LaScala "Same but different"

[Solly]

Hi, just bought some older LaScala's and copied some other folks ideas but changed a few things. Thought I'd share.

1. Add 2 braces per side in bass cabinet instead of 1 to stiffen sides and elinate some cabinet vibrations. I think it looks like old multi-cell horns. Did not extend braces to front to allow sound wave to exit as whole. Rounded leading edge at rear of brace to reduce sound diffraction from sharp edge.
2. Enlarged tweeter and squaker opening in mounting board to reduce sound reflection/distortion
3. Rounded edge with router at tweeter/squaker exit. I read somewhere that sound exiting horn should wrap around 90 degrees to reduce distortion caused by sound wave interacting with front baffle. (lots of bright people out there!)
4. Apply several light coats of rubberized automotive undercoating (very light and allow 24 hrs between coats)
5. Used 1/16 neoprene (50 duro) between tweeter and squaker mounting to front. My version of constrained layer damping. Sheet is available from McMaster Carr, trace and cut with scissors. Used mortite on my Heresy's before and LaScala squaker just to big for me attempt same.
6. Remove squaker driver from horn and smooth entry to horn with rat tail file. Lots of burrs and casting flash to distort sound wave entering horn. New gasket while I had apart.
7. Remove raised edge at horn exit and rounded corner on squaker also (simple hand files on aluminum). Again trying to eliminate diffraction/distortion
8. Secured the wire to the bass driver to the side of cabinet with silicone caulking to reduce/eliminate microphonics from sound vibrating wire. Did same with all internal wires in my Heresy's, but entire crossover gets blasted by sound in that cabinet.
9. Replaced caps with Sonicaps (mostly due to age, really nasty old rectangular caps) and replaced steel screw with stainless screw in inductor on crossover. See Bob Crites website on rebuilding AA crossovers for excellent explanation on why.
10. Ultra soft urethane from McMaster Carr (Sorbothane) 1/2 thick under crossover to isolate from vibrations/mechanical coupling. Should reduce microphonics also (my experience with Hersey's really made me believe in microphonics and eliminating them adds clarity IMHO)
11. Next to try, I also read (see Lynn Olsen, The Art of Speaker Design) that a 1 inch wide by 1/8 thick felt strip applied inside horn at exit will help. He says it will reduce output 1db, not a big sacrifice. I'm thinking that a roll of double stick-em' tape and felt can't be very expensive and easily undone.

I am thinking of making an X brace of 1/8 steel plate to allow me to use spikes to anchor to floor. That really helped my Heresy's with increased bass (shaking floor also?). If nothing else it will allow me to tilt if desired.

[Islander]

Your mods all sound very logical. I can't recall anyone else addressing the various potential resonance issues as you have. Can you hear any difference? Also, could you post a front view of the cabinet so we can see how the braces look?

Rounding off the fronts of the braces might also help in the same way. You could even add half-round wood strips to the bass horn's exit to eliminate the square edge of the plywood.

Another way to smooth the transition from the tweeter and squawker horns to the cabinet fronts would have been to mount them from the front and countersink them. I believe the La Scala II is made like that.

BTW, what year are your La Scalas? They look a lot like my 1974 models with their removable tops, top-loading woofers and forward-mounted crossovers.

[BE36]

Could you add some more pictures? 1,6,7

[aj01]

Did you do all of the mods at once? Kind of curious if the cap upgrade and bass bin reinforcement were the biggest change?

[Solly]

I front mounted my tweeter and squaker on my Hersey's. With the raised edge of cabinet, I sprayed entire area with texture type spray paint (except drivers/horns obviously). I thought the same thing and realized I faced two issues, raised pads in the squaker casting where the screws attach and not enough talent with my router to comfortably inlet the horns to the motor board.

IMHO, the caps were a cheap date and will undoubtedly avoid problems going forward. I will admit I want them to enhance the sound. I believe that when I listen at higher levels there is more clarity. I am guessing at low levels, the old caps may not have reacted adversely with the horns. I would do it again in a heartbeat. The bracing is harded to quantify. Clearly, the cabinet is more rigid and I probably need to listen to some bass heavy music to truly evalate further (J.S. Bach, toccata and fuge in D minor?) music used in original Rollerball movie sound track would test it to the limits.

Great thought on half round moulding! I haven't figured out how to integrate with top quarter of opening. I think it is do-able, just some more time to figure it out for asthetics. Black paint hides alot of sins! If you know the answer please share.

My serial number has a single digit followed by a single letter, then three more digits. I think makes pretty them early? Also my AA crossover did not have motor starter type caps. They were 2 single rectanguar cubes and a triple stack of cubes. Also caps seems to be assembled in reverse order to images I have seen of later model crossovers?

