RTA 8Ts

Believe it or not, my RTA 8Ts came with 4 mw6511s. Have long since sold drivers, but looking to replace. Would either 6503 or 6510 work?

Comments

  • skrol
    skrol Posts: 3,096
    Well that is a convoluted story. Based on the various schematics, the original RTA-8T used the MW6501. Then the revision used the MW6510. Then the RTA-8TL rev 2 calls for the MW6516, which I almost never see.

    Here are the specs for several MW-65xx drivers:


    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 6501 Driver's model #.
    Brand: Polk Driver's brand name.
    Fs: 31.0000 Hz (Free air resonance)
    Vas: 2.7545 ft^3 (Compliance volume)
    Qts: 0.2790 Total Q
    Qms: 1.4700 Mechanical Q
    Qes: 0.3440 Electrical Q
    Sd: 0.0130 M^2 (Piston area)
    Xmax: 3.1800 mm (Cone excursion, linear)
    Revc: 7.7500 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

    Driver: MW 6517
    BrandL Polk Audio
    * Size / Type = 6.50" treater paper cone woofer
    * SPL = 91 db @ 1w/1m
    * Wattage = 125 Watts RMS / 250 Watts Peak
    * Treated cone woofer, rubber surround
    * Response = 40 Hz. to 10 kHz.
    * Weight = Right a 4 pound ea.
    * Magnet = UnShielded
    * VC = 1" ( 25 mm)
    * Ohms = 4 ohms
    * f(s) - 55 Hz.
    * Q(ms) - 7.261
    * V(as) - 14.60 liters ( 0.516 cf. )
    * n(0) - 5.02%
    * M(ms) - 18.38 grams
    * R(e) - 1.86 Ohms
    * Q(es) - 0.048
    * SPL - 92 dB @ 1W/1m
    * C(ms) - 0.44 mm/N
    * Z(max) - 281.50 Ohms
    * Q(ts) - 0.048
    * L(e) - 31.08 mH


    This information won't tell you how a driver sounds, only what to plug in for basic mathematical modeling. For example, these drivers all used a doped paper cone & rubber surround (Polk made these themselves for many years, using cone & surround from Kurt Mueller Co in Gemany, don't remember where the basket & magnet assemblies came from), but the specs don't describe everything -- including the breakup/resonant modes of the drivers which have a lot to do with the resulting sound.

    So simply substituting a different driver brand or model with different construction but having identical specs will virtually guarantee it will sound different. Better or worse? No way to know without trying.
    Reply With Quote

    PartsExpress (Dayton) 295-305
    Power handling: 50 watts RMS/75 watts max
    Voice coil diameter: 1-3/8"
    Voice coil inductance: 1.40 mH
    Impedance: 8 ohms
    DC resistance: 6.0 ohms
    Frequency response: 33-4,000 Hz
    Magnet weight: 15 oz.
    Fs: 33 Hz
    SPL: 88 dB 1W/1m
    Vas: .98 cu. ft.
    Qms: 2.75
    Qes: .37
    Qts: .33
    Xmax: 3.15mm
    Net weight: 3 lbs.
    Dimensions: Overall Diameter: 6-1/2"
    Cutout Diameter: 5-3/4"
    Mounting Depth: 3-3/16"
    Magnet Diameter: 4"
    Magnet Height: 1-3/16"


    The MW6510 is no longer available through us and the MW6503 is the substitute. It is *close* but not an exact match. Here's some of the basic differences:

    6510 vs 6503
    Q 1.82 vs 1.39
    BL 5.24 vs 6.62 N /AMP
    Compliance 3.55E-3 vs 3.41E-3 N/M
    DCR 6.54 vs 6.57 ohms
    Fs 29 vs 31 Hz.


    These are the only drivers, aside from the RD tweeters, being manufactured to support vintage products, such as, Monitor, RTA and SDA. You should print this as a reference and keep it handy for the values it contains. There are no grill parts, cables, crossovers, plates or anything else available for the older loudspeakers, unless you know the Polk G O D.

