What specs would you look for and compare between products if your second top weighted criteria (beyond sound) for the purchase were speakers which would have less of a tendency to overreach (self-destruct or blow) no matter what was thrown at them. I see a lot of comparison between the ‘voices’ of speakers but not their sensitivity to being turned into a audible room vibrator effects machine.

I’m not referring to frequency range specs here although I know that frequency range affects the life of speakers if they are subjected regularly to frequency’s beyond their built-in capabilities.
I just read an interesting article (taken with a grain of salt) as it was produced by amp manufactory with some sort of individual controls for limiting each channel. That speaker manuf. build assuming that greater energy is demanded by lower frequencies and the clip rate that occurs at lower frequencies puts a ceiling on hard the tweeters will ever be pushed. The article put forth the question then why do tweeters blow more often and went on the discuss how modern amps handle and reduce the horrific effects of clipping to a point where the listener is often not even aware clipping is occurring. Then related the idea that ‘compression’ actually results in blown tweeters.

It got me to thinking…I know the component parts of a speaker, - the quality of the wire in tweeter coils as regarding its ability to dissipate heat and so forth…will directly affect the life span of the speaker.

How do you shop and what do you look for in speaker build, when this is a concern?

This is a new arena I want to research as time allows as I am already toying (bad girl) with the idea of a speaker upgrade, (at least across the fronts).
In addition what are the audible sound characteristics of clipping Vs distortion?
Did a web search on this topic and ran into unrelated subject matter.

Any thoughts?

Lena,

It's kind of hard to answer a question like this. The most obvious answer would be to look at the rated power handling of the speaker. However, as with most published specs on consumer electronics, it's probably way overrated.

There are a number of things that can blow up a speaker. You can overheat the voicecoils of the drivers, which can literally melt down the wire, causing shorts. The heat may sometimes melt the glue on the voicecoil former, which then binds to the magnet assembly, and locks up the speakers. These would all be considered "thermal" power handling issues. Most often this is the rating used for a speaker.

The other way speakers typically blow is from over excursion - that is, the cone/dome moves in or out further than the driver can handle. This can happen on both tweeters and woofers. Excursion is related to frequency, such that, the excursion necessary to maintain a constant SPL increases to the power of 2 or 4 (can't remember which). But basically, the lower you try to play, the bigger and bigger the physical demand on the driver's suspension parts (spider, and surround, mostly). If you start throwing the cone/dome in and out really far, the voice coil or voice coil former can actually "bottom out" and slap into the back plate of the driver and physically deform the voice coil. If you smack it hard enough you can mangle it enough to permanently destroy it.

I think it's fairly well accepted that there is a lot more energy in lower frequency material.

Now on to the matter of clipping vs. distortion. Clipping is actually a form of distortion. Distortion is anything that changes the original signal. To put it bluntly, speakers are distortion machines! Of all of the things in your audio chain, the speakers mess with the sound the most. The perfect loudspeaker would recreate the input signal exactly, and that's not even close to the case.

To visualize what the different kinds of distortion are, think of a sine wave. Looks nice and smooth, with peaks and dips. Now chunk off the tops and bottoms of those waves, leaving a flat line. That's clipping. It happens when the amplifier runs out of voltage. The effect this has on a speaker is presenting it with something like a square wave. Some would argue that this is the equivalent of giving the driver +DC and -DC voltages. That's sort of true, but the reality is that it is a bunch of really high frequencies laid on top of the original. Ok, way to technical there. Anyway, it's bad for your speaker because it suddenly throws way more energy at it that it was dealing with before. Lots of times that's what blows tweeters, but it can be equally bad for midrange and bass drivers as well.
Compression is a method for dealing with clipping. Rather than chunking off the top of the wave, they squish it down so it still fits within the amp's voltage limits. Basically, you end up suppressing loud peaks. Compression is actually a good thing for your speakers, keeping them from the nasty clipped signals. To your ears, it's not such a great thing, as it can substantially mess with the sound.

Now, how do you know what speakers are going to be good? That's even harder. Unless you are able to take the speakers completely apart or know the specific drivers being used (and just as importantly the crossover points and slopes) it's really hard to guess what's going to live longer than another speaker. Unfortunately, the only thing a manufacturer is likely to provide you with is an RMS/Max power handling rating.

