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Pros and Cons of Plastic-Framed Speakers

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I started this discussion in the wrong area, so I decided to move it. I recently noticed my friendly K dealer "proudly" displaying a Reference-class woofer in the "raw." I was amazed to see that the frame or "basket" was made of plastic! According to this website, it is called "cast polymer." Whatever the name, it sure looked like cheap plastic to me! Is this an advance in speaker technology, or is it a way to reduce costs? I heard somewhere that rigidity is a problem with plastic frames, which is why they aren't on speakers larger than eight inches. I notice all the woofers in the Reference line are plastic, with the exception of the RF-7, which uses 10" woofers. Is this why we're not seeing twelve inch woofers anymore except in the Heresy? It would seem to me that plastic speakers are less expensive to produce than metal ones, which may be why we've seen a slow degradation in the quality of speaker construction materials since the sixties. First, the awesome Altecs of the fifties and sixties were cast steel. Then came the stamped steel, and now we've arrived at plastic? I can see cunning and deceitful companies like Bose offering the public cheap, plastic, boombox-grade speakers enclosed in snazzy boxes. I can also see them charging exorbitant amounts of money because of the sleight-of-hand trickery they perform at the retail outlet may fool the average consumer into thinking they're getting quality (Acoustimass)! Is Klipsch heading in the same direction? I hope not. If they are, I can only hope that this pursuit of the almighty dollar doesn't infect their Heritage line.

I truly love my 2001 KLF 30s, but the quality of materials and construction is far beneath the 1980 Heresys that I auditioned at home, then quickly placed on lay away! Klipsch, please say it ain't so!

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Cerametallic -- GIVE ME A BREAK! What a lot of BS! I wish I had one of those little buttons right about now!

PWK, could you send me one PLEASE.

Plastic ANYTHING on a speaker except for wire-wraps -- NOT! So, if you drive them hard, do we exceed the glass transition temperature and does the magnet fall on the floor? What about shielding? Those extra rainbow colors on my TV kinda look neat (like my copper-tone woofers).

My 1978 LaScalas were owned by a person who thought they were 1000 Watt (that's right one thousand watt) speakers. They survived him and are still going strong.

The only way you are going to get quality in a speaker any more is DIY!


This message has been edited by oosting on 07-13-2001 at 08:38 PM

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I don't know if this is a real problem. More imagined than real, I think.

Yeah, a lot of things in the world used to be make out steel, and now they're plastic. With woofers, casting got more respect than stamped sheetmetal. And use of polymers and composits get even less respect.

But really. Do we need the strenght of steel in this application? Further, modern composit materials have impressive strength. Like it or not, a lot of components in auto engines these days are "plastic" rather than steel. Has performance suffered from that?

Like it or not, many speaker boxes are make of MDF rather than plywood. It works well enough when properly glued together. Another example of, arguable, cheapening.

However, all the woofer frame has to do is hold a magnet, the spider and the diaphragm.

If someone wants to come forward and present a known case of distortion of the basket or a mechanical failure, we'll have to take a closer look.

Yeah, it is probably a matter of cost saving. We hope the saving goes into better components in other areas.

By way of example, I'll probably keep on using expensive plywood in my home built units. Some of it is tradition. On the other hand, I can't claim that an identical unit make out of MDF will not perform pretty much the same, at significant cost saving.

Just be happy Klipsch doesn't color the basket copper. That would really draw fire. =8^o


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As I mentioned in the other thread, plastic (polymeric) woofer baskets do have their advantages over metal one. The sonic advantage is that they are much less resonant than metal. This is a good thing!

Just because something is made of plastic, doesn't necessarily mean it's of low quality. That probably used to be the case a long time ago, but there have been many advances made in the development of polymers (plastics) and composites. In fact, in some cases some polmers and composites are actually stronger than metals. Of course those are usually expensive, but they are out there.

B&W, which has always been a highly regarded speaker manufacturer also uses polymeric baskets in their woofers. In fact, they brag about this feature! Yes, because it improves the sound -- plastic is less resonant than metal.

You are familiar with Kevlar, right? You know, that material they use in bullet-proof jackets to stop bullets? Well it's a polymer. That's right, it's plastic!

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You guys are presenting good arguments, but I can't help but wonder if Klipsch is going the way of planned obsolescence and cost savings, rather than higher technology. I bought a VCR in 1986 that was built like a tank, and it cost nearly as much as one! (That was when I was in the Army--yes JMON I know all about Kevlar!) That Harmon-Kardon VCR was awesome--the best audio I had ever heard come from a tape machine, even better than most reel to reels. That beast withstood more abuse than I did while I was in the Army and still lasted until two years ago! Once it died, I immediately ran out to, ahem, Circuit City to buy a replacement. These new units are one-fourth the price of my old HK, one-tenth the weight, and ten times more features! What a deal! The damn thing crapped on me within six months, and by this time, I was only putting about three or four hours a week on a VCR, compared to twenty to thirty hours a week back in the eighties. Back then, I used to record everything, but nowdays, it's just the weekly movie or so (DVD has all but replaced it now). Why was this machine cheaper and lighter weight? Plastic (read cheesy) parts have something to do with it, don't ya think? My newer VCR was a prime example of planned obsolescence--the manufacturer never intended to last more than a few years. The word "plastic" doesn't have the chintsy connotation it used to have, so let me use a less misinterpreted word: CHEAP! True, the speaker baskets in question are made of plastic, but is it a high tech evolution, or a less expensive (or CHEAPER) means to an end?

