Something causing distortion on monitor 10a, please help

Lalala · January 2

Hello, I have a pair of monitor 10a. About a month ago something started to sound wrong, I can’t quite pinpoint what part of the speaker it is, the wrongness is subtle, but is hurting my brain. I did listen to the same thing on record and streaming though the speakers to determine it’s not that. I don’t have another receiver available to test. How can I figure this out and is it worth the effort and expense?

Toolfan66 · January 2

Hello,

Is it both speakers or just one?

Lalala · January 2

Toolfan66 wrote: »

Is it both speakers or just one?

Just one, I also already tested different speaker wires and a/b on the reciever

Toolfan66 · January 2

Lalala wrote: »

Toolfan66 wrote: »

Is it both speakers or just one?

Just one, I also already tested different speaker wires and a/b on the reciever

Swap the speakers from left to right, and see if the problem follows the speaker or stays on the same side..

xschop · January 2

The 10A's 6500 MW's are prone to coil rub due to age. Their Peerless tweeters also are prone to coil rub from the oxidation between the metal faceplate and magnet screws.

Gardenstater · January 2

The sound of coil rub can be subtle, but disturbing for sure. Try putting 3 fingers and your thumb spaced equally around where the dust cap meets the cones and gently exercise the cone and listen and feel for rubbing. It will be unmistakable. You might even be able to hear it by pushing gently on the passive radiator as a secondary less preferred method.

Lalala · January 2

Toolfan66 wrote: »

Swap the speakers from left to right, and see if the problem follows the speaker or stays on the same side..

It followed the same speaker after I switched them

Lalala · January 2

xschop wrote: »

The 10A's 6500 MW's are prone to coil rub due to age. Their Peerless tweeters also are prone to coil rub from the oxidation between the metal faceplate and magnet screws.

Gardenstater wrote: »

The sound of coil rub can be subtle, but disturbing for sure. Try putting 3 fingers and your thumb spaced equally around where the dust cap meets the cones and gently exercise the cone and listen and feel for rubbing. It will be unmistakable. You might even be able to hear it by pushing gently on the passive radiator as a secondary less preferred method.

Yes I heard rubbing. And yes I think that could definitely explain my disturbance. Is this something that can be repaired or do the coils need to be replaced?

mhardy6647 · January 2

Do you suffer from any tinnitus, @Lalala ?

Gardenstater · January 2

Lalala wrote: »

xschop wrote: »

The 10A's 6500 MW's are prone to coil rub due to age. Their Peerless tweeters also are prone to coil rub from the oxidation between the metal faceplate and magnet screws.

Gardenstater wrote: »

The sound of coil rub can be subtle, but disturbing for sure. Try putting 3 fingers and your thumb spaced equally around where the dust cap meets the cones and gently exercise the cone and listen and feel for rubbing. It will be unmistakable. You might even be able to hear it by pushing gently on the passive radiator as a secondary less preferred method.

Yes I heard rubbing. And yes I think that could definitely explain my disturbance. Is this something that can be repaired or do the coils need to be replaced?

Lots have fixed them themselves. It really depends upon whether you feel up to it or want to bother. Replacements can be had on eBay but sometimes you have to wait until they come up for sale. Always ask the seller to make sure there is no rubbing and that they pack them with lots of cushioning all around so they don't shift in shipping.

You can read through lawdogg's thread and get an idea of whether you might want to try the repair yourself. Usually it is a shifted magnet assembly issue but sometimes it can be a cracked spider but that is much less common.

https://forum.polkaudio.com/discussion/197152/diagnosing-fixing-shifted-polk-mw-drivers/p1

Gardenstater · January 2

Best to check and make sure that they are all the original drivers and that they match closely in dates. Assuming they do, check to make sure they are actually all MW6500s. If they are I found you a couple pretty early silver basket ones on eBay. Harder to find them when people don't post the model # lol.

https://www.ebay.com/itm/125832611748?hash=item1d4c3547a4:g:tBIAAOSwYRtkF3dn

Lalala · January 2

Gardenstater wrote: »

Best to check and make sure that they are all the original drivers and that they match closely in dates. Assuming they do, check to make sure they are actually all MW6500s. If they are I found you a couple pretty early silver basket ones on eBay. Harder to find them when people don't post the model # lol.

