Polk RTA-12 - No Sound From Tweeters

musicmanrs
musicmanrs Posts: 5
edited November 2010 in Speakers
I just picked up a pair of Polk RTA-12 speakers for $40. They worked perfectly, until I turned them up a little bit. No sound will come out of the tweeters. The tweeters themselves work fine, I tested both. Not sure what the problem could be. Only sound comes through the two 6.5" woofers, they sound the same as they did before the tweeters stopped. Anything I can try? There is a fuse on the top of each crossover. Both of them look fine though. Could I have fried part of the crossover?
Speakers: Polk Audio SDA 1C (with newer crossovers and homemade 12 gauge interconnect cable)

Amplifier: QSC GX3 Power Amplifier

Preamplifier: small Behringer mixer (temporary)

CD Player: Sony CDP-C715 Disc Changer
Post edited by musicmanrs on
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Comments

  • Polkie2009
    Polkie2009 Posts: 3,834
    edited September 2010
    After your tweeters quit working, did you shut the system off for awhile and try running the speakers again to see if the tweeters were working again? Try doing a search here, I think I've read recently someone had a problem like this with their tweeters and they may have ended up having to replace some caps or resistors in the crossovers??
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  • danger boy
    danger boy Posts: 15,722
    edited September 2010
    not sure if those RTA's have fuses on the backs or not. if so. replace the bad fuse.
    PolkFest 2012, who's going>?
    Vancouver, Canada Sept 30th, 2012 - Madonna concert :cheesygrin:
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  • fatpiggy
    fatpiggy Posts: 205
    edited October 2010
    I have a set of RT 12's all the drivers were blown.The voice coils in the tweeters were melted, all the woofers voice coils were melted and had seperated from the cones.The glue that attaches the cones to the voice coils on the woofers goes brittle with age and causes the speakers to fail and cause all the other speakers to overload and burn out the voice coils.I would say you possibly have failed drivers.

    The cross over boards does not have any fuses the board uses the a 2 ohm 5 watt white ceramic power resitior as the fuse.If the tweeter are overload the will blow and then the resitor will blow.The tweeter can only handle 90 watts RMS.If you send too much current to the tweeters they will blow.

    I would check the white ceramic resistor 2 ohm 5 watt on the cross over, mine were both blown as well.You can use a multi meter to test the tweeters they should be 8 ohms.You can use a multi meter to check the white resistor on the crossover board.The resisitor on the crossover board problem is a common fault.If you have a blown white resistor it would be a good idea to replace all capacitors on the cross over board as well.Its an easy soldering job.

    You can remove the woofers and inspect the cones for seperation, you will see the cones un glued from the voice coils where they attach to the yellow spider if you have a problem.You can test the speakers they should also read 8 ohms.The woofers will still work but sound muddy.The tweeters will badly hiss before they fail.The tweeters you can remove and inspect the voice coils for damage.


    Fat piggy
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  • messiah
    messiah Posts: 1,790
    edited October 2010
    Different speakers piggy. He's talking about the RTA (real time array) speakers from back in the 80's. Yours are the RT (reference theater) from the mid 90's.
    "They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety."
    Benjamin Franklin, February 17th, 1775.

    "The day that I have to give up my constitutional rights AND let some dude rub my junk...well, let's just say that it's gonna be a real bad day for the dude trying to rub my junk!!"
    messiah, November 23rd, 2010
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  • fatpiggy
    fatpiggy Posts: 205
    edited October 2010
    Thanks messiah,
    Just noticed that,RTA12 not RT12 please disregard.Can find wiring diagram at http://www.polkaudio.com/forums/showthread.php?t=38755

    maybe that can help to look at the tweeter circuit.

    Fat piggy
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  • fatpiggy
    fatpiggy Posts: 205
    edited October 2010
    Had a quick look at the wiring diagram and yes thier is a fuse on the cross over board.So if the fuses are not blown, dosnt make sense that both tweeters cross overs have gone bad at the same time.Maybe a frequency adjustment on the amp is incorrectly set.

    Fat piggy
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  • Joe08867
    Joe08867 Posts: 3,919
    edited October 2010
    Or they are both blown. Which can happen. I have done this myself with SDA2's. There is a fine line between clean sound and clip.
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  • fatpiggy
    fatpiggy Posts: 205
    edited October 2010
    Joe he was saying he tested the tweeters and they are fine, so if the fuses are not blown something wierd going on.I think what I would do is retest the fuses with new fuses very cheap option.then recheck the tweeters.Still no go.Connect another amp and see if its the amp.If still no joy it has to be in the cross overs.Cant be anything else.

    Fat piggy
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  • Joe08867
    Joe08867 Posts: 3,919
    edited November 2010
    Oops missed that he checked them out. I would guess there is a connection problem in the crossover. It is weird that it is both speakers though. Do you have any pics of the crossover we could see up close?

    Maybe someone will see something.

    Like fatpiggy said check the fuses with new ones just to be safe.
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