So, an option from the factory, two versions in the same type cabinet.
As I said, he can try driving the large speaker directly, it does seem to be a time related issue. Something causes a reversible failure.
Are both cutting out together, or shortly apart?
Both together will most likely be faulty amp protection circuit.
If apart, speaker problem, drift in component values will mean both sets are not same in value today.
That may help in tracking down the fault.
As I said, he can try driving the large speaker directly, it does seem to be a time related issue. Something causes a reversible failure.
Are both cutting out together, or shortly apart?
Both together will most likely be faulty amp protection circuit.
If apart, speaker problem, drift in component values will mean both sets are not same in value today.
That may help in tracking down the fault.
I think that 3.18 is a Wharfedale part number, Steve. 3.18 mH would have an inductive reactance of 100 ohm at 5,000 Hz.
But I think you may be on the ball when it comes to the fact that an amplifier protection circuit can be 'tripped' if the amp drives a second order crossover when the tweeter is blown.
So I measured the driver units today - 1st speaker Tweeter is 5.61 Ohm, Bass driver is 5.36 Ohm
2nd speaker Tweeter is 5.58 Ohm, Bass driver is 5.58 Ohm. Does this sound about right? Both Tweeters crackle with the 1.5 battery test.
2nd speaker Tweeter is 5.58 Ohm, Bass driver is 5.58 Ohm. Does this sound about right? Both Tweeters crackle with the 1.5 battery test.
What meter did you use?
Those readings are within limits, did the bass drivers crackle with 1.5V cells?
Now, please run one big speaker at a time, at low volume, and see if it trips out, after checking on a different amplifier, if possible.
Connect directly, out of the circuit for the entire speaker. That means the crossover and tweeter are not connected.
Repeat for the other speaker, tell us the results.
Those readings are within limits, did the bass drivers crackle with 1.5V cells?
Now, please run one big speaker at a time, at low volume, and see if it trips out, after checking on a different amplifier, if possible.
Connect directly, out of the circuit for the entire speaker. That means the crossover and tweeter are not connected.
Repeat for the other speaker, tell us the results.
I think Naresh is also suggesting you run with only one of the (complete) speaker cabinets connected to one of the stereo outputs on the amp.
Then to repeat with only the other (complete) cabinet connected.
This could possibly determine if the fault lies within just one of the cabinets and not both.
Then to repeat with only the other (complete) cabinet connected.
This could possibly determine if the fault lies within just one of the cabinets and not both.
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P.S. Whelkie.
I notice you are not answering all the questions that are being asked of you, and that does not help our troubleshooting. 🙁
I notice you are not answering all the questions that are being asked of you, and that does not help our troubleshooting. 🙁
Galu, we have to find the fault...so I suggested that only the big drivers be tested, one at a time.
Then, as you suggested, he can try with one complete speaker at a time (tweeter and crossover in circuit, ie. as it is supposed to be used).
I think the speakers need to be checked, also the amplifier.
Maybe he is getting a little confused...can you take it from here, you are much more experienced than I am in speakers...
Then, as you suggested, he can try with one complete speaker at a time (tweeter and crossover in circuit, ie. as it is supposed to be used).
I think the speakers need to be checked, also the amplifier.
Maybe he is getting a little confused...can you take it from here, you are much more experienced than I am in speakers...
We seem to be on the same page regarding the troubleshooting. 😎
Regarding the amplifier, Whelkie has said the problem occurs with more than one amplifier.
Sorry, was offline for a while. Just using a fairly cheap multimeter for the readings, I didn't try the 1.5v battery test on the bass driver. So just to be clear, should I just wire the terminals on the bass driver direct to the terminals on the amp? . I will also try the one-speaker-at-a-time idea to determine which one seems to be the culprit. Really appreciated your taking time to guide me through this.
That's OK, you have given good troubleshooting suggestions that are very helpful in solving this tricky problem.
This may not be correct. If the amp is cutting out and not making a fuzzy sound or letting out the magic smoke, then we have our answer. I have a feeling one of the caps has been run a little warm for a little too long and is starting to short thereby dropping the total impedance too low and allowing the amp to run for a few minutes before it overheats and cuts out. If this were my set up I would try the caps first. If you can't test them, just unhook the tweeters one at a time as you run the system. When you determine which one, replace both.
The woofs and tweets measure as they should, the poly switches are fine or the tweeters wouldn't work, and coils are rarely a problem.
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Thanks Cal, we were trying to eliminate the crossovers as the source of the problem, and your thoughts on the tweeter capacitor are very welcome.
I'd still like Whelkie to measure the resistance of each Positec to check they will not unduly attenuate the tweeter signal.
If they are in good condition, I would expect a reading of a fraction of an ohm.
Whelkie, remember to subtract the resistance of your test leads from the ohmmeter reading when determining the small resistance of a Positec.
An admirable suggestion Galu but I thought we were firstly going after why the whole speaker was cutting out. How would a failed polyswitch on the tweeter cause that?
My money's on horse #1, Calamity Cap.
Do we know the value of the resistor on the tweeter and whether it's series or shunt? It looks like series judging by the visual.
The Pioneer receiver Whelkie lists is rated only for 8Ω so...
That's obviously for after the root cause is discovered, Cal. I never suggested the tweeter Positec would cause the entire speaker to cut out!
We haven't got to actual capacitor and resistor values yet as we're still trying to determine the source of the fault. The resistor will be in series in this simple crossover.
OK, so I tried running one speaker at a time today. First one ran for 1.5 hours without a problem. Second one ran for 1.5 hours without a problem. (when run together they have been cutting out after 5 - 20 minutes.) Confused. Also, can anyone suggest a way of removing these crossovers without damaging them as they seem to be cemented to the cabinet and won't shift? That would hopefully make it much easier to measure values etc.
Either the crossover is at fault, or the amp can take the load of one but not two speakers.
Please be clear, you ran it with a complete speaker (tweeter and all), or only the big drivers?
Stage 2:
Connect both big drivers, together in the sense both are connected to separate channels, and run the amp at normal (earlier) levels.
If they pass this test, Cal is right, it is a crossover issue, need to replace the capacitors.
If you are dextrous, cut one lead of the existing cap near its body, and solder one lead of the new one there, the other lead wherever you can.
Removing old adhesive is dangerous for the cabinet, it may be epoxy.
Try softening with a heat gun, epoxy has a typical smell, will not budge until charred, by which time your crossover will be dead, other stuff may soften enough to release.
So the above method is suggested, assuming the resistors and inductors are within tolerance in value.
Otherwise, you need to put in a new crossover...Indian style is a 4.7uF / 50V in series with the tweeter, nothing else like resistors and inductors etc.
Please be clear, you ran it with a complete speaker (tweeter and all), or only the big drivers?
Stage 2:
Connect both big drivers, together in the sense both are connected to separate channels, and run the amp at normal (earlier) levels.
If they pass this test, Cal is right, it is a crossover issue, need to replace the capacitors.
If you are dextrous, cut one lead of the existing cap near its body, and solder one lead of the new one there, the other lead wherever you can.
Removing old adhesive is dangerous for the cabinet, it may be epoxy.
Try softening with a heat gun, epoxy has a typical smell, will not budge until charred, by which time your crossover will be dead, other stuff may soften enough to release.
So the above method is suggested, assuming the resistors and inductors are within tolerance in value.
Otherwise, you need to put in a new crossover...Indian style is a 4.7uF / 50V in series with the tweeter, nothing else like resistors and inductors etc.
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