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

Adam Czepiel
Adam Czepiel Posts: 46
edited August 2013 in Speakers
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 *
Post edited by Adam Czepiel on
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Comments

  • pitdogg2
    pitdogg2 Posts: 25,667
    edited July 2013
    where did you get the woofer from? dosen't sound right.
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  • Adam Czepiel
    Adam Czepiel Posts: 46
    edited July 2013
    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 *
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  • skrol
    skrol Posts: 3,391
    edited July 2013
    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
    Stan

    Main 2ch:
    Polk LSi15 (DB840 upgrade), Parasound: P/LD-1100, HCA-1000A; Denon: DVD-2910, DRM-800A; Benchmark DAC1, Monster HTS3600-MKII, Grado SR-225i; Technics SL-J2, Parasound PPH-100.

    HT:
    Marantz SR7010, Polk: RTA11TL (RDO198-1, XO and Damping Upgrades), S4, CS250, PSW110 , Marantz UD5005, Pioneer PL-530, Panasonic TC-P42S60

    Other stuff:
    Denon: DRA-835R, AVR-888, DCD-660, DRM-700A, DRR-780; Polk: S8, Monitor 5A, 5B, TSi100, RM7, PSW10 (DXi104 upgrade); Pioneer: CT-6R; Onkyo CP-1046F; Ortofon OM5E, Marantz: PM5004, CD5004, CDR-615; Parasound C/PT-600, HCA-800ii, Sony CDP-650ESD, Technics SA 5070, B&W DM601
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  • F1nut
    F1nut Posts: 50,735
    edited July 2013
    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 t-u-r-d by the clean end."

    President of Club Polk

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  • PolkieMan
    PolkieMan Posts: 2,446
    edited July 2013
    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.


    Adam Czepiel wrote: »
    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
    POLK SDA 2.3 TLS BOUGHT NEW IN 1990, Gimpod/Sonic Caps/Mills RDO-198
    POLK CSI-A6 POLK MONITOR 70'S ONKYO TX NR-808 SONY CDP-333ES
    PIONEER PL-510A SONY BDP S5100
    POLK SDA 1C BOUGHT USED 2011,Gimpod/Sonic Caps/Mills RDO-194
    ONKYO HT RC-360 SONY BDP S590 TECHNICS SL BD-1
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  • Adam Czepiel
    Adam Czepiel Posts: 46
    edited July 2013
    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 *
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  • soundfreak1
    soundfreak1 Posts: 3,414
    edited July 2013
    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:
    Krell KAV 250a biamped to mid/highs
    Parasound HCA1500A biamped to lows
    Nakamichi EC100 Active xover
    MIT exp 1 ic's
    Perreaux SA33 class A preamp
    AQ kingcobra ic's
    OPPO 83 CDP
    Lehmann audio black cube SE phono pre, Audioquest phono wire (ITA1/1)
    Denon DP-1200 TT. AToc9ML MC cart.
    Monster HTS 3600 power conditioner
    ADS L1590/2 Biamped
    MIT exps2 speaker cable
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  • Adam Czepiel
    Adam Czepiel Posts: 46
    edited July 2013
    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 *
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  • Adam Czepiel
    Adam Czepiel Posts: 46
    edited August 2013
    IMG_0912.jpg


    IMG_0977.jpg.html?sort=3&o=1

    IMG_0927.jpg
    * The Trouble with Doing Nothing , is that you Can't Tell if you are finished *
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  • Adam Czepiel
    Adam Czepiel Posts: 46
    edited August 2013
    IMG_0977.jpg?t=1375377050

    ready to rock

    just need the grill cloth replaced
    * The Trouble with Doing Nothing , is that you Can't Tell if you are finished *
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  • Adam Czepiel
    Adam Czepiel Posts: 46
    edited August 2013
    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 *
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  • GFOviedo
    GFOviedo Posts: 353
    edited August 2013
    Nice work!
    AVR: DENON X4000
    FRONT L/R: ARX A3RX-C
    CENTER: ARX A2RX-C
    SURROUND L/R: ARX A3
    SUBWOOFER: PSA-XV15

