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Author Topic: Diagnosing a bad crossover  (Read 6412 times)

Dave Guilford

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Diagnosing a bad crossover
« on: February 28, 2017, 11:44:01 pm »

 So I've been pulling apart some used EAW fr159z speakers  in order to load them up with new drivers. Apparently one of them has a bad crossover. I verified by swapping the part with the other box, and that one worked fine.

 Interestingly, it has the same symptoms as one of the bad woofers. That is, when driven should be wearing the lower level, they are very quiet. Very mid range E, not a lot below  200 Hz   

 The one speaker seems to be fine – no stripped wires, no seized cone. Thoughts on what that could be?

 The crossover yield the same results – even with a working woofer-  very  quiet output even when pushed with an itech 4000.   Obviously nothing above 2K-ish, but also nothing below 200 Hz ish. 

 Replacement woofer is already been ordered, and I have a local guy who is great with EAW  Who can hopefully fix the crossover. But I'm curious – what could be the problems?
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Stu McDoniel

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Re: Diagnosing a bad crossover
« Reply #1 on: March 01, 2017, 08:00:09 am »

So I've been pulling apart some used EAW fr159z speakers  in order to load them up with new drivers. Apparently one of them has a bad crossover. I verified by swapping the part with the other box, and that one worked fine.

 Interestingly, it has the same symptoms as one of the bad woofers. That is, when driven should be wearing the lower level, they are very quiet. Very mid range E, not a lot below  200 Hz   

 The one speaker seems to be fine – no stripped wires, no seized cone. Thoughts on what that could be?

 The crossover yield the same results – even with a working woofer-  very  quiet output even when pushed with an itech 4000.   Obviously nothing above 2K-ish, but also nothing below 200 Hz ish. 

 Replacement woofer is already been ordered, and I have a local guy who is great with EAW  Who can hopefully fix the crossover. But I'm curious – what could be the problems?
Call Full Compass.  The tech there is very helpful. He might do the repairs for you. 
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John Roberts {JR}

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Re: Diagnosing a bad crossover
« Reply #2 on: March 01, 2017, 10:18:03 am »

Passive crossovers have discrete components that can fail, or could suffer from a bad solder connection. If a visual inspections finds a discolored or burnt part, that is your smoking gun.

JR
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Jim McKeveny

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Re: Diagnosing a bad crossover
« Reply #3 on: March 02, 2017, 07:58:34 am »

Passive crossovers have discrete components that can fail, or could suffer from a bad solder connection. If a visual inspections finds a discolored or burnt part, that is your smoking gun.

JR

Passive crossovers can be a bear to diagnose. While gross failure can cook sand resistors or pop a cap, sustained overheating can compromise inductors without visually obvious indicators.
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Riley Casey

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Re: Diagnosing a bad crossover
« Reply #4 on: March 02, 2017, 01:16:40 pm »

EAW passive crossovers are the pits to work on because EAW puts so much effort into doing them right - unlike some speaker manufacturers I can think of.  Luckily even a complex passive crossover is a pretty basic circuit.  Easiest way to approach it is to drive the speaker with tone at the frequency of interest, usually the frequency that is not arriving correctly.  Use an alligator clip lead to short out components that are in series with the driver and use a wire cutter to cut the connection to ground for any components that are connected across the load.  Snip the lead in a way that makes it easy to solder back into operation of course.  What ever brings the tone back to appropriate level is the likely suspect.  More often than not I've found that inductors changing values because heat from excess power is the issue and that often doesn't show up as a burned component, it's just turns of wire burning through their insulating varnish to short together.

In the sample drawing for a woofer problem you'd short the ends of L2 and L3 to bypass them and see if the level came up.  You'd lift one end or the other of C3 to see what effect that had.  Any extra capacitors, inductors or resistors you would treat the same way depending on their place in the circuit.  Inductors are usually made to order for crossovers and thus rarely connected in parallel but capacitors often are paired up to get the correct value. In those cases treat them as one cap until you decide one or the other is the problem and then separate them.

So I've been pulling apart some used EAW fr159z speakers  in order to load them up with new drivers. Apparently one of them has a bad crossover....

 ... Replacement woofer is already been ordered, and I have a local guy who is great with EAW  Who can hopefully fix the crossover. But I'm curious – what could be the problems?

ProSoundWeb Community

Re: Diagnosing a bad crossover
ยซ Reply #4 on: March 02, 2017, 01:16:40 pm ยป


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