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Old 6th October 2009, 05:50 AM   #1
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Default Crossover nightmare!!!!!!!

Anybody out there can answer this, please do.

This continues from the feed about the celestion ditton 44's on this forum.
I bought two crossovers for the speaker that went, but both gave me the same result - much reduced volume and a highly distorted signal. Powered up individually the cones and tweeter seem faultless.

Q - Is there any other component in the cab that could have failed and has misled me to think that the problem lies with the crossover?

Q - Am I just plain unlucky, and I've tried to replace a buggered crossover with two equally knackered ones. After all, they all date back to 1970, as old as I am!

I will take the boards to be tested, but if they are gone, then my dilema is how best to replace the caps and components that have failed. Will a straight swap with modern equivilents be a sonic lottery.

There is a snap of the co here and on the previous thread.

Thanks to anyone with the patience to lend a hand
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Old 6th October 2009, 06:01 AM   #2
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Do you have a multimeter with capaicitance and or inductance settings. All the inductors should be fine. The capacitors can be measured. This will point you in the right direction.

Terry
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Old 6th October 2009, 06:36 AM   #3
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After 30 years, the caps would have been the ones to go - they dry up...

It would be an idea just to measure everything, then compare to a schematic or something to see what has died, then replace what has.

Chris
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Old 6th October 2009, 08:18 AM   #4
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Inductors should be ok.

Change all the caps with cheap electrolyts for investigation. Doesn't hurt.
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Old 6th October 2009, 08:23 AM   #5
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Quote:
Originally Posted by gainphile View Post
Inductors should be ok.

Change all the caps with cheap electrolyts for investigation. Doesn't hurt.
They should be non polar electrolytics
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Old 6th October 2009, 08:58 AM   #6
CLS is offline CLS  Taiwan
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Doesn't matter, actually If only the voltage rating is higher than, say, 50V or 63V, and it'll be fine in most cases. Like gainfile said, it doesn't hurt
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Old 6th October 2009, 09:56 AM   #7
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Default big picture

Gentlemen I think that you have all missed the mark, as was pointed out he has bought two complete new! Crossovers, which one would assume are in sound condition
This would lead one to think are the new also crook, could it be possible that both new ones have failed I think not
So is there any possible chance that there could be a problem with the amp, connections and or source of the signal?
We need to give thought to all areas of possible faults
I donít dispute checking the components as this will eliminate crossover failure
Cheers Speedie
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Old 6th October 2009, 10:45 AM   #8
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Quote:
Originally Posted by speedie View Post
Gentlemen I think that you have all missed the mark, as was pointed out he has bought two complete new! Crossovers, which one would assume are in sound condition
This would lead one to think are the new also crook, could it be possible that both new ones have failed I think not
So is there any possible chance that there could be a problem with the amp, connections and or source of the signal?
We need to give thought to all areas of possible faults
I donít dispute checking the components as this will eliminate crossover failure
Cheers Speedie
These are very old. They have electrolytic caps. The caps are likely dry from sitting on the shelf for 30+ years. Measure the caps.

Terry
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Old 6th October 2009, 11:50 AM   #9
81bas is offline 81bas  Germany
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Quote:
Originally Posted by pheonix358 View Post
These are very old. They have electrolytic caps. The caps are likely dry from sitting on the shelf for 30+ years. Measure the caps.

Terry
Dry caps are having reduced capacitance, but usually are NOT producing distortions, I think... More likely, that this crossover is simply wrong connected, what produces the low impedance load to the amp, which produces the distortions then... Connect directly the one more speaker to the amplifier, parallel to this crossover, and check, wether this speaker wil be undistorted...
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Old 8th October 2009, 12:36 AM   #10
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Hi. I'm Lorian's neighbour and friend. I did the soldering on the first attempt to replace the board with another 39 year old board, (which I was highly doubtful about, by the way) It was soldered in correctly, as far as I am aware. I have been soldering for a few years, and I've got some experience (I've made amps, made PCBs, repaired a lot of stuff etc., but I'm by no means an electrical engineer). The sound is like a whisper, and a distorted one at that, perhaps as though there is a horrendous solder joint somewhere. Perhaps I should wet them again....hmm...I presumed that it was the caps, as they are notoriously horrible at this age, but if you say this is an unlikely effect of caps going, perhaps we should rewire and solder first...yes, I'll do that. Thanks 81bas.

Lucas
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