    SERVER: UNRAID 15TB
    MEDIA PLAYERS: DUNE SMART SERIES D1
    HDTV: VIZIO M601D-A3R
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  • pitdogg2
    pitdogg2 Posts: 25,667
    edited August 2013
    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.
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  • Adam Czepiel
    Adam Czepiel Posts: 46
    edited August 2013
    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 :confused:
    * The Trouble with Doing Nothing , is that you Can't Tell if you are finished *
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  • pitdogg2
    pitdogg2 Posts: 25,667
    edited August 2013
    Adam Czepiel wrote: »
    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 :confused:

    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....
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  • Adam Czepiel
    Adam Czepiel Posts: 46
    edited August 2013
    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 *
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  • pitdogg2
    pitdogg2 Posts: 25,667
    edited August 2013
    Adam Czepiel wrote: »
    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.
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  • PolkieMan
    PolkieMan Posts: 2,446
    edited August 2013
    Doesn't matter, but is the tweeters upside down?
    POLK SDA 2.3 TLS BOUGHT NEW IN 1990, Gimpod/Sonic Caps/Mills RDO-198
    POLK CSI-A6 POLK MONITOR 70'S ONKYO TX NR-808 SONY CDP-333ES
    PIONEER PL-510A SONY BDP S5100
    POLK SDA 1C BOUGHT USED 2011,Gimpod/Sonic Caps/Mills RDO-194
    ONKYO HT RC-360 SONY BDP S590 TECHNICS SL BD-1
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  • dorokusai
    dorokusai Posts: 25,577
    edited August 2013
    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.
    CTC BBQ Amplifier, Sonic Frontiers Line3 Pre-Amplifier and Wadia 581 SACD player. Speakers? Always changing but for now, Mission Argonauts I picked up for $50 bucks, mint.
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  • Adam Czepiel
    Adam Czepiel Posts: 46
    edited August 2013
    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 *
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  • dorokusai
    dorokusai Posts: 25,577
    edited August 2013
    Yeah....you can toss that idea out the driver window Adam. I'd suggest putting that back to normal.
    CTC BBQ Amplifier, Sonic Frontiers Line3 Pre-Amplifier and Wadia 581 SACD player. Speakers? Always changing but for now, Mission Argonauts I picked up for $50 bucks, mint.
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  • westmassguy
    westmassguy Posts: 6,850
    edited August 2013
    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
    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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  • PolkieMan
    PolkieMan Posts: 2,446
    edited August 2013
    okay I can see you have a good reason to, thanks.
    Adam Czepiel wrote: »
    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
    POLK SDA 2.3 TLS BOUGHT NEW IN 1990, Gimpod/Sonic Caps/Mills RDO-198
    POLK CSI-A6 POLK MONITOR 70'S ONKYO TX NR-808 SONY CDP-333ES
    PIONEER PL-510A SONY BDP S5100
    POLK SDA 1C BOUGHT USED 2011,Gimpod/Sonic Caps/Mills RDO-194
    ONKYO HT RC-360 SONY BDP S590 TECHNICS SL BD-1
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  • Adam Czepiel
    Adam Czepiel Posts: 46
    edited August 2013
    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
    * The Trouble with Doing Nothing , is that you Can't Tell if you are finished *
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  • PolkieMan
    PolkieMan Posts: 2,446
    edited August 2013
    Adam all of them that I have seen the wires point down from the driver. a "frown"

    https://www.google.com/search?q=polk+monitor+5a&client=firefox-a&hs=mgZ&rls=org.mozilla:en-US:official&source=lnms&tbm=isch&sa=X&ei=5838UaLmFYfbrAG6kYGQDg&ved=0CAkQ_AUoAQ&biw=1577&bih=955

    Adam Czepiel wrote: »
    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
    POLK SDA 2.3 TLS BOUGHT NEW IN 1990, Gimpod/Sonic Caps/Mills RDO-198
    POLK CSI-A6 POLK MONITOR 70'S ONKYO TX NR-808 SONY CDP-333ES
    PIONEER PL-510A SONY BDP S5100
    POLK SDA 1C BOUGHT USED 2011,Gimpod/Sonic Caps/Mills RDO-194
    ONKYO HT RC-360 SONY BDP S590 TECHNICS SL BD-1
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