Just joined

Bzzzzzzt_pop
Bzzzzzzt_pop Posts: 10
in Vintage Speakers
Hi, I just joined the forum
I have owned Monitor 5's in the past, and currently own a pair of Monitor 10's and a pair of RTA 12s
I purchased the 12's today, 04/16/22. They came with a cable that had what looks like a capacitor attached to them.

q49bvle9lnvn.jpg

The 12's hey came with

hm5leyfs5eob.jpg

Any help with what these cap looking things are is very helpfull.
Thanks all
Brian
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Comments

  • Emlyn
    Emlyn Posts: 4,489
    edited April 2022
    Welcome! Those speaker cables are a model that Polk sold under the name “Cobra” a long time ago. Search on the forum or Google for “Polk cobra” and you’ll find a lot of info. The cables had high capacitance and presented problems to a small number of amplifiers when they were available. Personally I wouldn’t use them, even though they are a novelty, because there are better options.

    Those speakers look great!
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  • boston1450
    boston1450 Posts: 7,639
    Agree. The hats look very nice
    ..
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  • Hermitism
    Hermitism Posts: 4,261
    Those speakers are beautiful, congrats on the purchase and welcome to the forum.

    axs74z2wh6hx.png
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  • Gardenstater
    Gardenstater Posts: 4,468
    edited April 2022
    Welcome! The Polk Cobra cables are high capacitance, relatively high resistance, ultra-low capacitance cables that can give improved sound quality. That part that looks like a capacitor is probably a zobel network, which is a resistor in series with a capacitor and if placed across the + and - terminals of the speaker, will protect from any instability that a minority of solid state amplifiers can suffer from otherwise. They are Litz type cables made of magnet wire basically, and the weave gives the low inductance. Low inductance is very good. I remember the salesman offering me those cables when I bought my 7Bs in 1979 lol.

    I would prefer to use what I am using, which is a ribbon cable that is similar to the design of the Alpha Core Goertz cable. Also high capacitance. My Crown D150 has never had a problem with it, even without a zobel network.
    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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  • Tony M
    Tony M Posts: 11,151
    :pB)
    Most people just listen to music and watch movies. I EXPERIENCE them.
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  • Bzzzzzzt_pop
    Bzzzzzzt_pop Posts: 10
    Welp. I am certainly happy i came here to ask. So much information. Thanks everyone. I certainly do enjoy polk speakers
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  • Gardenstater
    Gardenstater Posts: 4,468
    Lets see some *grilles off* pics :)
    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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  • Bzzzzzzt_pop
    Bzzzzzzt_pop Posts: 10
    Sure, no problem

    61458xjq3z8z.jpg

    umsqowss7p7k.jpg

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  • Bzzzzzzt_pop
    Bzzzzzzt_pop Posts: 10
    I'm still trying to research which version these are. The serial number says 12, the crossover says 12, the tweeter is a SL1000.
    The white powdery substance I am going to try to just brush off with a soft brush. I should pull that driver and look behind it. Holidays get in the way. But family....
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  • Gardenstater
    Gardenstater Posts: 4,468
    edited April 2022
    I'm pretty certain you have the earliest R.T.A. 12 but someone has replaced the Peerless tweeters with SL1000s. It may very well have been a warranty replacement and that is what Polk sent. They switched to their own SL1000 sometime in 1984 I believe. This is from Audio Apr. 1979:

    svsonv1maj3l.jpg

    Audio Jan. 1980:

    32v5mavs2llj.jpg

    Audio Oct. 1979:

    17322c0wud0y.jpg

    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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  • Bzzzzzzt_pop
    Bzzzzzzt_pop Posts: 10
    I suspect that too. It also looks like something bumped one of the tweeters as it is out of alignment, no big deal. I'll see about replacing the SL1000's. Would there be any reason the crossover would have been changed when this was done? Or can I safely assume the crossover wasn't modified?
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  • Bzzzzzzt_pop
    Bzzzzzzt_pop Posts: 10
    Serial #'s

    ikacyqp91gf7.jpg
    g0mvitasriy5.jpg
    rld4o4f2hsoi.jpg
    jkjwn7446uht.jpg


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  • Bzzzzzzt_pop
    Bzzzzzzt_pop Posts: 10
    Is there a Left and Right to these speakers?
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  • Emlyn
    Emlyn Posts: 4,489
    96dB efficiency is pretty remarkable for a Polk product. Built for rocking out in the basement but 120dB peaks can be painful.

