Monitor 7, 7A, 7B. What are the differences?

So, I have early 7s with the small paper PR. Then 7s with the larger PR. Also 7A and 7B with plasticized PRs.
All have Peerless tweeters.

How would you rank them for sound quality?
What are the internal differences?

Thanks in advance for any insight.

Comments

  • F1nut
    F1nut Posts: 49,704
    edited February 2023
    Not trying to be a smarta$$, but since you might be the only one here with all of those versions perhaps your could share you thoughts on which is best.
    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

  • odcics2
    odcics2 Posts: 305
    A bit of work required on a few!
    But yes, I could do listening sessions, but then I would only be telling my opinions. And we all have differing opinions about sound.

    Ok, first, get them all usable!
    B)


  • My 7B sounded better than all those other ones that I haven't heard 👌
    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
  • The Model 7 in this picture predates yours by a bit, since it shows the Audax Tweeter:

    yr0hbgsn4tm0.png
    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
  • odcics2
    odcics2 Posts: 305
    edited February 2023
    Interesting. I wonder how many production units were made with that tweeter.

  • odcics2 wrote: »
    Interesting. I wonder how many production units were made with that tweeter.

    Yeah I do not know but was probably 1975 to 1976. It would seem that the earlier models didn't have as low of bass extension as my 7Bs and perhaps the 7A. They consistently gave the figure of 40 - 20ish kHz +/-2 dB. My 7Bs were 33 -20.5kHz +/- 2 dB. Doesn't necessarily mean they didn't sound as good.

    Also another thing that may factor in is whether or not the drivers are rabetted. My late 1979 7Bs were not rabbeted at all and later 7Bs had the PR rabbeted and the MW non rabbeted. I assume they were trying to get more bass performance by exposing more of the windows but not sure. Then at some point they also rabbeted the MW which may have been both to get better bass and to lessen diffraction off of the stamped steel driver flange.
    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
  • odcics2
    odcics2 Posts: 305
    Yup, they wanted to flush the drivers to lessen diffraction.
  • odcics2
    odcics2 Posts: 305
    odcics2 wrote: »
    Interesting. I wonder how many production units were made with that tweeter.

    Yeah I do not know but was probably 1975 to 1976. It would seem that the earlier models didn't have as low of bass extension as my 7Bs and perhaps the 7A. They consistently gave the figure of 40 - 20ish kHz +/-2 dB. My 7Bs were 33 -20.5kHz +/- 2 dB. Doesn't necessarily mean they didn't sound as good.

    Also another thing that may factor in is whether or not the drivers are rabetted. My late 1979 7Bs were not rabbeted at all and later 7Bs had the PR rabbeted and the MW non rabbeted. I assume they were trying to get more bass performance by exposing more of the windows but not sure. Then at some point they also rabbeted the MW which may have been both to get better bass and to lessen diffraction off of the stamped steel driver flange.

    What are your serial numbers?
  • Gardenstater
    Gardenstater Posts: 4,135
    197XX. Not sequential but 3 apart.
    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
  • joebass3
    joebass3 Posts: 243
    My 7b's were made in late 1981 and are not rabbeted. Serial #'s 325xx
  • odcics2
    odcics2 Posts: 305
    My latest find.

    pccvn990yo9k.jpeg
    bsjmxe65wpwe.jpeg
  • skrol
    skrol Posts: 3,330
    I attached a draft of a document that I had been working on many years ago. It has info on many of the vintage Polk Audio speakers. I can't guarantee it is 100% accurate.
    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
  • MrGeology
    MrGeology Posts: 83
    edited April 2023
    joebass3 wrote: »
    My 7b's were made in late 1981 and are not rabbeted. Serial #'s 325xx

    My 7B's were made in early 1983 (571xx) and late 1983 (592xx) and neither are rabbeted either. Both have Peerless tweets.

    Edit: I take it back, the passives are rabbeted on both.
    b8bsq8opuao0.jpg
    Post edited by MrGeology on
    "They’re not after me, they’re after you… I’m just standing in the way!” -Donald J. Trump, 45th President of the United States
  • Gardenstater
    Gardenstater Posts: 4,135
    Did your late 1983 one come with an SL1000 tweeter?
    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
  • odcics2
    odcics2 Posts: 305
    Dates of my crossovers.

    8yi2p0xub4gc.jpeg
    89fyg6s68vcq.jpeg
  • MrGeology
    MrGeology Posts: 83
    edited April 2023
    Did your late 1983 one come with an SL1000 tweeter?

    When I got it it had a Peerless. Edit: Crossover simply dated 11/83, MW driver dated 10/25/83.
    Post edited by MrGeology on
    "They’re not after me, they’re after you… I’m just standing in the way!” -Donald J. Trump, 45th President of the United States