Voice Coil Rub
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phillip559
Posts: 24
Hope I am in the right spot! Have an REL HT 1508 that needs work.To jump to the point, voice coil rub. Currently have it setting after adding a shim and soaking the spider with acetone.
It reads 4.5 ohm resistance and there is continuity. The symptoms are a very loud hum/buzz whenever sound goes through it. It is a higher pitched sound. Also, it makes a slight buzz when no sound is passing through. If I push the cone down when no sound is passing through, and it starts to rub, the slight hum almost goes away.
From the picture below, is this normal? Or is this a problem on top of the misalignment. Thank you!
It reads 4.5 ohm resistance and there is continuity. The symptoms are a very loud hum/buzz whenever sound goes through it. It is a higher pitched sound. Also, it makes a slight buzz when no sound is passing through. If I push the cone down when no sound is passing through, and it starts to rub, the slight hum almost goes away.
From the picture below, is this normal? Or is this a problem on top of the misalignment. Thank you!
Comments
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Does the resistance change when you exercise the cone and make the coil rub?George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Crown D150 amp
Logitech Squeezebox Touch Streamer w/EDO applet
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iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
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Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
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Gardenstater wrote: »Does the resistance change when you exercise the cone and make the coil rub?
I did not check that yet. I am hoping it will be fixed when I take out the shim, but for some reason I feel like it is more than just the rub.
Should it change? I never read anything about this, so what would it mean if it does/does not change?
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Looks like the tinsel leads got toasted.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
phillip559 wrote: »Gardenstater wrote: »Does the resistance change when you exercise the cone and make the coil rub?
I did not check that yet. I am hoping it will be fixed when I take out the shim, but for some reason I feel like it is more than just the rub.
Should it change? I never read anything about this, so what would it mean if it does/does not change?
It shouldn't change. It would mean some of the wire of the voice coil has the coating rubbed off and is shorting against the front plate. It could cause an overcurrent in operation. It looks like the voice coil got hot where the insulation on the leads on the cone got melted.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Crown D150 amp
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
So, it bounces around. Am I pretty much stuck having to completely recone and rewind?
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Why don't you reach out to REL.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
I bought it used. And now the damage is done, as I have removed the dust cover. The pole seems aligned properly, but it still has the same problem.
As soon as I move the cone while the multimeter is attached, the resistance goes all over the place. How come this test is never mentioned anywhere in the million articles I read? My dad lives about 45 minutes from Neal's Speaker Service. I am going to make a trip up there. The price for a worst-case scenario recone is extremely reasonable! -
phillip559 wrote: »I bought it used. And now the damage is done, as I have removed the dust cover. The pole seems aligned properly, but it still has the same problem.
As soon as I move the cone while the multimeter is attached, the resistance goes all over the place. How come this test is never mentioned anywhere in the million articles I read? My dad lives about 45 minutes from Neal's Speaker Service. I am going to make a trip up there. The price for a worst-case scenario recone is extremely reasonable!
I never read it anywhere either. It just seemed to make sense to check it that way with the symptoms you were experiencing.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Crown D150 amp
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
Got it, thank you!
Is anyone familiar with Neal's Speaker Service? Or know anywhere to get it done in California? I imagine he must be known since speaker repair services seem to be nonexistent. -
A recone won't help as you've melted the tinsel leads.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
A recone won't help as you've melted the tinsel leads.
Well, they call it recone, but it is more of a rebuild. He said whatever is required to bring it back to working will be done. I found him recommended on another forum. Not sure which one. I posted to a a few others but got no response. Polk Audio forums ftw.
Still wondering if anyone else has experience with Neals? Plenty of reviews on Yelp and Google.
http://www.nealspeakerservice.com/services.html
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2 words for ya....Wu coilDon't take experimental gene therapies from known eugenicists.
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- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit. -
Or you could contact REL.
No, I think I'll try bubble gum and hairspray first. I heard it works.
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There is about a 5% genetic difference between apes and men …but that difference is the difference between throwing your own poo when you are annoyed …and Einstein, Shakespeare and Miss January. by Dr. Sardonicus -
Or you could contact REL.
No, I think I'll try bubble gum and hairspray first. I heard it works.
Yeah if money is no object by all means ask the manufacturer for assistance on a 2nd or 3rd hand subwoofer. With a little luck they might want less $$ than to purchase a brand new sub from them under warranty. Another option might be to pick up a used driver for a mere pittance of $765 or so.
I think it is important to keep in mind too that in this case there may be electronic damage and not just a damaged voice coil.
https://www.ebay.com/itm/195945764093
https://www.ebay.com/itm/266385625258
https://www.ebay.com/sch/i.htmlGeorge / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Crown D150 amp
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
^^^ that is true @phillip559 - And do you know what caused the initial problem? If not, the same thing could potentially happen again.Gardenstater wrote: »I think it is important to keep in mind too that in this case there may be electronic damage and not just a damaged voice coil.
