Erland Posted October 11, 2006 Share Posted October 11, 2006 Again I have to turn to you "gurus" for advise regarding my K-horn project. As mentioned earlier, I have never build or seen the inside of a K-horn before, exept from pictures (that has been a lot of help). I have seen a picture in the Speakerlab building plans where the void around the woofer (blue arrow) is filled with this material used for purpose in speakers. Shall this void be filled? What about the void marked by green arrows. I guess it is a good thing to stuff this "dead void" before closing? As some of you mentioned, the angels on this thing is "wild", but with patience and preciseness it just falls together. Anyway, this is my progress so far. Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted October 11, 2006 Share Posted October 11, 2006 A definite NO to the woofer box, and the other side void areas are so strong, and of such bizarre dimensions that I can't imagine any spurious vibrations happening in their walls. I'd stay true to the original and not bother with any additional materials. If PWK had deemed it appropriate, there would be something in there. By the way, she's looking rather fine- congrats on your fine worksmanship! Michael Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted October 11, 2006 Share Posted October 11, 2006 you'll change the Tuning of the K-33 , if ya stuff the woofer box ....no Quote Link to comment Share on other sites More sharing options...
freddyi Posted October 11, 2006 Share Posted October 11, 2006 can't remember what polyfill in rear chamber did for Speakerlab's K - maybe waste $8? --seems like 1/2" access door on my single k-horn is a bit "drummy" when hit - dunno if matters or not. btw - fab work! (be cool if you could do Dana Moore's horn for comparison) - what your 5687 scheme look like? here's a CTS K33E Z curve - lotsa wire in series from woofer tester to string though 70 foot of house length ! same vintage K33E not much wire/dcr in series and different program with K15 Karlson box. Quote Link to comment Share on other sites More sharing options...
JohnA Posted October 13, 2006 Share Posted October 13, 2006 Stuffing the back air chamber for the woofer shouldn't be done. It is a thermodynamics thing, but it makes the chamber behave as though it were larger. It would "look" too large with stuffing. Adding Dynamat www.dynamat.com or rope caulk (non-hardening window sealing putty) http://herbiesaudiolab.home.att.net/rope.htm Ace Hardware to the woofer frame has been said to be helpful reducing resonances. I've not done it, but I did put Dynamat on my Squawker horns. The reduced ringing was pretty easy to hear. OTOH, An expanding foam like "Great Stuff" in the top and bottom voids will not hurt anything but your bank account. That is likely why Mr. Paul didn't do it on production models. http://greatstuff.dow.com/cons/ It may well kill some cabinet resonances. Quote Link to comment Share on other sites More sharing options...
ZAKO Posted October 13, 2006 Share Posted October 13, 2006 The only cabinet resonence in the chamber is the side access door ....Every thing else is solid.....I replaced side door with a 3/4" thick door......Every thing in the chamber is now none resonent......Do not alter chamber with any stuffing or padding. You will change back EMF of woofer. Quote Link to comment Share on other sites More sharing options...
D-MAN Posted October 13, 2006 Share Posted October 13, 2006 Yes, the void areas shown in your pic can be optionally filled with absorptive material to reduce resonances. All wood panels will resonate at a particular sympathetic frequency or set of frequencies, of course. The inclusion of absorptive material can alter that particular frequency - it is the same thing as adding a brace, more or less. The 1970's era Speakerlab "K" plans show a single piece of fiberglass stapled around the back of the driver. It does not fill the back chamber at all. This is to supress reflections from coming back through the speaker cone out of phase, not to alter the back chamber volume. The answer is YES, use it if you want, but only about as much as is shown in the plans. It will improve the response by "cleaning it up", not making it lower in frequency. I have a 3" thick piece of fiberglass in my horns, and it definitely prevent the bass horn from sounding "hollow" by damping the reflections a bit. DM Quote Link to comment Share on other sites More sharing options...
ZAKO Posted October 14, 2006 Share Posted October 14, 2006 Speakerlab is not a authentic Klipschorn..What they said to do is pure BS....In a personal letter from Paul Klipsch, Placing any type of filling in the woofer chamber will alter woofer response. I,m right your wrong, thats the end of this herasy. The stake is ready & torch is lit. Quote Link to comment Share on other sites More sharing options...
