Crossover failure?

charlied7401
charlied7401 Posts: 8
in Troubleshooting
Just connected my vintage sm 10,s ,purchased in 85 and dorment for 15 years. One works,sounds fine, the other barely any sound and some crackling.
Speaker was dropped at some point dislodging magnets which were reconnected. Don’t see any broken wires ,all spade connections clean and tight. Could crossover be bad, how would I check?
Visually crossover looks fine. I have limited (very) electronic skills but do have a voltmeter.
Big fan of the KISS METHOD ( keep it simple and stupid).
Any advice much appreciated.
Thanks
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Answers

  • Gardenstater
    Gardenstater Posts: 4,459
    More likely the voice coil is binding, due to being dropped. Try to manually exercise the cone with your fingers and see if you feel / hear any scraping sounds.
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Onkyo A-8017 integrated
    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
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  • charlied7401
    charlied7401 Posts: 8
    Appreciate the advice, I'm embarrassed to ask but where is the voice coil ,what does it look like ? Got a picture you could send. Thanks very much.

    Charlie
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  • Gardenstater
    Gardenstater Posts: 4,459
    This picture isn't very good but you get the idea. You can't see it without dissasembly such as removing the dust cap. Not easily repaired by those not experienced / skilled at it: o4w8ov8rb2pt.png
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Onkyo A-8017 integrated
    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
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  • Gardenstater
    Gardenstater Posts: 4,459
    edited January 2020
    https://www.explainthatstuff.com/loudspeakers.html

    s8gitkdq96p3.png
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Onkyo A-8017 integrated
    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
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  • charlied7401
    charlied7401 Posts: 8
    Thanks for the detail. I’ll be very gentle and see. Keep you in the loop.
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  • boston1450
    boston1450 Posts: 7,636
    You should apply a bead of glue on each side of the magnet. That may help prevent magnet shift in the future. I use Loctite Powergrab from HDepot. Put small bead on each side & use your finger & make it look clean. Have some paper towels ready. Also if the stock gasket between the cabinet & driver is not damaged/cut/ripped. Reuse it. It will be fine
    ..
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  • charlied7401
    charlied7401 Posts: 8
    I’m new at this so pull speaker,clean off any residue of old glue (alcohol) glue back. How can I tell if voice coil is free?
    Thanks
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  • boston1450
    boston1450 Posts: 7,636
    Probably no glue on there. Do as stated above with glue....Froze driver check = take 2 fingers n place them on each side of dust cap. Gently push them in & out. Feel & listen for any scratchiness. If it goes in & out freely they are good to go... if one of your drivers is working fine-do that one first. So you know how its suppose to feel. If you notice different on the other. You found the problem... now IF their the same. Try swapping out driver from one cabinet to the other & that will be a easy check on your crossover. If it follows. Then it's your MW driver
    ..
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  • boston1450
    boston1450 Posts: 7,636
    If the driver doesnt move at all. It is definitely a froze driver. This means the magnet shifted. That is why gluing the magnet HELPS for future possible mishaps
    ..
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  • charlied7401
    charlied7401 Posts: 8
    A big thank you to Boston 1450 walked me through locating the problem,would have been buying a crossover that wasn’t the problem.
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  • boston1450
    boston1450 Posts: 7,636
    Charlie it was a pleasure talking with you. I'm glad I was a help to you & you got to know your speakers better. I hope the forum can help get those up & running again. I will look up info on repairs for your damaged MW woofers. There is someone here that repairs them. Do keep us updated. Welcome to the forum
    ..
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