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Polk Monitor Series

Posted: Thu May 31, 2018 6:35 pm
by TazManiac
Found out one of these pretty nice speakers wasn't putting anything out the Bass Driver; popped the thing out of it's cabinet and found the coil was bound up somehow. The magnet on the back was able to turn (!?!) so I wedge it off, finding it had some misfortune and/or bad atmospherics over time that caused the 'glue' to coe loose. In my attempt to center it over the coil I fubar the winding & I'm not 12 years old anymore with the steady hand, close-in vision, and patience to rewind the thing from scratch so...

I'm on the Interwebz looking for a replacement driver, ala carte.

SR 142/17 (and tree dots)

(edit) seems the 142/17 is only related to the rubber surround; Metric numbers...)

Re: Polk Monitor Series

Posted: Thu May 31, 2018 6:48 pm
by Dave
What's the complete model number of the Polk?

Any physical measurements of the drivers you can offer, photos, etc. would also be helpful.

(Almost the first thing when I start applying Google-Fu is a page which says that Polk woofers can be very susceptible to mechanical shock... just dropping the cabinet or box 6" can be enough to pop the magnet loose from the frame. Apparently the epoxy doesn't hold well, with age. A similar thing happened to the magnet in one my car speakers... I have a feeling that epoxies and other glues have difficulty binding well to the alloys used in the magnets.)

Re: Polk Monitor Series

Posted: Thu May 31, 2018 6:50 pm
by TazManiac
(edit): Dave, I posted the eBay link before I'd seen you asked a question, bu tthe link pretty much represents what I think is in there.

This is pretty close to what I'm looking for...

https://www.ebay.com/itm/Polk-Audio-OEM ... SwQTVa~h3w

Argh:
Are the new OEM drivers (MW6503) the same quality as the original ones?
I know that the old ones are now subject to Magnet shift because of the old epoxy.
So, it's not me, they are just old and the glue crap(s) out. I might just try for a single used replacment, I _think_ they are MW6502, but the exact drive model number remains tobe discerned...

Re: Polk Monitor Series

Posted: Thu May 31, 2018 6:59 pm
by Dave

Re: Polk Monitor Series

Posted: Thu May 31, 2018 7:04 pm
by TazManiac
< bookmarked >, Thx.

Funky bit is that (These are Monitor 4 speakers btw), I had another pair; not woodgrain vinyl like these but black 'oak'- and I sold them before verifying this other pair. (Doh!)

Re: Polk Monitor Series

Posted: Thu May 31, 2018 7:34 pm
by Dave
Found one suggestion that this Dayton Audio driver might be an acceptable substitute. I'd guess that it won't exactly match the sound of the original, and that some crossover tinkering might be required. If it worked well, it might be preferable to change out the woofer in the other speaker in the pair as well, so you'd have a matched sound balance on the two channels.

It's an 8-ohm-nominal driver and might sub for the MW6502. The MW6503 is apparently the 4-ohm-nominal version (DC resistance would probably be in the 2-3 ohm range)... and, lo and behold, Parts Express has a 4-ohm version of their driver (the DC-160-4) that might work there.

EDIT: I'm seeing conflicting information about the MW6502, with a number of articles saying that it is a 4 -ohm driver. Best to measure the one you need to replace, and buy one of the same nominal impedance.

http://forum.polkaudio.com/discussion/1 ... 00-drivers is very useful as it provides some of the critical parameters that you would want to match, when evaluating other drivers to use as substitutes.

Re: Polk Monitor Series

Posted: Thu May 31, 2018 11:31 pm
by TazManiac
Thx for the further digging around; I'd likely want to replace them in pairs if it comes to that, yer right.

I ran out of daylight today (well actually I went to go see the Warriors vs the Cavs- good game and I'm not a Basketball fan, by any means).

Worse comes to worse I can convert the one good speaker into a 5 or 7.1 Center Channel speaker. (I'm going to have to ginger-foot it until I can get some of that Metallic imbued epoxy/resin to tack around the Driver magnet & it's base. Said to be the thing to do to keep the Magnet from shifting, going forward...)

Re: Polk Monitor Series

Posted: Fri Jun 01, 2018 11:14 am
by Dave
Another excellent thread on the subject, which I had found yesterday, forgot to quote to you, and then couldn't find when I Google-searched from home last evening. Go figure...

http://audiokarma.org/forums/index.php? ... ers.65109/