Westmassguy's Idea: Employing Damping to Mitigate Comb Filtering and Lobing

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Comments

  • plastic_avatar
    plastic_avatar Posts: 708
    edited April 2023
    I wonder if some damping in the passive chamber could bring that down a little...

    I know my Monitor 12 were tighter and less boomy when I did my dynamat-like coating of the passive chamber, but I attributed that to taming those cabinet vibrations.

    Curious what The Hive thinks.
    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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  • Gardenstater
    Gardenstater Posts: 4,455
    Once you start running sinusoidal sweep tones if it still looks bass heavy and still sounds bass heavy, a couple things to play with could be the amount of foam damping behind the other MW and the amount of weight on the passive radiator diaphragm.
    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
    More baffle bracing should fix that, however worn driver suspensions could be the culprit too.
    Don't take experimental gene therapies from known eugenicists.
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  • Gardenstater
    Gardenstater Posts: 4,455
    Just had the thought that you might want to first overhaul/upgrade the caps and resistors and then re-assess the situation because the electrolytic capacitor especially could have drifted value. I have read that the ESR (effective series resistance) of electrolytics can go up appreciably with age.
    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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  • joebass3
    joebass3 Posts: 283
    Gardenstater wrote: »
    Just had the thought that you might want to first overhaul/upgrade the caps and resistors and then re-assess the situation because the electrolytic capacitor especially could have drifted value. I have read that the ESR (effective series resistance) of electrolytics can go up appreciably with age.

    They are original so it makes sense to start there. Thanks!
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  • rodman53
    rodman53 Posts: 18
    Well i'll tell you what helps tame the bass of the 10's for me. All i have to do is turn my bass control down to 10 or 11:00 and for my ears that really helps. Just like if i have a pair of speakers that don't have quite enough base i will turn the bass control up a bit. Not a total fix of course but for me it helps. And it cost nothing to try.
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  • westmassguy
    westmassguy Posts: 6,850
    skipshot12 wrote: »
    Westmass,
    Has this been tried on the SDA SRS’s?

    There would be no point. SDA's dimensional woofers produce a different signal than the stereo woofers. This modification is for side by side woofers producing the same signal.
    Home Theater/2 Channel:
    Front: SDA-2ATL forum.polkaudio.com/discussion/143984/my-2as-finally-finished-almost/p1
    Center: Custom Built forum.polkaudio.com/discussion/150760/my-center-channel-project/p1
    Surrounds & Rears: Custom Built forum.polkaudio.com/discussion/151647/my-surround-project/p1
    Sonicaps, Mills, RDO-194s-198s, Dynamat, Hurricane Nuts, Blackhole5
    Pioneer Elite VSX-72TXV, Carver PM-600, SVS PB2-Plus Subwoofer

    dhsspeakerservice.com/
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  • joebass3
    joebass3 Posts: 283
    edited April 2023
    rodman53 wrote: »
    Well i'll tell you what helps tame the bass of the 10's for me. All i have to do is turn my bass control down to 10 or 11:00 and for my ears that really helps. Just like if i have a pair of speakers that don't have quite enough base i will turn the bass control up a bit. Not a total fix of course but for me it helps. And it cost nothing to try.

    Repositioning the speakers away from the wall and turning the bass control on the Marantz 2270 down to 10:00 made a big difference! I'll likely still rebuild the crossovers and as @xschop suggested I'll experiment with some cabinet bracing, but for now I'm a happy camper!
    Post edited by joebass3 on
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  • rodman53
    rodman53 Posts: 18
    That's great to hear! I think the monitor 10s are a great speaker, and with some mods here and there they can be even better. I never did post it but I also did Westmassguy's Idea on my 10s. Thank you Westmassguy! Great too hear someone else has done it to their 10s and also got great results.
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  • skipshot12
    skipshot12 Posts: 1,157
    westmassguy wrote: »
    skipshot12 wrote: »
    Westmass,
    Has this been tried on the SDA SRS’s?

    There would be no point. SDA's dimensional woofers produce a different signal than the stereo woofers. This modification is for side by side woofers producing the same signal.

    Thanks for the splanation….
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  • joebass3
    joebass3 Posts: 283
    edited April 2023
    Quick update on my 10's. I was so happy with my 7b's that the 10's didn't get much play time. I'm so happy I did this mod! It got me excited about this set of speakers again and motivated to do the other mods to see just how good they could sound. I just finished rebuilding the crossovers, installing Rob's @xschop semi-rings, and doing some serious bracing of the front baffle. Also got them off the floor and onto stands. OMG these bad boys now kick a$$! I can definitely hear (and feel in my chest) the improvement overall but especially bass response. Even though I could hear a difference, I also wanted to know if i could see it so I re-ran the Spectroid app on my phone. Obviously not done with fancy test equipment but it shows a change. Thanks again David @westmassguy!

    f49c7yima5ak.jpg


    hnask4c6wegn.jpg
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  • Gardenstater
    Gardenstater Posts: 4,455
    edited April 2023
    Would've been interesting to see a sine sweep fore and after but much smoother! And it looks like you got around 10Hz better bass extension. Well done.
    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: 708
    edited April 2023
    Spectroid... [goes to look]
    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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  • Jazzhead
    Jazzhead Posts: 533
    @joebass3 Excellent results! Your experience shows that 10's can shine with the right upgrades. They do need to be off the floor as I recall. My 12's are 13 in. up, away from corners/rear wall and have plenty of bass and slam. So, did you do Rob's @xschop suggestion of bracing at the 10 and 2 PR position? How's the imaging at this point?
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  • joebass3
    joebass3 Posts: 283
    edited April 2023
    I decided to brace 4 spots on the PR. I did the 10 and 2 positions that Rob suggested but also installed them at 4 and 8. I installed them so they could be removed if I didn't like the results, but I don't think they'll be coming out!

    1bec2q2imy2r.jpg

    zu1baeecgx9y.jpg
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  • Jazzhead
    Jazzhead Posts: 533
    You ain't messin' round.
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  • SIHAB
    SIHAB Posts: 4,891
    edited April 2023
    Might be time to try these mods and get rid of the lobing. :#
    jn1ql4o1p0h3.jpg

    Speakers: Polk Lsim, ATC SCM19 v2, NHT SuperzeroSpeaker Cables: DH Labs, Transparent, Wireworld, Canare, Monster: Beer budget, Bose ears
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  • treitz3
    treitz3 Posts: 19,004
    Lobing isn't....


    Awe, never mind.

    Tom
    ~ In search of accurate reproduction of music. Real sound is my reference and while perfection may not be attainable? If I chase it, I might just catch excellence. ~
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  • plastic_avatar
    plastic_avatar Posts: 708
    edited April 2023
    [tip of the hat, joebass3]

    I'm determined to do the damping mods in my 12, and your bracing in all of my Polks:

    1i6kao6fs519.jpeg

    Well done. Looks great.
    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
    · Share on FacebookShare on Twitter
  • xschop
    xschop Posts: 5,000
    Good engineering.You've effectively removed all the energy-robbing flex of that baffle.
    Don't take experimental gene therapies from known eugenicists.
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  • rodman53
    rodman53 Posts: 18
    Nice job. Looks nice and solid.
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