KT88 Posted June 12, 2006 Share Posted June 12, 2006 I have learned from several posts on this board, that a 100% sealed gasket should be a must for optimized bass performance and a good SPL delivered from the K33.. Today I wanted to reassemble my now nicely refinished La Scalas. Then I noticed, that the gaskets (as a part of the drivers) looks to be separated into 4 quater parts each driver. Each quarter round shows a gap of about 1 mm to its neighbour quarter. This causes definitely four unsealed areas of each driver. (Unfortunately I can´t post a picture now cause the speakers are in my office.) Is it NOT necessary to have a perfect seal, or in other words, has this design been constructed the way it shows now (the drivers are 29 years by now)? OR, was it intended to show one perfect round and has possibly shrunk due to aging? If it is so I already have some material to fill the gaps. Should I do so? Thanks for helpful replies, Heinz Quote Link to comment Share on other sites More sharing options...
D-MAN Posted June 12, 2006 Share Posted June 12, 2006 The cardboard in question may have shrunk. Can you post a picture? DM Quote Link to comment Share on other sites More sharing options...
John Warren Posted June 12, 2006 Share Posted June 12, 2006 Heinz- You are correct, the woofer seal should be complete around the entire circumference of the driver. On factory K33e sq magnet drivers, the factory seal is a double stack and consists of (4) sections that are interlocked, the joints looking like the letter "S". The double stack should seal thru the entire thickness. The dust cap is paper and the surround is coated fabric. Other drivers use one piece seals made from cork (McCauley for example), high density foam rubber or (on some mid-range units) o-rings. I would fill the gaps using a dab of polyureathane sealant on the outside diameter of the seal. jw Quote Link to comment Share on other sites More sharing options...
BEC Posted June 12, 2006 Share Posted June 12, 2006 This is probably what Heinz is talking about. The old K-33E gaskets were a sort of butt joint and most of the time at least one of the four joints has a gap. Bob Crites Quote Link to comment Share on other sites More sharing options...
BEC Posted June 12, 2006 Share Posted June 12, 2006 Newer K-33Es look like this and probably seal a lot better. Bob Crites Quote Link to comment Share on other sites More sharing options...
DrWho Posted June 12, 2006 Share Posted June 12, 2006 In all honesty I don't think that small "leak" is going to make any audible difference whatsoever. Heck, air can move fairly unobstructed through the paper surrounds and the dustcap (or is the K-33E pole piece not vented?). If anything were to change, you'd end up with more low frequency extension and an ever so slight drop in efficiency...I'd wager under 0.05dB difference. It's my understanding that the most important function of gasketing material is actually to dampen the transmission of vibration between the driver and the cabinet. Quote Link to comment Share on other sites More sharing options...
John Warren Posted June 12, 2006 Share Posted June 12, 2006 I disagree. Note that I specifically mentioned the dust cap material and surround construction used on the K33e. These are, IMO, "good" design practices for loudspeaker design and provide adequate sealing. Also an example of good pole piece vent design is the McCauley vented pole which pumps air from the enclosure rear, thru the pole piece and exhaust it "back" to the rear of the enclosure. They construct voice coils that are about 4" in diameter and about 4" long. The cylindrical surface area in contact with the bypass air flow is considerable. Quote Link to comment Share on other sites More sharing options...
DrWho Posted June 12, 2006 Share Posted June 12, 2006 Wouldn't the losses associated with the ported lascala mod be of a much larger magnitude? And I don't see anyone complaining about it... Quote Link to comment Share on other sites More sharing options...
D-MAN Posted June 12, 2006 Share Posted June 12, 2006 Question is, could you actually hear the difference with such a small leak? Just a guess but I would say - probably not at low volumes - however, the additional power compression at higher volume should be noticable as the leak effect is directly related to excursion! DM Quote Link to comment Share on other sites More sharing options...
3dzapper Posted June 12, 2006 Share Posted June 12, 2006 The gap in the second photo Bob posted should seal together with mounting compression. It looks to be designed that way. Rick Quote Link to comment Share on other sites More sharing options...