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Wonder what we would think if the local dealer said, when presented with plastic,"gee,I don't know if I want to take this cheesy plastic card in payment for these speakers.Boy,what's the world coming to?People usually pay in gold,silver,or some other precious metal!"cwm31.gif


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The glass-filled plastic frame used on many Klipsch woofers is stronger, less resonant and allows for better cooling of the voice coil via vents around upper side of the coil. In fact, these baskets survive a drop test from about three times the height of stamped and cast baskets we tested. In the RF-7, the equation tipped in the opposite direction and a cast metal basket is used.

Engineering is NOT about selecting the most expensive material that will do the job. Every design, material and approach has both strengths and weaknesses. My 1954 Bel Air was made of thicker metal than my curent car. Does that mean the '54 was better? Not in my opinion.

One can argue materials and other specifics of a design till one is blue in the face. It's an intellectual dead end. What matters is the ultimate performance of the product.

Is Klipsch allowed to do things that (in our opinion) enhance the attractiveness and salability of our products? HECK YES! It is true that the color of the cones in the Reference series is purely cosmetic. We don't claim any performance advantage based on the color of the cones. Similarly, we do not claim a performance advantage by using attractive finishes on the products, but we find consumers would rather have a speaker that is visually desirable as well as soncially desirable. The copper color is not at an increase of cost and does not detract from investment in sonics.

Want to build your own speakers that sound great and look ugly (or great or in between) go right ahead. Share with us your accomplishments. Help everybody here attain greater pleasure from our audio systems. That's why we all come here.

Lighten up just a tad OK?

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Yeah, I have to agree with BobG. It's easy to snipe at things which we aren't involved with or have never attempted. The proof will be in the performance over time. As Gil said, has anyone got any concrete evidence that this design does not work, or are all the arguments just speculation based on grand generalizations? I went to a dentist that hurt me once. Does that mean all dentists are bad? Geez, guys, how'd you like to have your accomplishments in your jobs/businesses scrutinized in a public forum on the Internet. Could your work stand up? Maybe. Would you take a bunch of shots? Certainly.

I'm all for informed, experienced discussion. I'm even in favor of speculation, as long as you present it as such.

Whew, I feel better all ready Smile.gif


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OK, I'll lighten up! Sheesh, I was just asking a question, not condemning the company! I simply asked if the use of plastics was to cut costs, or was it to improve the breed! Sounds like folks are really quick to the defense for some reason! I'm all for plastics; hell, some of my best friends are plastic! When BobG explained the polymer basket in greater detail, it sounded like they are making strides to develop a better frame rather than slapping something together to save money. For that, I feel that Klipsch should be commended. Boy, I sure raised a lot of dander just to get the answer to a question! One question that wasn't answered though, was why we're not seeing twelve inch woofers anymore except in the Heresy?

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Well, I hope the plastic IS cheaper.

A basic tenent of engineering is that the geometry of an object (length, width, & thickness) controls its stiffness. If the material is the same, this is easy to see: a 2x4 is stiffer than a yardstick.

The glass reinforced plastic frames may well be stiffer and maintain better alignment than a equal stamped steel frame. As with the floors of your house, strength is not an issue, stiffness is. You don't want your floor to feel like a trampoline and you want the stiffest woofer basket you can afford.

Good engineering is the CHEAPEST full performance solution.


This message has been edited by John Albright on 07-14-2001 at 02:59 PM

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Mr. Blorry - thanks for taking my response in the manner it was intended. I try not to get too defensive here especially since I am not unbiased.

Re 12" woofers - they don't cost any more to build than 10" woofers - at least not enough to avoid them due to cost factors. Certainly box size is a consideration and 12's have to live in a pretty large box to perform to their fullest. I think the RF-7 indicates Klipsch is not afraid to make big speakers as does our move away from products such as RP-3 and RP-5 in favor of large passive models. Klipsch is becoming more aware of what people want from us and we are working to deliver. At the point we have a compelling reason to use 12" woofers, and feel it can sell, we will certainly deliver. As more people have a chance to listen to RF-7's, I believe they will agree that the bass is superior to that on the KLF-30, a speaker with dual 12" woofers. As in all things, 12's have their trade-offs, and not merely in size or cost; there are many aspects where the larger woofer compromises overall performance.

Again, thanks for being a good sport. Constructive criticism is always helpful. By the way, if you get a chance, take a very close look at that RF-3 woofer; it's actually a pretty cool piece of engineering. Solid pole, big magnet, dissipates lots of heat. We are more than satisfied with its performance. Wish we could have used the same venting approach in the cast frame RF-7 woofer, but it was not possible - engineering trade off's again. OTOH, the RF-7 woofer is quite a piece; 90 oz. magnet structure and the lowest magnetic leakage of any woofer we've built. One of our techs showed it to me by putting it right up against my monitor screen - no picture distortion! Kids, don't try this at home, but still pretty cool.


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