Speaker Damage

[ehinton]

I have a Yamaha rxv-661 which outputs 90w per channel 7.1

I have a rc-52, and a pair of rf-52, SWS sub.

Theoretically I assume since each speakers handles at least 100w rms, then it should be impossible to blow these speakers with this reciever. But i know thats not how life works, because of bass overheating the voice coil. But then again I wouldn't want to turn it up to this point because I would be deaf in no time.

What I am asking is what really causes a speakers to be blown. I have the cross over on the mains and center on small/90 hz to keep excursion down. So should i be safe even at higher volumes, cause I just want to test to see how lound can they become before they distort a little, which I have achived ear bleeding volumes, but they still manage to stay clear.

Secondly If the speakers are still clear is it safe to assume that no harm is being done, such as an overheating voice coil.

[bigdaddy]

From what I understand if you push a receiver to the point of clipping that is where you can damage them. Too little power is worse than too much. As long as they sound clear I'd say your fine.

[ehinton]

Thanks BigDaddy, this is what I have assume, any other opinions are welcome as well.

[WMcD]

I would call what you're doing "pushing the envelope". Airframe designers have a graph showing combinations of airspeed and g-loading which defines safe operating combinations. Going near and beyond the limits is called pushing the envelope. It is suppose to be heroic to do so, but is really not a good idea from a safety standpoint. The same could be said of speakers with power and time combinations.

I blew out a tweeter in about 5 seconds with a test tone. I did not realize the test equipment was still on when I switched on the amp and then couldn't get to the power switch in time.

This is to say that in tweeters and mids, it appears that short term high power will just burn out the voice coil winding. You take the diaphragm and voice coil out and there is nothing much to see. The voice coil looks okay but someplace the very fine wire has melted. Some people IIRC have noted that failure can occur near the electrical terminal. Overall, the problem is that the wire is very fine.

An exception to this is one report from one of our moderators. He said that he's seen plastic midrange drivers just melted from the heat of the voice coil. It seems impressive to me that the voice coil survives that long to act as a toaster. I wonder whether such drivers use fero-fluid which transfers heat from the v.c. to the magnet structure.

I replaced two woofers in a non-Klipsch product owned by a young relative of mine about two years ago. I used an Xacto knife to remove the voice coils from the ruined units. The cardboard tube on which the v.c. is wound and glued is called the former. There was some charing in places. The glue had failed and the wire was a slinkey. The glue joint between the former and the diaphragm was damaged too and there was some deformation.

My guess is that the woofers were overdriven from some period of time. Hard to say how long but I'm thinking more than a minute and less than an hour. When they are going through a lot of excursion, the former and diaphragm bottom out against the magnet structure - hence the deformation. At the same time, or shortly therethereafter, there was probably enought heat build up to melt the glue. I don't know whether the wire eventually melted or it was mechanical failure of the wire / slinky.

The bottom line as I see it: Tweeters and mids fail usually because the fine wire burns out. In woofers the problem can start with mechanical and heat failure of the former. Of course a really good blast of power can simply fry the v.c. winding without mechanical damage.

Gil

[colterphoto1]

No speaker is blow-up proof. Too much wattage will deform voice coils. Too much distortion is instant tweeter death. Pro sound guys routinely use 2-4x the rated wattage of a speaker because they are smart enough to know that excess amp capacity for INSTANTANEOUS PEAKS is a very good thing. This does not mean that they peg the meters all the time. We would do well to use the same theory in our own sound systems. Have more power than necessary, but never use it for any kind of long term use.

Remember it takes TWICE the amplifier power to create only 3 db more output. TWICE. That's right.

If at any time your system sounds distorted, TURN IT DOWN, you are harming your speakers (and probably your ears).

Yes, this from the guy with 6 Klipsch PA's in his garage. But I do know how loud is too loud. And I've never burnt a Klipsch driver. Never.

Michael

[ehinton]

So is it safe to assume that as long as, excursion is kept to a minimum (visibly), then there should also be less movement and less heat?

But then you say that, underpowering a speaker is bad as well (clipping comes in when you try to get too much power out of the amp, and it just can do it)?

You can hear amp clipping, I have never pushed this reciever to this level, so should I be fine as far as the volume I have played it at so far (no clipping, no distortion, etc) , and assume that I amnot over/underpowering these speakers?

Besides if anyone has ears that can take what I have heard then it won't be long before you go deaf.

Thanks Klipsch for a great product.

[Islander]

No speaker is blow-up proof. Too much wattage will deform voice coils. Too much distortion is instant tweeter death. Pro sound guys routinely use 2-4x the rated wattage of a speaker because they are smart enough to know that excess amp capacity for INSTANTANEOUS PEAKS is a very good thing. This does not mean that they peg the meters all the time. We would do well to use the same theory in our own sound systems. Have more power than necessary, but never use it for any kind of long term use.

That's the simplest and clearest explanation of the relation between amplifier power and speaker power handling limits I've read in a while. It sums it up nicely.

There should never be any need to push the limits in a sound system. Either it plays loud enough or it doesn't. If it does, enjoy, it. If it doesn't, then buy the parts that will let it play loud enough.

[pzannucci]

Another thing you might be careful of is that typical 7.1 receivers don't put out what their specs say when running more than 1 or 2 channels. If you are running your surrounds that loud, you should definitely worry about clipping. 90w is very optimistic since their 130 watt receivers typically put out less than 50 watts per channel when running all channels. I would look for some technical write-ups on that particular receiver to give you a real sense of what it can do. You won't possibly see the woofer moving but could be frying a tweeter.

[ehinton]

So that raises my next question. I know what amp clipping is, but i do not know what a tweeter(horn), sound like before it about to blow, however I don't plan on playing the system at those volumes anyway.

the yamaha I have goes from

-80db to +16db, I never really play it past -20db, at -10db is where I was testing the speakers threshold, but as I said at that volume it really unbearable. I was just curious as to how speakers wattages are rated, and can they theoretically handle what I won't throw at them.

pzannucci(I think you made the most since, and my main worry was the tweeters being fried).

Thanks for all of your comments.

[colterphoto1]

Thanks Islander, that was very kind of you to say. Do you think maybe I could do this for a living? LOL

Here's another explanation I use when someone is trying to power a voluminous living space with, let's say Quintets. "Have you ever been to a concert" A- 'Yeah' - You know those really big walls of speakers they have there? We used to make those too. Behind a cinema screen can be 10 foot high stacks of Klipsch speakers. Sometimes it takes more equipment if you want it to be louder, bassier, clearer. It's a matter of expectations and dollars spent. Even Klipsch can't outrun the laws of physics. Big sound requires big boxes."

Distortion is the enemy. If you hear it, you're past the limit. Turn the wick down. (volume for you statesiders)

PZ is right on also. I usually give a 20 db allowance on the receiver for any long-term listening. If you receiver goes 0 db, -10 db, so forth, NEVER run above -20 for any length of time. Louder and you don't have any headroom. Headroom is 'power to spare' for peaks in music. If you push past that point, you stand a good chance of CLIPPING, which can damage speakers.

So it sounds like you are being a responsible Klipsch owner. Enjoy!