help needed capasitor question

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#21
The same drivers and are used in this CA R50.

The crossover for the R50 is a full four way - xo points 400Hz, 3kHz and 10kHz.
 

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#24
Galu said:
I presume you're using an analogue meter?

I suggest you replace the faulty 4.7uF capacitor as suggested earlier.

To check if the crossover is then working as intended, use any spare drivers you have (they don't have to be tweeters) as temporary substitutes for your damaged tweeters.

Best to do this before investing a large sum of money in new tweeters. 🙂
Click to expand...


I'm using a cheap digital meter
 
#26
Your crossover terminal readings are in accord with the above schematic. You will read an effective short (0Ω) across the inductor L5 in the 4001G leg and an effective open circuit because of capacitor C6 in the T27 leg.

Compare the capacitor values on your board with the above schematic and report back on how closely they match.

Oh, and please don't quote the entire previous post as it clutters up the thread! 😉
 
#29
I've put them away for the day .. will look at the boards tomorrow .. And thats great news about the open circuit .. Thanks Galu 🙂 .. I would never have been able to work tht out ..

. I've been looking for repacement drivers .. I'm presuming the 4001 is 8 ohms .. there is a cheap one available .. it doesn't match .. but it might have to do

The avaible T27's arn't so cheap .. and again they don't match .. so gotta make some desicions.. buget is gonna be a factor in this one i think


SJ .. i can hear the coles on the other speaker .. but I know what you mean 🙂
 
#33
You could save money by wiring a 15 ohm 10W wire wound resistor in place of each of the two 4001Gs and simply retain the unconnected supertweeters on the baffles as cosmetic eye candy!

Buying a second hand T27s is dodgy as it, too, could fail anytime. You may like to consider repacing both T27s with a modern equivalent as suggested in this thread:

Kef T27 substitute
 
#36
scottjoplin said:
Why?
Click to expand...
I suggested it after reading this:

"You may damage your amplifier if you drive a second (or higher) order crossover when the speaker's voice coil is open (the speaker is blown) or if no speaker is connected to the crossover's output. When the speaker is removed (or the voice coil opens), the circuit becomes a resonant circuit. This circuit will, at the crossover frequency (or some multiple of the crossover frequency), present a 0 ohm load to the amplifier. The actual resistance will be only the resistance in the speaker wire and the inductor. Any time that there is audio at the resonant frequency, the amplifier will be stressed the same as if the speaker wires were shorted together. This will drive some amplifiers into protection. Others will blow a fuse or die a horrible painful death."

What is your take on this SJ?

I suppose, to be on the safe side, one could just disconnect L5.
 
#37
Update

I tried to repair the drivers but it was beyond my skill set ..

I'm having trouble sorceing a 4001 ..

and with the costs of 2 drivers and recapping .. I'm wondering about breaking these for parts cut my losses and walk away ..



If anyone has a cheap 4001 for sale .. let me know Thanks
 
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