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test for damaged drivers / crossover


chaosrealm93
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hey all,

 

i suspect i may have damaged the drivers or crossovers in my speaker unit with an accidental and extremely aggressive 3-4kHz EQ boost (or it just may be my ears taking a long time to adjust back to normal, i cant tell which it is). is there any way to verify my suspicions using a multimeter?

 

ex. (higher / lower) than factory (resistance / capacitance) for the (drivers / crossovers)

 

are there any electrical / engineering gurus that can give me a few tips?

 

 

*also, is a damaged speaker (driver / crossover) really obvious (either it works or not)? or is it possible for it to pass tone sweeps and normal music listening while being damaged at the same time?

 

ex. suppose a new speaker has a symbolic threshold of 100 before it clips / blows / shows signs of problems and the damaged speakers has a threshold of 70. using it under 70 will still sound normal, but now it will take less power than usual for it to show problems

 

 

Thanks!

Computer >> Pioneer VSX 520 >> PSB Imagine B

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You could try recording the sound with a decent microphone at close range and look for anything anomalous in frequency response or distortion. Is one speaker OK? If so, comparing them shouldn't be too hard.

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How aggressive was the eq? Do you have a mono switch? If so, listen to some music at various levels and see if you can hear different behavior from each speaker. Use music with a lot of upper midrange/low treble content such as female vocals.

Auralic Aries G2, Ayre QX-5 Twenty, Ayre KX-5 Twenty, Ayre VX-5 Twenty, Revel Ultima Studio2, Iconoclast speaker cables & interconnects, RealTraps acoustic treatments, Sonore opticalModule (X2)

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What speakers are we talking about?

Auralic Aries G2, Ayre QX-5 Twenty, Ayre KX-5 Twenty, Ayre VX-5 Twenty, Revel Ultima Studio2, Iconoclast speaker cables & interconnects, RealTraps acoustic treatments, Sonore opticalModule (X2)

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Often if damaged, what happens is the voice coil gets overheated. It may get off center on the voice coil or the glue might have gotten bubbled up. You might gently press in on the midrange or tweeter(some tweeters) and see if you feel a sticking point or rough point as it moves back and forth. It might seem almost normal for smaller signals and then will sound a bit distorted or have too low a sound output for higher levels when the voice coil moves more. Or even get rather scratchy sounding depending upon the level of damage.

 

It is unlikely though not impossible that crossover parts have been damaged. Knowing what speaker it is might help. Also as suggested compare one channel to the other. It is unlikely you have damaged to identical levels both channels at once.

 

It also might be more noticeable if you did some frequency sweeps between 2 and 4 khz while listening. Start at low volumes and move up gradually. Don't go to far in volume. You may hear some distortion start creeping in at some point.

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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How aggressive was the eq? Do you have a mono switch? If so, listen to some music at various levels and see if you can hear different behavior from each speaker. Use music with a lot of upper midrange/low treble content such as female vocals.

 

the EQ was a +20dB boost in the 3-4kHz range, rolled off slightly at the extremities

 

i dont hear a big difference, which is why im asking

Computer >> Pioneer VSX 520 >> PSB Imagine B

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Often if damaged, what happens is the voice coil gets overheated. It may get off center on the voice coil or the glue might have gotten bubbled up. You might gently press in on the midrange or tweeter(some tweeters) and see if you feel a sticking point or rough point as it moves back and forth. It might seem almost normal for smaller signals and then will sound a bit distorted or have too low a sound output for higher levels when the voice coil moves more. Or even get rather scratchy sounding depending upon the level of damage.

 

It is unlikely though not impossible that crossover parts have been damaged. Knowing what speaker it is might help. Also as suggested compare one channel to the other. It is unlikely you have damaged to identical levels both channels at once.

 

It also might be more noticeable if you did some frequency sweeps between 2 and 4 khz while listening. Start at low volumes and move up gradually. Don't go to far in volume. You may hear some distortion start creeping in at some point.

 

Im running the PSB imagine B bookshelves

 

i've tried tone sweeping both channels independently of each other and they give comparable results to each other

Computer >> Pioneer VSX 520 >> PSB Imagine B

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but ideally id want to buy a multimeter and separate the drivers from the crossovers and take separate measurements of both and compare their readings to the manufacturer's nominal values

 

nothing says reassurance like that eh? ;D

Computer >> Pioneer VSX 520 >> PSB Imagine B

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but ideally id want to buy a multimeter and separate the drivers from the crossovers and take separate measurements of both and compare their readings to the manufacturer's nominal values

 

nothing says reassurance like that eh? ;D

 

Maybe, maybe not. If you just over-heated the coils and they moved, then resistance may measure the same even though damaged.

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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Maybe, maybe not. If you just over-heated the coils and they moved, then resistance may measure the same even though damaged.

 

"moved"........ like shifted out of place?

 

also do capacitors and resistors in crossovers look obvious when damaged (bulged out, blackened etc)?

Computer >> Pioneer VSX 520 >> PSB Imagine B

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Do you have a smart phone? You could download an SPL app and play test tones with mic at a fixed distance from speaker

 

yeah, i have the SignalScope app by Faber Acoustical on the iphone 4

id assume the measurements are calibrated to the mic characteristics on the iphone?

 

i play back a 20-20kHz sweep and find the graph looks pretty much like the factory measurements

is there any way it could still be damaged though?

Computer >> Pioneer VSX 520 >> PSB Imagine B

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"moved"........ like shifted out of place?

 

also do capacitors and resistors in crossovers look obvious when damaged (bulged out, blackened etc)?

Yes moved as in shifted physically.

 

Sent from my Nexus 6P using Computer Audiophile mobile app

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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