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What the H ll Happened Here?

I was listening to music two nights ago and heard what sounded like low level scratching through one speaker, then it went away. A short while later it happened again but this time the sratching was coming from both speakers with reduced bass response. Then, I lost bass in one speaker completely with maybe 1/2 output from the other. Tweeters seem OK but hard to tell as they sound kinda bad without the rest of the spectrum.

By the way, I have Harbeth C7s which are two ways.

I thought the problem may be tubes in the pre-amp so I plugged in a passive that was just boxed away, same problems. Tried another amp, CD player (with and without the DAC), same problems. Swapped speakers from side to side, problem with woofers went with them. Then I tried pressing slightly on the woofers, doing so causes changes in the distortion. So I'm pretty damn sure it's a problem with both speakers, but what the hell happened? And to both speakers at the same time?? I noticed no electrical surges, power problems of any kind.

Guys, any ideas as what's going on???
tomryan
tomryan OP
796 posts
 
Rockvirgo,

I did what you suggested and do hear a light but definite scraping sound from both woofers. I was playing organ music and then Hendrix (odd combo, eh?) and it was right after this the problem arose. However, I wasn't playing that loud and am using a Plinius 50 wt amp with more than enough power for my small room. Also, one woofer is outputting no sound whatsoever.

I presume I'll have to ship them to the importer for repairs? Or does anyone know someone in the southeast Michigan or Ann Arbor area who could do this? What actually needs to be done?

By the way, I've heard nothing about Harbeths being hyersensitive like this. Anyone have similar experiences with the C7s?
plato
1,543 posts
 
Tomryan,

I'd also have that Plinius amp checked out thoroughly before putting it back in service. If any of its active deviced failed, it could have been putting out DC to the speakers causing the woofer failure. If you have a voltmeter you could turn the amp on without speakers connected and measure the DC volts at the speaker terminals after giving the amp 5 or so minutes to stabalize. If it's any significant amount, then you'll probably need to send the amp back for service too.

My feeling is that some sort of failure within the electronic chain was responsible for the speaker's failure... You need to isolate that problem before hooking up good speakers.
timrhu
2,779 posts
 
I had a similar problem with Paradigm speakers, blown voice coils. Mine were overdriven by my son (damn that rap music) and he blew tree of the four woofers. I odered relpacement woofers from Paradigm; a snap to replace but not cheap.
You may have a warranty issue although it's hard to convince customer service people the speakers weren't overdriven/abused. Good luck.
warnerwh
539 posts
 
The fact it's in both woofers indicates the odds are good that it was electronics related so definitely get the Plinius checked out.
grannyring's avatar
grannyring
6,504 posts
 
If the voice coil was fried you would smell it! Sometimes they smoke, but you would smell an aweful burnt electronics smell. yes, your amp must have put out DC. Be most careful and get it checked out right away.

To be sure, simply remove one woofer and look at the voice coil. If copper and clean that is not the issue. If black, you found the problem!

Bill
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