John Warren Posted October 14, 2006 Share Posted October 14, 2006 Speakerlab is not a authentic Klipschorn..What they said to do is pure BS....In a personal letter from Paul Klipsch, Placing any type of filling in the woofer chamber will alter woofer response. I,m right your wrong, thats the end of this herasy. The stake is ready & torch is lit. Maron is correct, stuffing the the three chambers will effect the volume enough to offset the reactance annulling. The three volumes highlighted in the above photo ALL contribute to the rear chamber volume (the "ski-slopes" connect to the rear chamber by the little 45° notches). There is also an additional contribution due to the volumes on each side of the baffle. Theoretically, a 1.4x increase is possible with fiber-glass, a more realistic volume increase however is on the order of 1.2x, more than enough to reduce efficiency. Stuffing will attenuate frequencies with wavelengths on the order of the largest dimension of the stuffing. In other words, 3 ft of stuffing will attenuate 400Hz and higher. Stuffing the rear chamber to attenuate "bass" frequencies is, essentially, an act performed by one who is unaware of the physics. Quote Link to comment Share on other sites More sharing options...
ricktate Posted October 14, 2006 Share Posted October 14, 2006 I dont think the green area is connected to the woofer chamber.Because when i re-veneered my Ks i made sure the woofer chamber was air tight and i found some leaks due to bad glue or poor construction im not sure.But i did notice the leak came out of the horn flare and not in the green area.So i would use the foam in the green area but be carefull putting it in there if you put to much it will push on the panels and move them plus im not sure about how long it will stay puffed up.Maybe another material would be better or apply dyna-mat stuff to the panels.I put dyna-mat type stuff on inside woofer chamber in strips on the bigger panels.The idea of making the woofer door thicker is good ,it does move when played loud i might have to look into that.Rick Quote Link to comment Share on other sites More sharing options...
John Warren Posted October 14, 2006 Share Posted October 14, 2006 I dont think the green area is connected to the woofer chamber. It is, that is why the notches exist. I highligthed one "notch" with a red circle. When the side of the horn is in place, a small opening is made where the red circle is shown on the photo. That opening "communicates" with the rear chamber per the yellow line I drew on the opposite side of the photo. If you have a factory Klipschorn, remove the woofer door and look down (or up) to see the notches. They open to the volume in the ski-slope. Quote Link to comment Share on other sites More sharing options...
ZAKO Posted October 14, 2006 Share Posted October 14, 2006 Paul Klipsch made this modification in his K3X bassbin X for experimental unit. With an Ax, He liked the test result. And the design was then incorperated in production units. Quote Link to comment Share on other sites More sharing options...
JohnA Posted October 14, 2006 Share Posted October 14, 2006 Thanks, John. I didn't know that area was tied to the back air chamber. Quote Link to comment Share on other sites More sharing options...
John Warren Posted October 15, 2006 Share Posted October 15, 2006 John- Here's another picture that might give a better picture of how it works. The lime green simulates the plywood sheet attached to the horn. The red line is a "string" that can be passed from one chamber to the next. jw Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted October 15, 2006 Share Posted October 15, 2006 Ooohh ...... never gave that Volume a thought ..... wonder if it's open on purpose ...?? Quote Link to comment Share on other sites More sharing options...
ricktate Posted October 15, 2006 Share Posted October 15, 2006 Well you guys are right, i took my woofer door off and looked at mine last night and there is a hole into that other chamber.I never thought it was like that, im just glad i didnt seal it up i might have if i knew it was there ,lol.So that makes the back chamber area pretty big at least i know my back chamber is air tight, when i did my test and put air into it i could see the woofer door bulge out so its pretty tight.I did have some leaks though probably due to old glue after all mine are 1972 models.Well looks like alot of use learned something here huh.Glad you guys talked about this i dont think it has ever been brought up before.Rick Quote Link to comment Share on other sites More sharing options...
ZAKO Posted October 15, 2006 Share Posted October 15, 2006 Duke.......Yes.....Im still wadeing through His tech papers. Trying to find his results..Paul would start out on one subject & drift into another problem ...before drifting back to the main subject....Very hard to fllow. Thats how his multi task mind worked. Quote Link to comment Share on other sites More sharing options...
John Warren Posted October 15, 2006 Share Posted October 15, 2006 According to Klipsch, reactance annulling is achieved when the rear chamber volume is equal to (S * L) / 2 * pi where S is the throat area (2 x 3 x 13 = 78 sq. in.) and L is the wavelength of the cutoff frequency, Fc (50Hz = 337 in). This calculation puts the volume behind the cone at about 2.4ft^3. I have not made an attempt determine the actual volume. Perhaps someone else to like to do it? Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted October 15, 2006 Share Posted October 15, 2006 Interesting topic in this thread. In what way would the performance of the Khorn be enhanced by this additional volume in the rear chamber of the K33? Kind of ingenious the way PWK figured out a way to use otherwise wasted void space withing the cabinet walls. M Quote Link to comment Share on other sites More sharing options...
John Warren Posted October 23, 2006 Share Posted October 23, 2006 Interesting topic in this thread. In what way would the performance of the Khorn be enhanced by this additional volume in the rear chamber of the K33? M I was going to ask you now that you work in tech support(?) jw Quote Link to comment Share on other sites More sharing options...
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