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Help with Sonus Faber Extrema issue

I have a pair of Sonus Faber Extremas hooked up to a pair of Parasound JC1 monoblocks.  One of the speakers periodically will exhibit signicantly lower volume (down to almost no volume) in the middle of a listening session.  It seems to occur when during more dynamic passages and also when the amps have been on for a while.  If I turn everything off for a few minutes, the problem usually goes away.  I reversed the speaker cables at the speakers and the same speaker still exhibited the issue, so the issue is with the speaker.  What could cause this problem?  Could it be a bad connection somewhere in the speaker?  Could it be that crossover parts need to be changed due to age?
wcheng2

Showing 5 responses by georgehifi

georgehifi's avatar
georgehifi
10,312 posts
 
(mine came from Stereophile, your doesn’t say, except diy)

Which ever xover it has, the OP has to say to us.
What’s actually happening, is there nothing from the tweeter or nothing from the mid-bass
or very little from the tweeter or very little from the mid-bass
Only then can this problem be sorted before dismantling the speaker.


https://www.hifisentralen.no/forumet/attachments/diy-og-utvikling-ha-yttalere-forsterkere-etc/228418...
If it does have this xover then the mid/bass unit should be what the voice coil is of that driver my guess around 4ohms).
And the tweeter should be around 7.5ohms (because of the 2 x paralleled 15ohm series resistors and the almost short of the inductor)
Cheers George
georgehifi's avatar
georgehifi
10,312 posts
 
Maybe OP should disconnect the jumper and test the treble section and mid/woofer section separately


Agreed but first maybe the op wcheng2 OP should let us know,
What’s actually happening, is there nothing from the tweeter or nothing from the mid-bass
or very little from the tweeter or very little from the mid-bass


Cheers George
georgehifi's avatar
georgehifi
10,312 posts
 
Yes you got two sets, one for the bass and one for the tweeter.
The tweeter pair should measure open circuit because of the cap in series .
The bass will measure what ever the resistor is in series, (does anyone know what that is?) . https://ibb.co/BNtQdtJ



One of the speakers periodically will exhibit significantly lower volume (down to almost no volume) in the middle of a listening session.
BTW: you haven’t said what’s actually happening, is there nothing from the tweeter or nothing from the mid-bass or very little from the tweeter or very little from the mid-bass
Cheers George
georgehifi's avatar
georgehifi
10,312 posts
 
I agree with the crossover problem. There is a power resistor in series with the tweeter. If it is failing, the resistance rises with temperature and the signal voltage is converted to heat instead of music.
It wouldn’t cause this explanation, just muted high frequencies, he would still have all the bass and midrange.
" will exhibit significantly lower volume (down to almost no volume)"

Try another amp first, as these Extremas are put together like a Swiss watch, it would be a shame to break/damage all the seals to find out they’re fine.

Cheers George
georgehifi's avatar
georgehifi
10,312 posts
 

Awesome combination btw, JC1’s and Extremas, best Esotar dynamic tweeter with the high bias setting on the JC1 should sound absolutely maaaaaaaagic!!!

Hope it’s not the speaker. See if you can try another amp, before pulling the speakers apart.

There is nothing to the xover to really do what your saying, the inductor across the mid/bass unit either works or doesn’t the resistor the same, can’t really go semi faulty, and the cap on the tweeter would knock out the highs if open.
http://www.stereophile.com/images/archivesart/sfefigB.jpg

Cheers George
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