    :)
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  • Gardenstater
    Gardenstater Posts: 4,468
    Bzzzzzzt_pop wrote: »
    I suspect that too. It also looks like something bumped one of the tweeters as it is out of alignment, no big deal. I'll see about replacing the SL1000's. Would there be any reason the crossover would have been changed when this was done? Or can I safely assume the crossover wasn't modified?

    You can see everything on the outside and everything looks bone stock to me. I feel safe in saying that you would prefer the sound of the Peerless, especially if you get a couple that are around 79 or 80 production years.
    Bzzzzzzt_pop wrote: »
    Is there a Left and Right to these speakers?

    Nope. Not with the early ones. Both of the midwoofers receive the same signal. In the later model they rolled off the outer driver at a lower frequency to counter the comb filtering/lobing issue.

    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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  • Bzzzzzzt_pop
    Bzzzzzzt_pop Posts: 10
    I've tried everything short of re-caping the speakers. The SL1000 tweeters have got to be replaced in these RTA 12s. They sound like they're underwater. Sorry.
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  • xschop
    xschop Posts: 5,000
    New caps and silk domes are in order.
    Don't take experimental gene therapies from known eugenicists.
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  • Gardenstater
    Gardenstater Posts: 4,468
    These would be good, although they don't have the aperture tuning holes that Polk started putting in the domes at some point:

    https://www.ebay.com/itm/275286561227?hash=item40185b91cb:g:F7UAAOSwXMViZdLP
    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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  • mhardy6647
    mhardy6647 Posts: 33,802
    may I just add: @Bzzzzzzt_pop is a great name! :)
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  • Tony M
    Tony M Posts: 11,151
    edited April 2022
    Welcome.

    Now unhook those wires on your speakers immediately!

    Each wire is supposed to remain separate. How you haven't blown anything is beyond belief.
    OK, I see now, :o . You're supposed to run 2 wires to the speaker, not one.

    You're supposed to have a + (red) and a negative - black channel wires. 2 separate wires.

    How in the world these are functional is a miracle.
    fuzirsi8j8py.png

    dhtt3j07zlbw.png


    I see why your sound is underwater sounding. :s

    Get some regular speaker wire.


    Most people just listen to music and watch movies. I EXPERIENCE them.
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  • pitdogg2
    pitdogg2 Posts: 25,441
    edited April 2022
    Tony M Posts: 10,310
    11:20AM edited 11:23AM
    Welcome.

    Now unhook those wires on your speakers immediately!

    Each wire is supposed to remain separate. How you haven't blown anything is beyond belief.
    OK, I see now, :o . You're supposed to run 2 wires to the speaker, not one.

    He has two wires there and they are FINE, Do some research !


    Post edited by pitdogg2 on
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  • Tony M
    Tony M Posts: 11,151
    OK.

    But how does one research something one doesn't know about? :s

    Maybe, just maybe, YOU could've named what wires those are!
    Most people just listen to music and watch movies. I EXPERIENCE them.
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  • Gardenstater
    Gardenstater Posts: 4,468
    Here's a lil more info. which I had meant to share. From Audio Aug 1977. They actually called it Polk Soundwire before the Cobra:

    z8mh8zi3709b.jpg
    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
  • pitdogg2
    pitdogg2 Posts: 25,441
    Tony M wrote: »
    OK.