Now, to keep your speakers from blowing up, here are a few things you can do. Make sure that the amp you are using is putting out clean power. Oddly enough, using a really big amp that puts out more power than your speakers are rated for isn't necessarily a bad thing. Just make sure you use self restraint. This will avoid compression and clipping. Also, when you cross your speakers over to a sub, make sure the crossover point is sufficiently above the lower limits of the speaker's frequency response. This is particularly important for ported speakers. Below the port's tuning frequency, the woofer's excursion rises very rapidly, and can cause bottoming with only a few watts in some cases (at very low frequencies). If your speakers are sounding "strained" at all, you are probably feeding them with either too much power, or an unclean signal, either of which will probably kill your speakers prematurely.

So in conclusion, I don't have an answer for you, other than your only really safe bet would be to buy pro sound speakers, in which case you could hold a rock concert in your living room with complete peace of mind.

Jason

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Thanks Jason!
Basically, you end up suppressing loud peaks. Compression is actually a good thing for your speakers, keeping them from the nasty clipped signals. To your ears, it's not such a great thing, as it can substantially mess with the sound.

I thought I saved it in favorites but am not spotting it. The article I read suggested that the speaker manuf. are geared towards compression on the lower frequencies as this is what draws the most energy. However the reason tweeters blow more often is that net effect of compression when geared towards lower frequencies allows the higher frequencies to increase too close to the cutoff (the top and bottom of a very square sine wave charted during clipping) allowing those frenquecies too much uncontrolled range at higher dB. (I’m making a mess of wording this don’t know the proper jargon.)

Reality is that it is a bunch of really high frequencies laid on top of the original
splain please? Or know the way to a good link regarding?
Oddly enough, using a really big amp that puts out more power than your speakers are rated for isn't necessarily a bad thing. 770
Just make sure you use self restraint. Ummmm, I believe that might be becoming a problem around here particularly with satellite class speakers.

pro sound speakers, in which case you could hold a rock concert in your living room with complete peace of mind. Wouldn’t that be…. love…a…lee…

I guess that my take on your topic is that you are looking for speakers that will have a greater "impact" in your room over your satellites. It seems you are looking for a high sensitivity speaker that sounds good and doesn't cost you an arm and a leg. A high sensitivity allows a speaker to reproduce music and movies at a higher level with smaller amplifiers, or to put it another way, will demand less from your current amp (that's a broad stroke) to reach the "impact" you are searching for. Head over to your Klipsch dealer to take a look. This is exactly what they design for. SOme people are not fond of the sound, but I beg to differ. I would also suggest looking at the Reference line from Paradigm, which has pretty decent efficiency. These types of speakers, IMHO, are what you are looking for since you will have less of a chance of putting your amp into clipping.

Here's the longer explanation of how clipping works. Remember that truncated sine wave? What is happening in reality is that you are generating a whole bunch of "harmonics". Ok, crack out your Calculus book. Ever heard of Fourier? Basically, you can recreate any wave shape by adding up a bunch of sine waves at varing frequencies and amplitudes. To make a square wave (which is what a clipped signal starts to look like), you take a base frequency, and continue to add in the odd order harmonics. So if you had a clipped 300Hz, I think you end up with harmonics at 900Hz, 1500Hz, 2100Hz, etc. (I think that's right?). As the frequency rises, the amplitude of each of the harmonics decreases. However, if you had a high energy 300Hz tone, the harmonics may end up having lots of energy in them compared to what a tweeter might normally see at a given frequency. That clear things up any more - didn't think so...

My usual advice at this point would be to build some speakers yourself. I'm a huge proponent of DIY speaker building, for a number of reasons. First, you get awesome speakers for a fraction of the cost of a what you would pay at the retail store. (And yes, they most likely will sound BETTER) In your case, you would have the added benefit of knowing what's going into your speakers - the (true) power handling of each of the drivers, the quality of the crossover, etc. There are lots of proven designs out there. There are even several companies that sell "kits", some with and some without prebuilt cabinets. Your family obviously has some mechanical ability, so the cabinet building may not be out of the question.

