My power amp got damaged, sent DC to the speakers
i want to find out how can i test them to verify what damage they have suffered?
i know almost for sure that the tweeters are fried, but i want to check the X over and the base unit
any ideas?
what measures should i take?
what numbers should i look for?
i want to find out how can i test them to verify what damage they have suffered?
i know almost for sure that the tweeters are fried, but i want to check the X over and the base unit
any ideas?
what measures should i take?
what numbers should i look for?
VC of the tweeters is dead for sure -
they make no sound when i connect the speakers
the mid-base units do make sound
what impedance levels should i expect?
how can i know im not measuring the Xover?
they make no sound when i connect the speakers
the mid-base units do make sound
what impedance levels should i expect?
how can i know im not measuring the Xover?
Unscrew the binding posts plate screws if the xover is behind it check resistors aren't burnt and capacitors haven't swelled. Sounds like tweeters are fried though.
Some more info:
just check impedance in both speakers:
Numbers are First / Second (refering to L and R speakers)
At speaker posts (cross over)
Mid-base: 4.40 / 4.45 ohm
Tweeter: No reading / No reading
At drivers (separated from cross over):
Mid-base: 3.91 / 3.92 ohm
Tweeter: no reading, no reading
i think this verifies that tweeters are dead on both of the speakers, right?
in addition, the mid-base drivers has a sticker on them saying they should show 8ohm load, they only show 3.91 and 3.92, does this mean they're also fried?
just check impedance in both speakers:
Numbers are First / Second (refering to L and R speakers)
At speaker posts (cross over)
Mid-base: 4.40 / 4.45 ohm
Tweeter: No reading / No reading
At drivers (separated from cross over):
Mid-base: 3.91 / 3.92 ohm
Tweeter: no reading, no reading
i think this verifies that tweeters are dead on both of the speakers, right?
in addition, the mid-base drivers has a sticker on them saying they should show 8ohm load, they only show 3.91 and 3.92, does this mean they're also fried?
ron,
manufacturers often install 4 ohm bassmid drivers,
so your measurement is probably right. Try to push
gently the cone and see if it makes any kind of noise.
Should be silent if mechanically OK.
manufacturers often install 4 ohm bassmid drivers,
so your measurement is probably right. Try to push
gently the cone and see if it makes any kind of noise.
Should be silent if mechanically OK.
Hi,
The close matching of the midbasses indicates IMO they are fine.
DC usually blows midbasses and does not affect tweeters.
Tweeters get blown typically by rampant h.f. oscillation.
However your tweeters do seem to be both dead.
rgds, sreten.
The close matching of the midbasses indicates IMO they are fine.
DC usually blows midbasses and does not affect tweeters.
Tweeters get blown typically by rampant h.f. oscillation.
However your tweeters do seem to be both dead.
rgds, sreten.
thanks for the replies,
Tested the mid-base mechanically - moving the membrane, they move without any sound - i guess this means that mechanically they're ok.
i hope that they're also good on the electrical side - wish i could reach the true figures of a normal mid-base unit like this
i guess next step would be orderdering some new tweeters
Tested the mid-base mechanically - moving the membrane, they move without any sound - i guess this means that mechanically they're ok.
i hope that they're also good on the electrical side - wish i could reach the true figures of a normal mid-base unit like this
i guess next step would be orderdering some new tweeters
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Oscillation in an amplifier sometimes causes the kind of damage which then sends DC to the speakers so it is possible it blew the tweeters. In addition to this, imperfect connections somewhere in the system may have played a part. Sometimes a (faulty) amp will perform normally with a speaker connected but will oscillate if this connection is interrupted.
What happened to the speakers is somewhat a sad coincidence:
1. a well modified NAD 216 THX (DC and LF Filters removed, Protection bypassed etc)
2. old Meridian 541 Processor playing a preamp part
the Meridian went bad -
as i turned it on it sent DC (or this is how is sounded like) to the pre-out ports, the NAD, now with no protections at al amplified the signal and send it to the speakers.
since i was using the remote control and wasn't too close to the amp, it took me about 3-4 seconds to reach it and turn it off.
and that's the story of my now-fried CDM1NT's...
BTW -
as soon as the Meridian was fixed, the setup continue playing (with other speakers of course)*
* more about the NAD 216 and its issues can be found in the amp section of diyA
1. a well modified NAD 216 THX (DC and LF Filters removed, Protection bypassed etc)
2. old Meridian 541 Processor playing a preamp part
the Meridian went bad -
as i turned it on it sent DC (or this is how is sounded like) to the pre-out ports, the NAD, now with no protections at al amplified the signal and send it to the speakers.
since i was using the remote control and wasn't too close to the amp, it took me about 3-4 seconds to reach it and turn it off.
and that's the story of my now-fried CDM1NT's...
BTW -
as soon as the Meridian was fixed, the setup continue playing (with other speakers of course)*
* more about the NAD 216 and its issues can be found in the amp section of diyA
Never, ever play speakers without a DC protection. It can protect
a million $ worth boxes. In your case, as Sreten already said,
dc probably could not have fried your tweeters because dc can't pass
through cap, if the voltage rating of the cap is high enough.
a million $ worth boxes. In your case, as Sreten already said,
dc probably could not have fried your tweeters because dc can't pass
through cap, if the voltage rating of the cap is high enough.
a lesson well learned on my side...
yet, if this is the case, and the cap should have protect the tweeters, could it be that the cap broke too? how can i test this?
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