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Original La Scala vs. La Scala II's?


jimjimbo

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The necessity of braces for the original could vary depending on the condition of the cabinets.  I've heard someone use the term before and mine certainly could have been called "fart boxes" before I re-glued all the joints and installed braces.  Now, with not quite as much invested as II's would cost I'm hoping that they actually sound better than II's but I don't know from any experience.  I probably shouldn't call them La Scala's anymore since I'm only using the bass bin portion at this point.  I know that II's certainly look better!  

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7 minutes ago, Deang said:

PK had a Dope from Hope where he discussed what happens when you make a cabinet too rigid. 

 

There are two LaScala IIs. One built with plywood, the other with MDF. Ironically, I believe they both used the AL-4 network. 

 

--- and though not as glamorous as birch ply isn't MDF the more sonically inert?

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Yes - but it doesn't hold screws and nails worth a crap, and is a much cheaper build - which they now charge 3x more for.

 

Recently saw the price of the Forte III, and lost all interest. I can buy a mint pair of Klipschorns for that kind of money. 

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1 hour ago, Deang said:

Recently saw the price of the Forte III, and lost all interest. I can buy a mint pair of Klipschorns for that kind of money. 

Are you kidding?  You can buy a mint pair of Khorns AND one Jupiter Beeswax cap for that kind of money......

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19 hours ago, MookieStl said:

I have often wondered about adding the braces, but was never convinced it was worth the effort. I'm one of those people that really like the bass produced by the stock version, but always up for a little "tweaking". I would be anxious to hear from those who have done the "upgrade" and if it does in fact make a noticeable difference. I think @DizRotus did that mod on the LS's he gave to the local HS band.

 

The braces helped a lot with sidewall flexing and distortion on certain songs first noticed by the band director.  The quick and dirty fix was to cut some 3/4 dowels to temporarily wedge between the sidewalls and the vertical edges of doghouses immediately before the tapered "roof" of the doghouses.  That stopped the sidewalls from resonating at an audible frequency.  There was a distinct improvement.  

 

Later, while doing the djk bass mod, I made real braces from 3/4" Baltic birch plywood.  To make the patterns, I cut poster board into sections to fit the straight edges into the horn against the sidewalls and doghouse roof letting the poster board overlap.  The poster board sections were then taped together to hold the pieces in the shape of the opening.  Thus, patterns were made from which to cut the braces.

 

After fitting the braces in the openings, I drew lines on the sidewalls and doghouse to mark the 3/4 strip the braces would eventually occupy.  Pilot holes were drilled in the sidewalls and doghouse.  Obviously, it's necessary to open the doghouse to be able to run screws from the inside of the doghouse, through the pilot holes, and into the braces.   

 

A thin bead of Loctite Premuim PL on the braces holds everything in place.  The screws hold everything in place while the adhesive sets up.  I left the screws in place.

 

Prior to closing the doghouse, I smeared the screw heads inside the doghouse with RTV silicone sealer.  I also put silicone in all of the internal seams in the doghouse, just because it was open and the seams were relatively accessible.  The screws on the outsides of the sidewalls were covered with Bondo prior to Duratex.

 

Klipsch would not have increased the sidewalls of LS IIs to 1.0" had flexing and distortion not been a known problem.  

 

Feel free to contact me with questions.

 

IMG_0142.JPG

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10 hours ago, Coytee said:

Maybe one of the technical  or engineers can comment...

 

I always understood that something resonates at a certain frequency...  regardless of how soft/loud you have it.

 

Yes, if you are playing it quietly, maybe the resonance would fall below a certain audible threshold, but it's there none the less.

 

Louder volumes would unleash it more but the interference starts the moment it is hit with a certain frequency.

 

So, (to the technical inclined) is resonance volume dependent, frequency dependent or a combo of both?

 

 

you will have a threshold level to overcome, you need enough energy input to get a mass moving once it is going its off and running. So I suppose the answer to your question is that it depends.

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12 hours ago, DizRotus said:

 

 

Klipsch would not have increased the sidewalls of LS IIs to 1.0" had flexing and distortion not been a known problem.  

 

Feel free to contact me with questions.

 

 

With that detailed reply, I think you covered everything, but I do have one last question. Did your braces go all the way to the back of the speaker or did you stop flush with the motorboard?

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I did notice that when I put veneer on the outside of my Scalas the side panels were much stiffer to move by hand. Before I could actually move them in and out with out much trouble. But now they seem to be much stiffer. I did not test them side by side but its safe to say just veneer on the outside does help a bit.

   Now that I have said that I think I might try putting some veneer on a thin piece of ply and testing it. Will be easy to do I got some extra veneer. 

When I was refurbishing mine I did notice the side walls seemed to move a lot with just hand pressure . I remember thinking I might try and use braces but never did . 

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3 minutes ago, ricktate said:

I did notice that when I put veneer on the outside of my Scalas the side panels were much stiffer to move by hand. Before I could actually move them in and out with out much trouble. But now they seem to be much stiffer. I did not test them side by side but its safe to say just veneer on the outside does help a bit.

 I have had five sets of La Scalas. The fifth one which I intend keeping is an Industrial one piece fiberglass covered set. I think between the fiberglass and the aluminum corner reinforcements it is a much stiffer cabinet. Now it also has a K-43 and not a K-33 woofer which also adds to the sound quality but for sure I think the much stiffer industrial cabinet helps a lot.

 +1 for particle board is crap by the way, It is hard to imagine with the huge cost of new Klipsch they would opt for MDF over thicker plywood. I have read stories of plywood cabinets rolling down stairs and being beat up but surviving. Somehow I see big broken chunks in my minds eye with MDF. 

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7 hours ago, MookieStl said:

With that detailed reply, I think you covered everything, but I do have one last question. Did your braces go all the way to the back of the speaker or did you stop flush with the motorboard?

 

The braces do not go all the way back.  They stop just before the vertical piece that is parallel to the sidewall.  I don't recall if that is also the motorboard, I suspect it is.

 

To address the problem it's not necessary to have a brace run the full depth of the sidewall or doghouse.  The test fix by wedging a short piece of dowel between the sidewall and the motorboard (?) seemed to move the resonant frequency up away from the output frequencies of the bass horn.  The sidewall was only braced at that single point, but the artifacts disappeared, to the delight of the director.

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4 hours ago, DizRotus said:

 

The braces do not go all the way back.  They stop just before the vertical piece that is parallel to the sidewall.  I don't recall if that is also the motorboard, I suspect it is.

 

To address the problem it's not necessary to have a brace run the full depth of the sidewall or doghouse.  The test fix by wedging a short piece of dowel between the sidewall and the motorboard (?) seemed to move the resonant frequency up away from the output frequencies of the bass horn.  The sidewall was only braced at that single point, but the artifacts disappeared, to the delight of the director.

The thicker side wall panels were put in there by Roy to address a side panel resonance (which braces also removed). The thicker wall also improves flex at the mouth of the horn (the thicker side walls also look a lot better).The lower a horn goes more important cross braces become, check out the big pro SOTA bass horns. The brace that you installed addresses both issues. looks a lot like the Peavey FH1 brace.

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