Thump, thump (stepping off the soap box)

Jason

Lena,
If you really want a bullet proof speaker, I'd recommend you look at B&W or Wharfdale- especially those models using Kevlar drivers. Sorry-couldn't resist. My recommendation- find what you like, (be sure to spend more than you originally budgeted for!) sound-wise, then look within that manufacturer's models for those that will meet your room and listening requirements. By that, I mean that it sounds like you may have your HT set up in a fairly large room. If so, make sure what you buy doesn't have to be overdriven to fill the room with sound at the levels you (or other family members) like to listen at. The dealer or manufacturer should be able to help with some ideas on what models to look at within the different brands based on your room size. As for subs- if you have a big room- get 2 woofs. When you settle on what you like, at least take the mains home and try them in your room. If you blow them, take them back and plan on spending even more money. Fortunately you've got lots of power available. Good luck!

In my understanding, you would want to balance what the amp can output to what the speaker can handle. speed3 is right in that it is perfectly fine to send more power to the speakers than what their max is rated at. How much more, I can’t say. Maybe someone else would be able to advise more on this. It is very important to make sure the sound coming in is very clean (high signal to noise right?). Also, if you want high volume from the speakers with less amp power, find some speakers with high SPL levels. As mentioned before Klipsch is a very good brand for that. I liked Klipsch Reference towers when I listened to them, but I didn’t get them because I liked Mirage better. Super-high volume was not a goal of mine. I wouldn’t mind it, but I don’t need it.

How’s this for opening up a can of worms? Bose 901 SPL=106. I think stating this is living more dangerously than watching Donnie Darko don’t you Smart Little Lena? The dad of a friend of mine had them and he said you could hear them from several blocks (not houses) away. From what I’ve heard Outlaw amps have the very LEAST power you would want to send to them. They’ll take 450 Watts at 8 ohms. I can’t really comment on their sound quality, as I have not heard them in the best settings. I have exchanged the 701 set I had bought for Mirage OM-5 though. My friend is absolutely nuts about their clarity. Matching up an entire surround system to them would be kind of tough though.

[This message has been edited by BenjaminRigby (edited October 23, 2002).]

LEAD UP: Whilst sitting listening to Donnie Darko for the umpteenth time. I realized at a higher dB, - I was getting, (she faints dead away) vibration out of the fronts. My husband thinks both fronts, I think it’s only in the FR, with the effect bouncing into the FL corner a hair. These are bracket hung from the ceiling, and the FR has Attic egress and stuff stored all over (right above it). There was a son up there digging for camping gear last week. I’m getting a sensation more of a rattle/vibration as if the energy the speaker is dissipating is starting a resonance that is moving something actually in the attic. Because I am so sick (poor me) this week I’m not going up to check it out till next week, and the Hus. Is too busy.
How can I describe my husband fairly, HES NO HELP AT ALL RIGHT NOW.
I can sympathize with the stories I see clustered around the forums of wives whose eyes glaze over when a husband talks AV. Mine supports me, is proud of me, BUT, he’s in the middle of a couple of major ongoing projects for the foreseeable future, and he’ tired of me talking AV. At first I was ‘cute’ when I picked his brain in the begging for things I was just grasping, and now as I’m beginning to discuss the latest Surround Format’s currently available etc, (things he has not kept up with for years)…his eyes are rolling back. I’m not an unintelligent wife, so I just let him play in own space, (while I play in mine) and understand that he’s flat not interested at the moment. His favorite phrase is ‘You’re doing the research - whatever you want to do” at the moment. He has little flashes, when the 950/770 shipped in he grabbed the box (or practically ripped them out of my hands), and set them up himself the first time, relegating me to the setup manual menu’s, and when I came home with the Panamx and left for a few minutes, he hooked that up too. (Wrong, as far as sequencing power up).

It seems you are looking for a high sensitivity speaker that sounds good and doesn't cost you an arm and a leg. Yes and No. My first purchase before I had traveled much distance down this road has kept me purposely ignoring threads on speakers up till now. Mine are not even a year old and have so/so sensitivity. If memory serves 89 on all with 91 on the center. I have no business messing with an upgrade like this for a while. BUT - I have that niggely urge growing. What would towers (at least on FR/FL) better speakers sound like? Little boxes? Oh why oh why did I care about LITTLE boxes and hang them out of the way. What would ear-level fronts sound like?

IF, I capitulate into this (because a rattle set me off) I MIGHT spend a lot? (relative to what else is going on when I do it). And if I spend a lot, I wondered what specs I could watch out for, which would be indicative of build quality as regards greater leeway to ‘take whatever is thrown at them’.

