1977 Lascala. Reinforcement of the side walls.

[KT88]

In 2006 I have renewed my 1977 Lascala which I bought in 1999 visually. The previous owner had done "color tests" to paint the beautiful raw birch to match his ugly dark reddish brown cabinet. I gave the Lascalas to a carpenter to remove the paint from the test strips. Unfortunately, without asking me, the carpenter had planed off a little bit of the siding on the machine. Not much, but about half a millimeter (0.02 inches). Visually the result was good but I was a bit negatively impressed how much more bad resonance it makes in the upper bass range. Now that I have restored almost everything electrical to original condition in the last two years, I want to reinforce the sidewalls. You have to believe me, I remember very well the sound of my Lascala before it was planed. It was on the one hand without too many resonances and on the other hand it was very lively in sound. A tenor sax, a barritone sax, a cello etc all instruments in the critical range of the Lascala sounded very very lively in the original condition of the speaker.
Today, because of this very little planing, the balance is no longer in order. I want to fix this because I love my old Lascala very much. 

Well, is more and more sidewall reinforcement better and better? I want to avoid that the Lascala sounds clean but dead. I know that the new LS2 and AL5 have very thick walls of MDF. I have not heard them yet. For sure they sound very good. But it's a very different construction with different xover etc. 
In the case of my old Lascala, my gut feeling is that 3mm sidewall reinforcement might be ok. I want the Lascala to continue to have a lively and breathing sound. E.g. the cello. I sometimes think that the weaknesses of the original old LS regarding a dry bass and in rock music are at the same time the strengths in classical and jazz, when it is allowed to resonate a little in the bass. What do you think? Are 3 mm extra a good decision or should I better just take one mm or do you think I should rein in the bass as much as possible...like with an extra 12 mm?
Thanks for your time.

 

PS

One more note, I do not want to and will not use braces. The area of the opening of the bass should not be reduced and I do not like it visually on the Lascala.

[Bacek]

Not that it matters as this is different material but new La Scalas are 6mm thicker.

[JMeader]

I put  1/2 inch mdf on my 1987 La Scala's.  It totally eliminated the resonance, which gave the La Scala;s their "Live" sound . For me the resulting new sound was much more refined more similar to other high end speakers such as the newest La Scala's. I also changed the teeter and went to the Crites A4500 crossover.

 

I have no regrets and really enjoy my modified La Scala's.  I would recommend finding some new La Scala's and listen to them before you make any changes. No matter which way you go, the Basic La Scala design sound remains, it is merely which one you prefer.

 

Good Luck  and as always Enjoy the Music

 

 

 

 

[OO1]

On 6/5/2023 at 5:59 PM, KT88 said:

 

One more note, I do not want to and will not use braces. The area of the opening of the bass should not be reduced and I do not like it visually on the Lascala.

Heinz ,some of the 80's  LSI  had routed  corners and HF openings , 0 resonance  ,   Klipsch used a Tad over 3/4 inch thicker  heavier marine Birch/Fir plywood  on all the panels   ( side walls -top - bottom-rear  )

 

  PWK tested braces , but  he did not use braces    ,  the solution was the  2-3mm  thicker / heavier  LSI 

 

 

[KT88]

1 hour ago, OO1 said:

Heinz ,some the 80's  LSI  had routed  corners and HF openings , 0 resonance  ,   Klipsch used a Tad over 3/4 inch thicker  heavier marine Birch/Fir plywood  on all the panels   ( side walls -top - bottom-rear  )

 

  PWK tested braces , but  he did not use braces    ,  the solution was the  2-3mm  thicker / heavier  LSI 

 

 

 

 

Randy, thank you for your very informative post. This puts me on the safe side that a sidewall reinforcement of 2 to 3 mm will be sufficient. While I don't have marine grade multiplex like the 1980 LSI, this reinforcement will be sufficient for my purposes. Likewise, I will reinforce the top plate with about 1 or 2 mm. That was also sanded down a bit and it resonates too much when you knock.

As a result, I'll get a Lascala that still looks nice and won't be much too heavy.
What is the exact thickness of the original sidewalls on my 1977 standard Lascala in raw birchply? With the info I can use a thickness gauge to see exactly how much the carpenter planed off back then.

[OO1]

1 minute ago, KT88 said:

 

What is the exact thickness of the original sidewalls on my 1977 standard Lascala in raw birchply?  

Heinz     ,   1976 - 1983  plywood  was ...19mm ,  5 ply with a birch veneer on each side , so  7  plys 

[babadono]

yes that was back in the day when the ol'man was still around and cared how raw speakers looked wen delivered to paying customers. Those days are long gone.

