My tweeter blew! Why? (1 Viewer)

[RobP]

I recently upgraded my reciever from a cheaper Kenwood model to an HK 520. After I had hooked up my new reciever and had the house to myself I thought I would test the new unit out. After about 10 min of Metallica, I was very dissapointed when then the tweeter suddely stopped working on one of my Paradigm Monitor 7v.1 Thankfully I still have about 4 years waranty on them so It has since been repared. I found out they had to replace the tweeter's "diaphram".

Well the technician suggested maybe it blew because I was underpowering them and driving them too hard. Well I use to drive them just as hard with my old kenwood which could not possibly be more powerful than the new HK I purchased. Or as I thought maybe it was just a bad tweeter to begin with and its time had just come. I guess I'm just not exactly sure what causes a tweeter to blow like that. Any insight would be greatly appreciated. Thanks.

Rob

 

[Evan S]

Most tweeters cannot handle extremely high power loads with any distortion. Some (as in Paradigm's Studio line and other "reference" products from other manufacturers) can handle more power, but most cannot.

When you went from the Kenwood to the HK, you may have stepped down in watts per se, but actually the HK is a high current receiver. It's probably going to play louder and with more "real" power than the Kenwood. If your speakers cannot handle high wattages, if you played the HK at a high level for a decent period of time to where you could hear audible distortion in the music, you are putting the tweeter (and the whole speaker for that matter) in jeopardy.

Most times a speaker "fries", it's in the tweeter, as tweeters typically cannot handle the power reserves that mids and woofers can.

Why this never happened with the Kenwood I cannot tell you. Maybe the Kenwood produced a lot of the damage and the HK simply put that baby over the edge. If you weren't hearing any audible distortion in the music prior to it blowing, I would say it was just a defective driver. Otherwise this could be the cumulative buildup of prior damage.

 

[RobP]

Thanks for the quick reply Evan. I don't have the most trained ear but I didn't hear any distortion before the tweeter went. My tech explained to me that a lot of the time what we percive as loud is actually distortion. He went on to say that they (in the shop) have cranked some systems to their limits with thousand dollar Mcintosh amps yet it didn't sound loud to them because it was so clean. So I guess he was suggesting It was distorting but I only percieved it as being loud. Whether or not this is the truth I cannot say for certain.

Rob

 

[John Royster]

True about loud vs distorted. However, most metalica adds some distortion to their guitars (the good kind) and you can sometimes interpret this to be nice and loud. When in fact it is nice and clipped (overdriving the amplifier).

Clipping the sound is very audible and disaster for a speaker. Only time I've blown tweeters has been on a Van Halen solo. Crossovers actually melted as well. Way to go EDDIE!

 

[Ted Lee]

i'm guessing here, but i suspect you blew the tweeter because you were pushing your amplifier too hard.
when an amp "clips", the sound wave-form is not a normal hump, instead it looks more like a plateau. that is, the top of the hump is flat.
i'm not really technical, but i know that speakers don't like that kind of shape and it often causes all sorts of problems.
if anyone has more insight on this, or if i'm totally off-base, please let me know.

 

[Legairre]

Rob,

What's you receivers min and max treble? Where did you have the treble set and at what volume where you playing it at when it blew? Before I knew what good sound was I blew both my tweeters with the treble maxed and the volume way too high.

 

[John Royster]

Maybe I can elaborate on clipping and why it is so bad for speakers. This kind of follows the "It is easier to harm speakers with a 30 watt amp than a 200 watt one". When an amplifier "clips" it looks like someone took some scissors and clipped off the highest peaks of the waveform (positive and negative). These clipped portions are a kind of direct current, DC. Direct current very bad for speakers - remember there is a tiny electo magnet in your tweeter wound with very thin copper wire. strong direct current to this copper wire = excessive heat and eventual melting. Most of the sound from a speaker comes from the tweeter so they get the brunt of the damage.
So, clipping a 30 watt amp can and will blow speakers while running at peak of a 200 watt will just sound good
Generally most components are at their limits when the volume knob is in the 12:00 position. That's the way it used to be but I'm not sure now adays. Let your ears tell you. If it sounds compressed and harsh - you're playing it too loud.
edit - oh yeah. HKs are good strong current amps. when you clip 'em you're sending some serious juice to those poor little tweeters.

