Now Iblew the tweeter in the other R50?

BrettSelinsky · February 2005

I had blown a tweeter in my new R50's about 2 weeks ago. Well I thought the problem was my cheap a-- Sony reciever. So, I bought a new Yamy RX-V2500. WOW! What a difference. The sound is so much cleaner and better. But, I blew the other tweeter last night???????? I was playing it pretty loud (over 1/2)but the sound wasnt distorting or anything. And I had no clipping at all. Just quit working?
Polk sent a replacement tweeter at no charge ( and I really appreciated this / great customer service). And when I opened the box they sent me 2 replacements. So I do have a replacement for the one I just smoked.
Well to get to the point, I wonder If it was just a bad lot of tweeters and they sent me 2 because they've been having a problem?? And, if I do keep having this problem what tweeter would one recommend for a replacement for the tweeters that come with the R50's. I have RT15i bookshelves in the rear. Are they a better tweeter? Should I swap them?
Hopefully they were just a bad lot of tweeters.
What actually happens when a speaker blows? When I barely touch the center dome on the tweeter it comes back on? Just wondered?
Sorry so long winded.

Thanks
Brett

hoosier21 · February 2005

playing music OVER 1/2 or past 12 oclock (older equipment with analog volume control) will bring on clipping, I thing you fried the second tweeter just like the first one.

Turn the volume down, it is unrealistic to think you can play concert levels and not kill something in the system. No offence, but but 500.00 speakers and a 600.00 receiver will not play that loud without clipping. Clipping equals dead tweeters.

BrettSelinsky · February 2005

Ok I shouldnt have said half. It was -13dB. Is that too loud. Is that over half? And no offense taken but this $600 receiver and $280 speakers really sing clearer than anything I have ever heard. I couldnt imagine what you guys are hearing with your systems. But I have to start somewhere.

Thanks
Brett

danger boy · February 2005

congrats on your new Yammy.

My friend kept cranking the volume on his Onkyo and kept blowing tweeters in his CS400i. after three blown tweeters he finally gave up and went with another brand of center speaker. no more blown tweeters.

i can't say why some people experience lots of blown tweeters and others don't. I can only guess it's by playing the volume loud for extended periods of time.. like for hours and high volume. that was his case.. it may not be the same with yours however.

Tour2ma · February 2005

Doesn't necessarily take hours... driving a speaker to near it's limits will progressively warm voice coils and as it does the impedance drops. Dropping impedance demands more current, generating more heat, etc... until clipping occurs. And sustained clipping kills tweeters...

If rock is your music of choice, its relative lack of dynamics feed the above cycle very well... and fairly quickly...

The 2500 at 130 wpc, albeit near the top end of the recommended range for the R50, is a mid-power AVR, and I see nothing to indicate that it has significant current reserves beyond its power rating. You have not commented on it here, but I'd be willing to bet the your AVR is getting hot during your listening sessions and this would indicate that you are reaching its limits...

Listening at lower levels is the only solution with the gear you have, but you can rearrange your listening to help regain some volume... namely move closer... Halving the distance between you and your speakers will increase the SPL by 6 dB. So you can set your AVR to -20, rock on and see if everything holds together.

madmax · February 2005

Another possibility is that the second tweeter was damaged but had not given out yet. Before they blow the coil wires get very hot and sometimes short together. They may still play that way but tend to get even hotter with less power. I think you probably damaged both tweets with the sony.
madmax

Tour2ma · February 2005

Good observation, max...

I'd still urge caution in approaching the listening levels at which the last failure occurred, but it is possible that the Sony set up tweeter failure #2...

BrettSelinsky · February 2005

Mad max and Tour2ma I think your both right. I went home turned it on put a cd in turned it up to -13 and off went the tweeter in about 20-30 secounds. I really think the Sony may have got both of them. I just cant believe it was at to load a volume because it was not shrill sounding at all and it was a very pleasing volume. Can you hear clipping?

steveinaz · February 2005

Your tone controls are set to flat correct? Increasing treble past 0dB can also contribute to blown tweeters.

Tour2ma · February 2005

Clipping is sometimes accompanied by audible distortion, but it's major component is ultrasonic, in the 100 kHz area.

When a tweeter tries to reproduce this high of a frequency (as opposed to the normal upper limits in music of 20 kHz or so), it overheats and "fries".

Replace the 2nd bad tweet and approach with caution...

madmax · February 2005

You can hear it when it is way too much. The problem with cheap amplifiers of the sony range of power (not sure of exact wattage but close to the speaker limits) you end up not having enough power to stay away from distortion but yet have enough power to do damage before realizing it. There are two ways around this. One is to go with really low power and the other is to go with really high power. That may sound strange but with a much higher power (300 to 1200 watts) you can drive the speakers much louder with no distortion and little chance of damage.

