How might PWK designed a wallhorn to go deeper than LS?

[freddyi]

could there have been a good sounding compromise PWK-style to beat LS at its bulk level with some acceptable tradeoffs? if so, how might it have been done? University's S9 was large as were top end Frazier in the 1950's mono era.

Here's Klipsch A447/La Scala vs A7 Altec with K-horn LF sketched in pencil. I like sound of K-horn and don't remember La Scala sounding as solid.

(PWK was so kind to Klipsch owners to take time out to answer letters)

http://img142.imageshack.us/img142/9582/a447yn2.jpg

[mas]

Wouldn't that be the Jubilee? ...which could essentially be seen as the next step up from both the KHorn and the LaScala.

[JohnA]

I doubt it could be done with similar bulk, but a taller LB-76 (J horn) might do it. I calculated the dimenstions of a taller LB-76 and did a layout in pencil. I gave up on it because of the construction costs, since I don't have the tools or the skill myself.

I've toyed with a taller LB-76 style bass horn firing "backward" into the corner to extend it s cut-off frequency, but you'd just about have a K-horn sized footprint. The "firing into a corner" would likely limit the HF of the bass horn to that of a K-horn. Since the K-horn has been thouroughly developed and mine hasn't, I'd expect it would not sound as good.

[D-MAN]

I agree with John, I don't think it could be done in the same footprint & overall size, simply due to lower Fc requiring a longer and larger horn mouth size. Dual drivers would also make it larger by necessity. The LB was smaller but had essentially the same response (albeit with other additional requirements). Even a double-stacked LB setup would be taller (although the footprint would be smaller than the LS), but no lower in response.

Nope, not likely, at least not with a smooth (or acceptable) response.

DM

[D-MAN]

Here is what I figure PWK would come up with for a 1/4 space design. I've included all of the PWK "trademarks"... in keeping with the traditions of the Khorn.

Bifurcated at the throat, single driver, symmetrical folding, bifurcated at the rear, you know, everything that points to a PWK design...

DM

[freddyi]

that might be it" ! (did he leave any notes/sketches?) How would PWK pick bulk and cutoff vs Jubilee and would he use K33E, K43 or something else?

here's Ray Newman's bifurcated 70's Sentry 4/TL5050 loaded with two Pyle PYM1298 in parallel just to give one example of a large W-bin vs a K's bottom. Pyle 12" have fs ~45. Fc ~50Hz but 1/4 wave path ~70hz

PWK would have it look nice too

mic closer to EV

mic in room center - in-room is messy but what does a non-pro do with horns?

Klipshorn's bottom looks great.

[D-MAN]

I am unaware of any info concerning a PWK 1/4 space horn, I am just proposing this as a possibility based on some assumptions.

As a guess, given his historical propensity for using what he had in stock, I would guess the venerable K33E would be in order, as well as the crossovers, etc. virtually the same as the Khorn albeit with a more-likely 50Hz overall Fc.

I would also guess that the height and appearance would be very close to the Khorn, preferably the style "B". At least that's what I'd want to see!

DM

[freddyi]

I put graph of 50Hz Fc Sentry in post above. K33E sounds right for this imaginary project. Do you think the bassbin would be more than 10 cubic foot?

[freddyi]

Hi John - did you use McBean's to simulate a Tall LB? I hope Tony's LB turns out to be a fun project.

[D-MAN]

Probably a bit larger, i.e., 15 cu ft.

I estimate the outside dimensions as 30w x 24 d x 39 h. Probably could be paired down a bit, but 10 cu ft is pretty small, depends on the Fc your going for.

Could go smaller for dual 12" drivers vs. the single K33E, of course.

DM

[freddyi]

wonder how this basshorn might sound as its mouth's exit would be hugging the walls vs typical beaming of folded horn mouth pointed at listener? would it has less localization and perhaps a deeper sounding image?

re:2-12" givng a smaller horn - is that based on larger throat and less path? which 12" might be suitable?

with 1-15", might width be kept to 36" or so? maybe - 33Wx25Hx24D - would sufficent mouth be had at this bulk/aspect?

how far might one have to keep one mouth from adjacent corner? - or is this a benefit up to a point

what might one do thats (in theory) a good compromise within 1.4-1.5X Belle's bulk? - say 11 cubic foot max? Is 15CF needed to make an experiment worthwhile?

here's a 15CF 55Hz horn kinda like worse version of S9. IIRC it had ~55 inch path and 720sq.in. mouth

[D-MAN]

Dual 12's each would have a smaller throat area requirement, and that means less width is required for the throat channels (especially if bifurcated at the throat). Depending on the drivers employed the Vb could also be smaller (the K33E needs about 3 cu. ft.) as small as 2 cu ft. Overall path length and mouth size would remain the same (the path length could lengthen, even), especially the mouth size which is basically fixed by flare rate and radiation angle.

