RTA15TL MW's with extra donut magnets

brgman
brgman Posts: 2,859
edited January 2011 in Vintage Speakers
I am taking apart my 15's to mod.The first was non eventful but now that i started into the second every 6503 has an additional donut magnet stuck to the back of the standard magnet.
What is up? Why does one have these and the other not?
Has anyone seen this or maybe know why this is?:confused:
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I’M OFFENDED!!!!
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  • comfortablycurt
    comfortablycurt Posts: 6,745
    edited January 2011
    Hmm...Just taking a guess here, but they could be bucking magnets to make the speaker magnetically shielded. It's possible that at one time, the one speaker was sitting right next to a CRT TV and was distorting the picture. The magnets would have magnetically shielded the one speaker, so it wouldn't affect the TV's picture. If that is the case...the other speaker must have been far enough away from the TV to not impact the picture.

    That's just a guess though.
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  • Toolfan66
    Toolfan66 Posts: 17,251
    edited January 2011
    Pics!!!!!!
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  • ken brydson
    ken brydson Posts: 8,762
    edited January 2011
    comfortablycurt wrote: »
    Hmm...Just taking a guess here, but they could be bucking magnets to make the speaker magnetically shielded. It's possible that at one time, the one speaker was sitting right next to a CRT TV and was distorting the picture. The magnets would have magnetically shielded the one speaker, so it wouldn't affect the TV's picture. If that is the case...the other speaker must have been far enough away from the TV to not impact the picture.

    That's just a guess though.

    I think that's it. A few years ago I ordered a new driver for one of my LS50's. When I questioned why it looked different than the original that was Ken S's exact response.
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  • brgman
    brgman Posts: 2,859
    edited January 2011
    I'll get some pics to post...
    Main Rig-Realistic AM/FM Record player 8 track boasting 4 WPC

    Backup Rig-2 CH-Rogue Audio Zeus w/Factory Special Dark Mods,Joule-Electra 300ME Platinum Preamp,OPPO-105 w/Modwright Tube Mod, Auralic Aries G2.1,Polk 2.3TL,3.1TL's,Dreadnought,RTA-15TL's,1C's All Fully Modded,2xRTA-12c's ,Benchmark DAC3 HGC,Synology NAS,VPI Scout w/Dynavector DV-20XH and Rogue Audio Ares Phono Preamp,Sony PCM-R500 DAT,HHB-850 Pro CDR,Tascam CC-222SLMKII Cassette/CDR,MIT S3.3 Shotgun Cables,Shunyata Hyra-8,Shunyata and Triode Labs Power Cords

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  • F1nut
    F1nut Posts: 50,567
    edited January 2011
    As CC stated, it's a bucking magnet. No worries, no need for a pic.
    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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  • brgman
    brgman Posts: 2,859
    edited January 2011
    For those that are curious
    Main Rig-Realistic AM/FM Record player 8 track boasting 4 WPC

    Backup Rig-2 CH-Rogue Audio Zeus w/Factory Special Dark Mods,Joule-Electra 300ME Platinum Preamp,OPPO-105 w/Modwright Tube Mod, Auralic Aries G2.1,Polk 2.3TL,3.1TL's,Dreadnought,RTA-15TL's,1C's All Fully Modded,2xRTA-12c's ,Benchmark DAC3 HGC,Synology NAS,VPI Scout w/Dynavector DV-20XH and Rogue Audio Ares Phono Preamp,Sony PCM-R500 DAT,HHB-850 Pro CDR,Tascam CC-222SLMKII Cassette/CDR,MIT S3.3 Shotgun Cables,Shunyata Hyra-8,Shunyata and Triode Labs Power Cords

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  • brgman
    brgman Posts: 2,859
    edited January 2011
    just cannot figure why they put them in one and not the other.The guy i bought them from wasn't smart enough to do this himself.Hell he left another pair he had sitting in water rotting away.Didn't strike me as someone that cared.
    Anyhoo.Thanks for the feedback.I guess i can keep these off for the modded version.
    Main Rig-Realistic AM/FM Record player 8 track boasting 4 WPC

    Backup Rig-2 CH-Rogue Audio Zeus w/Factory Special Dark Mods,Joule-Electra 300ME Platinum Preamp,OPPO-105 w/Modwright Tube Mod, Auralic Aries G2.1,Polk 2.3TL,3.1TL's,Dreadnought,RTA-15TL's,1C's All Fully Modded,2xRTA-12c's ,Benchmark DAC3 HGC,Synology NAS,VPI Scout w/Dynavector DV-20XH and Rogue Audio Ares Phono Preamp,Sony PCM-R500 DAT,HHB-850 Pro CDR,Tascam CC-222SLMKII Cassette/CDR,MIT S3.3 Shotgun Cables,Shunyata Hyra-8,Shunyata and Triode Labs Power Cords

    I’M OFFENDED!!!!
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  • Tour2ma
    Tour2ma Posts: 10,177
    edited January 2011
    Agree...

