Help with CornScala's

[Guest David H]

Hello, I am considering building the CornScala's

The last speaker project I worked on was Project Lilscala. I received so much help from the Klipsch community solving the problems I ran into, I thought I would ask for help on this one before I started.

The drivers I am using are K77 K55 K33 with the speakerlab 350horn lens...basically k400.

I am considering using the ALK universal crossover, which may need to be modded for this application.

This may be blasphemy but I am cosidering the use of MDF on the cabs, then cherry laminate. On the Lilscala I only used mdf on the bass bin.

Any thoughts would be appreciated.

[Jeff_R]

Follow this discussion to page 6, jw cullison's post.

ALK Cornscala with K401 or Trachorn

He has the pdf file on page 6 of that thread.

Hope this helps.

Jeff

[Guest David H]

Thanks, I found that a few weeks ago and started the build Titled another cornscala...

[Jeff_R]

I kind of wondered if my reply would be dated.

If I were building as opposed to rebuilding I would use his plans for a guidline on dimensions. I am more in favor of using my dado blade for edge joints with bridging as opposed to just using bridging blocks, but apparently I have more equipment than he did. I would also build the woofer enclosure face and horn motorboard, as one piece, and my woofer box/horn-crossover shelf would be dadoed into the sides and backside of the woofer/motorboard face.

I used MDF to build a pair of Infinity SM 122's that arrived destroyed in shipping. MDF is much more sonically dead than plywood. So that is a positive in favor of MDF imho. Another plus for MDF is no sanding except for edge sanding after sealing. Seal with famowood or similar and sand smooth. So a lot less surface preparation for whatever you are going to end up with, paint or laminate.

The downside of MDF is it is heavier, and even more prone to handling damage than plywood. Where a bump is a nick or a gouge in plywood, it can be a crush area on MDF.

I think it would be fun to try Piano Black Wilsonart on top of MDF. I think Wilsonart is one color all the way through. If so, no odd edge appearance. A pair of Cornscalas' built with MDF and Wilsonart would be extremely heavy. Formica on a rectangular box is a cinch. But the cabinets would be as sonically dead as giant blocks of concrete.

I considered using regular formica or Wilsonart on the La Scalas' I am redoing. Price and degreee of difficulty of the horn area put me off Wilsonart or regular formica. I have decided to opt for a piano black paint job as in the forums, and I am going to build a woofer bass bin, also in the forums. My bass bin is going to end up being the same dimensions front to back and left to right as the La Scalas'. So I suppose I have to build my bins to about 12 inches tall, inside height.

Have fun

jeff

What is the easiest approach to a job that meets or exceeds the required specifications? Then why aren't we doing it like that?

[Albatross]

I'm going to build a pair too...did you get the Cullison plans for the build? if not lets talk. I too am going to use MDF, but probably am going to use Bob Crites Woofer. How far have you gotten?

[Guest David H]

Mine are almost complete, but I didn't use MDF, the box was going to be far to heavy. as it is they are over 100lbs, and the lumberyard near me was clearing out nice 3/4 ply for $19 for 4x8.

I hope you post build pics. My pics are in the another cornscala thread.

I also wanted to use the Crites woofer, just not in the budget this week so I used my speakerlab K woofer and an AA x-over. It really sounds nice and well balanced so I am assuming the Speakerlab 15 is 100+db. Since then I have been looking for 101DB woofers that meet Klipsch criteria.

[Guest " "]

"I am more in favor of using my dado blade for edge joints with bridging as opposed to just using bridging blocks,"

yep, it's a matter of preference.....I have dado blades, the machine that cuts grooves for the football looking wafers, as well as the dowel guides.....and for the most part use bracing if the joints will not be exposed and the wafers if they are going to be exposed.

If you use non expanding water base glue and wet both of the surfaces to be joined with a sponge, use clamps, bracing, dowels, waffes are really not required....test show that the wood breaks before the joint does....the wafers, dowels, and bracing in my mind is really insurance in case a bad joint slps in.

[PrestonTom]

Good Luck on the cabinet build. It should be a fun project.

Just a few quick comments.

1) Wilsonart Laminate: the color does not go all the through (look at samples), but it should be durable. I tend to stay away from the high gloss finishes, since they reveal every imperfection (and by implication my sloppy workmanship). At Home depot it is about $1.50 per sq ft. This is the same ball park price as "average" veneer, but it would be easier to apply.

2) MDF: folks will argue incessantly over this one. Yes it is heavier. MDF is about 3lbs/sq ft while Plywood is only about 2lbs. In a big cabinet, this difference can add up. Plywood from different stores can vary dramatically. My opinion is that the quality of MDF is more similar than dissimilar when you buy it from different stores. I have never had a problem with the stuff from Home Depot. Obviously the more plys the better and if you can afford Baltic Birch that is better yet. Although this needs to purchased from a "real" lumberyard and will cost at least 100 per sheet (measured as 5x5 ft, and not 4x8). Of course some of the techniques regarding dadoing will differ between the two. The Baltic Birch is unlikely to warp, the others might. You have already identified the issue with MDF regarding dings and nicks. Keep in mind also that MDF really should be sealed or painted on surfaces that might get water contact (basements in New England, where I live, are prone to flooding).

Anyhow, you probably already knew most of this, but perhaps it will help others.

Good Luck,

-Tom