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Thoughts on Lascala and PWK's philosophy


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I've owned my Lascalas for over ten years now and have just gotten around to identifying the serial numbers. It looks like they are from 1975, serial numbers 4N891 and 892. They've got AA crossovers which I changed with the Crites capacitor kit a few years ago. I also built the ported bass bins which really added more than it subtracted, so they are staying put for now. I may one day try the Qpie bass bins, we'll see.

 

They were my initiation into the world of Klipsch and have led me to buying Forté Is, Heresy Is and recently RB75s. They sound terrific and I'm not currently looking to upgrade any of the drivers or horns, nor changing the crossovers. Having said that, are there any recommended steps to insure that they are in tiptop shape? I'm thinking gaskets or tightening screws or anything else that may be pertinent to verify. Being from 1975, is it safe to assume that they are Alnico drivers? The k77s are round. 

 

Interesting side note, I've noticed that the internal wiring is all tinned copper, which Jeff Day has been advocating on his blog for a couple of years now. Seems that tinned copper is all the rage with those seeking richer tone over ultimate resolution. 

 

Lastly, I've got a couple of questions regarding PWK's 8 cardinal points to reproduction of which I just recently became aware. In his first point he states that "corner placement reduces distortion three fourths". Does this mean that by placing the Lascalas in corners it will reduce their distortion, or is he referring to the woofer in the folded horn? I'm no sure if that's clear. In point 2 he says that by placing the speaker in the corner it increases the effective size 4X. Just what concretely does that mean? Points 3, 4, and 5 are straightforward and logical. Point 6 is up for debate as I've never heard a system setup on the long wall of a room. I trust that it's amazing with a third center channel and very distant flanking speakers, as he suggests is best for imaging in Point 7. In point 8 I'm compelled by the "reduced shift in the virtual sound source for different listener locations" created by corner flanking. If I understand correctly, he means that there isn't a narrow little sweet spot but rather a large listening window for several listeners to enjoy... hmmm, must try that one day.

 

Thanks,

Daniel

 

 

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40 minutes ago, Ray_pierrewit said:

Does this mean that by placing the Lascalas in corners it will reduce their distortion, or is he referring to the woofer in the folded horn? I'm no sure if that's clear.

Any loudspeaker, not just horn loaded, or corner horns.  The reason is the reduction in necessary travel of the woofers due to the room itself acting as a horn--eighth space loading. "Anything that moves...distorts."  If you reduce the required travel of the woofer, you disproportionately reduce distortion. 

 

40 minutes ago, Ray_pierrewit said:

In point 2 he says that by placing the speaker in the corner it increases the effective size 4X. Just what concretely does that mean?

The mirror reflections add to the effective output of the bass bin, just like you put separate bass bins on the floor side and two side wall sides. Conversely, when you place a loudspeaker in the corner of the room, you need to EQ the bass response to flat again due to the added corner loading.  Voila!

 

Wall_loading_graphic.png

 

40 minutes ago, Ray_pierrewit said:

Point 6 is up for debate as I've never heard a system setup on the long wall of a room. I trust that it's amazing with a third center channel and very distant flanking speakers, as he suggests is best for imaging in Point 7.

This has a lot to do with the design of the Klipschorn itself.  If you remove the time misalignments of the Khorn's drivers via DSP crossover delays, then the minimum distance that you can listen to Khorns is much, much closer.  The idea is that, as you get further away from the Khorns, the better the imaging because of coalescing of the loudspeaker's phase into a more cohesive whole.  Setting Khorns on the long wall improves their imaging performance in this way, and by a great degree.  The other Heritage models also have improvements in soundstage imaging when spaced far apart, as far as ~25 feet before a center channel is needed to fill the hole in the center.

 

40 minutes ago, Ray_pierrewit said:

In point 8 I'm compelled by the "reduced shift in the virtual sound source for different listener locations" created by corner flanking. If I understand correctly, he means that there isn't a narrow little sweet spot but rather a large listening window for several listeners to enjoy... hmmm, must try that one day.

Try it today.  Remove all the reflections from between the loudspeakers (including electronics racks and furniture) or at least place them very close to the floor, away from the midrange horn mouths of the loudspeakers.  This trick works pretty well with all Heritage Klipsch models.  It works less well with the K-402 horn on top. 

 

See this article: http://www.libinst.com/PublicArticles/Setup of WG Speakers.pdf

 

Chris

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Well, that pretty much sums it up.  @Chris A strikes again!  I always appreciate your knowledge and willingness to share.  Ray, try what he says.  I have some influential placement, toe-in, first order absorption panels, a couple of bass traps, due to his suggestions.  Guess what, it works, and well I might add.

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Corner placement is indeed best for any speaker except those not designed for it (planar, omni, semi-omni, certain vertical arrays). The phrases "mirror image" or "mirror reflections" have been truisms in audio texts for 70 plus years...but they're misleading. A mirror is a theoretically perfect reflector of the incident wave. Real room walls are hardly perfect reflectors, expecially the usual sheetrock on 16 inch centers. It's true that a corner, even of typical construction is fairly rigid. But these typical corners are by no means perfectly rigid. My sub is in an inside corner, and the construction is the typical sheetrock over 16 inch centers. There's a closet on the other side, and the bass line makes the sheetrock boom along with it. FWIW the floor is wood laid directly on top of the slab, no underlayment.

 

PWK understood this when he designed the famous false corners of plywood over 2 x 4s. Much better than sheetrock.