I live in the real world of teenage idiots, who pop in DVD’s and (their own CD’s on rare occasions). And I’m tired of teenagers ruining EVERYTHING they touch. Therefore what they can take is of equal importance to sound quality, at this stage of evolution in my household.

That clear things up any more - didn't think so... Jason my brain is fogged with a cold. I promise to reread 5 times then do a search to look up definitions and related terms. And try to get it in my own dim way, in the next weeks. However, if you had a high-energy 300Hz tone, the harmonics may end up having lots of energy in them. That one got me, I’ll have to look up Fourier I know I don’t have odd/even harmonics down etc. The sum energy of each of the harmonics added together exceeds?

in a fairly large room. No it’s tiny, but we like our HT experiences at Theater reference dB’s at times.
And I personally have been known to crank a CD or two when alone.

SPL=106. I think stating this is living more dangerously than watching Donnie Darko don’t you Smart Little Lena? I’ve never heard of anything other than horns listed at that level and surely BOSE does not make those? Have to look at that PR. Sounds like a ‘tangent universe’ to me. You brought up a problem I may be experiencing - the 770 may be a little much for these satelite level speakers. I always understood underpowered to be more of a risk than over powered. I believe they are in spec range to the amp, (just not possibly at the dB we force them to) but as I noted on another topic I have not learned how manufactures ‘fudge’ and weight these things and when and where you need to be skeptical.

especially those models using Kevlar drivers Funny Man!. Do they make those in the Mae West versions similar to female Swat officer issue? If they use space age ceramics/plastics, why not!. Maybe I’ll take Jason up and DIY a kevlar something or other. I have a friend whose an Officer maybe he wouldn't mind me nipping out little sections of his vest for a go at some experimental fabrication.


[This message has been edited by Smart Little Lena (edited October 23, 2002).]

Is SPL the same as sensitivity? That's what I meant to say. I looked up the Klipsch towers and they go from mid 90s in the Synergy to upper 90s for the Reference towers, 102 for the RF7. Maybe that's why these and the Bose can sound harsh to many people.

I hope you start feeling better soon I wouldn't make any decisions until your head clears up a bit. What equipment do you have in their now? How big is the room?

Lena,

Sounds like there could be several things going on here. It is entirely possible that you are shaking the walls/ceiling, which could be causing the problems. If you can put the speakers on stands, that may help. If you still have problems, you may be pushing the speakers too hard. With smaller satellites, that can be a problem. Still, if you have them crossed over to a sub, they shouldn't be getting much low frequency information. Maybe you really are pushing them quite hard?

As a general rule of thumb, bigger speakers can handle power better. Maybe that's too broad of a statement, but it generally holds true. In the case of tweeters, most are about the same size, so different approaches are taken to make them more durable. The biggest is ferrofluid cooling. They actually fill the voice coil area with a fluid that helps dissipate the heat. It also provides some mechanical damping, but that's another story.

In your case, I don't really think what you necessarily need is a higher effeciency speaker. That's really only necessary when you have a whimpy amp, which you obviously don't! You need something that can take the power. If you want to keep the speakers relatively small, go with a bookshelf speaker that has atleast a 5-1/4" woofer. 6" or larger would probably be even better. Bear in mind that not all drivers are created equal. More than likely, if the speaker itself is heavy and seems sturdy, it will probably perform the same. A manufacturer isn't going to waste money on a heavy cabinet, if the drivers are wimpy. Likewise, if the manufacturer is going to sink real money into the drivers, they'll build the whole system to that standard. I've been pretty impressed with the Definitive Technology speakers I've heard. I actually have a bunch of their raw drivers, and they are particularly well built. Their speakers seem to me to be very well built. The tower speakers are particularly nice. They aren't exactly in the budget category, but I think you get quite a bit for your money there. I also like some of the Boston Acoustics stuff. The VR-M series are nice sounding (maybe a little bright for some tastes), and are some of the nicer looking speakers out there, in my opinion. Again, they aren't cheap. I'm not particularly thrilled about Klipsch. The horn sound is a little unnatural to my ears. I will admit that their big stuff is pretty nice. Not cheap.

If you are planning to keep your next set of speakers longer than the ones you have now, consider spending a little more than you are comfortable with. Speaker technology really doesn't change (despite whatever marketing gimmicks the dealers/manufacturers would have you believe). If you find a set of speakers that sound good to you, they are going to sound good always, and not become obsolete.

Jason