    But how does one research something one doesn't know about? :s

    Maybe, just maybe, YOU could've named what wires those are!

    They were named at the top of the thread with his first pictures. Try and keep up here big boy. 😉

    Polk Cobra cables.

    For someone who has "collected" sooo much audio gear I'm shocked SHOCKED I tell you, that this is the first you've heard of them. Even after you emoji'd George's answer to them once again at the top of this thread.

    Now you're up to speed!


    https://www.hifiengine.com/gallery/images/polk-‘cobra’-speaker-cable.shtml
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  • rebelsoul
    rebelsoul Posts: 756
    Get rid of those speaker cables there garbage.
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  • Tony M
    Tony M Posts: 11,151
    pitdogg2 wrote: »
    Tony M wrote: »
    OK.

    But how does one research something one doesn't know about? :s

    Maybe, just maybe, YOU could've named what wires those are!

    They were named at the top of the thread with his first pictures. Try and keep up here big boy. 😉

    Polk Cobra cables.

    For someone who has "collected" sooo much audio gear I'm shocked SHOCKED I tell you, that this is the first you've heard of them. Even after you emoji'd George's answer to them once again at the top of this thread.

    Now you're up to speed!


    https://www.hifiengine.com/gallery/images/polk-‘cobra’-speaker-cable.shtml

    Thank you.
    I appreciated and read the link you posted. B)

    I read about cobra cables here 20 years ago and have seen them mentioned here once a year or two maybe. I've forgotten how they were made. I even forgotten the first few posts showing the Polk name AND comments about Polk's cobra cable. :#



    Also, cables is not an area I have much knowledge of. I do have enough to buy OFC when ever I do. 14ga. or 12ga. is my size preferences. That's about it. :)

    My memory isn't what it was. :/ Something has happened the past 6 months or more. Maybe something has started. :'(

    Speakers, yes I've owned a lot and know a lot about how brands sounded, BUT, my memory is slipping away even on those.

    Most people just listen to music and watch movies. I EXPERIENCE them.
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  • F1nut
    F1nut Posts: 50,554
    Tony M Posts: 10,310
    11:20AM edited 11:23AM
    Welcome.

    Now unhook those wires on your speakers immediately!

    Each wire is supposed to remain separate. How you haven't blown anything is beyond belief.
    OK, I see now, :o . You're supposed to run 2 wires to the speaker, not one.

    Better have your eyes checked.


    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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  • Tony M
    Tony M Posts: 11,151
    F1nut wrote: »
    Tony M Posts: 10,310
    11:20AM edited 11:23AM
    Welcome.

    Now unhook those wires on your speakers immediately!

    Each wire is supposed to remain separate. How you haven't blown anything is beyond belief.
    OK, I see now, :o . You're supposed to run 2 wires to the speaker, not one.

    Better have your eyes checked.


    How many wire manufacturers weave the positive and negative wires together?
    Most people just listen to music and watch movies. I EXPERIENCE them.
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  • SeleniumFalcon
    SeleniumFalcon Posts: 3,785
    Actually the Polk speaker wire is the only Polk component to be listed in Stereophile's 100 most influential audio products. I'm not sure why it doesn't have a better reputation here on Polk's forum. I know Matt Polk used some on his LSi speakers on the treble connections. For dedicated audiophiles six pairs are paralleled to reduce the resistance for best bass.
    If you look at your amplifier's schematic and you see an inductor in series with the positive output it means the basic circuit is not comfortable with capacitive loads and the inductor was used to increase impedance at higher frequencies.
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  • mhardy6647
    mhardy6647 Posts: 33,802
    SeleniumFalcon wrote: »
    ...I'm not sure why it doesn't have a better reputation here on Polk's forum...

    Pretty sure that was catalyzed by the folks who lost marginally stable amplifiers to it. ;)
    I had a friend in college who used it with a pair of Monitor 10s and a GAS Son of Ampzilla. That combination worked well and sounded excellent.


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