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Speaker scratchy bzzzzzz on my M90


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#1 blu_fuz

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Posted 08 January 2015 - 01:10 PM

I have had my M90 for a few years now, never heard anything strange. It is never really cranked even to 1/2 way and is usually playing streaming internet through the RCA line-in at 'office volume' so I can still talk on the phone/employees.

 

 

Friday the M90 sounded fine (and everyday before that). Come Monday I noticed the left VU wasn't moving and no sound from the left speaker. I figured out that the line-in/phono switch wasn't making contact and was cutting out the left channel. Fiddled with it and the left VU started swinging and sound was back.

 

Strange thing is now the left speaker is making a scratchy noise with the bass notes of anything I play through it. Almost like if the voice coil is f'd up from playing it too loud and might be kind of blown. If I play it louder, you can still faintly hear this scratchy bzzz but it is drowned out more because the music is louder but it is still there.

 

 

I thought maybe the switches are not making contact or the headphone jack is dirty. I flipped some switches hoping for a quick fix. Didn't make a change.

 

 

Right channel is clear.

 

I plugged in headphones and the sound clear, no scratchy noise.

 

 

Can a speaker just 'blow' from age even if the surrounds are good? If the coil is bad for some reason, is there hope for the speaker to be fixed/used?



#2 JVC Floyd

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Posted 08 January 2015 - 01:43 PM

joe my m90 does the same thing sometimes , usually a good cleaning fixes it up but lately its been getting worse , usually i just push in the band selector switches and fiddle with the toggle switches and it clears it up.



#3 blu_fuz

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Posted 08 January 2015 - 01:44 PM

joe my m90 does the same thing sometimes , usually a good cleaning fixes it up but lately its been getting worse , usually i just push in the band selector switches and fiddle with the toggle switches and it clears it up.

 

 

^ I thought that would help mine too but it didn't make it better :sad:



#4 blu_fuz

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Posted 08 January 2015 - 02:01 PM

I was reading that maybe the voice coil wire adhesive let go of one of the coils and it is rubbing on the magnet. Maybe the speaker basket is tweeked and I should try re-mounting the basket using a X pattern when I install the screws. Or possibly the speaker cone is sagging and simply rotating the speaker could keep the coil from rubbing in the magnet.



#5 riker1068

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Posted 08 January 2015 - 03:20 PM

I'm interested to follow the findings on this thread. Might be time to swap them speakers out.



#6 baddboybill

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Posted 08 January 2015 - 04:09 PM

When you turn bass down does scratching go away?

#7 blu_fuz

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Posted 08 January 2015 - 04:11 PM

The less bass, the less it scratches.



#8 baddboybill

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Posted 09 January 2015 - 09:22 AM

I would try what Norm recommended with swapping speakers to see difference and I agree with him about the switch.


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#9 BoomboxLover48

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Posted 09 January 2015 - 09:21 PM

Scratchiness seen with headphones? If not it could be a speaker issue ...

#10 blu_fuz

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Posted 09 January 2015 - 09:32 PM

Headphones are clear.

#11 BoomboxLover48

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Posted 09 January 2015 - 10:21 PM

Possibly the woofer/ mid range speaker is bad .... voice coil, spider suspension has gone bad...



#12 skippy1969

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Posted 09 January 2015 - 10:47 PM

Sounds like a bad woofer to me too,especially if it sounds ok with headphones.  :cool:



#13 Beosystem10

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Posted 10 January 2015 - 06:41 AM

Sounds like a bad woofer to me too,especially if it sounds ok with headphones.  :cool:

Possible, but the headphones take their feed from IC601, a chip dedicated to headphone duty, where the speakers are driven by (final A/F), IC301, the power amp.



#14 JVC Floyd

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Posted 10 January 2015 - 07:46 AM

joe there is a way to remove the original m90 woofer cone and overlap it onto a different woofer frame that already has the voice coil.its a total and complete pain to do ,but you would never know the difference appearance wise.



#15 Cpl-Chronic

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Posted 10 January 2015 - 01:14 PM

Just temporarily hook another woofer up to the leads from the amp & see if that woofer sounds bad too.....

 

Cpl



#16 blu_fuz

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Posted 27 January 2015 - 12:17 PM

Skip stopped over and gave me some Crown SZ5100 white speakers and Cpl-Chronic sent me a set of M90 woofs.

 

Thanks guys.

 

Attached File  woofs.jpg   62.64K   41 downloads



#17 Cpl-Chronic

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Posted 09 February 2015 - 02:36 AM

Still waiting to see if the M90 woofers did the trick & glad we could trade woofs for straps....

 

I always love me some BLU-FUZ straps...

 

Cpl



#18 blu_fuz

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Posted 16 February 2015 - 10:58 AM

Just got back from vacation. Its busy here with our kitchen remodel so it will be awhile until I can get to it. Thanks again!

#19 trippy1313

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Posted 24 February 2015 - 01:47 AM

Vacation??? What's that? Sounds like fun.