Have fun, my take on these modifications is that they can all be reversed with a little time and effort. I am amazed at the skill and knowledge levels people share with all of us.

Last thought, all of the drivers were loose, every single screw could be tightened more a full turn, probably not good.

[Islander]

My serial number has a single digit followed by a single letter, then three more digits.

The letter indicates the year of production. See: http://www.progressive-engineering.com/klipsch/klipsch_date_codes.htm

1962-1983 Letter format

A = 1962	F = 1967	K = 1972	R = 1977	X = 1982
B = 1963	G = 1968	L = 1973	S = 1978	Y = 1983
C = 1964	H = 1969	M = 1974	T = 1979
D = 1965	I = 1970	N = 1975	U = 1980
E = 1966	J = 1971	P = 1976	W = 1981

[Islander]

That bracing looks very solid. It likely won't give you more bass, but it may eliminate a resonance that occurs around 150Hz, so the bass response will be smoother.

I also replaced my capacitors with Sonicaps and there was a noticeable improvement in clarity at all volume levels.

[DrWho]

Have you considered replacing all your diaphragms too?

How do things sound now? Looks great [Y]

[Daddy Dee]

very neat work on the bracing. those cabs are now solid as heck.

[BE36]

Looking forward to inspecting horn throats for burrs.

Biggest improvements to my La Scalas:

McIntosh MC240

McIntosh MX132 Preamp

ALK Unversial networks (tried three others)

Bob's Tweeters

Currently Considering Bob's Woofer

[nola]

MC240 amp Q.

I own 2 of them; each with different tubes. Intended to bi amp Khorns post Katrina. Might end up tri amping with actve xover, ? dbx PA plus, later this yr.

Also have LSs and HIs, all from late 70s. I did Crites Sonicaps on the AAs, changed out inductor screws and bought ALK kit - mind you ALK for the KHs. I like the other ideas listed by the thread starter.

Also add possible issues of demag'd Alnico drivers to his list of things to check/do.

Did he check the ohms across drivers?

Per the MC 240 amp, I have talked to a few people in the last couple of months who have noted that the 240 is the most solid state sounding tube amp that they had heard. I have to admit, that compared to my SS amps, I had a hard time noting differences.

What are your thoughts?

GO WINGS!! (Spent 2 yrs at U of M).

[Solly]

Islander, my s/n's are 2M624 & 2M625 so that makes them 1974 vintage. Thanks for code showing year of manufacture.

[Solly]

BE36, I realize picture is marginal at best, but if you look at lower edge of horn where it meets the motor board it is smoother/shinier looking. That used to be a raised ridge about 1/8 wide by 1/16 high that I filed down smooth.

[Solly]

BE36, you can see the side of the horn throat that was rough and had casting flash. I just rounded it with a rat tail file. I also made sure the gasket center hole is as large as the horn opening or just slightly bigger so that it doesn't impede the sound or vibrate and add distortion.

[Solly]

aj01, I made the mods in 2 week period. I had prior experience modding my Heresy's, so I knew something I wanted to do immediately. I then looked at this site and grabbed some ideas from others. The cap upgrade was absolutely the most universal improvement. I think the bass bin falls into the thought of any energy I am not using to vibrate and flex the structure should continue to be radiated as sound. I have noticed that I have had to raised the output level on my Velodyne sub since I added the braces. I am only guessing that the bass is going deeper. I personally believe that cleaning up the horn throat, casting flash and exit of squaker is most audible to me. I am amazed at how much better/bigger the LaScala squaker sounds compared to the smaller Heresy squaker. Voices/mid range are what I enjoy most.

[Solly]

DrWho, If Titanium diaphrams were available I would absolutely go that route. From what I read, if they work, they are OK. Time to sit back, enjoy, and work on placement for awhile. Big soundstage and excellent imaging along with that effortless wall of sound. Thank you for the complement, satin black can hide allot of sins! I had my wife help with installing the braces (hold for alignment, pilot holes and final assembly/glueing) so she has some buy in. They aren't quite as big and intrusive now! (She doesn't visit this site either!)

[Solly]

BE36, You have brought electronics into discussion which is great. Amp wise, I am using Dynaco Mark III monoblocks that I have wired as PP triodes reducing output to 30 watts versus original 60 watts. Secondly I installed Triode Electronics driver boards. But I used 12AU7 driver instead of 12AX7. AX is high gain triode and AU is medium gain triode. This greatly reduced low level noise, almost to dead silent (actually were dead silent with Heresy's). Also have Mac SS pre-amp, C29. Triodes and Alnico magnets on these horns are best sound I have ever had.

[DrWho]

From what I read, if they work, they are OK.

Except in cases of a work-hardened driver...