KT88 Posted June 13, 2006 Author Share Posted June 13, 2006 The gaskets shape looks like in the first picture Bob has posted. But the material looks identical to the second photo. I must add some info. My post from yesterday evening was very late after work and I actually did not remember how the driver looked directly after removing from the cabinet ten days ago. Now I can remind that it had shown one plain and seamless surround, which was on the same level as the metall basket because of the mounting compression. And I was wondering if this gasket - on the same level - is sealing well, because the material of the gasket does not give a flexibel feel. It´s more like that from a harder cardboard. But now, it is not only divided into 4 quarters of the gasket. It is also about 1 mm more thickly than the edge of the basket. This would mean that it develops a permanent counter acting force to seal constantly well for a long period of time. To me that explains two aspects, first is that I am sure I would have noticed the four sections 10 days ago (which did not show up), but much more important, the material seems to be flexible! in a good but slowly way, still after 29 years. Today I will make a picture of the gasket in is momently shape. Than I will assemble one driver back to it´s mounting board and do a second photo after removing it again in lets say a day or so. If it seals well and the gaps disappear I would think about not to add some material. We will see... Heinz Quote Link to comment Share on other sites More sharing options...
KT88 Posted June 13, 2006 Author Share Posted June 13, 2006 "Now I can remind that it had shown one plain and seamless surround, which was on the same level as the metall basket because of the mounting compression." Just after reassembling the K33 I think it is not so flexible and I had just a halluzination about a seamless gasket ten days ago... Quote Link to comment Share on other sites More sharing options...
KT88 Posted June 13, 2006 Author Share Posted June 13, 2006 a second picture Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted June 13, 2006 Share Posted June 13, 2006 So, do you think it will be a satisfactory seal, if installed as from the factory? Quote Link to comment Share on other sites More sharing options...
KT88 Posted June 13, 2006 Author Share Posted June 13, 2006 "So, do you think it will be a satisfactory seal, if installed as from the factory?" As to see on Bob´s photographs, the factory has changed the shape of the gasket connections to reach a more sealed result. Therefore I should take the chance to enhance the sealing as well, nevertheless if the old version of the K33 has had those gaps from new or if the gasket shrunk over the years. Any advice, if someone has already done it to use best materials? I could take perhaps some window kit or kneading rubber, but don´t know, what works and stands best over the time. Quote Link to comment Share on other sites More sharing options...
mark1101 Posted June 13, 2006 Share Posted June 13, 2006 I can't believe that that tiny gap would make any difference what-so-ever. Klipsch only uses 4 of the available bolt holes anyhow, and EVERY K-33 I ever inspected had loose screws, LaScala cornwall all included. Plus is the motor board absolutely perfectly flat? Not warped in the slightest? I agree that it is good design practice to have good seals. But the fact is, most probably don't have perfect seals. There probably isn't a single individual on this board that could here a 1 millimeter leak. C'mon. Quote Link to comment Share on other sites More sharing options...
KT88 Posted June 13, 2006 Author Share Posted June 13, 2006 I would agree so far as the lowest frequencies to reach are about a little less than 60 hz. And it is horn loaded technology. Probably is the need of a really sealed driver more important with designs like a BBC LS3/5 mini monitor, also in terms of there needed air suspension. But nevertheless I will close the gaps a little bit. Heinz Quote Link to comment Share on other sites More sharing options...
John Warren Posted June 13, 2006 Share Posted June 13, 2006 Fine then, don't take "my" word for it... "Leakage losses are the most significant, giving Ql values of between 5 and 20. The last result is surpising, because the enclosure tested were well built and appeared to be quite leak-free. In fact, some of the more serious leaks were traced to the drivers. These leaks were caused by imperfect gasket seals and/or by leakage of air through a porous dustcap and past the voice coil." Small, R. H., "Vented-Box Loudspeaker Systems Part I: Small-Signal Analaysis," J. Audio Eng. Soc., 1973 June. Quote Link to comment Share on other sites More sharing options...
Klipschguy Posted June 13, 2006 Share Posted June 13, 2006 I have to agree with John on this one, especially since the La Scala K33 is in a sealed enclosure. I have seen sealed speakers where people complain "the woofer in my right channel bottoms out sometimes and the other one doesn't." On inspection an air leak turns out to be the culprit. On one speaker it was merely an unfilled screw hole. Seems like there was someone here several years ago who had problems with their Heresy woofers bottoming out because they took the risers off and didn't seal the screw holes. BTW, those gaps looked pretty big on those K33's. Andy Quote Link to comment Share on other sites More sharing options...
mark1101 Posted June 13, 2006 Share Posted June 13, 2006 So are you saying that this is important enough that we should all disassemble our speakers and seal the gaps shown in Bob's pictures? [] And that if we do that, we'll hear an improvement? [] What is your recommendation to solve this problem we all have? The woofers all have an inherent leak as shown by the pictures. I want my speakers to sound their best.[6] Quote Link to comment Share on other sites More sharing options...
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