    So they were in one, but not the other? Previous owner must've had one channel close to a TV...

    If I remember correctly, the bucking mags do depress output ~1 dB, so you'll want to remove them.

    Might make a good karma...
    More later,
    Tour...
    Vox Copuli
    Better to remain silent and be thought a fool, than to open your mouth and remove all doubt. - Old English Proverb

    "Death doesn't come with a Uhaul." - Dennis Gardner
    "It's easy to get lost in price vs performance vs ego vs illusion." - doro
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  • brgman
    brgman Posts: 2,859
    edited January 2011
    yep.consecutive s/n's also.
    Main Rig-Realistic AM/FM Record player 8 track boasting 4 WPC

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    I’M OFFENDED!!!!
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  • F1nut
    F1nut Posts: 50,567
    edited January 2011
    Tour2ma wrote: »
    If I remember correctly, the bucking mags do depress output ~1 dB, so you'll want to remove them.

    I don't recall that. What I do recall is that there is the potential for a slight change in the driver Q. However, there are a number of folks who think that adding bucking magnets improves the sound quality of the driver.

    You know all those speakers out there that state they are shielded? Yeah, they all use bucking magnets.

    For example, Polk's LSi 15's are advertized as, "Magnetically Shielded
    All models* are magnetically shielded for safe placement near CRT displays.
    *Except LSiFX, but you wouldn't put your surround speakers next to your TV anyway…"

    Yep, bucking magnets.
    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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  • dorokusai
    dorokusai Posts: 25,577
    edited January 2011
    I wouldn't remove them as there's no real need to do so.
    CTC BBQ Amplifier, Sonic Frontiers Line3 Pre-Amplifier and Wadia 581 SACD player. Speakers? Always changing but for now, Mission Argonauts I picked up for $50 bucks, mint.
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  • Tour2ma
    Tour2ma Posts: 10,177
    edited January 2011
    F1nut wrote: »
    I don't recall that. What I do recall is that there is the potential for a slight change in the driver Q.
    I looked into them for my SRS's (which ate a tv picture tube once... pretty colors...). Talked to Ken S. about the magnets and I am sure he said they drop the efficiency (sensitivity)...

    What I'm not sure of is the amount, but it was slight, around 1 dB. This wasn't the reason I did not buy them. The replacement TV (a Proton) was shielded much better...

    In any case I'd either add magnets to the speaker that did not have them, or remove them from the one that does.

    JMO...
    More later,
    Tour...
    Vox Copuli
    Better to remain silent and be thought a fool, than to open your mouth and remove all doubt. - Old English Proverb

    "Death doesn't come with a Uhaul." - Dennis Gardner
    "It's easy to get lost in price vs performance vs ego vs illusion." - doro
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  • brgman
    brgman Posts: 2,859
    edited January 2011
    I guess what i need to nail down is which is more advantagous,with or without.i reckon polk cs still sells these.
    i will be doing the dynamat and mortite as well when they get reassembled
    Main Rig-Realistic AM/FM Record player 8 track boasting 4 WPC

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    I’M OFFENDED!!!!
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  • dorokusai
    dorokusai Posts: 25,577
    edited January 2011
    Unless you've noticed a difference before you knew about the magnets, why bother? If it's that big of a deal just swap some drivers between the cabinets, that way at least you'll have some balance. Move two bucking magnet drivers over to the other cabinet and vice versa....problem solved.
    CTC BBQ Amplifier, Sonic Frontiers Line3 Pre-Amplifier and Wadia 581 SACD player. Speakers? Always changing but for now, Mission Argonauts I picked up for $50 bucks, mint.
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  • FTGV
    FTGV Posts: 3,649
    edited January 2011
    I don't recall that. What I do recall is that there is the potential for a slight change in the driver Q.
    A small reduction in the Q would be expected as would possibly a slight increase in sensitivity.
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  • brgman
    brgman Posts: 2,859
    edited January 2011
    dorokusai wrote: »
    Unless you've noticed a difference before you knew about the magnets, why bother? If it's that big of a deal just swap some drivers between the cabinets, that way at least you'll have some balance. Move two bucking magnet drivers over to the other cabinet and vice versa....problem solved.

