Phase Plug design for MW65xx

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  • xschop
    xschop Posts: 5,000
    Bump for the nearfield question...

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  • xschop
    xschop Posts: 5,000
    Getting around to building an adjustable jig so I can quickly clean up the shoddy factory pole-piece OD finish that I have been encountering....


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  • xschop
    xschop Posts: 5,000
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  • xschop
    xschop Posts: 5,000
    edited July 2023
    True up the T-Yoke OD
    Dial indicate in jig, then make the Pole Piece OD concentric...
    This was one of the way out-of-round ones by 0.006...


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  • Gardenstater
    Gardenstater Posts: 4,497
    That's interesting and maybe you can get an idea of the flatness of the backplate where it interfaces with the magnet. I wonder how much more magnetic flux you can get if you had it flatter and an adjustable collar/heatsink that allows a no adhesive assembly that allows centering and future disassembly.
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
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    Logitech Squeezebox Touch Streamer w/EDO applet
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    iDefender w/ iPower PS
    Custom Steve Wilson 1m UPOCC Interconnect
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    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
    This is the way to do it correctly. B)
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  • Gardenstater
    Gardenstater Posts: 4,497
    xschop wrote: »
    This is the way to do it correctly. B)

    Yeah, and couldn't hurt to do a #10-32 threaded blind hole in the pole piece for removable phase plugs while one was at it? Could also be a disassembly aid in the future.
    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
    Could be used to interface a copper shorting ring ;)
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  • plastic_avatar
    plastic_avatar Posts: 708
    xschop knows about my side post for my 5(B) mod/upgrade project, but I want to interject here for everyone following his work:

    Phase plug opinion and methods

    I'm really, really pleased with the midwoofers he modified for me (they're fancy, with removable plugs and a drilled out pole piece).

    Listening with and without plugs, plus with and without the modified pole piece, in comparison to my spare mid, there is, to my ear, a definite improvement in clarity. I've heard no negative result on my 5(B).

    Switching out to plugless, after hours of listening, I could hear a difference. Switching out left and right plugs, same thing.

    Example of what I hear

    Listening position is a little cluttered (the 1C are too close to them), but wow. I am not a horn guy, but the detail of the guy's breath in the notes is fantastic.

    https://youtu.be/uO5isb99wCA

    On other tracks, my oldest daughter was confused that it wasn't the 1C and the 5(B) running at the same time.

    Interesting bonus opinion

    She prefers the song Bubbles on the 5(B). She says it sounds more realistic, like there's a giant table in front of her, and some of the 'balls' spill out of the speakers on the left and right as others bounce down across the soundstage towards her.

    https://youtu.be/4CuJqtNdcJU

    Imaging

    In a slightly different arrangement, with the 5(B) 10 inches forward and 10 inches in, I did an imaging experiment.

    I mapped out where sounds were, and how they projected themselves.

    I did this on the 1C and 5(B).

    Purpose?

    To see if the imaging was affected negatively by the plugs in the 5(B), and then how a plugged 5(B) compared to the plugged 1C.

    The only other SDA attempt I know of experienced a negative (smearing, loss of detail?). All the stereo plug modders appear to experience the opposite.

    - Overall, my 5(B) were clearer and felt more precise w/ plugs than without.

    - When mapping music in the room by ear, there wasn't a noticeable change in the direction and location of sounds, but they were clearer and more defined, less diffuse, with plugs.

    - Location of sounds were largely consistent between both speakers (with and without plugs) on the 5(B)). The 1C went to the walls, while the 5(B) extended slightly past their outside edges. Some sounds came forward of the speaker plane, just like the 1C, but not to the enveloping extent, distance, nor force of the larger speaker (to be expected).
    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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  • plastic_avatar
    plastic_avatar Posts: 708
    Bass sounds a little boomy. I blame the iPhone mic and my corners.

