LARRY Posted June 18, 2008 Share Posted June 18, 2008 I need some advise, etc. from those who know about horns. The build will be an exact copy of the Belle Bass Bin, with the possible exception of the back chamber volume. The system will be two way with a GPA 902 driver mated to an Altec 511B horn and use an ALK steep slope 600 Cycle crossover and a BEC cast frame woofer. The center channel will be used with left and right Jamboree horns, which are two way GPA 902/Altec 511B/ALK steep slope/Bec Cast woofers. If my calculations are correct, the Lascala back chamber volume is approximately 4120 cu in and the stock Belle is approximately 3900 cu in, while the Klipschorn is approximately 4800 cu in. The Belle clone will have to be 23 inches deep to accomodate the above driver and horn. This depth would allow a larger back chamber volume. In order to keep the 8 inch front center, the initial expansion could be modified as per the Lacala which keeps the initial expansion for about 7 inches before the actual expansion begins. If this is not feasible, then an extended Belle clone will be built with no modification to the back chamber. I have a set of 'real' Belles and a set of Altec 19s. The Altec is not better than a Belle, but has a presence (sound stage) that is clearly evident. Probably a combination of the two way and a larger horn. I set the Belle up with the GPA/Altec combo, and it sounds better than the Altec 19! I apologize for being so 'wordy', but wanted to make sure that it is understood that the Belle with no other modifications (no ports, etc.) is the criteria. As soon as I learn how to use TrueRta, I will be able to give feedback on the above horns. Thanks for advise! Larry Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted June 19, 2008 Share Posted June 19, 2008 Larry, This sounds like you've got a very cool project going here. I'm sorry not to be able to comment on the expect impact of changing horn dimensions, but do have a couple of thoughts. Just noting the PWK and his engineers built and rebuilt prototypes when real world issues were not precisely what was expected from what "should" have been based on the math. Being a non tech type, this would encourage me to stick with a Belle clone or a LaScala clone. You might well end up with a perfectly fine sounding bass bin based on what "should" happen as a result of the changes. However, these designs are tried and proven to be excellent. To stick with the Belle, I'd think there are some creative options to extend the top plate back to accomodate the longer horn. Quote Link to comment Share on other sites More sharing options...
LARRY Posted June 19, 2008 Author Share Posted June 19, 2008 Daddy Dee, Thanks for the reply. I will stay with the Belle bass bin if there is not an advantage to changing the back chamber volume. The Belle and Lascal have different volumes even as though they have the same cutoff, etc. My thoughts are as long as I am able to make a change and improve the low frequency response, then take advantage of it. I agree with you, the Belle bass bin is a proven design, however sometimes there are compromises for manufacturing purposes. Any extra bass would be appreciated![] Larry Quote Link to comment Share on other sites More sharing options...
seti Posted June 19, 2008 Share Posted June 19, 2008 I haven't heard of too many people tweaking Belle's. I owned Belles for many years and are among my favorite speakers to date. It is the quality of the bass that amazed me and not necessarily the quantity. If that makes any sense than good : ). Here is a doghouse for ya. and a Belle. Another man owns her now *sigh* Quote Link to comment Share on other sites More sharing options...
LARRY Posted June 19, 2008 Author Share Posted June 19, 2008 seti, I agree, quality not quantity. My thouhgt is not more but lower bass. If a larger back chamber would help, then since they will be built, why not. The Belle is also one of my favorites, that is why I will keep my set in the den (could not ever let them depart). Thanks for the reply. Larry Quote Link to comment Share on other sites More sharing options...
seti Posted June 20, 2008 Share Posted June 20, 2008 seti, I agree, quality not quantity. My thouhgt is not more but lower bass. If a larger back chamber would help, then since they will be built, why not. The Belle is also one of my favorites, that is why I will keep my set in the den (could not ever let them depart). Thanks for the reply. Larry It sounds like a worthy experiment especially since you already have a pair. I would try posting on some of the DIY speakerbuilder sites or perhaps Audio Asylums high efficiency speaker forum. Have you looked into the DIY Klipschorn Jubilee? Several forum members have built it. http://www.jubilation.ws/ Good luck and have fun. Quote Link to comment Share on other sites More sharing options...
LARRY Posted June 22, 2008 Author Share Posted June 22, 2008 Well, it appears that the Belle is a speaker that has not been modified! Since this is the case, I am not going to modify it either, however I am going to use a depth of 22 3/4 inches rather than 18 3/4 inches. The expansion will be continue for the 4 inch difference, plus two braces inside the back chamber to make the sides and top and bottom more rigid. The net extra cuboc inches will be approximate to the Lascala back chamber. Since I have just learned how to use TrueRta, (finally), I will report results compared to a stock Belle. Thanks for[] all input and replies. Larry Quote Link to comment Share on other sites More sharing options...
seti Posted June 22, 2008 Share Posted June 22, 2008 What would be interesting is to look at what Klipsch did with the La Scala in 2006. This would be the current model. If you carried what they did to the La Scala to the Belle it would be most interesting. The more rigid bass bin due to 1 inch mdf really improved the sound. The guys at Klipsch were really impressed with the improved as were we. Check it out. Quote Link to comment Share on other sites More sharing options...
seti Posted June 22, 2008 Share Posted June 22, 2008 Actually when I had Belles one of the mods I was kicking around was going two way. This was an actual possiblity with the Belle since the bass bin can go abit higher than the Khorn or La Scala. The K510 is what has been used on the Jubilee and LaScala by some adverturous DIY and modders. It is a great tractrix horn and one of my favorites. It will also fit in the top hat of the Belle without changing size. A two way system was one of PWK's goals which was finally realized with the Jubilee. You gotta love the simplicty of fewer crossover points. This lends itself to a more cohesive sound as well. Just food for thought. Since you already have Belles it would be fun to compare the two. here is a blurry pic of the k510 on the Jubilee. Quote Link to comment Share on other sites More sharing options...
JohnA Posted June 24, 2008 Share Posted June 24, 2008 ................... If my calculations are correct, the Lascala back chamber volume is approximately 4120 cu in and the stock Belle is approximately 3900 cu in, while the Klipschorn is approximately 4800 cu in. The Belle clone will have to be 23 inches deep to accomodate the above driver and horn. This depth would allow a larger back chamber volume. In order to keep the 8 inch front center, the initial expansion could be modified as per the Lacala which keeps the initial expansion for about 7 inches before the actual expansion begins. If this is not feasible, then an extended Belle clone will be built with no modification to the back chamber. Larry I had not realized the backair chamber of the Belle, La Scala and K-horn differed so much. It is selected to match the woofer and to balance the reactance of the horn in front. I wouldn't go larger than a K-horn, but I would build the bass horn so it is longer and has a larger mouth than the Belle to get more low bass. Quote Link to comment Share on other sites More sharing options...
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