jdm56 Posted September 23, 2008 Share Posted September 23, 2008 Just curious. I'm sure the decision not to stuff was made for a good reason...I'd just like to know what it is! Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted September 23, 2008 Share Posted September 23, 2008 One of the purposes of damping material inside cabinets is to reduces internal standing waves. In a LS doghouse there isn't that much internal volume and very little parallel surfaces, therefore not an issue. Stuffing a cabinet with polyfill material increases the apparent volume of the cabinet (to the cone) by a certain factor. In the LS doghouse the cabinet volume isn't a highly critical design parameter, so again not an issue. Why do it if it doens't make a hill of beans difference. Quote Link to comment Share on other sites More sharing options...
Blvdre Posted September 23, 2008 Share Posted September 23, 2008 My Un-educated guess is that stuffing the doghouse would change the back-loading of the driver. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted September 23, 2008 Share Posted September 23, 2008 "In a LS doghouse there isn't that much internal volume and very little parallel surfaces, therefore not an issue. " yep. what little parallel surfaces that do exist, has a woofer in the way to break up reflected waves. Quote Link to comment Share on other sites More sharing options...
DrWho Posted September 23, 2008 Share Posted September 23, 2008 I believe PWK wrote about trying to keep the rear chamber as capacitive as possible....adding some insulation would add some resistance to the capacitance. Quote Link to comment Share on other sites More sharing options...
jdm56 Posted September 23, 2008 Author Share Posted September 23, 2008 OK. Sounds logical to me. Thanks, guys! Quote Link to comment Share on other sites More sharing options...
DrWho Posted September 23, 2008 Share Posted September 23, 2008 Just outta curiousity, why do you ask? If you're noticing any kind of box resonance with the Lascala, then you might want to look into stiffening up those side walls... Quote Link to comment Share on other sites More sharing options...
jdm56 Posted September 24, 2008 Author Share Posted September 24, 2008 Like I said, just curious! I saw some pictures on here somewhere of la scala's for sale and the owner had taken pics inside the doghouse. It just got me wonderin' why there's no absorptive material in there. I'd think if it was stuffed full of polyfil or some such thing, that it would make some audible/measureable difference, but I guess not. Quote Link to comment Share on other sites More sharing options...
twistedcrankcammer Posted September 24, 2008 Share Posted September 24, 2008 Like I said, just curious! I saw some pictures on here somewhere of la scala's for sale and the owner had taken pics inside the doghouse. It just got me wonderin' why there's no absorptive material in there. I'd think if it was stuffed full of polyfil or some such thing, that it would make some audible/measureable difference, but I guess not. jdm56, Neither the Klipschorn nor the LaScala bass bins use any absorbitive material in them, reason is extremely simple- they are horns and are supposed to resonate. It is part of their design and efficiency. Roger Quote Link to comment Share on other sites More sharing options...
Don Richard Posted September 24, 2008 Share Posted September 24, 2008 Neither the Klipschorn nor the LaScala bass bins use any absorbitive material in them, reason is extremely simple- they are horns and are supposed to resonate. It is part of their design and efficiency. When a horn loads the driver's diaphragm that loading is resistive, therefore non-resonant. Below Fc the enclosure behaves like a sealed box and is a resonant system in that range. In some horn designs output below Fc is a significant part of the performance of the system. Quote Link to comment Share on other sites More sharing options...
twistedcrankcammer Posted September 24, 2008 Share Posted September 24, 2008 Don, Honk Honk!! Roger Quote Link to comment Share on other sites More sharing options...
DrWho Posted September 24, 2008 Share Posted September 24, 2008 Btw, the Jubilee has absorption in its rear chamber... Quote Link to comment Share on other sites More sharing options...
twistedcrankcammer Posted September 24, 2008 Share Posted September 24, 2008 Btw, the Jubilee has absorption in its rear chamber... DrWHO, Attends, Stayfree, or Playtex??? Roger Quote Link to comment Share on other sites More sharing options...
DrWho Posted September 24, 2008 Share Posted September 24, 2008 WOW [] lol I believe it's a foam of some type if I remember correctly. I wonder if it's used because the rear chamber is considered to be undersized? I dunno. Quote Link to comment Share on other sites More sharing options...
Don Richard Posted September 25, 2008 Share Posted September 25, 2008 I believe it's a foam of some type if I remember correctly. I wonder if it's used because the rear chamber is considered to be undersized? I dunno. Maybe to affect the Q of the tuning? I dunno either. Quote Link to comment Share on other sites More sharing options...
DrWho Posted September 25, 2008 Share Posted September 25, 2008 I think it's because the rear chamber is undersized and putting in some stuffing can make it appear larger....I wonder if it looking larger is merely the effect on the Q? I think it also helps attenuate the vertical standing waves that build up in the rear chamber too (since it is the only set of parallel walls). Quote Link to comment Share on other sites More sharing options...
Marvel Posted September 25, 2008 Share Posted September 25, 2008 I'm trying to remember where I read this, and I won't remember the correct terms, but... I thought I had read that an ideal horn loaded speaker would have the impedance caused by the horn to be equal to the loading/reactance (whatever the correct term would be) from the sealed chamber the driver is mounted in. Mike, have you read this anywhere? I have been thinking about how you calculate the size of the cabinet (apart from the horn on the front side) Bruce Quote Link to comment Share on other sites More sharing options...
DrWho Posted September 25, 2008 Share Posted September 25, 2008 Are you talking about reactance annulling? Gil posted an article on it (though I've not read it myself):http://forums.klipsch.com/forums/p/86302/869228.aspx A lot of people reference this article (which I've not read either):http://www.aes.org/e-lib/browse.cfm?elib=3894 Quote Link to comment Share on other sites More sharing options...
Marvel Posted September 25, 2008 Share Posted September 25, 2008 I'll have a look at those. I hadn't read Gil's posted article yet... [:$] Thanks Mike. Quote Link to comment Share on other sites More sharing options...
PrestonTom Posted September 25, 2008 Share Posted September 25, 2008 As I understand things in the Jubilee, the rear chamber volume is determined for reactance annulling (increasing the output at the very low frequencies). In the Jub, the chamber is a bit small relative to calculation. The stuffing will have little effect on standing waves since the thickness of the material is tiny compared to the wavelengths at low frequencies (as someone suggested). However, the velocity of the waveform will change due to the stuffing material (changes density and consequently changes the velocity). It is this change in velocity that will make the chamber "seem "larger. As I understand it at least, -Tom Quote Link to comment Share on other sites More sharing options...
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