    That's what i was thinkin'.Throw 2 of the 4 in the other for balance.:wink:
    Main Rig-Realistic AM/FM Record player 8 track boasting 4 WPC

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    I’M OFFENDED!!!!
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  • Toolfan66
    Toolfan66 Posts: 17,251
    edited January 2011
    Thats what I would do and forget about it..
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  • Tour2ma
    Tour2ma Posts: 10,177
    edited January 2011
    FAGEDABOWDIT? Not arguing, but since removing the bucking mags is a big deal, I have to assume that they are glued.... yes?
    FTGV wrote: »
    ... as would possibly a slight increase in sensitivity.
    For a second that made more sense than the reduction I'm remembering, but then I had to go and think about...

    FTGV,
    Check me out here...
    - Using a bucking magnet to negate the external magnetic field would also reduce the axial field; therefore
    - A given current through the VC would produce less movement since the attraction/ repulsion to a reduced axial field would be reduced; and
    - Less movement = reduced sensivity...
    More later,
    Tour...
    Vox Copuli
    Better to remain silent and be thought a fool, than to open your mouth and remove all doubt. - Old English Proverb

    "Death doesn't come with a Uhaul." - Dennis Gardner
    "It's easy to get lost in price vs performance vs ego vs illusion." - doro
    "There is a certain entertainment value in ripping the occaisonal (sic) buttmunch..." - TroyD
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  • FTGV
    FTGV Posts: 3,649
    edited January 2011
    Actually Tour I'm thinking it will focus more of the magnet strength(flux density) into the voicecoil gap,therefore increase voltage sensitivity ?
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  • brgman
    brgman Posts: 2,859
    edited January 2011
    Not glued,just slapped on the back of each driver.Strong little suckers too!
    Main Rig-Realistic AM/FM Record player 8 track boasting 4 WPC

    Backup Rig-2 CH-Rogue Audio Zeus w/Factory Special Dark Mods,Joule-Electra 300ME Platinum Preamp,OPPO-105 w/Modwright Tube Mod, Auralic Aries G2.1,Polk 2.3TL,3.1TL's,Dreadnought,RTA-15TL's,1C's All Fully Modded,2xRTA-12c's ,Benchmark DAC3 HGC,Synology NAS,VPI Scout w/Dynavector DV-20XH and Rogue Audio Ares Phono Preamp,Sony PCM-R500 DAT,HHB-850 Pro CDR,Tascam CC-222SLMKII Cassette/CDR,MIT S3.3 Shotgun Cables,Shunyata Hyra-8,Shunyata and Triode Labs Power Cords

    I’M OFFENDED!!!!
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  • twochannel
    twochannel Posts: 171
    edited January 2011
    Bucking Magnets! I installed them on my SDA-SRS's because my CRT TV had distorted colors only three feet away. I purchased a Sony XBR RPTV 7 years ago and have only recently removed the magnets from the mid bass drivers because I was curious how much they effected the sound. Yes, the bass is much better without the magnets. I left the bucking magnets on the tweeters until I replace them with RDO194's. Mine were not glued to the back of the drivers.
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  • F1nut
    F1nut Posts: 50,567
    edited January 2011
    Yes, the bass is much better without the magnets.

    I think it is more likely that you got a better seal when you reinstalled the drivers. I don't see how the bucking magnets could decrease the bass response.
    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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  • brgman
    brgman Posts: 2,859
    edited January 2011
    The plot thickens.Poking around for info everything i am reading is to reverse polarity when installing.Hence forcing the bucker onto the driver mag and using epoxy to keep it on.
    Mine are all opposite of this.They are just stuck on by equal polar magnetics.:eek::confused:
    Main Rig-Realistic AM/FM Record player 8 track boasting 4 WPC

    Backup Rig-2 CH-Rogue Audio Zeus w/Factory Special Dark Mods,Joule-Electra 300ME Platinum Preamp,OPPO-105 w/Modwright Tube Mod, Auralic Aries G2.1,Polk 2.3TL,3.1TL's,Dreadnought,RTA-15TL's,1C's All Fully Modded,2xRTA-12c's ,Benchmark DAC3 HGC,Synology NAS,VPI Scout w/Dynavector DV-20XH and Rogue Audio Ares Phono Preamp,Sony PCM-R500 DAT,HHB-850 Pro CDR,Tascam CC-222SLMKII Cassette/CDR,MIT S3.3 Shotgun Cables,Shunyata Hyra-8,Shunyata and Triode Labs Power Cords

    I’M OFFENDED!!!!
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  • dorokusai
    dorokusai Posts: 25,577
    edited January 2011
    Look man, do what you want. You have all the information you need to make a decision and they should be connected as they are right now.