 

On 3/14/2018 at 12:48 PM, Ray_pierrewit said:

In point 2 he says that by placing the speaker in the corner it increases the effective size 4X. 

 

No, what Mr. Klipsch said was "By corner placement, the solid angle of radiation and required area [of the horn mouth of a bass horn] are reduced by a factor of 4."

The size of the horn mouth does not "scale" the overall system acoustic size in direct proportion. And PWK was speaking of a bass horn, not a direct drive system with less-than-optimum coupling to the corner. 

So I think it's time to get real about one oft-heard claim about corner placement. It doesn't increase the speaker "8X", it's more like 6X over the bass range.

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I have question regarding the folded horn bass bin of LaScalas and KHorns. I have Googled folded horns and looked at numerous images of other styles that seem to have more folds or pathways inside. Some almost like a labyrinth. Would the addition of such pieces increase the bass level that some find missing? I don’t really understand the physics of this.

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On 3/17/2018 at 7:00 PM, YK Thom said:

I have question regarding the folded horn bass bin of LaScalas and KHorns. I have Googled folded horns and looked at numerous images of other styles that seem to have more folds or pathways inside. Some almost like a labyrinth. Would the addition of such pieces increase the bass level that some find missing? I don’t really understand the physics of this.

I recommend you find Harry F.  Olsons' "Acoustical Engineering" and also look at Paul Klipsch's original Klipschorn paper, "A Low Frequency Horn of Small Dimensions" (Journal of the Acoustical Society of America, Vol. 13, No. 2, 137-144, October 1941).

 

A very generalized statement is: Longer horns can indeed be folded in a myriad of ways, and if properly designed, can go low in the bass. . However, the greater the number of folds, the lower the effective upper frequency limit of the resulting bass horn, assuming that it performs satisfactorly otherwise. This means that the designer must now design or buy a larger straight midrange horn and driver. The cost of horn drivers that can cover the range of 400-5 KHz is high; the very few than can go to 300 Hz are very costly indeed. Many a home constructor has been surprised to find that his midrange horn and driver are much more expensive than the bass horn.

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Bill, thanks for publishing those graphics, that is the kind of long-running  "truism" or mantra I was speaking of. I notice the Klipsch brochure uses the phrase "if the walls and floor were optical mirrors..." but they're not, of course.

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When PWK first espoused his eight cardinal points of sound reproduction, homes were not being built like they are being built nowadays.  First of all, the walls back in those days were more often than not plaster over lath, which had been applied to 3/4" wood nailed horizontally across the studs.  And the lumber dimensions of the framing were TRUE 2x4...altogether this amounted to a much more structurally-solid corner within a room.  I remember back in 1969 when the framing lumber dimensions were further reduced in size to thickness of 1.5 inches and width (for so-called 2X4) to 3.5 inches...this was an overall reduction in dimensional thickness of 1/2 inch since the 1940's, and another reduction in width (of a "2X4") by another 1/2 inch by 1969 from the "TRUE" 2X4 dimensions used in the 1940's.  Not only that, but the studs were generally on 24-inch centers in the 1940's, NOT 16-inch centers like now.  The 16-inch center became popular for 4x8 sheet materiel such as drywall and plywood towards the end of the 1940's and into the very early 1950's.  BTW, a "2X4" was actually dimensionally-sized by standards at  1 5/8" thickness, and (for 2X4) 3 5/8" width in the 1920's until 1969....when it became 1.5" X 3.5" ("2X4"). 

 

Needless to say that structural strength reductions go hand-in-hand with standardized lumber dimensional reductions, ESPECIALLY when other factors are also down-graded...such as numerical  grading allowing for more knots and voids in the boards over time. 

 

BUT, the point here is that homes tended to be BUILT differently in the 1940's...when PWK came out with his 8 points.  And average CORNER strengths were higher back then, meaning more SOLID, which also affects reflecting ability due to less FLEX in underlying structure, with increased STIFFNESS being the result.  They ALSO used what became called "fire-stops" between the studs back in those days, which stiffened the entire wall structure....again adding more "reflective" positivity while reducing ABSORPTION of sound.

 

Just a little something to think about.

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On 3/23/2018 at 5:05 PM, HDBRbuilder said:

When PWK first espoused his eight cardinal points of sound reproduction, homes were not being built like they are being built nowadays.  First of all, the walls back in those days were more often than not plaster over lath, which had been applied to 3/4" wood nailed horizontally across the studs. 

 Yup, and subwoofers belting out 40-15 Hz thumps were unknown. I have always thought that an old house in New Orleans would be great for Klipschorns, what with the plaster on lath and 12 foot or higher ceilings. That high base molding would be problematic in getting a fit in the corner but could be overcome. 

 

And in 1948 if you had a 78 rpm disk that recorded 50 cycles per second, and the playback chain to support it, you were in a distinct minority of phonograph owners.

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On ‎3‎/‎24‎/‎2018 at 8:31 AM, Blvdre said:

HDBR, did you mean 12-inch on-center in the 40s?

Nope...I meant 24" centers...which were falling out more in favor of 16" centers throughout the 1940's...and by the 1950's, 16" centers were most likely to have been used UNLESS no sheet stock was planned for use, and the builder was using locally-sawn actual 2X4 framing.  Even today, if you live nearby a "Mom & Pop" sawmill in my area (Arkansas), and you plan on using sheet stock, anyway (such as drywall or paneling) for interior surfaces, you actually come out better using unfinished lumber because construction adhesives actually grip it better than re-sized smoothened framing.  Who really cares if the lumber underneath the wall covering is rough-sawn or not, anyway?

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