No input = potential damage to tweeters ?

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No input = potential damage to tweeters ?

Postby Blair » Tue May 14, 2013 9:34 am

I was joking up the ST-70 today, and I was kind of in a hurry. I forgot to connect the input RCAs, and a few seconds after startup, I could smell a funky odor. Electric, but more like a motor smell. Turns out it was the tweeter on my left channel. I shut it down and blew on the tweeter to cool the diaphragm. It's a planar. Connected the input RCA and the tweeter seems to be fine and whatever caused the issue is gone. Is there an oscillation or something that can damage tweeters with no input?

Thanks!

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Re: No input = potential damage to tweeters ?

Postby Shannon Parks » Tue May 14, 2013 9:56 am

I think this is where a zobel circuit across the speaker output connectors can be beneficial to prevent some type of high frequency oscillation. I use a 0.1uf-10 ohm zobel circuit in my Ikes, and I think it's helpful on any power amp with a lot of feedback. Who knows what ultrasonic load characteristic these speakers have, and once you start adding long runs of speaker cable??? I think the 680 ohm resistor on the outputs of the MKIII achieved the same result.

Patrick Turner has some miscellaneous notes on the zobel use for stability:
http://www.turneraudio.com.au/education+diy.html

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Re: No input = potential damage to tweeters ?

Postby Blair » Tue May 14, 2013 10:03 am

Do you have a schematic diagram of your networks and how to install it?

I think I caught it in time to save the tweeter. I hope so at least. It's a $100 tweeter:(
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Re: No input = potential damage to tweeters ?

Postby Shannon Parks » Tue May 14, 2013 10:28 am

It shows up on the parts list and both logical layout drawings:
http://www.diytube.com/ike/IKEREVB.pdf

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Re: No input = potential damage to tweeters ?

Postby Blair » Tue May 14, 2013 10:32 am

Thanks Shannon!
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