel with one of them, and an open air coil across the leads leading to the high end driver. Whatcha think, the caps next?.....
Halfway there.....
Well, I replaced the resistor, and now the horn sounds fine! However, on very heavy bass, (stuff that thumps) the woofers rattle (buckle) on the heavy thump. Actually, the system sounded fine at first, but when "Baby Got Back" started playing (after running 30 minutes or so) the rattle started. Then it appeared to go away. Didn't actually notice it the rest of the evening (another 3+ hours)
P.S. There is always the possibility that one (or both) of the woofers is (are) flakey on strong passages. Is that possible?
Well, I replaced the resistor, and now the horn sounds fine! However, on very heavy bass, (stuff that thumps) the woofers rattle (buckle) on the heavy thump. Actually, the system sounded fine at first, but when "Baby Got Back" started playing (after running 30 minutes or so) the rattle started. Then it appeared to go away. Didn't actually notice it the rest of the evening (another 3+ hours)
P.S. There is always the possibility that one (or both) of the woofers is (are) flakey on strong passages. Is that possible?
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