Thank you. They are MW6600X, and I don’t think I can repair them myself after reading that post, I think it’s beyond my skill set and tools and space and ventilation available. I didn’t realize how soldered in the wires from the speaker were and broke the metal clip and an interior wire trying to use wire cutters that need to be replaced. There may be a speaker repair near me. If so, and depending on price obviously, do you think it’s better to pay someone to repair vs buy replacements.

image of my coil

Gardenstater · January 2

I would think once you get into paying a speaker repair shop to do it, if they even could, it would be better to just buy a good condition used one on eBay.

Are both drivers rubbing in the speaker in question? If it is just one, then there is a MW6600X available right now which you could pounce on.

Edit - looks like that seller has 3 available still.

https://www.ebay.com/itm/266230406392

Toolfan66 · January 2

I would lightly press in the driver on the speaker giving you an issue, and see if you feel any rubbing/scratching, I would also pull the passive radiator, and inspect the crossover. If you do this take pictures, and post them..

This could be a tweeter issue..

Lalala · January 2

Toolfan66 wrote: »

I would lightly press in the driver on the speaker giving you an issue, and see if you feel any rubbing/scratching, I would also pull the passive radiator, and inspect the crossover. If you do this take pictures, and post them..

This could be a tweeter issue..

The drivers on that speaker are rubbing. So I think that’s what it is. Do you think I should also pull the passive radiator before ordering replacement parts? (another forum member linked me to an ebay account selling 3 of the ones in my speakers)

boston1450 · January 2

? How bad were they rubbing ? I've heard some have rotated the woofer 180° & it worked ??? Is it worth a try ?

F1nut · January 2

If you don't push the cone in EVENLY it will rub and make you think the driver is bad.

Lalala · January 2

F1nut wrote: »

If you don't push the cone in EVENLY it will rub and make you think the driver is bad.

I have the other speaker where there isn’t coil rub (yet?) to compare, so I can feel and hear the difference.

F1nut · January 3

Very good

xschop · January 3

What is the DCR of the good 6600?

Lalala · January 3

Now I’m more confused. The other one that rubs is a MW6500 (same speaker). It also has two loose wires hanging off it in addition to the wires that connect to the other part of the speaker. So I don’t know what I should do about replacements.

I asked the relative who gave them to me (original owner) and they said that Polk had repaired or replaced voice coils in the mid 80s. but from dates it looks like the 6600 was a replacement and the 6500 original.

I have not unscrewed to check model numbers from the other speaker that’s working.

images of both drivers from the same speaker

pitdogg2 · January 3

xschop wrote: »

What is the DCR of the good 6600?

It should be the same as this one.

MW 6501 1.47 5.96 N 3.25 E - 3N/M 7.75 Ohms 31 Hertz

xschop · January 3

Then the Wu-coil could be swapped in...IIRC, it was @7.7 ohm

Gardenstater · January 3

Well, hold off on buying those MW6600X until you can figure out what's going on. Does your relative remember if it was a Polk authorized dealer that did the work? That is most likely the case.

Regarding loose wires......there shouldn't be any lol. The drivers were wired in parallel so there would be two wires going to each terminal of the driver that is wired first (closest to crossover). There shouldn't be any loose ones however. But didn't you say you accidentally cut something?

Lalala · January 3

Gardenstater wrote: »

Well, hold off on buying those MW6600X until you can figure out what's going on. Does your relative remember if it was a Polk authorized dealer that did the work? That is most likely the case.