Tour brought up another point that there are differences in music also. I have power meters on my equipment and I've noticed some music stays very low with huge peaks. That is very speaker friendly. Other music is constant and the meters don't jump around very much. (same continuous sound level throughout). With this type of music you have to watch your power setting much closer. I'm sure you can figure out which music is which and keep that in mind.

madmax

edit: Tour and I are always right except when we argue with each other in which case I'm always right.

Tour2ma · February 2005

max,
We've been agreeing wa-a-a-y too much lately...

madmax · February 2005

Read my edit on the previous post.

Tour2ma · February 2005

LOL... That EDIT could be "quote" worthy...

MacLeod · February 2005

Technically, clipping isnt what kills speakers. A speaker doesnt know the difference between a clipped signal and any normal one. It doesnt know the difference between a distorted or clean signal either. The thing that kills the speaker is too much power.

When an amp clips it can produce as much as twice its normal power. Say an amp rated at 100x2 @ .08% THD clipped would produce something like 200x2 @ 10% THD. So if your speakers are rated at 300 watts, you could clip this amp all day long and not hurt the speakers. That 10% is also why people mistakenly associate distortion with dead speakers when it was the doubled power that was the culprit.

So when you turned up your amp into clipping, it doubled its power output and thus ended the life of your tweeter.

Getting a bigger amp can only help in that youre less likely to clip it because you have more headroom and are more likely to get it loud enough before the amp clips. However, if you get a 150x2 amp and stick it on 50 watt speakers, you can kill them with a super clean signal just as easily and quick as a dirty distorted one.

hoosier21 · February 2005

MacLeod, that post is very confusing, and has some bad information in it.

Clipping

Amplifier distortion occurring when a high energy wave form (a very loud sound resulting in a large output) is input into an amplifier and the amplifier is unable to fully reproduce it due to power supply limitations or amplifier design limitations resulting in the audio output waves being cut off (the rounded tops sliced off resulting in short waves with flat tops). Clipping creates audible distortion and can be damaging to speakers especially if the clipping is hard and frequent.

Clipping generally occurs when an amplifier is playing at a high level and it is asked to output a large amplitude waveform (tall wave with lots of power). The amplifier clips when it does not have the power capability to correctly create the waveform. Instead, as the wave is built it hits a ceiling essentially not allowing the wave to go any higher. Since the amplifier cannot recreate the remaining portion of the wave rising above the ceiling, the wave is cut off.

Generally, the more power an amplifier has (especially relating to the quality of the amplifiers power supply) the more immune it is to clipping. For this reason, larger amplifiers tend to provide better quality sound at loud listening levels since they clip less often (if at all) compared to similar but less powerful amplifiers.

Clipping may be heard in loudspeakers as an abnormal, non-musical sound. It is unpleasant and it may damage speakers (with tweeters being particularly susceptible). This occurs because a speaker cannot produce the flat-topped waveform sent to it by the clipping amplifier.

In order avoid clipping, do not play a sound system at excessively loud levels and make sure the amplifiers being used are large enough to recreate the sound levels in the given space. Generally, use the largest amplifiers reasonable, as they are less likely to clip and damage speakers. It is much more dangerous to clip loudspeakers by using a small amplifier lacking in power than to use a large amplifier even if that amplifiers power ratings are greater than those recommended for a given speaker (distortion, and clipping in particular, causes damage not clean power from a quality amplifier).

hoosier21 · February 2005

good read

http://sound.westhost.com/clipping.htm

Tour2ma · February 2005

Originally posted by hoosier21
MacLeod, that post is very confusing, and has some bad information in it.

Agree... Does not agree with my readings on the nature of clipping.

And one side point in particluar about speaker ratings is inaccurrate. Speaker ratings are nominal ratings. Speakers can handle transients that many times their nominal rating. Julian Hersh showed this time after time for a couple decades.

Originally posted by hoosier21
Clipping

Since the amplifier cannot recreate the remaining portion of the wave rising above the ceiling, the wave is cut off.

Yup... turns a sinusoidal input into something approximating a square wave output.

Source I read decades ago went into the examination of what happens to the unreproduced input, i.e., the peaks that are "clipped" off. Their measured result was the creation of the ultrasonic element I referred to above.

While the cause of clipping is amp power limitations, this is usually associated with bass demands the amp is unable to meet. However, the impact of clipping falls upon the tweeters.

MacLeod · February 2005

Originally posted by hoosier21
Clipping

Amplifier distortion occurring when a high energy wave form (a very loud sound resulting in a large output) is input into an amplifier and the amplifier is unable to fully reproduce it due to power supply limitations or amplifier design limitations resulting in the audio output waves being cut off (the rounded tops sliced off resulting in short waves with flat tops). Clipping creates audible distortion and can be damaging to speakers especially if the clipping is hard and frequent.

