tweeters shut down on sda's

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gearhead
gearhead Posts: 3
edited August 2001 in Technical/Setup
I recently bought a pair of sda 1 c's, and at moderate volume levels the tweeters shut down. By moderate i mean # 4 on the volume control. I have already called polk and they sent me new poly switches(fuses). At least I think that was the term used. Anyway I soldered the new ones in the xover and I still have the same problem. I called polk back and they said they couldnt help me. I dont know what else that it could be. I am using a NAD 218 power amp @225wpc to power them. Could the tweeters themselves be at fault? They still have the silver coil dome tweeters in them. Any suggestions would be helpful.
thanks in advance

David
Post edited by gearhead on
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  • JohanK
    JohanK Posts: 29
    edited August 2001
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    My brother had this problem with a pair of monitor 10Bs. He took out the protective thingy and soldered in some wire. Of course, there is less protection for the tweeter when this is done.

    I just bought some used Monitor 7Cs and I'm having the tweet shut down also at 'loud' listening levels. I'm contemplating removing the protective relay also.
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  • BobMcG
    BobMcG Posts: 1,585
    edited August 2001
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    Hi David,

    If I remember right, you used to be a member of my SDA Club and asked how to fix your tweeter cut-out problem. I suggested getting the newer, upgraded tweeter protection devices (semi-conductors) from Polk. You've done that and STILL have the problem? Not normal. It's a new one on me. (Seems like a new one on Polk too.) This is a fix that normally works.

    Saying you run your volume control on #4 doesn't tell me much.....do you know how many dBs down this is?
    What's your pre-amp?

    The NAD 218 power amp, 225watts per channel. I take this as meaning 225 watts p/c RMS into 8ohms?
    Just out of curiosity, do they offer a watts p/c RMS into 4ohms measurement for this amp?

    On the surface, it wouldn't seem you're UNDER-POWERING the speakers, but it still sounds to me as though the amp is LOOSING CONTROL of the current sent to the tweeters. (For whatever reason... amp problem?)
    I would suggest you try using a different amp for a while. The only problem might be, once the stock self re-setting thermal protection devices started tripping, they got real trigger happy... I've never heard of the replacement ones popping open, so I'm not sure if they will follow suit. You can only try another amp to see.

    BTW: I don't believe the tweeters are the problem, and personally, I wouldn't hard-wire the crossovers to bypass the tweeter protection. (Less protection? How about NO protection.) This could cost you your SL2000s which aren't currently available.
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  • JohanK
    JohanK Posts: 29
    edited August 2001
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    There is still some protection afforded by the crossover. For example, will the tweeter in the 3000p take 200W continuous power...of course not. So why doesn't it blow when one feeds the 3000p 200W?

    BTW, is there any chance that the SL2000 can become available again? IMO, it's a better sounding tweet than current Polk tweets.
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  • BobMcG
    BobMcG Posts: 1,585
    edited August 2001
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    Let me rephrase:

    If you bypass/ remove the tweeter protection circuit from the crossover, guess what? You have NO tweeter protection circuit any more!!!

    Do you like it put that way better?


    And I too, feel the SL2000 is a fine tweeter.
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  • JohanK
    JohanK Posts: 29
    edited August 2001
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    Yes. :)

    Bob, the SL2000T tweeter is available. Do you know how this tweet differs from the SL2000? Thanx.
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  • BobMcG
    BobMcG Posts: 1,585
    edited August 2001
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    That's a good question. I don't know off hand. I haven't looked through all my Polk information yet. But, if I were to throw out a guess... seeing as how the SL2000 is a silver-coil polymer-dome model, maybe the SL2000T refers to it being a trilaminate polymer dome model.

    Polk Ken? Can you shead some light on this?
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  • JohanK
    JohanK Posts: 29
    edited August 2001
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    I did some digging.

    http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=1259187384

    Notice the SL2000T on the box; the tweets sure do look like the ones in my 7Cs.
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  • BobMcG
    BobMcG Posts: 1,585
    edited August 2001
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    I believe the "Part Number" for the SL2000 1" Silver-Coil Polymer-Dome Tweeter is "SL2000T".

    And it happens, although it's still listed in Polk's parts list, to be out of stock and not available from them.
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  • JohanK
    JohanK Posts: 29
    edited August 2001
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    Thanx for the info Bob...I appreciate it.
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  • gearhead
    gearhead Posts: 3
    edited August 2001
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    Hi Bob,

    Yes you are correct, I used to be a member of your sda club. At that time I was using a pair of sda2a's. And the tweeter problem I had, was fixed with a new tweeter because it eventually quit working. The sda1c's I just recently bought. As far as the pre amp, (don't lol too loud) im still using my Yamaha receiver as a pre amp until i can get another one. Although Yamaha is decent equipment they tend to on the bright side (too bright?). The amp only shows specs for 8 ohm loads of continuous power. But it does list a short term power rating @4 ohms of 470wpc.

    I unfortunately don't have another amp to use. But I have used other speakers with this amp and I dont have any problems. Very loud and clean. Even at the 2oclock position on the volume it sounds very good with my other speakers. The other speakers I have are a pair of AR 428ps and a old pair of Pioneer hpm 100's.
    Hope this helps, thanks again.

    David
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  • BobMcG
    BobMcG Posts: 1,585
    edited August 2001
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    Hi David,

    It looks like you could be the proud(?) owner of a unique problem. I don't know what to say except for checking out the 1Cs with another amp. I know you probably don't care for the idea, but if I were you, I'd see if I could get another pair of slightly higher value semi-conductors to install too. Or, if that's not recommended by Polk, I'd go ahead and re-install another set like the ones Polk sent you, and then try another amp. I wouldn't give up on the 1Cs though.

    BTW: Did you find a SL2000 to replace the bad one in your 2B?
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  • JohanK
    JohanK Posts: 29
    edited August 2001
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    David, here are some:

    http://www.partsexpress.com and select Raychem under Search by Brand Name

    I think (but not positive) that Polk uses the equivalent to the RXE050.
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  • crystal-clear
    crystal-clear Posts: 19
    edited August 2001
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    I had to replace the tweets in my sda srs 2.3's. 2 of them sounded like they were about to leave me, so I went ahead and replaced all of them (6) with new ones. Anyway, I have the 4 other origional SL3000 with the date of manufacture on the back. They sound and look fine. If anyone is interested, let me know what they are worth to you. You can e-mail me if you are interested;

    Boobman@bellsouth.net

    I will honestly answer any questions.

    Chow.....Yall


    Crystal clear:D
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  • gearhead
    gearhead Posts: 3
    edited August 2001
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    Hi Bob,

    I ended up getting a SL2500 for the sda2's, because I was told the SL2000 was no longer available. Which was fine I guess, because the other speaker already had a SL2500 in it.

    I will talk to Polk again to see if they recommend a slightly higher value semi-conductor. I guess I will have to look around to see if I can find another amp to try with these speakers. I just have to wonder why I dont have the same problem with my other speakers. Thanks for your time guys.

    David
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