Mr. P Posted February 14, 2004 Share Posted February 14, 2004 Andy, These LaScalas were used at an outdoor concert in front of "Old Main" hall at the Univeristy of Arkansas in about 1977 or 1978. My money says you built them. Quote Link to comment Share on other sites More sharing options...
jt1stcav Posted February 14, 2004 Share Posted February 14, 2004 What a fine read this thread turned out to be! Keep the stories and pictures coming. I think it's truely fascinating how you both recall certain events/projects concerning PWK and Klipsch and Associates, Inc. As an owner of a fine pair of '79 Andy-built Cornwalls, I really appreciate the personal touch to the stories and recollections, and Curtis's viewpoints are just as insightful and charming! I love this forum...the legend in sound continues right here with these two gentlemen. Imagine the book these guys could write! Quote Link to comment Share on other sites More sharing options...
HDBRbuilder Posted February 14, 2004 Share Posted February 14, 2004 Curtis, you talking about the brace that is barely visible on the LaScala in the far left in the attached pic? You may recognize the gentleman on the right in this pic...he is perusing one of the production birch Heresy cabinets that I built right after the change from flush-front decorator Heresys cabinets to the drop-in front decorator Heresys. Remember the problem of centering-up those drop-in fronts on those cabinets so that the woofer flange would be able to consistently clear the glue block at the bottom of the front? I had cut as few under-length(read shorter) by about 1/16th of an inch and adjusted the router form for them so that the holes all moved up 1/16th of an inch , then just pulled the top of the front all the way up, centered it from side to side, stapled the top on, then centered the bottom from side to side, stapled it down, then ran staples up the sides...it worked, and solved the problem...PWK wanted to check it out, though, before we continued to march with it as a solution to the problem. This way, we could always use the same fronts for either the decorator cabinets OR the mitered ones...without having to adjust for minor variations in the thickness of the side/top/bottom panels on the mitered ones. Quote Link to comment Share on other sites More sharing options...
Mr. P Posted February 14, 2004 Share Posted February 14, 2004 Since was not as close to production as you, I had completely forgotten the drop in front. Do you remember the "World Map" coffee table that is in that picture with crossovers stacked on it? I fished that out of the "trash truck" and it was my coffee table for 20 years!! That is the brace I was speaking of, and it make big difference in the sound of the bass around 150Hz. There is a resonance that occurs when the sides start to vibrate wildly on a pure sine wave input and increases with volume. The best description of the change when listening is that it "Tightens up" the bass, particularly at higher volumes. The sales force said it was ugly.....so it was dropped. Quote Link to comment Share on other sites More sharing options...
HDBRbuilder Posted February 14, 2004 Share Posted February 14, 2004 Curtis, On the Oak Lascalas that I built, I had to redesign the joinery techniques involved in order to build them with no nail holes in the sides, and in order to have all of the mitered parts that are normally just butt joints work out. Part of the redesign in joinery consisted of a change in how the bass bin goes together. The upper horizontal panel of the bass bin that sits on top of the doghouse is actually glued into a dado made in the sides...a TIGHT dado...and is reinforced by glue blocks on its UPPER surface inside the H/F portion of the cabinet. THis joinery also provides about twice the glue surface of a standard build. This stiffens up the upper left and right seams of the bass bin's sides so that it won't be AS LIKELY to resonate at higher volumes. The bottom horizontal panel of the bass bin UNDER the doghouse is joined to the sides with rabbeted "double overlapping butt joints", which provide a stiffer joint along the bottoms of the sides AND provide 1.5 times the effective glue surface of the standard construction. The back panel of the bass bin is ALSO attached to the sides with those same rabbeted "double overlapping butt joints, therby stiffening the rear of the sides of the bass bin and providing 1.5 times the glue surface of a standard build. You can't see this joinery in the pictures because I applied mitered veneer banding over the front edges of the cabnets on the front edge plys of the plywood, but a rear view would show this joinery. All of this somewhat stiffens up the side panels in order to reduce the tendency to resonate at higher volumes. Although this leaves the front edges of the sides without stiffening properties, and the braces could be used to help in that area, if wanted, the overall stiffening of three of the four effective edges of the bass bin at the sides does alot to stiffen up the bass bin enclosure portion of the cabinet. The problem with installing the braces would be the necessity of custom-fitting each brace on each side of the doghouse...very time consuming...since in order to get a good tight fit, one would have to make each brace separately...there is no way to ensure that the distance from the sides to the doghouse will remain within 