15" RCF bass driver - cause of ticking sound? - Page 2 - diyAudio
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Old 12th March 2013, 01:34 PM   #11
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Quote:
Originally Posted by JMFahey View Post
A voice coil *may* be black (although I never saw one) but it will never be black for part of the winding and enamelled copper colour for another section of same winding.
Thanks, those pictures are helpful. I would say the transition is more aprupt in the case of my VCs, consistent with black paint applied with some sort of roller so it couldn't get to the first turn that happens to sit on the inner layer. As I said, I will look more closely.
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Old 12th March 2013, 02:14 PM   #12
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Catch it before it goes if it is the voice coil! No one likes a smoke filled room because of a blown driver!

Last week i had a 3000 Watt DVC sub that was making a strange noise and because i couldnt be asked to check it out the whole place filled with a lovely odor and gray smoke when i put it on a brand new amp!
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Old 12th March 2013, 03:41 PM   #13
JMFahey is offline JMFahey  Argentina
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Maybe you can get a recone kit (or spare parts) and recone it for relatively low cost.
*Somebody* in Europe must sell speaker parts .
In USA you can try MWA Speaker Parts
Speaker Parts Voice Coils Speaker Repair Kits - MWA Speaker Parts, Inc.
In theory they only sell to established speaker reconers, and they have "exclusive area" agreements, so they have "one" reconer in each area, but if you write from Germany as "the" reconer in XXX City who has a problem with a customer and Mackie or RCF doesn't help, they probably will sell you.
As of freight cost, kit will be very light but bulky.

Alternatively write RCF themselves.

Personally, being in Argentina and quite away from supply sources , not because of distance but because of obnoxious Customs, problems with funds transfer, etc. , I have repaired such speakers by disassembling them and making new voice coils.
Even rewinding on the same form, how's that?
But it's not for the faint of heart.
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Old 13th March 2013, 11:18 AM   #14
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I'll take everything back. Looking at the VCs in bright daylight, I have to agree they were toasted even if no single turn is sticking out. I removed one of the dust caps so I can use my fingers to expand the VC former. When I do this close enough to the pole, the chattering stops whereas it doesn't when I do it a few mm above the uppermost turn. So I suppose there are indeed some loose turns.

One of the coils measures at 3.9 Ohms which is almost high for a 4 Ohm driver. The other one measures about .35 Ohms lower so I am not sure if this is regular tolerance or I am facing one or several shorted turns.

Since the venting underneath the spider is quite generous, I was hoping to apply some sort of lacquer with a paintbrush or a pipette. I have found some alkyde based lacquer for electronics use that is good to at least 125C which should be fine for home use. The advantage compared to epoxy is that the lacquer can be removed with acetone, should I screw up.

By the way, do professional VCs rely only on the tension of the wire after winding or do they usually have epoxy or some other resin to keep the turns from moving?

Yes, rewinding on the existing former is something I might try should the lacquer not work. It might be a whole lot easier with square wire but I have not found a source yet.

In case I have to remove the soft parts, some are glues with clear stuff that will normally turn opaque and softer when exosed to water. However, the dustcap and spider are glued with glossy black glue that does not absorb water. Any ideas how to tackle that?

Thanks again for all the input so far!

(two pics of the toasted VC and one brand new black P-audio)
Attached Images
File Type: jpg Mackie_VC.jpg (97.3 KB, 78 views)
File Type: jpg Mackie_VC_2.jpg (116.5 KB, 74 views)
File Type: jpg P-audio_VC.jpg (98.1 KB, 65 views)
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Old 13th March 2013, 12:44 PM   #15
JMFahey is offline JMFahey  Argentina
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Save money and frustration and send it back.

Quote:
By the way, do professional VCs rely only on the tension of the wire after winding or do they usually have epoxy or some other resin to keep the turns from moving?
Usually winding tension is low, only as much as needed so wire follows the form curve, it's held with adhesive.
Standard is a special Epoxy but modern wires come with a pre-applied dry adhesive to simplify winding in high speed machines.
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Old 18th March 2013, 06:25 PM   #16
Mid Low is offline Mid Low  United States
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I hate when speakers act like that once i have some 15" Celestion mid bass drivers in my car and one day i started to notice that they sounded strange when they hitted lower frequencies but they where sounding on higher frequencies normally. Turns out that when i take'd them out the VC was like shattered on the lower side a lil bit, making them to do a scraping sound i keeped using them until it completely broke =\
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Old 19th March 2013, 10:48 AM   #17
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i blew a coil on some 3000 watt DVC drivers where something got under the dust cap where the heat from last summer melted the adhesive Smoke everywhere....

Was fun..sorta :/
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Old 19th March 2013, 03:08 PM   #18
JMFahey is offline JMFahey  Argentina
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Quote:
Originally Posted by Mid Low View Post
I hate when speakers act like that once i have some 15" Celestion mid bass drivers in my car and one day i started to notice that they sounded strange when they hitted lower frequencies but they where sounding on higher frequencies normally. Turns out that when i take'd them out the VC was like shattered on the lower side a lil bit, making them to do a scraping sound i keeped using them until it completely broke =\
Well, you may hate *the speakers* if you wish, I bet they hate you more
The "VC shattered on the lower side" means you drove them with *way* too much bass in a poorly loaded enclosure, so they "bottomed out".

Quote:
i blew a coil on some 3000 watt DVC drivers where something got under the dust cap where the heat from last summer melted the adhesive Smoke everywhere....
I very much doubt even staying under the Sun at noon had anything to do with it.
Don't you think your 3000W amplifier maight have had even a tiny little something to do with your speakers bursting in flames?
Just sayin'
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Old 19th March 2013, 03:34 PM   #19
Mid Low is offline Mid Low  United States
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Lol not really really those are the only speakers that i have had that kind of problem and problably because i was sending them to much power >.<
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Old 19th March 2013, 03:43 PM   #20
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Quote:
Originally Posted by JMFahey View Post
I very much doubt even staying under the Sun at noon had anything to do with it.
Don't you think your 3000W amplifier maight have had even a tiny little something to do with your speakers bursting in flames?
Just sayin'
the amp outputs 5000watt at 1ohm (monoblock) into 4 parallel wired voice coils (4 ohm each) providing a 1ohm load for the amp. The speakers are 2x DVC (Dual Voice Coil) ~3000Watt Peak (1500 RMS) @ 2ohms for 2coils wired parallel into one.

The sun comment was a joke.... what happened to banter people !!!!?!?!

Please read the comment before replying Mr JMFahey.

Me and my team did the maths smarty pants

(Didnt mean to come across nasty btw im in it for the laughs)

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Last edited by ClackS02; 19th March 2013 at 03:53 PM.
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