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post #1 of 9 Old 03-30-2014, 04:02 PM - Thread Starter
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I was wondering if someone can please tell me whats going on with my speakers. First of all they are Polk RTi A7s. They were hooked up to a Sony 555ES receiver in my basement room as a secondary stereo system. Anyway, I was jamming out semi-loud when the music started crackeling real bad so I rushed and turned off the receiver. When I turned it back on the sound was terrible, like it had no bottom or top end, no dynamics what so ever. Just a low flat sound. I tried another cd player and it was the same. Even tried different wires and cables. Sadly, I thought my 15yo receiver had finally died. Well, I bought a new integrated amp (Onyko A-9070). When I hooked everything back up to my new amp, guess what, it still sounded real bad like before. So I dragged out an old pair of Infinity R5 speakers that I had in the closet and hooked them up and wha-laa, sound is back. So, it looks like my Polks are the culprit. BUT, what in the world could cause BOTH speakers to suffer the same fate?? By the way , the Sony receiver also works fine with different speakers. I did a side by side comparison with the Infinitys and the Polks. The Polks are definitley bad. Thanks for any input. Mike D.
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post #2 of 9 Old 03-30-2014, 08:07 PM
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You turned it up more than the amp / speakers could handle. Whether it was because the amp was clipping the waveform or it was just too much power for the speakers to handle is the question......

I would guess the former.
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post #3 of 9 Old 03-31-2014, 04:48 AM
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Originally Posted by RayGuy View Post

You turned it up more than the amp / speakers could handle. Whether it was because the amp was clipping the waveform or it was just too much power for the speakers to handle is the question......

I would guess the former.

Actually, clipping doesn't affect speakers. It affects amplifiers and the sound of the music. Too much current is what fries voice coils. In other words, too much power.
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post #4 of 9 Old 03-31-2014, 04:59 AM
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wow just wow.

clipping doesn't effect speakers?

rolleyes.gif

Krell Evolution 900e x 7

Bose Jewel speakers.

 

Jealous of my speakers?

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post #5 of 9 Old 03-31-2014, 05:34 AM - Thread Starter
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The Sony is a 120w receiver, and it was turned up about halfway. Speakers can handle 300w. I dont believe they were overpowered.
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post #6 of 9 Old 03-31-2014, 05:36 AM
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BUT, what in the world could cause BOTH speakers to suffer the same fate??
Playing both of them way too loud. rolleyes.gif
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Originally Posted by FMW View Post

Actually, clipping doesn't affect speakers.
Woofers, no. Tweeters, yes.
http://www.jblpro.com/pub/technote/lowpower.pdf

The ultimate reason why clipping can destroy tweeters is over-powering, but it is clipping that allows a low powered amp to generate enough power to cook tweeters.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
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post #7 of 9 Old 03-31-2014, 06:23 AM
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Quote:
Originally Posted by fatbottom View Post

wow just wow.

clipping doesn't effect speakers?

rolleyes.gif

That's right. What destroys speaker voice coils is excessive current. Excessive current is the issue whether clipping is present or not. Did that wow you as well?
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post #8 of 9 Old 03-31-2014, 07:02 AM
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how much current will make a speaker catch fire

i saw that on yoo tube

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post #9 of 9 Old 03-31-2014, 12:33 PM - Thread Starter
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I decided to ohm out the drivers starting with the tweeters and what I found is that both tweeters are reading "open". So its obvious that I blew both tweeters at the same time. I already blew up a mid driver in these last month. These speakers are very unreliable. Ive owned a pair of cheap Infinity R5s that play way louder than I every played these Polks with the same receiver. The Infinitys are 15 year old and still going strong. I played the Polks loud, but never "that loud" The receiver's volume knob never goes past halfway. Luckely I have just finished building a pair of Paul Kittinger's "Marcato" speakers. And after hearing them, I realized how poor the Polks sound (in comparison to the Marcatos). But of course they are a "cheap" speaker. But they look good. Maybe I will plant flowers in them.
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