Which Polk Monitor speakers have the internal brace ?

Monkey_Relish
Monkey_Relish Posts: 11
in Vintage Speakers
Hi all,

I have a set of Polk Monitor 5A’s with the Peerless tweeters.
When I refurbished them, I noticed they have a brace between the cabinet back and between the tweeter and woofer on the baffle.

The polyfill was cut like a set of pants, you roll it up and place it behind the tweeter, and the “legs” go either side of the brace, and roll up behind the woofer.

I then finally found a set of Polk Monitor 7C’s, and refurbished them as well.
These didn’t have the internal brace.

So, I thought it must be a Monitor 5 thing.
But I have seen some cabinet pics on here that show a 5B with no internal brace.

So, my question is what models were they used on ?
5A’s only ?

If so, why were they dropped, price ?

Which also gets me wondering, if Matthew Polk thought they were required originally, then they must have made SOME difference, reducing cabinet resonance on these small cabinets.

Which also gets me wondering if my Monitor 7’s would benefit from a brace in the same place, being larger cabinets ?

Mr Relish
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Best Answer

  • Monkey_Relish
    Monkey_Relish Posts: 11
    Answer ✓
    And the answer to my original question is , not Monitor 5’s or 7’s.

    I pulled out the woofer on the 5A’s and, NO BRACE.
    The front baffle is ample in thickness, none would be needed

    Too many speakers over the years and too feeble a memory.
    Ignore this whole post.
    Think I need a lie down.

    Mr Relish
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Answers

  • Gardenstater
    Gardenstater Posts: 4,459
    That's interesting. I woulda thought that the brace would go between the MW and the passive. Do you have photos?

    I can verify that my 7Bs have no brace. I can also verify that they would've benefitted from a brace or two. Rob's semi rings made such a huge improvement in bass slam that there must be considerable baffle flex. Don't quote me but I believe the M10 has a brace?
    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
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  • Gardenstater
    Gardenstater Posts: 4,459
    As far as no brace being needed with 3/4" particleboard.......well you'd be surprised.
    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: 5,000
    edited August 2022
    Yeah, the 7's baffle flex would be the worst of the early monitors given its larger span.
    A front to back dowel between MW and Passive would be a great improvement.
    It would also prevent the batting/Dacron from falling down near the Passive Rad.
    Don't take experimental gene therapies from known eugenicists.
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  • odcics2
    odcics2 Posts: 331
    Here’s a pic of an Ohm C2.
    A brace from the front to rear REALLY stiffens the front baffle. 4i4aksphd9v5.jpeg
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