rtaylor Posted March 16, 2005 Share Posted March 16, 2005 Here goes, finally got off my keister and put these together to try out the mods that help the lascala go a little deeper. Please don't make fun of the woodwork, these are testbed quality! When I find the right combo then I'll make some nice bottoms. Can't wait, Randy Quote Link to comment Share on other sites More sharing options...
yaffstone Posted March 16, 2005 Share Posted March 16, 2005 Could you explain this please? Is the idea to port to the front from the bottom? Quote Link to comment Share on other sites More sharing options...
NOSValves Posted March 16, 2005 Share Posted March 16, 2005 So I take you haven't tried it yet? Get it in gear I'm dying to hear what you think. I have wanted to do this for a while. I really want to know if it takes away from the awesome definition the Lascala has with the bass response it has in its orignal cofiguration. I would not want to give much if any of that tight defind bass up just to go lower. Craig Quote Link to comment Share on other sites More sharing options...
rtaylor Posted March 17, 2005 Author Share Posted March 17, 2005 Yaff, it is supposed to allow the speaker to go lower without losing the qualities of the lascala. Yes, the bottom is open and the ports go to the front. I read about this mod here on the forum. If you do a search you should be able to find some really good info on this mod. It can also be done just using the open area where the squawker and tweeter are. I am trying the bottom version because I think I'd like the upper horns at a higher level more like their cousin, the K-horn. Craig, I know! I've had the wood cut out for better than six months. Golf season is almost here so I have to get going on these or they'll be waiting for another six months. Randy Taylor,,,,,the Cincinnati one. Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted March 17, 2005 Share Posted March 17, 2005 I don't get it? Do the LS sit on top of these with the doghouse door open? So the back waves from the speaker go through this extra cavity and exit the port tubes then? How was this engineered? Looks interesting and I like that it doesn't require butchering the original cabinets. I take it some kind of weatherstripping seal would be necessary between the boxes but the weight would pretty much hold the contraption together.... Michael Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted March 17, 2005 Share Posted March 17, 2005 Michael, That's correct. The LS sits on top without bottom hatch. Quote Link to comment Share on other sites More sharing options...
Klewless Posted March 17, 2005 Share Posted March 17, 2005 rtaylor, I love to see ways people experiment with their systems. I would like to suggest that you seal the LaScala compression chamber back up and put a powered sub-woofer in your base. I think you'll love the result even more. Place the sub to face the corner. I have been thinking of trying this for a long time. Obviously more expensive to do. I also agree that the LaScala needs to be a bit higher. As I see it, the problem with porting the compression chamber, while giving more bass, unbalances the rear of the woofer from the horn load on the front. In general, this is a bad thing to do. The woofer can become non-linear down there which will increase the distortion, especially if you like it as loud as I sometimes do. Other than trying to second guess you (sorry), you did a great job and should be encouraged to keep on keeping on! Quote Link to comment Share on other sites More sharing options...
NOSValves Posted March 17, 2005 Share Posted March 17, 2005 If this works and doesn't kill the definition of the Lascala bass this is a really cool 100% reversable modification. Accomplusing killing 2 birds with one stone. Gives you Khorn bass response and raises the tweeter and mid horn up to a better level. Pretty cool I need to get off my dead a$$ and do it myself. Craig Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted March 17, 2005 Share Posted March 17, 2005 Has anyone actually finished this project and have test results? Michael Quote Link to comment Share on other sites More sharing options...
