Blasting away and then nothing. Swapped for another and nothing. Not biamped. What should I look for?
Thanks......
Blasting away and then nothing. Swapped for another and nothing. Not biamped. What should I look for?
Thanks......
check to see if the x over potentiometer turns freely ............if it feels crunchy its fried..........check for loose wires and isolate your pre amp and amp connections to check bad connections......sometimes the rca connectors on the back of amplifiers will loosen and twist the wire off inside the the case.i just test one component at a time to eliminate it until i root out the bug
Probably a faulty capacitor in the Hi-pass section of the crossover....or a fried L-Pad.Originally Posted by SteveW
Check the crossover for burned components or broken leads, melted solder joints, etc.
Edgewound...JBL Pro Authorized...since 1988
Upland Loudspeaker Service, Upland, CA
Click that "Int/Ext" switch back and forth a couple of times.
Try doing it with the system playing at LOW volume to see if the switch is intermittant....
Thanks for the tips guys!
With known good replacement driver installed I exercise the switch and it comes alive again. Zilch hits it on the head! Re-install original driver and no workum. Hmmm... Swap spare back in and all is well. What happened to the driver?
Gotta admit I was running 100db+ with an old Sheffield Lab disc. Failure occured immediately after pulling faders down and pushing them right back up (without over-excursion)
Thinking of (fast-acting) fuse/circuit-breakers again. Amp is non-bridged K1, and that Crown protection card won't work with it.
Suggestions?
A $300.00 driver will protect a 25 cent fuse every time.
AMEN!
Bart
Should each component be protected individually, or do the whole cab?
Best I can ascertain, fuses won't get it. JBL uses light bulbs in a few products, and there are a variety of relay and clamping circuits of indeterminate utility....
Hello
What era 4435's do you have? The early ones had 2421 drivers and the later ones used the 2426 driver. Good news is if yours has the 2426 drivers the diaphragms are readily available from many sources. If it's a 2421 I think you can still get original diaphragms from JBL, special order = more expensive. I don't know if the drivers/diaphragms are interchangeable between the two 4435 era speakers. The difference would be (if any) in the passive crossover doing any special tweaks for the between the two driver types. The 2421 uses a aluminum diamond surround and the 2426 is titanium diaphragm. Here is a link to JBL pro service showing the crossover with a 2426 driver, I could find no crossover showing a 2421 driver. You can put the newer titanium diaphragm in the 2421 driver. Unless something in the crossovers shorted out sending lower frequencies to the drivers my guess is that amp clipping did them in. A 100db+ while loud would not really be working the speakers that hard unless the amp was pushed beyond it's limits. The 2426 drivers can take a lot of good clean power, they do all time in my bi-amped stage monitors. Normally over powering a diaphragm or too low of frequecy crossover point will shatter the metal and one that is blown from excessive amp clipping will have a burned voice coil.
Mike Caldwell
Could use a polyswitch. These are available cheap as surplus and are intended for use with speaker protection. I use them in my garden railroad engines to avoid wire burn-outs on derailment. I don't know if they have any sonic implications, but like I noted, they are noted for use with speakers.
I agree it sounds like clipping and its likely to happen again at some point.
Ever thought about biamping those 4435. Not a total cure but it will prevent the clipped signal on the woofers burning out the HF driver voice coil and it will probably sound better. Surprised you aren't already if your running them that hard.
The is nothing that will protect a driver of any type from the extended effects of clipping.
Current limiters, i.e. light bulbs, polyswitches, fuses, have no effect on the HF harmonic content and DC offset of a clipped signal.
The only cure is to turn it down or install a higher power amp that has at least 6dB headroom.
In the case of the 4435 you should be looking at 600 watts and above for passive operation, or 600 watts plus 200 watts for biamp mode...if you need to listen loud. The catch 22 is killing your ears in the long term.
Edgewound...JBL Pro Authorized...since 1988
Upland Loudspeaker Service, Upland, CA
Could a steep low pass filter set at around 17Khz help or is that harmonic content within the pass range of the driver itself?
Bart
Limit High Frequencies to reduce susceptibility to clipping damage?
An interesting idea.
Opinion: No.
Harmonics of clipped bass signals (20-200Hz?) would have significant energy within a passband below 17KHz... mostly odd order harmonics 3, 5, 7 with
decreasing amplitude, the higher the harmonic.
-grumpy
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