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  1. #1

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    Default Just rebuilt Monitor 5A 's with new MW6502 drivers and rebuilt xovers..questions..

    Just rebuilt Monitor 5A 's with new MW6502 drivers and rebuilt xovers...
    one of the original woofs was toast, the magnet motor had been separated.

    the original MW6500 woofs measure 6.6 ohm, that the old complete speaker measured about 6.8 ohm impedance..

    The new factory MW6502 driver measures 4 ohms, and when assembled , brings the
    newly rebuilt speaker to about 4.4 ohms impedance..

    Any concerns about the drop in resistance ? going from 6.6 to 4 ohms ?
    It appears that the MW6502 drivers are NOT actually exact replacements..


    I tried them out last night, and I will say I'm impressed with the sound..

    this is a vintage system I'm rebuilding for a friend..

    Sansui 1000X receiver 99% recapped.....
    Techics TT SLD2 , rebuilt power supply, and new ortofon cartridge (was $32 from Amazon___wow !)
    Polk Monitor 5As
    junky Sony dvd player (missing remote) for a cd source (looking for a remote)

    played some Diana Krall, and a bunch of others..on CD, .and of course a bunch of Vinyl
    Started with Frampton comes Live ! BTO, Boston, ELP

    that cheapie Ortofon cart. is killer .. ( in the old Tech hifi days Audio Technica AT11E and AT71E were staples)

    VERY nice !
    * The Trouble with Doing Nothing , is that you Can't Tell if you are finished *

  2. #2

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    where did you get the woofer from? dosen't sound right.

  3. #3

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    I called polk. They sent me a pair of mw6502 woofs 4 ohm

    I explained that the 5A,s had mw6500 originals

    6502 is what they sent me......

    They might not be right, but they sure sound
    * The Trouble with Doing Nothing , is that you Can't Tell if you are finished *

  4. #4

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    I hate to say it but I believe the replacement should have been the MW-6503. It has closer specs to the 6500.

    Driver: MW 6500 Driver's model #.
    Brand: Polk Driver's brand name.
    Fs: 31.0000 Hz (Free air resonance)
    Vas: 2.6486 ft^3 (Compliance volume)
    Qts: 0.2190 Total Q
    Qms: 1.3000 Mechanical Q
    Qes: 0.2640 Electrical Q
    Sd: 0.0130 M^2 (Piston area)
    Xmax: 3.1800 mm (Cone excursion, linear)
    Revc: 6.5000 ohms (DC resistance)
    Znom: 8.0000 ohms (Nominal impedance)
    Pmax: 35.0000 watts maximum rated power

    Driver: MW 6502 Driver's model #.
    Brand: Polk Driver's brand name.
    Fs: 44.0000 Hz (Free air resonance)
    Vas: 1.2360 ft^3 (Compliance volume)
    Qts: 0.2790 Total Q
    Qms: 1.9700 Mechanical Q
    Qes: 0.3250 Electrical Q
    Sd: 0.0130 M^2 (Piston area)
    Xmax: 3.1800 mm (Cone excursion, linear)
    Revc: 3.5200 ohms (DC resistance)
    Znom: 4.0000 ohms (Nominal impedance)
    Pmax: 35.0000 watts maximum rated power

    Driver: MW 6503 Driver's model #.
    Brand: Polk Driver's brand name.
    Fs: 29.8600 Hz (Free air resonance)
    Vas: 3.0017 ft^3 (Compliance volume)
    Qts: 0.3100 Total Q
    Qms: 1.7680 Mechanical Q
    Qes: 0.3760 Electrical Q
    Sd: 0.0130 M^2 (Piston area)
    Xmax: 3.1800 mm (Cone excursion, linear)
    Revc: 6.5400 ohms (DC resistance)
    Znom: 8.0000 ohms (Nominal impedance)
    Pmax: 35.0000 watts maximum rated power

    Stan
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    Main 2ch:
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    Other stuff:
    Denon: DRA-835R, DRA-825R, DCD-660, DRM-700A, DRR-780; Polk: RTA11TL (RDO198-1, XO and Damping Upgrades), S8, Monitor 5A, TSi100; Pioneer CT-6R, PL-530; Onkyo CP-1046F; Ortofon OM5E, Marantz PM5004, CD5004

  5. #5

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    Default

    the original MW6500 woofs measure 6.6 ohm, that the old complete speaker measured about 6.8 ohm impedance..

    The new factory MW6502 driver measures 4 ohms, and when assembled , brings the
    newly rebuilt speaker to about 4.4 ohms impedance..

    Any concerns about the drop in resistance ? going from 6.6 to 4 ohms ?
    It appears that the MW6502 drivers are NOT actually exact replacements..
    How are you measuring the impedance?
    '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 turd by the clean end."

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    Did you talk with Helen Yarbor she has Monitor 5's and has been with them 30 year started working out in the shop putting them together. Anyway they made a mistake of sending me a MM 6510 rather than a MW 6510 back in 1993 so they do make mistakes, very few though.



    Quote Originally Posted by Adam Czepiel View Post
    I called polk. They sent me a pair of mw6502 woofs 4 ohm

    I explained that the 5A,s had mw6500 originals

    6502 is what they sent me......