1/64th" tolerance, that is just the nature of the cabinet build...even moreso of a problem on standard factory builds. It wasn't just the sales folks' opinion that the braces were ugly that kept PWK from incorporating this change...it was also the necessity of custom-fitting each of the two braces on every LaScala that had them...which drove up production costs far more than the cost of materials needed to do this change....figure about an extra two hours labor or more per speaker, not including materials....then add in the extra time in the sanding room and the paint room (for ones not sold "raw"). If I were to use braces, then I would want to use mortice and tenon to join them to the sides and doghouse, so that no nail holes or other fastener holes show on the sides...I guess I could screw them on using countersunk screws and solid wood plugs to cover the screw heads in the outside of the sides. The use of screws for attachment to the doghouse would be a non-issue, since those screw heads would only be seen from the inside of the doghouse. I would also want to make the braces in a DIHEDRAL FORM (kinda like wing cross-sections or the braces found in the mouth of the old wooden H/F horns on the old K-horns) out of solid stock...IOW whatever the veneer of the speakers is, would be the kind of wood solid stock I would use for the braces. The solid wood for the braces would be a necessity if shaped to wing-cross sections, since using plywood would be ugly. This would actually enhance the aesthetic qualites of the bass bin instead of detracting from them, IMHO. There is another option, but I am unsure of just how well it would work in stiffening up the front edges of the sides...although it is BOUND to help some...that option would be to use THICKER plywood for the sides...maybe 1" thick would do it...or to laminate two sheets together for each side giving it 1.5" thick sides. That may be all that is needed, but the cost in veneered panels would be high...MUCH higher than the cost of 3/4" plywood in nice veneers, since it would have to be custom-ordered! If I ever get to do this thing as a semi-retirement deal, then maybe I could offer up the wings as an additional cost option...or thicker side panels as an additional cost option...or both...who knows? Quote Link to comment Share on other sites More sharing options...
TBrennan Posted February 14, 2004 Share Posted February 14, 2004 Here's a well built and braced basshorn, the Peavey FH-1. These ones had an extra 1/4" of MDF and a veneer added and had Klipsch K-33 drivers. They were flat down to 50hz when placed tight into the corners of my basement. First time I measured them (used an RTA and a calibrated mic) they were flat down to 30hz. No way I thought. Then I shut off the furnace. :-) They also extended nicely up to 500 and then rolled off nicely, I could run the Altec topend with a simple 1st order 500hz highpass and no lowpass, nice and simple. Quote Link to comment Share on other sites More sharing options...
Mr. P Posted February 14, 2004 Share Posted February 14, 2004 Andy, I had forgotten about the manufacturing cost issue, but that was the real issue that stopped the change. However, I remember the sales force screaming more than the factory. I would be interested in reading an outline of your assembly process sometime. Your process obviously uses a lot of furniture clamps since you have so many miter and dado joints. The double wall thicknes would work to stop the resenance, but would not enhance the apperance. We talked about using the Russian 13 ply wood to see if the added stiffness would take care of it, but I don't know if that ever happened. TBrennan, That Peavy cabinet did the trick to take out the resenance. Quote Link to comment Share on other sites More sharing options...
Mr. P Posted February 14, 2004 Share Posted February 14, 2004 I have had fits getting this jpg file to load and it finally went after a resave as a different name. This photo was taken the same day as the one I posted earlier with the twin LaScala's at an outdoor concert at the University of Arkansas. We had twin stages set up with the 4 LaSalas on one stage and the MCM's on the other. You can see the Crown DC300, the Crown crossover and small 60 watt per channel amp for the midrange and tweeter. I will post a couple of Promotional pictures later with the second generation system that was vastly improved by mid bass cabinet. I don't know if these pictures were ever published anywhere, or if they were just for use by the sales force. Quote Link to comment Share on other sites More sharing options...
Mr. P Posted February 15, 2004 Share Posted February 15, 2004 Ok, I decided it would be good to venture back to the topic!! Here is a response curve of the crossover network I was working on for the Industrial LB-76. As a young engineer fresh out of school, I didn't take the kind of notes I should have while in the presence of a true legend. Quote Link to comment Share on other sites More sharing options...
Mr. P Posted February 15, 2004 Share Posted February 15, 2004 This was the LB-76 response curve with my network and the industrial woofer. It was not acceptable. The notches at 70Hz and 700Hz and the peak at 150Hz would have taken a lot of work to deal with. I did get a pat on the back from Paul for my network! So all was not dark! Quote Link to comment Share on other sites More sharing options...
