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Tweeter Replacement

IslandCamIslandCam Posts: 4
in Vintage Speakers
Hello Everybody,
I am new to this forum, and new to vintage audio gear, but I have rapidly gone down the rabbit hole.I recently purchased some RTA 11TL's. I'm am powering them with a Cyrus One (class D 2x100watt)which is pretty kick ****. Loved the sound coming from my system. Partied a little hard with my friends last night and much to my dismay( I believe) I blew a tweeter on one speaker. Looks like I need replacement RD 0198's for my SL3000's. I will pull them out and put a meter on them next.
My questions are as follows:

1. I was playing music pretty damn loud but only about 60% on the dial. I thought these speakers could take that. Is it common for these tweeters to blow or am I idiot for pushing them to hard?
2. Is it possible that the crossover has a problem? should I replace these too? How do I test this?
3. Should I ohms test all the speakers?

Thanks for any advice.
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Comments

  • DaveHoDaveHo Posts: 2,949
    100wpc really isn't that stoudt of an amp. Amp was probably clipping. That'll kill tweeters fast. Just because the volume knob goes to 11, doesn't mean you can do so safely. RDO198 is the correct replacement for sl3000.
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  • F1nutF1nut Posts: 45,429
    1. I was playing music pretty damn loud but only about 60% on the dial. I thought these speakers could take that. Is it common for these tweeters to blow or am I idiot for pushing them to hard?

    The speakers will take a LOT more power than your 100wpc integrated. Your problem is the integrated ran out of clean power and sent clipped signals. Clipping kills tweeters. The golden rule, never go past half way on the volume knob. There are exceptions of course, yours isn't one.

    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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  • GardenstaterGardenstater Posts: 1,663
    The schematic doesn't show any polyswitch. Does it have a fuse? Manual makes no mention of a fuse. Hmmm.
    George / NJ

    Polk 7B main speakers, most mods comp. (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Crown D150 amp
    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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  • IslandCamIslandCam Posts: 4
    Didn't see any when I took out the crossover. Just wondering what else could be wrong before I spend $150 on new tweeters. Is it likely that other stuffs has blown up? I'm a total newbie my speaker wires are quite long 60 feet and only 16 gauge could this have caused a problem too.I thought of maybe taking the tweeter out of the working speaker and putting it in the damaged one to check if that is truly the problem, is this a bad idea?
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  • GardenstaterGardenstater Posts: 1,663
    edited August 2020
    60ft x 16AWG???? That's like having 15ft x 22AWG or 7.5ft x 25AWG. Way too much DCR and puts a major whammy on the Damping Factor!. The resistance of that wire is almost 0.5 Ohm, so your amplifier is no longer seeing a load of 6 Ohms but more like 6.5 Ohms assuming your connections are really good. If your amp has a damping factor into 6 Ohms of 100 normally, it has now been reduced to around 11 by those long small wires.

    But yeah it's definitely a good idea to diagnose by switching the tweeters and see if the problem stays in the speaker or follows the tweeter. Most likely you blew a tweeter and apparently there is no fuse or polyswitch protection.

    PS: Important! Check both tweeters with a meter for DCR first. Make sure neither of them are shorted or have abnormally low DCR.

    PPS: The SL3000 should have a DCR of around 5.4 Ohms. See https://forum.polkaudio.com/discussion/182943/the-tale-of-5-tweeters-sda-tweeter-replacement-guide/p1
    Post edited by Gardenstater on
    George / NJ

    Polk 7B main speakers, most mods comp. (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Crown D150 amp
    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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  • F1nutF1nut Posts: 45,429
    edited August 2020
    Sorry, but there's no good reason to have 60 foot runs of speaker cable in a house. Regardless, that's not the reason you cooked a tweeter. Correct, there is no polyswitch in the RTA 11TL crossover.
    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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  • GardenstaterGardenstater Posts: 1,663
    edited August 2020
    I would check your amplifier for DC offset also to make sure nothing is amiss there. Probably should do that first:

    http://hudsonvalleyhifi.com/tutorials-and-tech-support/checking-for-dc-offset

    Also, 0.5 Ohms of additional resistance ain't a whole lot as far as the amplifier is concerned BUT it does mean that to get the same SPL from your speakers, which is when you the operator decides the volume control is up high enough for your *needs* :) , the amp has to work a little harder to do that, and therefore is a bit closer to where it might clip on some dynamic transients.

    PS: The manual says power into 6 Ohm load (both channels driven) is 110W. It doesn't say 110W per channel though. I'm wondering if your amp may be more like 55W per channel. It's much easier to damage speakers with low wattage amps being driven closer to their limits because you will get clipping much more easily.
    Post edited by Gardenstater on
    George / NJ

    Polk 7B main speakers, most mods comp. (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Crown D150 amp
    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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  • IslandCamIslandCam Posts: 4
    Thank you all for the advice.I have more learning and work to do!
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  • IslandCamIslandCam Posts: 4
    After testing for DC offset,I'm Getting 31 mvolts on one side and 19 mvolts on the other. I guess this could be part of the problem. Is this enough to help blow speakers?
    Guess I should take it in.
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  • DaveHoDaveHo Posts: 2,949
    No, those readings are fine. Anything less than 50mv is ok. Over that the effects may be become audible. Would take much more than that to cause real issues. Besides, huge DC offset cooks woofers not tweeters.
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  • stevepstevep Posts: 179
    edited August 2020
    DaveHo wrote: »
    Besides, huge DC offset cooks woofers not tweeters.

    Because the series capacitor in the tweeters crossover tends to block DC.
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