Second - for a quality brand sub, personally, first thing I would be asking is whether any/all parts will be replaced with factory oe. Can't see that it would be. Personally, I wouldn't want this, since it changes the design.
Again, if you haven't yet called REL, you should start there. Doesn't matter if you bought it used. I've not had an issue yet with a vendor not talking to me just because I didn't buy a piece of gear new. In fact, that only comes up if you need to send something in for warranty service, and in many cases they'll still do repairs for you.
You need to know why that damage occurred in the first place, or else you may be...Inside view of a spectacled toilet in the village - hole in the wooden floor - street toilet"
By andrey gonchar
< *Crediting inspired by @mhardy6647; not to be confused with Imagery inspired by @mhardy6647 >
I disabled signatures. -
^^^ that is true @phillip559 - And do you know what caused the initial problem? If not, the same thing could potentially happen again.Gardenstater wrote: »I think it is important to keep in mind too that in this case there may be electronic damage and not just a damaged voice coil.
Second - for a quality brand sub, personally, first thing I would be asking is whether any/all parts will be replaced with factory oe. Can't see that it would be. Personally, I wouldn't want this, since it changes the design.
Again, if you haven't yet called REL, you should start there. Doesn't matter if you bought it used. I've not had an issue yet with a vendor not talking to me just because I didn't buy a piece of gear new. In fact, that only comes up if you need to send something in for warranty service, and in many cases they'll still do repairs for you.
You need to know why that damage occurred in the first place, or else you may be...
Unfortunately, I do not know the initial problem. As I was thinking more about it, I was thinking the same thing... since it is just an amplifier with an attached driver, someone who works on amps would be able to test and diagnose any potential problems? I paid $400, and the "recone" is $300. At the price I am invested, I would be willing to pay a fee to ensure it doesn't happen again. I did contact REL via phone and email, but waiting to hear back.
I did ask him, and he said if we can keep the original parts, we will. I made clear I wanted the cone and surround to be kept, and he said he should be able to reuse them. From the picture provided, and if anyone has any knowledge, would there be a reason any of the parts would NEED to be changed if they are all in good condition?
At this point, my plan is to pay for the recone, and if possible, pay to get the amplifier tested/repaired. Is there any other course of action I could take in this situation? Hopefully, I could sell it for a few pennies and get some money back, but I feel like the cost after repairs is still a fair enough used price for this sub.
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I think you need to closely examine the spider for any damage or distortions or cracks because that would be likely to cause a rub if there was no glue slippage between magnet and pole pieces. Also, you mentioned putting a shim in. Well if you take the proper size shim that is a slip fit and put one of them at each of the four quadrants of the pole piece, are they all a nice slight drag slip fit? If so, then how is the voice coil rubbing? It would have to mean that it is hitting the front plate somehow despite being centered on the pole piece.
It is possible but highly unlikely, unless the driver was simply manufactured incorrectly.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Crown D150 amp
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
NM, I just realized that stuff on the driver is glue.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Before I put the shim in and soaked the spider, one side of the pole was nearly touching. It is even now, but still rubs if I very slightly apply pressure one one side of the cone.
Also, I spoke to "Audio Doctor" is SLO and he said you can test the amplifier by hooking up a regular speaker to it?
He also mentioned if it is blown just buy a replacement driver from REL or one from Parts Express. I imagine REL is going to want an arm and leg though... -
OK so this shim is a one piece cylindrical one? You would be better off with the feeler gage type so you can go all around and find the tight spot.
If you use another woofer to check the amp just make sure it is the same impedance rating but that seems like a good idea.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Crown D150 amp
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
FYI that sub I linked earlier sold for $950 plus $130 shipping!
George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Crown D150 amp
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
Every driver will do that. You must apply even pressure.It is even now, but still rubs if I very slightly apply pressure one one side of the cone.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Plot twist... the amp seems to be what is causing the noise. Not sure if the driver is okay or not?
I want to test the driver, but I really don't want to hook it up to another sub amp and mess it up. Can I use a preamp output from my AVR into a monoblock and test the driver? -
I would think the ohmmeter test while moving the cone (slowly?) proved that the driver is defective. But I'm at a disadvantage because I can't see exactly what the results were. Should be a pretty stable reading though because VC resistance should not change with displacement relative to pole piece/front plate, even if it makes contact ie. rubs. Make sure when you did that test that you had really solid test lead connections.
I'm curious.....where did you get the soaking the spider with acetone procedure from? Acetone has the property of breaking down lots of polymer and adhesive materials but it also flashes off quickly.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Crown D150 amp
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
Is voice coil rub anything like Rattlesnake Shake?
https://youtu.be/NaTd_oItViI?si=P6UUAr73tW35k0Gy
Just -- you know -- academically curious.
