Monitor 10 Series II question

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hobbyist49
hobbyist49 Posts: 19
in Vintage Speakers
Hi,
I'm a new member, having just purchased these awesome speakers. Based on what I'm reading here, it sounds like I should glue the magnets on the mw6503's, rebuild the crossovers, and eventually replace the sl2500 tweeters with rdo198's. And maybe use Mortite to seal the woofers (replacing the thin gaskets). I was reading another recap thread that has a parts list, but my crossover looks different than the pics in that thread. I was hoping one of you helpful guys might be able to advise me on which caps I need to buy? I will be using cheaper stuff, Dayton's I think (I'm on a budget). Thanks in advance!
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  • hobbyist49
    hobbyist49 Posts: 19
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    I just found the speaker schematics thread, so that may be exactly what I need. I'm assuming that the the m10 series ii, I should use the m10s_rev2 schematic, is that correct? Thanks.
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  • Gardenstater
    Gardenstater Posts: 4,187
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    Welcome and nice speakers! Thin polyethylene gaskets are what is preferred and as long as they are intact there's no way I'd replace then with mortite or anything for that matter. Do the test where you push in the passive radiators and hold them there and see how many seconds it takes the MW's to go back to normal positions. If you have no leaks and your gaskets are sound, leave it alone.

    You need to help us out and give us the values of your capacitors and resistors wherever possible to read them. Obvious difference is that schematic shows 3 caps and you have 2 plus 2 in parallel. Caps in parallel add. You need to do some work and compare what you have to the schematic. Polk was known to make mid model changes.
    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
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  • hobbyist49
    hobbyist49 Posts: 19
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    Thank you for your reply and advise about the gaskets! That push test--while holding the passive radiator in, it takes about 2.5-3 secs for the woofers to move back in.

    These are the only values I'm able to read without breaking the glue apart:

    Blue cap: 27 MFD 5 0v NP K85 deg C, 12 uF

    Big yellow: TI 4.4 j 100v

    Is that enough info? I can break it apart if necessary. I'll also post additional pics just in case that helps. Thanks again!
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  • hobbyist49
    hobbyist49 Posts: 19
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  • Gardenstater
    Gardenstater Posts: 4,187
    edited May 2020
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    You also have a 12uF blue one, which is probably C3 in parallel with the resistor. You can look underneath and check the copper traces, or remove the 4 screws and do so. You can check the resistor with a multimeter without removal and verify that it is 2.7Ohms, even if you can't read the markings. The blue and yellow caps in parallel, which I'm guessing are C1, might add up to 16 uF, as shown in the schematic.

    I'd be inclined to save money until I could afford Sonicaps for the high frequency caps C3 and C1, or maybe ClarityCaps CSA's. The low frequency cap C2 could be lower end I guess, like maybe a ClarityCap PX or maybe even a Dayton. Others can weigh in who have more experience with crossover mods.

    PS: If you carefully cut through the hot melt between the blue and yellow in parallel, you should be able to read the uF values. The assembler at Polk was not kind to you.

    PPS: That 2.5 to 3 secs is pretty fast in my opinion. Make sure you hold the Passive in and don't release it.
    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
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  • westmassguy
    westmassguy Posts: 6,850
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    Welcome to Club Polk. The new square circuit boards they used on the revision 2 Monitors are a PITA to work on. Even less real estate than the old round boards. Instead of Daytons for a budget build, I'd recommend Clarity PX caps. They're very nice, very smooth entry level Capacitors versus the Dayton/Bennic variety. Try Madisound 1st, and Parts Connexion also carries them.
    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

    dhsspeakerservice.com/
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  • hobbyist49
    hobbyist49 Posts: 19
    edited May 2020
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    Thanks guys for your help! This gives me a lot to think about.
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  • F1nut
    F1nut Posts: 49,805
    edited May 2020
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    Apply denatured alcohol with a Q-tip to the hot glue. After a few minutes you can peel it off.

    Use Sonicap or Clarity. Do not use Dayton, Bennic or Solen. Use Mills resistors. For God's sake, do not use Mortite.
    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

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  • hobbyist49
    hobbyist49 Posts: 19
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    Thank you, F1nut!
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  • hobbyist49
    hobbyist49 Posts: 19
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    I have one more question, guys. If I'm going with Clarity CSA caps, and can't find a 16uF, I'm assuming (hoping) that a 15uF will be ok. Or do I need to add a 1uF as well? Just worried about real estate. Thanks again!
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  • pitdogg2
    pitdogg2 Posts: 24,582
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    maybe two 8uf in parallel if they have those.
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  • F1nut
    F1nut Posts: 49,805
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    It's best to keep the values as close to even as possible, so in your case I'd go with two 8.2uF caps.
    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

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  • hobbyist49
    hobbyist49 Posts: 19
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    OK, great--thank you both!
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  • hobbyist49
    hobbyist49 Posts: 19
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    Just a quick update, I ended up ordering ClarityCap CSA (2x 8.2uF and 12uF) for the tweeter and a Solen 27uF for the woofer, as well as the Mills resistors. I also just received new RD0-198 tweeters from Midwest (sold the SL-2500s online). The new tweeters sound great. I realize that with 120 in the tweeters and 100 in the caps, I'm probably over-spending for this particular speaker, when I only paid 160 for the speakers themselves. But not intending to re-sell them, so it's all good.
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  • StantonZ
    StantonZ Posts: 439
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    hobbyist49 wrote: »
    I realize that with 120 in the tweeters and 100 in the caps, I'm probably over-spending for this particular speaker, when I only paid 160 for the speakers themselves. But not intending to re-sell them, so it's all good.

    You'll find it's worth every penny! Capacitors (especially) degrade/age over time. The RDO-198 tweeters are a "no brainer"...and I wrote an article about re-building my Monitor 10 XO's here (good thing electricity doesn't care about "pretty").
    Yamaha RX-A2050 AVR (5.0.2); LG OLED77C2 4K TV
    (4) Polk Monitor 10B's w/SoniCaps, Mills, and RDO-194 tweets (R/L F/R)
    (2) Polk RC80i (Top Middle)
    Polk CS300 center channel
    Analog: B&O TX2 Turntable, Nakamichi Cassette Deck 1
    Digital: Pioneer CLD-99 Elite LD, Panasonic DMP-UB900 UHD Blu-Ray
    Bedroom: Arylic Up2Stream AMPv3 driving Polk Monitor 4's w/peerless tweets
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  • Gardenstater
    Gardenstater Posts: 4,187
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    I had a similar dilemma with my 7Bs where I paid $350 for them new in 1979 after reading a High Fidelity (?) review, which I wish I had kept grrrr, saying how they were very accurate and matched the value of speakers many times their price, but now I am spending about that just to upgrade them. Well I can tell you that it was worth every penny! I don't know how much I'd have to spend to get similar SQ from brand new speakers but I bet it's more than that.
    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
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  • hobbyist49
    hobbyist49 Posts: 19
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    Thanks guys. StantonZ, I read your excellent article just the other day! Great stuff. I appreciate the encouragement, makes me feel better about spending the cash on these things--they already sound great, and I'm sure they will sound even better.

    I glued all my magnets this evening while I wait for the caps to arrive. Hopefully I did it right. I had some 2-part expoxy in the house so I just used that (both sides of the magnet).
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