Clipping generally occurs when an amplifier is playing at a high level and it is asked to output a large amplitude waveform (tall wave with lots of power). The amplifier clips when it does not have the power capability to correctly create the waveform. Instead, as the wave is built it hits a ceiling essentially not allowing the wave to go any higher. Since the amplifier cannot recreate the remaining portion of the wave rising above the ceiling, the wave is cut off.

Agreed. I didnt say anything contrary to this only added that when an amp clips it is making as much power as it possibly can given its input voltage which is usually double what it normally puts out at normal listening levels.

Generally, the more power an amplifier has (especially relating to the quality of the amplifiers power supply) the more immune it is to clipping. For this reason, larger amplifiers tend to provide better quality sound at loud listening levels since they clip less often (if at all) compared to similar but less powerful amplifiers.

Yup, agree with that too. But all amps will clip eventually. Its just that with more powerful amps you dont need to push them that far.

Clipping may be heard in loudspeakers as an abnormal, non-musical sound. It is unpleasant and it may damage speakers (with tweeters being particularly susceptible). This occurs because a speaker cannot produce the flat-topped waveform sent to it by the clipping amplifier.

This I disagree with. A speaker will produce a flat wave just as it will produce a sine or triangle wave. Its not the shape of the wave that is hurting the speaker but too much power. Go get you a 1000 watt sub and hook a 100 watt amp to it then clip the hell out of it. Itll sound like crap but the sub wont even whimper.

In order avoid clipping, do not play a sound system at excessively loud levels and make sure the amplifiers being used are large enough to recreate the sound levels in the given space. Generally, use the largest amplifiers reasonable, as they are less likely to clip and damage speakers. It is much more dangerous to clip loudspeakers by using a small amplifier lacking in power than to use a large amplifier even if that amplifiers power ratings are greater than those recommended for a given speaker (distortion, and clipping in particular, causes damage not clean power from a quality amplifier).

I disagree with this too. Again its not the distortion or clipped single that hurts the speaker. You take 150 watts of super, shiny clean power from the best amp on the market and run it thru a 50 watt speaker and youll kill it just as if youd ran a crappy Kraco amp signal thru it.

Tour2ma · February 2005

I was editing, while you were posting...

I disagree with your disagreements...

MacLeod · February 2005

I dont understand why this is confusing.

I agree with everything you guys are saying other than its not the distortion or the squared wave that hurt a speaker, but rather the substantial increse of power at the point of clipping. If the increase is within the power handling of the speaker tho, itll just shrug it off.

100 watts of pure distortion wont bother a speaker capable of handling 200 watts.

I hope some of my car audio homies come over here and help me out. Im getting outnumbered! LOL

Tour2ma · February 2005

Rallying the troops, eh?

I'm really arguing the ultrasonic created being the destructive force associated with clipping.

Clearly the only way to avoid clipping is to stay within the limits of a given amp. So if you want louder, you have to go with more power and exceeding the rating of a given speaker should be a non-issue in a home application where your ears should protect your speakers and you. Car audio differs when the objective of being the loudest on the block is added...

As for the waveform.... let's use your car as an analogy...

A sine wave is like gradually accelerating in the forward direction, holding a speed for a bit and then slowing to a stop before going into reverse, accelerating, sustaining, slowing and stopping then going into first and repeating.

A square wave is full speed forward, dead stop, full speed in reverse and repeat.

A triangle wave is full speed forward, full speed in reverse, etc.

It's easy to how mechanically destructive the latter two are for a car vs. the sine wave. The same is true for the drivers in the loudspeaker.

MacLeod · February 2005

This is fun. I Havent had a good debate in a while!

Originally posted by Tour2ma
As for the waveform.... let's use your car as an analogy...

A sine wave is like gradually accelerating in the forward direction, holding a speed for a bit and then slowing to a stop before going into reverse, accelerating, sustaining, slowing and stopping then going into first and repeating.

A square wave is full speed forward, dead stop, full speed in reverse and repeat.

A triangle wave is full speed forward, full speed in reverse, etc.

It's easy to how mechanically destructive the latter two are for a car vs. the sine wave. The same is true for the drivers in the loudspeaker.

That is a good analogy so Ill stick with it.

Say you accelerate to 25 MPH, then stop then reverse to 25 MPH. Big deal.

Now accelerate to Mach 1, stop then reverse to Mach 1. Squish!

Same with the clipping. If the clipped signal is at 500 watts and the speaker is able to handle 200 watts, squish. If its a 500 watt speaker and the clipped signal is at 200 watts then the speaker will have no problem.