    They might not be right, but they sure sound

  7. #7

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    Trying to call them this AM

    so far I cannot get in touch with them
    * The Trouble with Doing Nothing , is that you Can't Tell if you are finished *

  8. #8

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    Also be aware of the "break in " time on the new caps! 100 to 300 hours brfore they get sorted out and settle in! Untill you very well may hear a change in them every time you turn them on untill full break in!!
    Main Rig:
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    Monster HTS 3600 power conditioner
    POLK RTA-12C'S W/ RDO194 TWEETS, clarity ESA caps mills risistors (full mod)
    MIT exps2 speaker cable

  9. #9

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    Default

    I finally got ahold of them, according to ppolk
    the replacement driver is a 6502 as used in the monitor 5B

    No good explanation as to the dcr measuring 4 ohms as opposed to 6 ohm originals

    It does sound good though...
    * The Trouble with Doing Nothing , is that you Can't Tell if you are finished *

  10. #10

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    Default






    * The Trouble with Doing Nothing , is that you Can't Tell if you are finished *

  11. #11

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    ready to rock

    just need the grill cloth replaced
    * The Trouble with Doing Nothing , is that you Can't Tell if you are finished *

  12. #12

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    These sound great ! too bad they are for a friends system....

    now I'll have to look for some Monitor 7s or Monitor 10s
    * The Trouble with Doing Nothing , is that you Can't Tell if you are finished *

  13. #13

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    Nice work!
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  14. #14

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    why was the bypass cap used?
    If it was used to make up the difference of the original that cap should of been split ie. if said cap was 27uf should of been 2 x 10uf and 1 8.2uf should of been more close in uf factor.

    it would of also been better to use mills resistors instead of cement.

  15. #15

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    The bypass cap was used to make 34uF

    I agree the Mills, eagle, and other resistors are much higher quality, but I had the xicons on hand

    one in the hand is worth two in the bush

    These sound great, and I don't think that 'better' resistors would help..

    maybe somebody could do a "Resistor - Off" just like they do caps
    * The Trouble with Doing Nothing , is that you Can't Tell if you are finished *

  16. #16

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    Quote Originally Posted by Adam Czepiel View Post
    The bypass cap was used to make 34uF

    I agree the Mills, eagle, and other resistors are much higher quality, but I had the xicons on hand

    one in the hand is worth two in the bush

    These sound great, and I don't think that 'better' resistors would help..

    maybe somebody could do a "Resistor - Off" just like they do caps
    you should of done two 17uf it would of been much better now it really is a bypass cap. When using better film caps there is no need for a bypass. They will introduce weird artifacts

    I can agree that if you have them use them on the resistors, but I really think you should reevaluate that better resistor thinking. It all matters and Mills are cheap and much better than cement.
    most here have done the resistor - off you speak of. we keep going back to Mills or Mundorf and if you have the coin Dueland....

  17. #17

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    Pit.. thanks for the info & input....

    since these are being rebuilt for a friend, I tried to use as many parts on hand as I could.
    The guy & his wife had a nice vintage setup ( and are NOT audiophiles) I made it sound
    MUCH better (and rebuilding the xovers, new drivers, and rebuilt the receiver--made it dependable)

    If I got a pair for myself, I certainly would entertain better parts for "Mine"
    * The Trouble with Doing Nothing , is that you Can't Tell if you are finished *

  18. #18

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    Quote Originally Posted by Adam Czepiel View Post
    Pit.. thanks for the info & input....

    since these are being rebuilt for a friend, I tried to use as many parts on hand as I could.
    The guy & his wife had a nice vintage setup ( and are NOT audiophiles) I made it sound
    MUCH better (and rebuilding the xovers, new drivers, and rebuilt the receiver--made it dependable)

    If I got a pair for myself, I certainly would entertain better parts for "Mine"
    No problem it was never meant as a dis to you or your skills. Just passing along knowledge I have picked up from those here who are FAR more intelligent in this arena than I am.

  19. #19

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    Doesn't matter, but is the tweeters upside down?

  20. #20

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    Polk chose to support a few drivers, not all, years ago and you may not always get a like for like. It will work, it will be fine.

    If I were a savvy Polk fan, I'd get some spares for the future....across the board.

  21. #21

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    The tweets were opposite eaxh other..one up, one down


    I swapped/inverted the tweets when reassembly, as i was taught
    to rotate the drivers, to even up sag in the surrounds and spiders
    Usually 90' from original orientation
    * The Trouble with Doing Nothing , is that you Can't Tell if you are finished *

  22. #22

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    Yeah....you can toss that idea out the driver window Adam. I'd suggest putting that back to normal.

  23. #23

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    I had a very early pair of 5s, SL1000 Tweeters, the Driver and PR had the old style fiber gaskets in front, and the woofers were also MW65000s. The crossover didn't match anything posted here on the forum
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  24. #24

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    okay I can see you have a good reason to, thanks.

    Quote Originally Posted by Adam Czepiel View Post
    The tweets were opposite eaxh other..one up, one down


    I swapped/inverted the tweets when reassembly, as i was taught
    to rotate the drivers, to even up sag in the surrounds and spiders
    Usually 90' from original orientation

  25. #25

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    Is there a "correct " orientation for the tweets ?

    as I posted when factory built, one tweet pointed up, one down...

    so I just rotated 180' from original position...

    Since it is a dome tweet, I'll guess the dispersion is the same up or down
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  26. #26

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    Adam all of them that I have seen the wires point down from the driver. a "frown"

    https://www.google.com/search?q=polk...w=1577&bih=955


    Quote Originally Posted by Adam Czepiel View Post
    Is there a "correct " orientation for the tweets ?

    as I posted when factory built, one tweet pointed up, one down...

    so I just rotated 180' from original position...

    Since it is a dome tweet, I'll guess the dispersion is the same up or down

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