    Good luck.
    CTC BBQ Amplifier, Sonic Frontiers Line3 Pre-Amplifier and Wadia 581 SACD player. Speakers? Always changing but for now, Mission Argonauts I picked up for $50 bucks, mint.
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  • inspiredsports
    inspiredsports Posts: 5,501
    edited January 2011
    brgman wrote: »
    Not glued,just slapped on the back of each driver.Strong little suckers too!

    I'm curious if they were installed correctly if they are just slapped on north/south/north/south instead of being oriented to repel, centered at the null, and securely glued in place. I thought the idea was that they repel/cancel the extraneous field of the existing magnet . . .

    https://www.madisound.com/store/product_info.php?products_id=8285

    "Bucking magnets are used to reduce the stray magnetic field of a woofer. This will allow you to put the woofer closer to a CRT TV screen. The magnet is glued to the back of the existing magnet system with the magnets repelling each other. When the magnet are centered, the magnetic field will cancel and it will be possible to glue the magnet on."
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  • FTGV
    FTGV Posts: 3,649
    edited January 2011
    F1nut wrote: »
    I don't see how the bucking magnets could decrease the bass response.
    Well a possible scenario .If the electrical Q of the driver is dramatically changed with the additional magnet it would increase damping in the bass.Increased damping would make the bass tighter which some equate to less bass.
    brgman wrote: »
    The plot thickens.Poking around for info everything i am reading is to reverse polarity when installing.Hence forcing the bucker onto the driver mag and using epoxy to keep it on.
    Mine are all opposite of this.They are just stuck on by equal polar magnetics.:eek::confused:
    To be effective at reducing stray magnet fields they have to be installed with opposing poles.Installing them otherwise just increases the stray field(worse for a CRT)and will change driver characteristics.


    Edit.I see post above already covered the last point.
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  • inspiredsports
    inspiredsports Posts: 5,501
    edited January 2011
    brgman, yours were installed improperly from what I can tell.
    VTL ST50 w/mods / RCA6L6GC / TlfnknECC801S
    Conrad Johnson PV-5 w/mods
    TT Conrad Johnson Sonographe SG3 Oak / Sumiko LMT / Grado Woodbody Platinum / Sumiko PIB2 / The Clamp
    Musical Fidelity A1 CDPro/ Bada DD-22 Tube CDP / Conrad Johnson SD-22 CDP
    Tuners w/mods Kenwood KT5020 / Fisher KM60
    MF x-DAC V8, HAInfo NG27
    Herbies Ti-9 / Vibrapods / MIT Shotgun AC1 IEC's / MIT Shotgun 2 IC's / MIT Shotgun 2 Speaker Cables
    PS Audio Cryo / PowerPort Premium Outlets / Exact Power EP15A Conditioner
    Walnut SDA 2B TL /Oak SDA SRS II TL (Sonicaps/Mills/Cardas/Custom SDA ICs / Dynamat Extreme / Larry's Rings/ FSB-2 Spikes
    NAD SS rigs w/mods
    GIK panels
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  • FTGV
    FTGV Posts: 3,649
    edited January 2011
    inspiredsports wrote: »
    brgman, yours were installed improperly from what I can tell.

    Agreed.
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  • brgman
    brgman Posts: 2,859
    edited January 2011
    FTGV wrote: »
    Agreed.

    That's what i thought.Thanks for confirmation
    Main Rig-Realistic AM/FM Record player 8 track boasting 4 WPC

    Backup Rig-2 CH-Rogue Audio Zeus w/Factory Special Dark Mods,Joule-Electra 300ME Platinum Preamp,OPPO-105 w/Modwright Tube Mod, Auralic Aries G2.1,Polk 2.3TL,3.1TL's,Dreadnought,RTA-15TL's,1C's All Fully Modded,2xRTA-12c's ,Benchmark DAC3 HGC,Synology NAS,VPI Scout w/Dynavector DV-20XH and Rogue Audio Ares Phono Preamp,Sony PCM-R500 DAT,HHB-850 Pro CDR,Tascam CC-222SLMKII Cassette/CDR,MIT S3.3 Shotgun Cables,Shunyata Hyra-8,Shunyata and Triode Labs Power Cords

    I’M OFFENDED!!!!
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  • F1nut
    F1nut Posts: 50,567
    edited January 2011
    twochannel wrote: »
    Mine were not glued to the back of the drivers.

    Not sure how I missed this, but like brgman's, yours were installed incorrectly.
    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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