It remains interesting, though, that PWK concluded in 1976 in the LB patent that the horn pathlength could be as short as 1/12 wavelength. For 40Hz, that is roughly about 32 inches. This is predicated on having a fully-annulled back chamber on a front-loaded horn, in Plach's words, "a conjugate match".

720 sq. in for a 55Hz horn is rather small for a 1/4 and is not intended for 1/2 space placement, but is indicative that it was designed as 1/8th placement (a corner).

The distance from the reflective walls minimum is .5 of a wavelength (on-axis from corner), which means that the higher frequencies (60Hz) on up would not benefit from reflections if the mouth channel terminus (walls) are over 18" from the walls, etc.

You can have up to a 20% variance in SPL at those frequencies for an on-axis corner placement in the corner. Off-axis placements would be calculated as .75 wavelength, because one side is closer to a reflective wall than the other, of course.

Wavelength is calculated as 1125 (ft per sec) / frequency. The mouth-to-reflective-surface distance determines the upper crossover frequency point limit, as you can see.

DM

[freddyi]

(I "designed" & cut that crummy 55hz pictured with bass guitar)

always a dilemma picking out what makes a good wallhorn and can depend on the midhorn's ability to work low. I think one manufacturer is working with a 6.5" driver and Orthophonic-cobraflex type path to get ~55Hz in-room and reasonable bandwidth/sensitivity - probably ~9CF finished product.

then another dimemma for cornerhorn finding two usable corners.

are La Scala/Belle best options for wallhorn of small dimensions? - at some point someone might want to add a sub.

[Mighty Favog]

I would still like to see a CornScala come to be from the factory. I read Bob Crites' thread on building his test-box speaker and it looks good enough to use all the time. I would just want the back of the horns to be covered by the cabinet too.

I'd build it myself but I'm terrible with cutting veneers.

[garyrc]

Related question?

What do you folk think of the idea of flush mounting a Belle or La Scala -- the way some studios flush mount their speakers, and Jeff Cooper recommends? That should increase deep bass a bit, but how? I assume that concerns about treble and mids spilling sideways and being reflected could be handled by putting absorptive materials to either side of the mid/tweet top of either of these speakers, which may have less side radiation than some studio flush mounted speakers, anyway.

[D-MAN]

It won't go any lower, but it will not suffer from mouth diffraction effects if flush mounted in a wall.

Note that placement (radiation angle) won't overrule the horn expansion rate! It is "written in stone" so-to-speak. Best you could do is reinforce the bass that is already there (i.e., corner placement), not add "new" LF frequencies!

DM

[pauln]

A crazy idea? What if one pointed the LS into the corners to extend the horn, and reversed the direction of the top box to point the mid and tweet horns into the room...?

What this ever done?

[jwc]

I have thought of this several times. But technically it shoudn't work as the flare to mouth already set at about 70Hz horn.

Now..if you built a scala from scratch with a "lower" flare to make the mouth at about 140cm at the total length of horn.......yep.....you have a low boy. Wide and low profile. "W" horn.

Better yet...make a scala with an 18 inch woofer with the throat about 105 sq in. Same depth but the width about 30-31 inches. Back channel depth 4 inches. Now you have about a 55Hz cutoff. The 18 inch eminence magnum HO should work with that throat and have about the right amount of volume in sealed chamber. Of course I have heard Dana state there is a problem with big mouth on a short horn.........maybe he can fill in here.

I have this drawn out on a full scale graph paper. Easy build. Would be beautiful. I am just running out of room on projects like this. Also not enough time.

jc

[D-MAN]

You can add another lower flare rate which will lower the overall Fc, very much like placing it backwards in a corner. However, it's square shape makes this difficult to be as efficient as a horn actually designed to do it.

Lot's of horns out there use this approach, especially in the PA and single-driver world. How good they are, I'll leave up to you.

Here's a Danley subwoofer for instance...

DM

[djk]

The B-DEAP32 from Danley looks like it will eat either a Klipschorn of the Jubilee for bass below 100hz. Being much shorter in height, it would be the right size to park the mid and HF horns from these on top.

The B-DEAP32 is also simple to build, angles are either 45° or 90°, and the lay-out is minimum waste from 5X5 Baltic Birch.