 

[Patrick Sun]

Exactly how loud were you listening to Metallica? You'll need a SPL meter to measure the SPLs to determine the loudness.

 

[Marc H]

You can't rule out that the tweeter may have been defective to begin with too.

Rob, You said 'After I had hooked up my new tweeter'

I gather it's not the first one?

 

[Sean Conklin]

Why this never happened with the Kenwood I cannot tell you. Maybe the Kenwood produced a lot of the damage and the HK simply put that baby over the edge.

Oh sure blame it on the Kenwood
The Kenwood amplifier section is very under rated IMO(and some other respected peoples opinion). Kenwoods actually perform very well in the continuous power output range(RMS).
Kenwood may rate their receivers in peak power(usually 100 watts), but they have been proven to play at 50-55 watts RMS with less than 0.06% THD all channels driven and in stereo, and are capable of clipless power up to 95-100 watts (0.7% THD). The receivers that have demonstrated these figures are the 406,407,409,506,507,509 models.The 410 and 510 are slightly better in the RMS and peak power stage.
The H/K, which I find to be an awesome product, shouldn't have underpowered your tweeters. I think the 520 is rated 75x5 watts RMS, but I have not seen any peak power THD specs. But I'm sure you do not have an underpowered speaker situation.
I would blame the tweeter or the Metallica for the damage.
Don't underestimate Metallica's distortion factor, they use huge amounts of distortion and it's possible the tweeters did not like it.

 

[Jack Gilvey]

Don't underestimate Metallica's distortion factor, they use huge amounts of distortion and it's possible the tweeters did not like it.

Recorded distortion like that would not be delivered to the reproducing tweeter as a clipped waveform unless the receiver itself were being overdriven (just like any other signal), so I don't imagine that James' raging Mesa Boogies had anything to do with it.

 

[RobP]

Thanks for all the replys guys. Sorry it took so long to respond but I've been away for a couple days. Anyways as far as how loud I was playing; I used an SPL meter and VE to set the reference point at 0 on the control knob. I was mostly playing at 0 but at times I would jump up to +1 or +2 just to see if it could handle it. I know thats driving them pretty damn hard but I didn't hear any distortion or clipping infact it was sounding pretty good to me. But again maybe my ear is just untrained. I was surprised the way the tweeter just suddenly went 100% dead. I didnt hear anything unusual leading up to it and the tweeter made absolutely no noise after.

Rob

 

[RobP]

Note: My mistake, In my first post I ment to type, "After hooking up my new reciever..." not, "After hooking up my new tweeter". I just went back and fixed the error.

Rob

 

[Legairre]

Rob,

When my tweeters blew they just went. There wasn't any buzzing or hissing or anything. All of a sudden I noticed I had lots of mids and bass but no highs. No warning signs at all just. One second I had them the next they were gone. It sounds like the same thing happened to you. It sounds like too much volume and treble. It sounds like the receiver was clipping even though you couldn't tell.

 

[RobP]

Yea that could very well be. One note; I keep the tone control set to off, So there was no excesive treble being added.

Rob

 

[Patrick Sun]

The other possibility is that a capacitor in the tweeter's crossover circuit gave up the ghost and is presenting an open circuit condition for the tweeter.

 

[Allan Jayne]

If the audio is unusally rich in higher frequencies, the tweeter will blow long before the speaker system is receiving its rated power.
The distortion that some musicians add to their instrumentation generally consists of more higher frequency content than typical sounds found in nature and made by acoustic instruments.
If an amplifier is driven to clipping, the high frequency content of the output goes way up even if the tone controls are set to minimum treble. This is one of the consequences of "cutting off the top of a sine wave leaving a flat top". This is why "a 30 watt amplifier can do more damage than a 100 watt amplifier". A full understanding requires expertise in mathematics and Fourier analysis.
Video hints:
http://members.aol.com/ajaynejr/video.htm

 

[Scott O'Keeffe]

Ha, first I had two Kenwoods that blew up by themselves. (VR-2080).
Then I blew a tweeter from one of the same Kenwoods.
I'd say it was the Kenwood and not Metallica.
Hehe, in all seriousness, I'd say it was the Mighty Met at crazy volume coupled with the HK clipping.
Don't do that anymore!