Damaged Scanspeak Driver

Ken98

Member
2017-06-04 12:20 pm
Hi Fella's I have a pair of DIY speakers with Raal 70-10, Accuton C50 mids and Scanspeak 18wU/4747T00 illuminator woofers.

Have been enjoying the speakers for around 2ish years now but have noticed in the last day or 2 a buzzing/rattling noise come from one of the scanspeak drivers in one of the speakers.
The driver in question also makes a weird sort of scratching noise when I gently press on it.

I have found that by pressing firmly on the rubber surround on the right side of the driver it makes the buzzing/rattle go away, though it comes back sometimes requiring me to do this again.
Also when I gently press on the right side of the driver it self it doesn't make a weird noise.

Is this driver toast? and can it be fixed?
I live in Australia and these drivers are like $500aud to replace.

Woofer sound - Google Drive

The first recording is me playing a 70hz tone with the left speaker making the rattling/buzzing noise
The second is of me gently pushing against the driver and it making a weird noise, completely different to the other scan speak driver in the other speaker.
 
Found a similar issue with some of the small Vifa NE drivers as the gap around the voice coil is small and the voice coil can rub. To correct, all I did was to push the cone all the way down a few times to help centre it.

Other than that, take the driver out, lay it flat (cone up) and run a 20-30Hz test tone through it for an hour. Use enough power to make the driver move about half the xmax. Can help centralise the voice coil and even out the spider and surround.
 
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afa

Member
2008-07-31 12:57 pm
Maybe a bit of debris has got into the voice coil gap? (this driver has an exposed voice coil former underneath the spider to help with ventilation and noise reduction)

Perhaps take the driver out and have a look

And as Fenalaar suggest it could also be cone sag

Or, maybe the end of the voice coil former has hit the back plate (due to excessive excursion) and it is now bent over and rubbing on the pole piece

Arthur
 

Ken98

Member
2017-06-04 12:20 pm
Thanks for the help guys.
I removed the driver, and had it positioned flat facing straight down, I then played some 40hz sine wave tone for around 2hours before flipping the driver 180 degrees and reinstalling it.

I no longer hear any buzzing noise and there is no longer and scarping noise when i manually depress the cone.

The speakers are in my small bedroom, it is way to small to do these speakers justice and my room gets pretty hot, especially with the how the weather in Australia has been lately. The speaker with the problematic driver is also next to a window and gets lots of sunlight, while the other speaker is opposite in the shade.
Combined with the hot weather I have been playing music a fair bit louder and for longer than I have in the past.
 
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Fenalaar

Member
2011-04-25 10:49 pm
The driver rotation trick only works if the source of the buzzing is the voice coil former being slighly off center, because the suspension has sagged a little over the years.

It won’t work if the buzzing comes from a slightly overcooked voice coil ;D

Johan-Kr
 

NinetySix

Member
2016-05-28 8:22 am
Maybe a bit of debris has got into the voice coil gap? (this driver has an exposed voice coil former underneath the spider to help with ventilation and noise reduction)

Perhaps take the driver out and have a look

And as Fenalaar suggest it could also be cone sag

Or, maybe the end of the voice coil former has hit the back plate (due to excessive excursion) and it is now bent over and rubbing on the pole piece

Arthur
I realise this thread is over 2 years old now, but I just had to add my 2¢...

I think the quoted text from afa was almost certainly the problem, as I have experienced the same with these exact speakers (aluminium cone illuminator woofers) ... It would come and go from time to time, presume where offending debris would move around and not many contact with the coil, but it always came back and sounded awful. My samples have lived in my car's doors for 5 or 6 Australian summers, with little trouble to report :cool:

Except for.... Where they appear to have sucked up a sprinkling of metal filings somewhere along the line, which is actually extremely easy to fix, don't go pulling the cone and spider out, it's just 3x M4 screws holding the magnet assembly onto the cast basket, separate into two halves and slide some masking tape or similar down into the coil gap to fish out the offending ferrous intruders. Suggest it wise to mark the magnet assembly and one of the basket legs so it goes back on the same way it came off, which I didn't do but I believe I got away with it 😁

I did notice the very slightest hints of corrosion on the copper, err, pole piece? Work of art either way, and it buffed to an extremely clean finish with the tiniest bit of brasso on a cloth.

Hopefully this might help somebody in a bad situation before they consider doing something silly like buying a AU$500 replacement, or even something different! I've also had the exact same problem with a set of 12m/4631 revelators, and the fix isn't even close to being as simple... Tinsel leads desoldered from terminals, cone and spider pulled, then go to work with the tape in the gap.... One of the two is proving to be a saga to realign without coil rubbing....

Cheers
 
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