M7B DATS Cabinet Impedance Sweeps (Pics)

MrGeology
MrGeology Posts: 86
edited April 2023 in Vintage Speakers
Cabinets Have Different Caps.
Cabinet A Crossover.
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Cabinet B Crossover.
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3 sample drivers:
Original 1983 M7B driver
Wuhan VC Repaired 1983 M7B driver
1980 Silver Basket MW 6500 with original coil.

For each drivers standalone T/S parameters, see my post here:
https://forum.polkaudio.com/discussion/198508/mw6500-dats-t-s-parameters-revised-pics

Apologies, forgot to save impedance sweep of 1980 driver in cabinet B so it is missing.

2 pics Cabinet A Impedance Sweep, (3 drivers, overlay).
2 pics Cabinet B Impedance Sweep, (2 drivers, overlay).
3 pics Cabinet A Vs Cabinet B Impedance Sweep, (original 7B driver, overlay).
1 pic Cabinet A (original driver) Vs Cabinet B (Wuhan Coil) (Impedance Sweep overlay).

Cabinet A Impedance Sweep, (3 drivers, overlay).
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Cabinet B Impedance Sweep, (2 drivers, overlay).
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Cabinet A Vs Cabinet B Impedance Sweep, (original 7B driver, overlay).
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Cabinet A (original driver) Vs Cabinet B (Wuhan Coil) (Impedance Sweep overlay).
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"Pride is concerned with who is right. Humility is concerned with what is right."
-Ezra Taft Benson
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Comments

  • Gardenstater
    Gardenstater Posts: 4,769
    edited 8:53AM
    So it looks like system tuning frequency Fb ( the minimum between the two impedance maxima) may have drifted a tad upwards to around 42 Hz. Arguably should be around 38 Hz.

    For the sake of discussion, what would one do to correct this? I can think of several things to try before adding weight to the PR.

    It would be EPIC if someone who owns 7B, 7C, and 7 Series II and also has DATS could do a thread comparing the cabinet impedance sweeps and also the driver free air sweeps. @DeRod 🤣 . You have said your 7C has the best bass by far. Not to give anyone any holiday homework of course 😁
    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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  • xschop
    xschop Posts: 5,097
    edited 10:54AM
    I've seen alot of dried out doping on many of the vintage mids. The most pristine/sticky ones came out of the RM1000 subwoofer I rebuilt for comparison, as if the enclosure was hermetically sealed. Imagine that.
    Post edited by xschop on
    Don't take experimental gene therapies from known eugenicists.
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  • xschop
    xschop Posts: 5,097
    LOL'ing the dried out doping comment, or just smoking some?
    Don't take experimental gene therapies from known eugenicists.
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  • Gardenstater
    Gardenstater Posts: 4,769
    Ahh well......some people are blinded by science and some are intimidated by it and some are offended by it? 🤣
    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
    · Share on FacebookShare on Twitter
  • plastic_avatar
    plastic_avatar Posts: 734
    edited 3:06PM
    [siri dictation removed to edit]
    Post edited by plastic_avatar on
    The Thrifty Setups in Mah House Big thrifty stereo in the basement w/ my custom SDA-1C (built with help from kind forum members) * Beautiful 1966 MCM GE console upgraded w/ Bluetooth, Dual turntable, and Paradigm speakers in family room * Swanky 1980 Realistic system and great TEAC eq with dancing colored lights in the living room * custom 5B on a system for my Dad * Ye Olde college stereo in the garage
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  • xschop
    xschop Posts: 5,097
    edited 4:13PM
    Some are triggered by it...

    https://www.youtube.com/watch?v=V83JR2IoI8k
    Don't take experimental gene therapies from known eugenicists.
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