Stuffing LaScala Bass Cabinet

[MacKevin]

I have recently purchased some LaScalas that Have the Bass Cabinets Stuffed with Foam and Batting. Everything tells me to get that out of there but I am interested in knowing what Klipsch normally puts in there? Also how does Klispch seal the plywood to the bottom of the cabinet?

Kevin

[blindman]

I have three 1970's era La Scalas, so my answer to your question is based upon what I have on hand.

Klipsch left the bass bin completely empty (i.e. no foam, no insulation, no acoustical batting, no damping material whatsoever). I know this flies in the face of almost every other speaker manufacturer: but Klipsch was a leader, never a follower.

The plywood on the bottom was attached via wood screws. A funky (extremely sticky, almost like black tar)gasket originally ran around the perimeter of the bass bin "lid". After opening the bass bin, scrape off the residue, and replace it with your favorite gasket material (foam, rubber, caulk, etc.)

[MacKevin]

Thanks.

I got another question if that's alright.

My Crossover for my professional pair( I have two pair that I just bought) is an AL type. Is that a good crossover. I read that there is an A, AA, and a AL at least. Which is better?

Kevin

[Daddy Dee]

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On 11/26/2004 9:49:40 PM MacKevin wrote:

Thanks.

I got another question if that's alright.

My Crossover for my professional pair( I have two pair that I just bought) is an AL type. Is that a good crossover. I read that there is an A, AA, and a AL at least. Which is better?

Kevin

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Kevin,

Welcome to the forum. The LaScala's come from the factory with the bass bin bare. I have read posts from a member or two who like the way the stuffed bass bin sounds, but haven't tried it personally.

Haven't heard the AL crossover. Most posts I read folks prefer AA or A, but there are folks who prefer the AL, too. Again, haven't heard AL.

[colterphoto1]

Usually damping material is placed inside a speaker cabinet to break up standing waves that occur between two parallel walls. Hence, you would normally see some type of batting or foam on the bottom, back, and one side of a rectangular box. I beleive the interior woofer cavity on the LaScala bass section (help me geometry experts) is trapezoidal, which helps break up any standing waves. Therefore no 'stuffing' is necessary.

In small bookshelve speakers, expecially sealed acoustic suspension designs, the entire box cavity is sometimes filled with insualtion or spun material of some sort. This has a complicated physics background, but it somehow make the speaker act like the enclosure is bigger than it really is. Ask a real engineer for further details, I know just a bit as an old amateur PA speaker builder.

Michael

[rtaylor]

Welcome Kevin, I'd listen to them for awhile to get a feel for their sound before changing anything. Hang around here for a couple of months and pick some brains, maybe a couple of searches on the topics you are interested in before doing anything. Randy

[MacKevin]

You are probably right about listening to them for a while. Since I had actually never heard LaScala's before I bought the two pair I had nothing to compare them to. Fortunately I was not disappointed. With the cabinets stuffed the bass is tight and punchy but rolls off in the very low frequencies. I thinks with all the work done to tune the driver to the cabinet I wouldn't think that by adding so much material to the enclosure it would restrict the woofer excursion causing the punchy sounding bass. Still the bass does sound good and I was wondering if this was a normal practice.

Thanks for all your responses

Kevin

[Frzninvt]

I would remove the stuffing, it was not designed nor intended to be there and could be harming the performance of the speaker. The La Scala has some of the tightest, punchiest bass there is but they drop like a stone around 45Hz and need a really good subwoofer to back them up. That or you could trade one pair for a pair of Cornwalls with the Corns and La Scala's you will have the best of both worlds.

[D-MAN]

I would question the ENTIRE back-chamber being full of stuffing. Klipsch always left the back chamber empty in all of the Heritage line horns which I do not hold with, AND they are typically 15-20% undersized, which raises the driver fc slightly.

However, I am a proponent of having SOME insulation behind the woofer frame mainly to prevent reflections, and to a lesser degree, provide the proper amount of damping to somewhat "equalize" the back chamber air volume with the air volume in the horn, reducing modulation distortion. This equation is

a=V/2.9R

where a=throat area in sq. inches

V=back chanber volume in cu. inches.

R=exponential area doubling point in linear inches

For the LS/BELLE the value of a=78 sq. in, R=12 in (60Hz),

and V=2714.4 cu in. (I haven't worked out the actual back-chamber area of the LS/BELLE, but I would guess that it is 15-20% less than the value, as is PWK's propensity in this matter. The throat area is the cross-sectional area of the throat - NOT the area of the throat cavity opening which is 39 sq. inches, which acts as a upper frequency limiting slot! BTW, this is the same throat area as the Khorn.

If you remove ALL of the insulation, you will hear what I am talking about... for clearer bass response, I would then add a little behind the woofer only.

DM

[Duke Spinner]

"stuffing" the box ... raises it's apparent size that the woofer see as it's load ....you are re-tuning the design .. take it out .. i like to hear the "knock" that an empty cab has ...

[MacKevin]

The more I listen to them the more I agree with you and I am going to empty the cabinets. I'm planning to do it this weekend and I will report back my results.

Kevin