"F it! just paint it black"

[KT88]

2 hours ago, OO1 said:

Heinz     ,   1976 - 1983  plywood  was ...19mm ,  5 ply with a birch veneer on each side , so  7  plys 

👍🥂

[KT88]

2 hours ago, OO1 said:

Heinz     ,   1976 - 1983  plywood  was ...19mm ,  5 ply with a birch veneer on each side , so  7  plys 

Randy, If it is true that the sidewalls were 19 mm on the standard LS in 1977 then the stupid carpenter has planed off almost 2mm. see photo of the sidewall. 
how thick is the motor board of the squaker. Can it be that the carpenter has also planed off? see photo.

 

 

 

 

 

 

 

[OO1]

35 minutes ago, KT88 said:

 

Heinz , you lost 1mm  

 

klipsch used   Georgia  Pacific 3/4 inch plywood , but your 77 LS do not seem to be the standard  GP 19mm    , they are 18 mm  thickness ......  0.71 inches   and you can see the 2 birch plys very clearly .

[KT88]

6 minutes ago, OO1 said:

Heinz , you lost 1mm  

 

klipsch used   Georgia  Pacific 3/4 inch plywood , but your 77 LS do not seem to be the standard  GP 19mm    , they are 18 mm  thickness ......  0.71 inches   and you can see the 2 birch plys very clearly .

I just took a picture of the ceiling. Was the ceiling also sanded?

 

 

[KT88]

12 minutes ago, OO1 said:

Heinz , you lost 1mm  

 

klipsch used   Georgia  Pacific 3/4 inch plywood , but your 77 LS do not seem to be the standard  GP 19mm    , they are 18 mm  thickness ......  0.71 inches   and you can see the 2 birch plys very clearly .

Regardless of my sanding problem, perhaps export models were made a little thinner and thus lighter for freight?

[OO1]

3 minutes ago, KT88 said:

I just took a picture of the ceiling. Was the ceiling also sanded?

yes   by 1mm,

 

 

[OO1]

Just now, KT88 said:

Regardless of my sanding problem, perhaps export models were made a little thinner and thus lighter for freight?

I doubt it ,  in North America in the 70's  3/4 inch or 19mm was not always  a full 3/4 inch  ,  it varied slightly , 1mm  is acceptable , this has all changed of course nowadays ,  quality control standards are now dead accurate in the paper and wood pulp industry  , and even more so with Canadian wood products which use the metric system .

[KT88]

2 minutes ago, OO1 said:

I doubt it ,  in North America in the 70's  3/4 inch or 19mm was not always  a full 3/4 inch  ,  it varied slightly , 1mm  is acceptable , this has all changed of course nowadays ,  quality control standards are now dead accurate in the paper and wood pulp industry  , and even more so with Canadian wood products which use the metric system .

Last question in this topic, Randy, was the front/motor board also sanded, please see the pic above in the post where you can see the K400.

[OO1]

2 minutes ago, KT88 said:

Last question in this topic, Randy, was the front/motor board also sanded, please see the pic above in the post where you can see the K400.

do you mean  this picture  ,  maybe slightly  sanded  , the birch ply closer to your finger seems to be thinner than the upper ply by about .25mm

[KT88]

3 minutes ago, OO1 said:

do you mean  this picture  ,  maybe slightly  sanded  , the birch ply closer to your finger seems to be thinner than the upper ply by about .25mm

I hope it doesn't affect the bass response if the bass horn got a little shorter this way. I had the same impression as you that it was slightly abraded....

[OO1]

19 minutes ago, KT88 said:

I hope it doesn't affect the bass response if the bass horn got a little shorter this way. I had the same impression as you that it was slightly abraded....

Heinz , here is a picture of  a pair of LS that were added with 1/2 inch BB by a forum member  ,   the cabs were 3/4 inch plywood , they are now 1,25 inches thick on all outer panels   using screws , PL glue , and Duratex paint + klipsch LSI handles +  routed corners and  tweeter /midrange openings ala LSI

[KT88]

3 minutes ago, OO1 said:

Heinz , here is a picture of  a pair of LS that were added with 1/2 inch BB by a forum member  ,   the cabs were 3/4 inch plywood , they are now 1,25 inches thick on all outer panels   using screws , PL glue , and Duratex paint + klipsch LSI handles +  routed tweeter /midrange openings ala LSI

 

What means routed tweeter /midrange openings ala LSI? And do you think that the slight shortening of the bass will have an effect? I would say, it has not, I hope, by reducing the length by 0.25 mm.

[KT88]

16 minutes ago, OO1 said:

Heinz , here is a picture of  a pair of LS that were added with 1/2 inch BB by a forum member  ,   the cabs were 3/4 inch plywood , they are now 1,25 inches thick on all outer panels   using screws , PL glue , and Duratex paint + klipsch LSI handles +  routed corners and  tweeter /midrange openings ala LSI

left and right speaker, this should be ok regarding the horn length?