HDBRbuilder Posted February 15, 2004 Share Posted February 15, 2004 Well, Curtis... If I had about an hour with an LB-76, my tape measure, my clipboard, my screwdriver set, my sliding bevel, and my protractor, and I would have all I need to produce working drawings of that thing. Reverse engineering is what I have been doing for a number of years as a pattern maker, anyway! LOL! I always wanted to build a pair LB-76's just to have around for parties and such...they were sure great party speakers at the Little Missouri River swimming hole north of Blevins! The big problem would be getting somebody to build the crossover networks for me, since I am primarily a woodworker kinda guy. You think a K-22, K55V on a K600 lens, and K77 tweeter would do it?...or would I need to go with a K-33 in lieu of the K-22? Can I even use the K-600 lens or would it be better to go with a K700? I really don't want to shell out the bucks for a K-500 lens! What was the name of that engineer who worked at K&A around 1980 for a couple of years and lived in the big old house over at Oakhaven? He was the one who re-did the LaScala network and played a trumpet or cornet. He had a pair of LaScalas in his living room with his networks in them...they always seemed too bright in the midrange for my taste, but he WAS a horn player, so I guess that is what he wanted to hear the most out of them! Quote Link to comment Share on other sites More sharing options...
Mr. P Posted February 15, 2004 Share Posted February 15, 2004 That engineers name was Dan Bynum. We kept in touch for a while but I don't know where he is these days. He had a double major, I think it was a Electrical Engineering degree with a Masters degree in Music!! His major instrument was Classical Guitar. He played a nice D-28S Martin guitar. He did like things brite. The network I built in the two curves were built with parts we had from other networks, or ones I modified. Some of the inductors were our standard units with the iron taken out, or windings taken off etc. Yes you could use a K700, and if you did I would say down scale to the K-22. We sat the LB-76 I was working on outside one time in front of the old lab on secretaries day when Bob sat a Keg on the wood shop loading dock. It gave us good sound all the way over to the dock. That one had the K-43 industrial 15" in it. I could just about come up with the dimensions of that box with out one handy. The height of the mouth of the bass horn is the one dimension that would be a little questionable. Later. Quote Link to comment Share on other sites More sharing options...
HDBRbuilder Posted February 16, 2004 Share Posted February 16, 2004 Dan Bynum...yep...that's him! Had kinda curly dishwater blonde hair. I also remember he played classical guitar...I guess the combo of acoustic guitar and horns is why he liked his midrange and upper bass so bright! It seems like most musicians tend to favor speakers that show off the instruments they play the most...even going to the point of modifying them to get that particular sound. Quote Link to comment Share on other sites More sharing options...
Mr. P Posted February 16, 2004 Share Posted February 16, 2004 Yeah, you want clarity and the sound you hear when playing. Otherwise known as accuracy. Quote Link to comment Share on other sites More sharing options...
Mr. P Posted February 17, 2004 Share Posted February 17, 2004 wooo, almost lost this little bastard! Quote Link to comment Share on other sites More sharing options...
BEC Posted March 24, 2006 Share Posted March 24, 2006 bump Quote Link to comment Share on other sites More sharing options...
bhendrix Posted March 24, 2006 Share Posted March 24, 2006 Thanks, Bob! These threads are priceless!! John Fricks (in one of the pics) was our sales rep and was a really great guy. I wish we could get all these folks together and write a book. . . Quote Link to comment Share on other sites More sharing options...
meagain Posted March 24, 2006 Share Posted March 24, 2006 Bob - you are on a roll. Thank you. I'm going to save these in case the forum ever goes poof and loses archives. This one gets printed out for a cozy read later. Quote Link to comment Share on other sites More sharing options...
Seadog Posted March 24, 2006 Share Posted March 24, 2006 Thanks, Bob! These threads are priceless!! John Fricks (in one of the pics) was our sales rep and was a really great guy. I wish we could get all these folks together and write a book. . . Shortly after I bought a pair of KG4s (spring 1985) I noticed that one of the 8" drivers had developed a slight buzz at certain frequencies. I called the Klipsch factory, and the following week, John Fricks came to my apartment in Fort Worth and replaced all four of the drivers. He was really a nice guy. He stayed for about an hour and listened to LPs until we were satisfied that the problem was fixed (how many other companies would do this sort of thing?). At the 2004 Pilgrimage, I asked Jim Hunter about John . Unfortunately, Jim said John had past away a few years ago. Bob, thanks for bumping this thread! Quote Link to comment Share on other sites More sharing options...
firesisle Posted April 22, 2011 Share Posted April 22, 2011 I have an original pair of LB-76. They're in pretty good shape. Anybody have an idea of what they're worth? I'm not really looking to sell them; I still use them with my band; have been for the last 30 years and they still beat anything I've ever seen. They were build in 1978 for a local radio station KYSN, in Colorado Springs. Thanks! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.