A noob question

kb3yaj

kb3yaj

New Member
Hello, I've been a member for almost a year, (I think) but mostly just lurk around, reading and learning. I started out like most of you, long ago in the 70's and 80's. blah blah blah......

I scored some Polk monitor 10's a few months back. I have them hooked up to an Onkyo tx3000. I love the way they sound.

Today I scored a pair of RTA 12's. They are in good condition however they have a white powdery substance on the dust cap of the smaller drivers.
  1. Is the powdery substance removalbe/cleanable?
  2. should I be worried about it?
The worked for Polk in Marland in the 80's she purchaced them for her late husband as a gift. They came with Monster cable, with what looks like a capacitor attaced to one end.
  1. WTH is it for?
  2. is it a way to match the speaker's impedance to the receiver?
The literature for the Onkyo states at least 4ohm impedance.
  1. Should they be used with the Onkyo? or am I safe without the Monster cable cap gizmo?

Pics for help.
IMG_3295.JPG

IMG_3291.JPG IMG_3289.JPG


Thanks for any help

Brian
 
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I would suggest using a subject that talks about the topic - almost impossible to attract anyone with a subject that is completely generic.

You can click the button to report your own post and ask a mod to move the thread and change the subject.

Also, what is the value of the capacitor? Probably a high-pass filter to offload the speaker from very low bass (usually done when used with a sub). It’s impossible to know without knowing what capacitor it is.
 
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peterp1 said:
I would suggest using a subject that talks about the topic - almost impossible to attract anyone with a subject that is completely generic.

You can click the button to report your own post and ask a mod to move the thread and change the subject.

Also, what is the value of the capacitor? Probably a high-pass filter to offload the speaker from very low bass (usually done when used with a sub). It’s impossible to know without knowing what capacitor it is.
Click to expand...


Thanks for the advice, I'll look at the values and get the thread moved.
 
Perfectly fine post that belongs here as far as I know. Welcome!
I like a mystery, so I'll get things started with these two links I found while we wait to hear from experts with first-hand knowledge.

https://polkcobracable.blogspot.com/2020/05/polk-cobra-speaker-cable-user-guide.html

https://polkcobracable.blogspot.com/2021/01/polk-cobra-amplifier-killer.html

Looks like it's called "Litz" cable and has high capacitance "baked in" due to the way the wires are twisted close together.
I wont pretend to know anything else.

One more link to search for Polk Cobra Cable: https://www.google.com/search?q=Polk+Cobra+Cable&rlz=1C1CHBF_enUS843US843&sourceid=chrome&ie=UTF-8

I guess the capacitor is a bass-blocker as mentioned. But it should not be wired in parallel.

As for the dust cap, I'd try to clean that mess off. If you need to you can also replace it easily enough.
 
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thesteve, wow thank you, I did get a similar response on the Polk forum, and they advised not to use them, Thanks for the info about how to wire it. I removed it, and I'm still using the cables, but I think I may replace them.
 
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