    1 Driver Type Q BL Compliance DC Resistance Fs

    3 MW 6501 1.47 5.96 N 3.25 E - 3N/M 7.75 Ohms 31 Hertz
    4 MW 6502 1.97 5.16 N 1.47 E - 3N/M 3.52 Ohms 44 Hertz
    5 MW 6503 1.82 5.24 N 3.55 E - 3N/M 6.54 Ohms 29 Hertz
    6 MW 6509 2.1 4.57 N 3.54 E - 3N/M 8.97 Ohms 30 Hertz
    7 MW 6510 1.39 6.32 N 3.41 E - 3N/M 6.57 Ohms 31 Hertz
    8 MW 6511 1.405 4.34 N 3.496 E - 3N/M 3.13 Ohms 29 Hertz
    9 MW 6512 1.905 4.99 N 1.588 E - 3N/M 3.466 Ohms 40 Hertz
    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
  • deronb1
    deronb1 Posts: 5,039
    Thank you sir! I will print for future reference. It wasnt until i joined the forum, that i found having 6511s in the 8Ts as odd. Bought them in Germany, so dont know if that would have made a difference. Sounds like either 6503 or 6510 will work fine.
  • skrol
    skrol Posts: 3,096
    That is quite a difference in impedance between the 6510 and 6511. I'm curious about what the crossover components are and if they match any of the schematics.
    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
  • pitdogg2
    pitdogg2 Posts: 19,499
    I'd be interested in that as well.
  • deronb1
    deronb1 Posts: 5,039
    I really dont know. I bought them at the PX on Ranstien AB in Germany in 1990.
  • deronb1
    deronb1 Posts: 5,039
    Found two 6503s on Ebay for a decent price. Need two more!
  • verb
    verb Posts: 9,925
    Hello @deronb1 - Do you still have the MW6511's? I am in need of one. Thanks !!!
    Basement: Polk SDA SRS 1.2tl's, Cary SLP-05 Pre with ultimate upgrade,McIntosh MCD301 CD/SACD player, Northstar Designs Excelsio DAC, Cambridge 851N streamer, McIntosh MC300 Amp, Silnote Morpheus Ref2, Series2 Digital Cables, Silnote Morpheus Ref2 Series2 XLR's, Furman 15PFi Power Conditioner, Pangea Power Cables, MIT Shotgun S3 IC's, MIT Shotgun S1 Bi-Wire speaker cables
    Office: PC, EAR Acute CD Player, EAR 834L Pre, Northstar Designs Intenso DAC, Antique Sound Labs AV8 Monoblocks, Denon UDR-F10 Cassette, Acoustic Technologies Classic FR Speakers, SVS SB12 Plus sub, MIT AVt2 speaker cables, IFI Purifier2, AQ Cinnamon USB cable, Groneberg Quatro Reference IC's
    Spare Room: Dayens Ampino Integrated Amp, Tjoeb 99 tube CD player (modified Marantz CD-38), Analysis Plus Oval 9's, Zu Jumpers, AudioEngine B1 Streamer, Klipsch RB-61 v2, SVS PB1000 sub, Blue Jeans RCA IC's, Shunyata Hydra 8 Power Conditioner
    Living Room: Peachtree Nova Integrated, Cambridge CXN v2 Streamer, Rotel RCD-1072 CD player, Furman 15PFi Power Conditioner, Polk RT265 In Wall Speakers, Polk DSW Pro 660wi sub
    Garage #1: Cambridge Audio 640A Integrated Amp, Project Box-E BT Streamer, Polk Tsi200 Bookies, Douglas Speaker Cables, Shunyata Power Conditioner
    Garage #2: Cambridge Audio EVO150 Integrated Amplifier, Polk L200's, Analysis Plus Silver Oval 2 Speaker Cables, IC's TBD.
  • deronb1
    deronb1 Posts: 5,039
    verb wrote: »
    Hello @deronb1 - Do you still have the MW6511's? I am in need of one. Thanks !!!

    No. I have ( 4) 6503 tho
  • xschop
    xschop Posts: 2,050
    So 6516's are unobtainium at this point?
  • agfrost
    agfrost Posts: 2,362
    Believe so. Ebay/scour CL for speakers to part out. Just the 8TLs have them, as noted above.
    Jay
    SDA 2BTL * Musical Fidelity A5cr amp * Oppo BDP-93 * Modded Adcom GDA-600 DAC * Rythmik F8 (x2)
    Micro Seiki DQ-50 * Hagerman Cornet 2 Phono * A hodgepodge of cabling * Belkin PF60
    Preamp rotation: Krell KSL (SCompRacer recapped) * Manley Shrimp * PS Audio 5.0
  • xschop
    xschop Posts: 2,050
    edited January 12
    So the 8TLs have the front ports raised as opposed to the bottom-mounted 8T ports. Can anyone measure their 8Ts' port length and Inside diameter to compare? My 8TL's ports are exactly 5" length X 2.25" ID.
  • smglbrth
    smglbrth Posts: 1,341
    5" length X 1 3/4" ID.
  • xschop
    xschop Posts: 2,050
    This makes sense and possibly how Polk got rid of the chuffing of 8Ts and had the 8TLs dig lower?
  • smglbrth
    smglbrth Posts: 1,341
    Ya got me, I wouldn't have a clue. I've never heard the 8TL so can't compare. However, when I went through mine head to toe, including the crossovers, there was absolutely no internal bracing of any kind. This surprised me some. The manual for the 8t states frequency response at, overall, 30Hz-26KHz. From what I can find on the TL it's 30Hz-25KHz, plus it's an 8 ohm speaker verses 6 ohm for the 8t.
  • xschop
    xschop Posts: 2,050
    Do you guys think that the plastic wave guide is still needed when installing RDO plates? The RDO plates have a tweeter throat wave-guide whereas the SL2500s just have a flat foam piece around dome. It is difficult to say whether the plastic glue-on plates have curved and went out of angle alignment over time....

    tao3uxundevs.jpg
  • xschop
    xschop Posts: 2,050
    edited January 16
    Bueller....Bueller...

    Can anyone double- check their factory plastic wave-guide angles? I'll be making a set out of billet and want the correct angle. Thanks