Regarding loose wires......there shouldn't be any lol. The drivers were wired in parallel so there would be two wires going to the driver that is wired first (closest to crossover). There shouldn't be any loose ones however. But didn't you say you accidentally cut something?

Relative said it was a replacement where they shipped them to Polk, Polk did its thing and shipped them back. Given my understanding that warranties used to be longer, seems like they were probably only 5-6 years old at that point and I’d guess were still under warranty.

The piece I broke was on the 6600 and it was on the driver itself (the clip), the wires going to that are ok I think. This 6500 I did not detach, it’s like it had loose wires in there which is weird and doesn’t make sense to me. On this 6500 are two wires attached to the back of the speaker from the clip, two attached inside the driver from the clip and 2 loose wires.

Gardenstater · January 3

Probably they put a 6600 in instead of a 6500 which is wrong.

Make sure of three things:

1) There is a black wire going from the 6500 + terminal (the red one) to the + terminal of the 6600
2) There is a white wire going from the 6500 - terminal to the - terminal of the 6600
3) There are also black and white wires going from the 6500 to the crossover PC Board.

Shouldn't be any loose wires so something is disconnected.

pitdogg2 · January 3

Probably they put a 6600 in instead of a 6500 which is wrong.

The Monitor 10 came with the MW6501 driver at one time. The MW6600 is a very good replacement driver for the MW6501. In fact many Polk speakers that came with the MW6600 then came with a MW6501 with no XO changes. My SDA 1 signatures came from the factory with both the MW6600 and the MW6501. The MW6600 was the only driver used in both the non-SDA and SDA speakers at the time.

Gardenstater · January 3

pitdogg2 wrote: »

Probably they put a 6600 in instead of a 6500 which is wrong.

The Monitor 10 came with the MW6501 driver at one time. The MW6600 is a very good replacement driver for the MW6501. In fact many Polk speakers that came with the MW6600 then came with a MW6501 with no XO changes. My SDA 1 signatures came from the factory with both the MW6600 and the MW6501. The MW6600 was the only driver used in both the non-SDA and SDA speakers at the time.

The date on Lalala's MW6500 is 6/18/79. I doubt that Polk warranty service would've put that into a speaker that was from 1984, which is the date (5/30/84) on the MW6600X. Most likely these speakers were manufactured mid 1979. Maybe his(?) relative just squeaked by on the 5 year warranty.

Toolfan66 · January 3

Most Likely Polk did not do this to that speaker. Just sayin..

Gardenstater · January 3

Toolfan66 wrote: »

Most Likely Polk did not do this to that speaker. Just sayin..

Customer service shipped the currently used ones in the Monitor 10, instead of matching the ones that were in this speaker manufactured 5 years earlier? Perhaps they didn't have the MW6500 in stock? Still no excuse IMO.

pitdogg2 · January 3

Gardenstater wrote: »

pitdogg2 wrote: »

Probably they put a 6600 in instead of a 6500 which is wrong.

The Monitor 10 came with the MW6501 driver at one time. The MW6600 is a very good replacement driver for the MW6501. In fact many Polk speakers that came with the MW6600 then came with a MW6501 with no XO changes. My SDA 1 signatures came from the factory with both the MW6600 and the MW6501. The MW6600 was the only driver used in both the non-SDA and SDA speakers at the time.

The date on Lalala's MW6500 is 6/18/79. I doubt that Polk warranty service would've put that into a speaker that was from 1984, which is the date (5/30/84) on the MW6600X. Most likely these speakers were manufactured mid 1979. Maybe his(?) relative just squeaked by on the 5 year warranty.

The earliest schematic we have is from 1984 and it shows the MW6501, either way Polk covered stuff for much longer than many other companies. What we know for certain is the the M10 used MW6500, 6501 and 6503. We also know for certain that the MW6600/MW6501 was used in the RTA12, another side by side driver speaker.

Something causing distortion on monitor 10a, please help

Answers