johnnyp Posted November 17, 2000 Share Posted November 17, 2000 I am thinking of tinkering with my home-built cornerhorns again. In the Paul Klipsch designed Heritage horn bass units (Klipschorn, Belle, LaScala), what is the optimum distance the woofer should be mounted above the slot? Correct me if I am wrong but Klipsch, at one time, mounted the woofer directly to the board containing the slot. I think I recently read a thread on this BB where Klipsch is spacing the woofer from the slot using a double-thick gasket. At other times they mounted the woofer to a 1/2" or 3/4" plywood spacer with a ~14" dia. cut-out. Volvotreter has elected to use a spacer above the slot in his LaScala project. http://www.klipsch.com/ubb/uploads/volvotreter/MiniLaScala.jpg (Volvotreter: I hope you don't mind me showing your work -- I am envious of your woodworking skills!) I have tried mounting my woofer to a 1.5" thick cut-out I have available from another speaker project but I wasn't impressed with the results. What would be the characteristics of the sound if the woofer is mounted too close to the slot or too far away? ------------------ John Packard Quote Link to comment Share on other sites More sharing options...
pzannucci Posted November 18, 2000 Share Posted November 18, 2000 When the woofer is doing long excursions, you don't want it to hit the board. Give it only as much room as needed. Peter Z. Quote Link to comment Share on other sites More sharing options...
stevef Posted November 20, 2000 Share Posted November 20, 2000 The slot loads the throat of the horn.. so, just enough space to keep the woofer diaphram from striking the baffle board. If you have the Xmax spec from the woofer, use that plus a couple extra millimeters, and that should work. Also, make absolutely sure that you have NO AIR LEAKS anywhere. Good Luck! Quote Link to comment Share on other sites More sharing options...
johnnyp Posted November 20, 2000 Author Share Posted November 20, 2000 Thanks for the replies. I am using a pair of Dayton 15" drivers which have an X-max of 7.9mm. The drivers' complete specs can be found at: http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Product_ID=7751&CATID=49 I installed one driver in the bass unit with no spacer and only (2) screws. Then I ran some 40hz test tones. When I turned up the volume, I could hear the speaker diaphragm smacking the wood! That's when I tried the 1.5" spacer but didn't care for the sound -- too subdued. Now that I have secured both speakers with (8) mounting screws (each) and no spacers I can't hear the diaphragm collision anymore. I believe the drivers are sealed to the board now. At moderate volume, does the slot create a "cushion of air" between the slot and the speaker diaphragm, limiting diaphragm movement and collision with the board? Quote Link to comment Share on other sites More sharing options...
JLH Posted November 20, 2000 Share Posted November 20, 2000 johnnyp, I thought about trying the Dayton speaker you are talking about. Can you give us an idea of what you think of it's performance in your horn? A lot of people on this BB are always interested in new speakers to use in their horns. Thanks! JLH Quote Link to comment Share on other sites More sharing options...
JLH Posted November 20, 2000 Share Posted November 20, 2000 johnnyp, Almost forgot. Most likely the reason you were getting cone smack with (2) screws is because of an air leak. You have to have an air tight seal, or you are going to get cone flap. The small chamber of air created from the area between the cone and mounting board creates a compression chamber to dampen the cone so it doesn't flop around. This is the reason the cone flap stopped after you installed all (8) screws. Or at least that's my take on it. JLH Quote Link to comment Share on other sites More sharing options...
WMcD Posted November 21, 2000 Share Posted November 21, 2000 While we're on the topic, can someone tell me the size (depth) of the spacer on the factory unit? I've heard some describe it as an extra gasket. TIA, Gil 1 Quote Link to comment Share on other sites More sharing options...
johnnyp Posted November 22, 2000 Author Share Posted November 22, 2000 JLH: I cannot comment on how the Dayton woofer sounds in a genuine Klipsch enclosure. My bass units are not Klipsch made but are modeled after the Klipsch design. I can say that I much prefer the Dayton woofers over the McCauley woofesr which I used previously. I'm NOT saying the McCauley is an inferior speaker -- the ones I tried just weren't designed for horn loading. The Dayton gives me at least an extra octave of bottom end compared to the McCauley. The T/S parameters are similar for the Dayton and the Klipsch K-33E. If you have genuine Klipsch enclosures I'd stick with the factory drivers. Gil: Yes, I wish someone would clarify the woofer spacer issue. The optimum spacer distance is probably woofer dependent. But which T/S parameter would affect it? Perhaps the plywood spacer (with the circular cut-out) was used on earlier K-horns to simplify manufactuiring and woofer installation? Quote Link to comment Share on other sites More sharing options...
Shock-Late Posted December 15, 2000 Share Posted December 15, 2000 My Scalas don't use any spacing between woofer and slot. The woofers are not K33, they're TESLA (see description of my Scalas in the topic "Scalas pro: now i have them at home!"). I never heard the woofer hitting the board. But I use a low powered amp, maybe if I used a 100W amp they would actually hit the board (brrr, it makes me shiver to think about it: ask for the price of a re-coning!!!). Someone told me the less space the better, because it helps getting flat response up to 400Hz. Logically if you add space you add air volume in front of the cone and thus you lower the higher reachable frequency. Frans Quote Link to comment Share on other sites More sharing options...
John Warren Posted December 15, 2000 Share Posted December 15, 2000 the k-33-e has two paper gaskets stacked together for total thickness ~5/8". there is no seperate spacer. the woofer is bolted directly to the 1/2" baffle board using 4 bolts. there is no chamber between the cone and throat. earlier units had the woofer mounted to a 1/2" thk 16" sq. board that was then mounted to the baffle with a rubber gasket in between. the board had a slot in it that matched up to the slot in the baffle, no round hole. initial slot cut-out was 6"x13" now is 3" x 13". old units where made with extra geometric stiffening like I showed in the DIY khorn pics elswhere in this section. Quote Link to comment Share on other sites More sharing options...
johnnyp Posted December 15, 2000 Author Share Posted December 15, 2000 Thanks, John W. I read PWK's paper on the Khorn long ago and I think I remember there was a calculation and a statement regarding the critical-ness of the volume of air between the woofer cone and the slot. I hope to try an extra gasket in my enclosure soon. I have already tried the 6" x 13" slot but didn't much care for the results. Have you ever tried the larger slot and what were your impressions? ------------------ John Packard Quote Link to comment Share on other sites More sharing options...
John Warren Posted December 15, 2000 Share Posted December 15, 2000 Quote Link to comment Share on other sites More sharing options...
Stig Posted December 15, 2000 Share Posted December 15, 2000 John, What was reason for reducing the Khorn throat by half and what effect did it have? Would a 1950's Khorn have different response with a K-33-E installed in it than a new Khorn with K-33-E? All comments welcome-- Thanks Stig Quote Link to comment Share on other sites More sharing options...
John Warren Posted December 16, 2000 Share Posted December 16, 2000 Quote Link to comment Share on other sites More sharing options...
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