As long as you don't cut the original cabinet, I'd say give it a shot.

 You can always reverse the process.

NorthofSixty:

Has anyone tried something similar? What were the results?

Bruce 

If you like it, but don't like your cabinets to be so tall, you can do the following:

Enclose the back of the top section that houses the mid horn and tweeter. Open up the top of the doghouse, to give you about the same internal volume as the box underneath. A small amount of acoustic fill goes in either design. If you don't like the second mod after you've lived with it, you can seal back up the top of the doghouse and it still won't be visible from the outside.

Thanks,

Both great ideas. If the passive radiators do not produce good quality results I'll probably try the first concept to see how they perform. My enclosures are in pretty rough shape so if I like the results I would try building the second concept into new cabinets.  The advantage of the second concept is that it does not add any height or, more importantly, weight to the existing cabinets.  In fact it would reduce the weight slightly.

NorthofSixty:

I would like to try a modification to the speaker to smooth out the base response but thought I would pass the idea on for an opinion first.

The bass response of the La Scala is pretty smooth, now.  It does have a hump near 200 Hz.  You can reduce that by bracing the sides like this:

http://forums.klipsch.com/forums/storage/3/1053246/mocksys1sm.jpg 

NorthofSixty:

What I propose to do is remove the bottom plywood cover for the bass driver access and install a 15" passive radiator in its place.  In particular I would use the 15" SLAPS radiator from the EarthQuake SuperNova MKVI-15. The La Scala's would be raised off the floor on a base to give the radiator room to work.

The other alternative would be to place the passive radiator in a subwoofer cabinet constructed to match the  width x depth of the La Scala. The bottom of the La Scala with the access cover removed would form the top of the subwoofer cabinet.  

The first option maintains the original cabinet and volume for the 15" base driver.  The second option substanially increases the volume and alters the shape of the bass cabinet.

Has anyone tried something similar? What were the results?

La Scalas do lack low bass.  The best use of the EarthQuake passive radiator would be to build an EarthQuake subwoofer and attach it to an arc welder for power. 

Your idea won't damage anything, but it doesn't look likely to do any "smoothing".  The EarthQuake passive radiators are extraordinarily stiff.  It surprises me the subs can go so low.  But, the woofer, chamber volume and passive's stiffness all must be matched in order to get good low frequency response.  Since the back air chamber volume is relatively fixed, you need to find a passive and woofer that work with that volume.

It's your time and money, but it would be simpler to just add a sub.  Even a modified La Scala won't go that low, while a good-quality sub will reach down to 25Hz or lower.

Islander:

It's your time and money, but it would be simpler to just add a sub.  Even a modified La Scala won't go that low, while a good-quality sub will reach down to 25Hz or lower.

Why not just build a K horn bottom box... You have the mids n highs for it..hehehehehe

Sorry, just too easy here.. 

Add the subs.. 

IndyKlipschFan:

Why not just build a K horn bottom box... You have the mids n highs for it..hehehehehe

IndyKlipschFan:

Add the subs..

Add me to the group that suggests adding a sub.

K.I.S.S. usually is the best approach.

I'm sorry, but K.I.S.S.  would not be adding more electronics and sepakers. The porting is much more simple.

Once I get my mods done thhis summer, I will be more than happy to arrange to haul them up to Indy so they can be tested. I am sure that canbe worked out. Even without the e.q. put in between the pre and power amp, I think it is worth it.

Marvel:

Once I get my mods done thhis summer, I will be more than happy to arrange to haul them up to Indy so they can be tested. I am sure that canbe worked out. Even without the e.q. put in between the pre and power amp, I think it is worth it.

Islander:

Marvel:

Once I get my mods done thhis summer, I will be more than happy to arrange to haul them up to Indy so they can be tested. I am sure that can be worked out. Even without the e.q. put in between the pre and power amp, I think it is worth it.

Good idea!  After all, the proof is in the listening.

Hi Marvel,

A couple of questions, if you don't mind, regarding the bass bin addition. Is 9" of internal height the goal? Using 3/4" plywood that would leave the outside 10 1/2" tall, is that ok? From all the threads I've read regarding this, it doesn't seem that any crossover mods are necesary. Is that true? Is adding material (batting) critical and if so, how much, what kind? For the record, I have an older pair of LS courtesy of John Foley and I have updated the tweeters and crossover from Bob, type A. Thanks, David.