Rta 12b woofers not connected and barely working

These have been in my family since my brother bought them new. Their sound always seemed a little lacking. I decided to open them up and found that the left woofer on both speakers was disconnected. When I connected them there was barely any movement and no discernible sound. It made me wonder if they were never connected. How could I tell if it needs new crossovers? What else could explain this? Recommendations?

Comments

  • gp4jesus
    gp4jesus Posts: 1,723
    Either that or the VCs are sticky or frozen
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  • CH46E
    CH46E Posts: 3,357
    If you press evenly on the said drivers do the scratch, rub, or make any noises?

    Did you make sure you hooked them up right? I THINK in those speakers the black is positive.
  • westmassguy
    westmassguy Posts: 6,748
    On the 12 B & C, the two woofers receive power differently. On the left speaker, the left/outside woofer receives its signal from the upper crossover section. The right/inner woofer receives its signal from the lower crossover section. The right speaker is the opposite/mirror image.

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  • Dr Rick
    Dr Rick Posts: 3
    The drivers are frozen. 😡. Still seems like it wouldn't be coincidence that the same drivers on both speakers froze. Something I should fix before I replace them, so it doesn't happen again? Also, where do I find a replacement? I searched polk for mw 6501 and found nothing. Some ebay options, but they are originals and I don't trust the longevity or quality.
  • pitdogg2
    pitdogg2 Posts: 19,473
    It's not unusual actually. The thing is you can also use the mw6600 driver as well. They pop up on ebay more often than mw6501. They are sonically the same. First thing to do is glue up the good drivers. Original JB weld or power grab express heavy duty.
  • Gardenstater
    Gardenstater Posts: 2,020
    Well maybe the previous owner knew they weren't working and thought that it was best to disconnect them, perhaps out of a lack of knowledge of how a loudspeaker works or fear that there was a short circuit or something. We need Colombo (ahh one more thing.....) to question that guy.

    You definitely want to go with the originals (6501 or 6600X). They really do hold up very well over time, except for the vulnerability to magnet/pole piece shift, probably due to adhesive that wasn't up to snuff. The surrounds seem to last a long long time, being of butyl rubber (maybe neoprene?), which doesn't deteriorate very easily unless the storage conditions are very bad.

    Just ask any eBay sellers whether the voice coils are rubbing or not and ask them to make sure to pack them with lots of cushioning around them.
    George / NJ

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  • F1nut
    F1nut Posts: 46,275
    Dr Rick wrote: »
    The drivers are frozen. 😡. Still seems like it wouldn't be coincidence that the same drivers on both speakers froze. Something I should fix before I replace them, so it doesn't happen again? Also, where do I find a replacement? I searched polk for mw 6501 and found nothing. Some ebay options, but they are originals and I don't trust the longevity or quality.

    You're not going to find new ones....lol
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  • westmassguy
    westmassguy Posts: 6,748
    Home Theater/2 Channel:
    Front: SDA-2ATL forum.polkaudio.com/discussion/143984/my-2as-finally-finished-almost/p1
    Center: Custom Built forum.polkaudio.com/discussion/150760/my-center-channel-project/p1
    Surrounds & Rears: Custom Built forum.polkaudio.com/discussion/151647/my-surround-project/p1
    Sonicaps, Mills, RDO-194s-198s, Dynamat, Hurricane Nuts, Blackhole5
    Pioneer Elite VSX-72TXV, Carver PM-600, SVS PB2-Plus Subwoofer
    Cables: Speaker: Furez 10/2 with GLS Locking Banana Plugs
    Interconnect: Furez 10/2 with SpeakONs
    ICs: Custom Furez by Douglas Connections
    Den:
    Bose 901 Series II Continentals Restored, Re-Built Equalizer with Elna Silmic IIs, Sonicaps, and Silver Mica Caps
    Carver CT-3 Pre, Carver C-500

    dhsspeakerservice.com/



  • Dr Rick
    Dr Rick Posts: 3
    I contacted Polk. They, of course, don't make replacements. They suggested these: MW Audio MW-6503-8: 6.5 inch Polk Audio Copy Woofer | Midwest Speaker Repair.

    Turns out the glue on the magnet completely failed on those speakers. Now I need to learn how to repair them. Looks like I would have to take off the cone to get them to line up perfectly.

    Good idea on the JB Weld for the current speakers. Might as well keep them running as long as possible
  • audioluvr
    audioluvr Posts: 3,708
    edited March 10
    Dr Rick wrote: »
    Good idea on the JB Weld for the current speakers. Might as well keep them running as long as possible

    That is what we do. Though I have not heard these models, if they are cosmetically good the restoration process is very desirable and satisfying! You'd be surprised at how many really good sounding speakers are tossed because drivers fail, surrounds fail, crossover components fail or just sound like crap! I've restored several old Polks, Infinitys, Klipsch's and Boston Acoustics all of which turned out superb using the knowledge gained from this forum and it's great members!
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  • Gardenstater
    Gardenstater Posts: 2,020
    That eBay seller is accepting offers (only 3 left!) and the price ain't terrible. Your speakers are more than worth it! There are members here who have repaired them successfully but I would go with the eBay ones and keep yours to repair as spares. Keep us posted and good luck.
    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
  • pitdogg2
    pitdogg2 Posts: 19,473
    Looks like I would have to take off the cone to get them to line up perfectly.

    No you do not remove the cone
  • lawdogg
    lawdogg Posts: 397
    Dr Rick wrote: »
    I contacted Polk. They, of course, don't make replacements. They suggested these: MW Audio MW-6503-8: 6.5 inch Polk Audio Copy Woofer | Midwest Speaker Repair.

    Turns out the glue on the magnet completely failed on those speakers. Now I need to learn how to repair them. Looks like I would have to take off the cone to get them to line up perfectly.

    Good idea on the JB Weld for the current speakers. Might as well keep them running as long as possible

    Let me know if you'd like to know how to build a jig to re-center them. Or, if you'd like me to do it for you if you wanted to mail them to me, no charge.
    <3 my 3.1TLs

    I will fix your shifted magnets for free. :)