    Did not sound that severe sitting in 'the chair'.
    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: 5,000
    Great write-up. On my plugged 5Bs, I don't have to toe them in, as I still get a wide listening spot.
    Alot of older recordings I'm finding sound as if they've been remastered, due to the extra resolution.
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  • Gardenstater
    Gardenstater Posts: 4,497
    edited July 2023
    I find the off axis response of my 7Bs is better than ever with the phase plugs. Makes sense because they help the midwoofers to act more like a theoretical point source of sound, rather than multiple sources on opposite sides of the dust cap which interfere with each other, causing a lobing effect. I think that manufacturers take advantage of this effect to allow them to design a narrower angle cone which may make for a stiffer cone and less cone breakup modes. The cone acts as a waveguide which would reduce dispersion but the phase plug helps to get some of that back due to making it more like a point source. The phase plugs are more effective at higher frequencies and in a highly damped cone those high frequencies are mostly produced near the center of the cone.

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    Post edited by Gardenstater on
    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
    I'll be phase-plugging a set of B&O speakers soon :)
    Don't take experimental gene therapies from known eugenicists.
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  • Gardenstater
    Gardenstater Posts: 4,497
    edited July 2023
    Silence is golden.
    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
    Especially in and echo chamber.
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  • xschop
    xschop Posts: 5,000
    edited August 2023
    Another set of 7C's in the works...

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    Full Monty....

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    Post edited by xschop on
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  • xschop
    xschop Posts: 5,000
    edited August 2023
    Will glue magnets and we're all set...

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    Post edited by xschop on
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  • xschop
    xschop Posts: 5,000
    edited February 19
    Looks like Dayton stepped up their game too...

    https://www.parts-express.com/Dayton-Audio-SIG180-4-6.5-Signature-Series-Woofer-80W-Driver-4-Ohm?quantity=1

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  • xschop
    xschop Posts: 5,000
    Bump for @inanortherntown.
    Very effective modification on early monitors as well.
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  • F1nut
    F1nut Posts: 50,643
    ^ Desperately seeking victims ^
    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."

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  • xschop
    xschop Posts: 5,000
    ^Desperately seeking attention^
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  • F1nut
    F1nut Posts: 50,643
    I don't need or desire to seek attention.
    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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  • xschop
    xschop Posts: 5,000
    Says the keyboard surfer with 50K forum posts. :D
    Don't take experimental gene therapies from known eugenicists.
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  • Gardenstater
    Gardenstater Posts: 4,497
    edited February 27
    F1nut wrote: »
    ^ Desperately seeking victims ^

    So gotta ask, are you saying that Toolfan was a victim and just not savvy enough to know it?

    Amongst those who have done this as an isolated mod, I certainly wasn't and neither was Jazzhead.
    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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  • Toolfan66
    Toolfan66 Posts: 17,289
    No victim here, I had fun with my M7's, I have no regrets, and I like the sound they are producing, Jesse hooked me up with a set of drivers that I will do an A/B test when I get the opportunity to do so.
    These 2.3TL's have all my free time at the moment..

    IMHO Rob did a great job on my drivers, I appreciate him taking the time to do them for me, also IMO for the crazy project I did to these M7's I think they look right at home..

    I can, and totally get the love/hate on this mod. I for one love the mod on my M7's but hate the thought of the mod on my SDA's, It's just not going to happen. No offense to Rob's work, I think he does great work, and put's a lot of time and thought into what he does, and I can appreciate that..
    Polk Audio SDA 2.3tl Fully Hot Rodded. 😎

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  • xschop
    xschop Posts: 5,000
    Thanks Larry. My only agenda here is better sound, whether from your drivers or mine.

    I've had the pleasure last summer to hear a fully modded set of 7's with phase plugs and foamed baskets with RDO billet plates.
    Nothing vintage Ive heard before matched their accuracy and tonality, accompanied by incredible transients. JM2C.
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  • skipshot12
    skipshot12 Posts: 1,169
    Has anyone done the phase plug mod on the sda srs? Thats a lot of drivers.
    Would like to hear a pair with that mod…

    Skip
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  • F1nut
    F1nut Posts: 50,643
    skipshot12 wrote: »
    Has anyone done the phase plug mod on the sda srs? Thats a lot of drivers.
    Would like to hear a pair with that mod…

    Skip

    It was done on the CRS+ with less than favorable results.
    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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  • F1nut
    F1nut Posts: 50,643
    xschop wrote: »
    Says the keyboard surfer with 50K forum posts. :D

    I've been here for 22 years...Hello!
    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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  • xschop
    xschop Posts: 5,000
    Unfortunately there are no term limits here.
    Don't take experimental gene therapies from known eugenicists.
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