Marvel Posted March 17, 2005 Share Posted March 17, 2005 Michael, Some folks have made this mod. I did some 3D drwings of it, which you can find on here if you search. djk posted what the results would be, and has done this for others. He says they have not gone back. Repsonse to 32Hz if I remember correctly off the top of my head. Works better with a K43. If you like the way it works, you can take a stock LS, open up the top of the doghouse where the mid/high horns are and enclose the back, with ports going out the rear. Early models had a hatch into he top section. Very cool mod. Marvel ps: Below is dennis' original post on AA about this: The taper rate of a LaScala is 100hz, and the mouth area is good for 125hz. Below this it is a big woofer in a small sealed box. If we plug the T/S parameters for the K33E into a box program we will see that the Qtc=.85, the Fc=82.5hz, and the F3=70.9hz. If we close in the back of the high frequency cabinet and open the woofer rear chamber up into this volume and fill with fiberglass we now have Qtc=.577, Fc=58.2hz, F3=73.6hz. Bessel=Qtc.577=D2 gives the best transient response and the least group delay of all the sealed boxes. At 30hz the Qtc=.577 has 4.5dB more output than the Qtc=.85. Compared with sealed enclosures,the transient performance of the best vented enclosure is worse than the best sealed box enclosure. Since we have made great gains in performance some may elect to stop here. But please read on. The next step is to port it. The K33E is not the optimum woofer for this but it works pretty good. With the box size optimized for a D2 we can port the stock woofer to an SC4. The transient response of an SC4 while not as good as an SBB4 (more on this later) is better than the more common QB3. Unequalized the F3=49hz and has 3dB more output at 30hz than the D2. The response curves are parallel with the D2 the only difference being the Fc being a half octave lower with the SC4 and the output being 3dB higher from 30~70hz. The output of the SC4 does not drop lower than the D2 until you go below 17hz. Again this may be a stopping point for some. But by adding a simple two pole high pass filter ahead of the power amp we can now have a C6 with a -3dB point of 31hz. Since this is the Fb of the system there is no increase in cone excursion or distortion. The filter consists of a cap an inductor and a pot. The pot allows adjustment at Fb of +/- 3dB. This is similar to being able to change the Qtc of a sealed box from .5~1.0. If you think about it we have the choice between a D2, SC4, and a C6 in the same box by plugging the port and/or bypassing the eq. If you have a SET amp or simply want to get the most out of the LaScala you will want to upgrade the woofer to something with a lower Qts. The Klipsch K43E does the trick, as do the EV DL15W and the JBL 2205. The EV and JBL drivers require some minor network changes. The lower Qts drivers allow for an SBB4 alignment which has the best transient response of the vented alignments. With no eq they have 3dB more output at 30hz than the stock woofer. With eq we have a maximally flat B6 and the F3 of the system is 27~28hz. If using a solid state amp with the low Qts woofers a small resistor must be added in series with the driver to have the same Rg as the SET does. This mod can be backed out of a stock LaScala with no externally visible changes if you don't like it. No one has ever gone back to stock after hearing this mod. Paul Klipsch was violently opposed to the venting of horn speakers bassed on his experience with venting the K-horn. In retrospect it is easy to see why. The 12" Jensen field coil woofer he was using had an Fs of 60hz and a quick calculation of the vent area vs the Vb based on the photographs of this experiment looks like an Fb of ~80hz. I am sure this sounded horrible. Paul Wilbur Klipsch is a giant in audio. If I appear to see farther than PWK it is only because I am standing on his shoulders. Quote Link to comment Share on other sites More sharing options...
jwc Posted March 17, 2005 Share Posted March 17, 2005 marvel, I wondered why this hasn't been brought up in a while. The above post is a little out of my understanding. Was the above experience with the ported high frequency cabinet? Was there any experience with the bottom port as seen above. jc Quote Link to comment Share on other sites More sharing options...
Marvel Posted March 17, 2005 Share Posted March 17, 2005 Either one gives you the same change. I don't own LS. Dennis has made plenty of the mods, and I believe he has done both kinds (underneath box and enclosed top). I won't put words into his mouth. If I were to build a set of LS clones, I would at least make the provision for the enclosed top as I was building them. Marvel Quote Link to comment Share on other sites More sharing options...
rtaylor Posted March 17, 2005 Author Share Posted March 17, 2005 ---------------- On 3/17/2005 3:14:47 PM Marvel wrote: Either one gives you the same change. I don't own LS. Dennis has made plenty of the mods, and I believe he has done both kinds (underneath box and enclosed top). I won't put words into his mouth. If I were to build a set of LS clones, I would at least make the provision for the enclosed top as I was building them. Marvel ---------------- Hey Marvel, glad you kicked in! I don't understand the where or whyfor but am trying it anyway. Haven't had any bad info yet from the forum and it is all reversable. Randy Quote Link to comment Share on other sites More sharing options...
rtaylor Posted March 17, 2005 Author Share Posted March 17, 2005 here's a start, taking pictures all the way thru. can you believe it, can't find any 1 1/4 inch drywall screws and i know i have a least a quadrillion somewhere, Randy Quote Link to comment Share on other sites More sharing options...
rtaylor Posted March 17, 2005 Author Share Posted March 17, 2005 one Quote Link to comment Share on other sites More sharing options...
rtaylor Posted March 17, 2005 Author Share Posted March 17, 2005 two Quote Link to comment Share on other sites More sharing options...
rtaylor Posted March 17, 2005 Author Share Posted March 17, 2005 lookin inside stock bass bin Quote Link to comment Share on other sites More sharing options...
rtaylor Posted March 17, 2005 Author Share Posted March 17, 2005 inside bin with new bottom Quote Link to comment Share on other sites More sharing options...
Marvel Posted March 17, 2005 Share Posted March 17, 2005 I guess we'll know pretty soon whether or not it was worth the work, heh? Bet the cat doesn't like the moving around of everything. Marvel Quote Link to comment Share on other sites More sharing options...
rtaylor Posted March 17, 2005 Author Share Posted March 17, 2005 These are the modified AA's. I know I should replace the old cans, they are probably out of spec's. Any suggestions? Thanks for letting me bore you.Randy Edit: djk, do you have any recommendations on changing the AA crossover for this mod? Quote Link to comment Share on other sites More sharing options...
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