There are only 2 things that will kill a speaker. 1- pushing the cone further than the suspension can handle. 2- Giving it too much juice which builds more heat than the speaker can dissipate.

The shape of the wave has no effect on either of these. Take a 500 watt speaker. A 200 watt signal, clipped and distorted all to hell wont make a dent. A 1000 watts of pure, clean, sonic goodness will tear it to shreds.

The shape doesnt matter. If the movement of the cone is within the suspensions limit and the power is less than the limit of the speakers ability to dissipate the heat then the clipped, distorted signal will not hurt the speaker.

So, again, Ill take an Orion H2 sub, capable of handling well over 1500 watts RMS, and you take a 100 amp and clip it til the cows come home and that badass Orion wont so much as be tickled.

Yeah, who's ya daddy?!

MacLeod · February 2005

Since Im on the subject of the badass Orion H2, check out this video.

I dont care what kind of audio youre into, home theater, home audio or car audio, this is just cool!

danger boy · February 2005

well maybe the tweeters can't handle the same amount of power given to them as say a mid driver or a woofer. or else maybe something in the crossover got fried when they were pushed that hard.

Tour2ma · February 2005

db,
Actually tweeters can handle remarkable amounts of power.

McL,
You're talkin' subs, and saying speakers and meaning subs
... I'm talking tweeters...

Been saying all along... Clipping kills tweeters ...
It's the #1 cause. Far more prevalent than overpowering them.
It's what this thread is about...

Sub's... different story... Even inside the house, subs are killed by being overdriven, bottoming-out. A sub won't even try to reproduce a 10 kHz signal, let alone a 100 kHz.

We are in agreement about heat being the culprit in voice coil destruction. I am saying is that if you ask a tweeter to reproduce a 100 kHz signal, an artifact of clipping an amp, it will "melt down" trying... A single, pulse of power will not have this effect.

Meanwhile back at the analogy...
Rate of change of direction is most important to mechanical devices which cycle. If you don't think so, then just get rolling at 5 mph and then throw your car into reverse.

danger boy · February 2005

I think you're right.

my friend who kept frying tweeters was clipping his receiver now that i think of it. it would some times shut itself down. just recently he added a 2 ch. amp and he hasn't had that clipping problem anymore. huh. go figure.

steveinaz · February 2005

Far more tweeters are toasted due to not enough power, than by too much---due to people pushing their under-powered amp too far, causing clipping.

Now, if this has changed for some reason in the last 40 years, I'd like to read about it....

BrettSelinsky · February 2005

Had the house to myself last night and did a little test. Ran that Yamy at -13dB to -7dB for about 1 1/2 hrs. No problems at all. Im almost positive the Sony got both of them. I wouldnt have done it but it was driving me nuts because there is no sound distortion at all and it sounds sweet. I cant believe the difference in sound between the two receivers.

Thanks

madmax · February 2005

Originally posted by MacLeod
I dont understand why this is confusing.
LOL

I'm not sure why you are confused either. Better get some of your car audio buddies in here. They can learn too.

Just kidding. In any case I can play my LSi7's with 600 watts per for hours. Good clean power.

madmax

Tour2ma · February 2005

Glad to read you're back in business Brett S....

Slept on this overnight...

Originally posted by MacLeod
Now accelerate to Mach 1, stop then reverse to Mach 1. Squish!

What was getting me were two questions:
- can something moving slower than the speed of sound create sound??? and...
- does a driver move at the speed of sound???
Let's see...

Speed of sound is around 770 mph or 1130 fps or 94 ips...

If a woofer is moving 1/2" total distance per cycle (not a big excursion... 1/8" out and 1/4" in and 1/8" out to return to starting position) in a response to a 30 Hz (pretty slow) sine wave input, it moves:
1/2" x 30 cycles per seond = 15" per sec
Of course this is an average speed since each cycle includes periods of acceleration and deceleration. Maybe the max speed is 20 ips, but this is still not the speed of sound... Hummmm.... I'd think you'd hear this :rolleyes:, so lower than speed of sound movement does make sound... Makes sense that the two are unrelated as the speed of sound through a medium is just its transmission rate and is not dependant upon the speed of the wave being transmitted...

As to the second question...
For the above excursion we'd have to reproduce a 141 Hz signal for the driver to reach the speed of sound... getting up there for a sub, but doable...
Of course 70 Hz with twice the amplitude (1/4" excursion, or 1" total travel per cycle) gets you to the speed of sound...

Bottom line... drivers do reach speeds of Mach 1...

Originally posted by MacLeod
Yeah, who's ya daddy?!

Want my addy so you can send me a Father's Day card???

Now Iblew the tweeter in the other R50?

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