Dana - False Corner / Flare question

[tigerwoodKhorns]

Dana (and other speaker building guru's),

I recently sold my K Horns and plan on using a factory set of Speakerlab Bass Bins. I saved my false corners intending to use them with the Speakerlabs. The problem is that the speakerlab bass bins are shaped differently than tbe K Horn bins. (See attached).

The Speakerlabs have straight sides rather than a full extension at 45 degrees. I am now thinking that I should construct new false corners that follow the shape of the Speakerlab Bass bins. I think that it will be better looking in the end (more of a Jubilee look).

I will have to use AutoCAD to determine where to make the break in flare. Am I missing anything else? Will this negatively affect bass response?

Thanks,

Chris

_0418124308_001.pdf

[HarleyMo]

That is a very strange shape for a speakerlab bass bin. The bass bin that is built with the speakerlab plans I have doesnt look anything like that. It is the same shape as the Khorn bass bin. Could they have had two different styles ?

[ajsons]

Chris,

I have not heard from Dana in the last three weeks, neither have I seen a post from him in the last three weeks. Before he "disappeared", he sent me some horn literature and plans, mostly he wrote/designed himself, and they were very good. I'll send him an email to see how he's doing.

Has anybody heard from Dana?

Anyway, I sent you an email with a CAD drawing of the old SK bass bin attached. Maybe you can use it...cut and paste, trim, whatever. It was drawn actual size, using the 2002 version of AutoCAD. I have also a .dwg file of the new SK like what you have but it is slightly modified at the front assembly. I can send it to you if you are interested. Let me know.

I think your idea is great. I wish I thought of it. I was thinking of getting rid of my SK's, but your idea changed my mind. I am thinking of the Hartsfield look.

Your SK's don't have tailboards. I'm not a speaker building guru like Dana, but I know he'll agree with me on this one. The old SK's have tailboards, but they need to be Huygen's reflectors, like the Jubilee's. The exit angles are different, though. I think before you build your false corners, you have to decide on the correct reflectors' angles first. I tried, but can't come up with a good solution. You can try radius reflectors, as option B. The old SK's tailboards will be the least likely choice. And there are other things wrong with those tailboards.

More to follow. (I need to figure out how to attach pictures using the new software).

Armando

[ajsons]

There is a difference in the distances from the room corner between the old and the new SK's, as you can see from this picture. The "new" has to be 8" from the room corner. The "old", by design, pushes the enclosure forward by about half an inch. This is something to be aware of, I think.

Also, the tailboard is 4" from the rear opening, and the distance between the wall and the rear opening corner is 3 1/2. In other words, the path went from 4 to 3-1/2 while its making a turn. I don't know if this has any negative impact but if I have to build a false corner, I'll pull the enclosure forward (into the room), to correct the expansion. But then again, the taiboard's angles/reflectors issue have to be taken care of first.

[ajsons]

Here's my take on breaking the flare. I'll break it at the circled point shown on the previous attachment, and rotate the path 32 degrees inward.

[ajsons]

Then, I'll move the broken path down to correct the elongated path, extend the lines to the wall and finalize the false corners dimensions.

[ajsons]

I don't think bending the flare like this will have any negative impact on the bass output, it worked for the Jubilee, didn't it?. Maybe a speaker guru can comment on this.

Now, where's Master Yoda ?

[ajsons]

HarleyMo,

Here's a picture of Chris' SK.

[WMcD]

I was quite surprized by the drawing of the factory SK.

The set of plans for the SK I have mimic the K-Horn. A good buddy has a set he built from an SK kit. They are like the K-Horn. Two other friends built kits and to the best of my recall no one found such a variance.

The side wall you draw seems like the very earliest of K-Horn. That was before he started hunting for ways of increasing the back chamber volume. No variation I've ever seen has the triangular front panel. Not even the X-3 or K-3 by PWK, or the Fairchild unit.

It would be interesting to hear why you are saying these are factory SKs. Not that I doubt you. But it is very, very odd. It could well be that the SK people were experimenting and a few of these went out the door. But I also wonder if it is not the product of a gifted home builder.

Going back to the original question. It seems to be a concern regarding a small variation of geometry at the mouth (the big end of the bass horn). I.e. that now we have about a three or four inch section which is not like the production K-Horn.

I'm quite confident that there is no reason to build a new false corner to squeeze down the area there. As you imply, it is getting a bit more of a flare. None the less, three inches of path is not going to have any effect as long as you have the false corner.

It is interesting that the earliest K-Horn had a top plate which was more triangualar than "home plate" in geometry. Apparently PKW did not find much advantage to maintaining a seal over the last three or four inches.

This changed with the Jubilee. That, though, had more to do with the response at the high end.

I had promised you guys my comparison of the three bass horns in the Jubilee paper. I overlayed the three plots. Next weekend maybe. Overall, you can see about 2 or 3 dB difference which counts for a couple of Hertz if you're looking for some cut-off.

Overall, I'd say you have nothing to worry about in putting the SKs in the old false corners.

Best,

Gi

[ajsons]

A midrange-tweeter-midrange (MTM) setup is probably something worth trying.

[tigerwoodKhorns]

Armando,

I'd like copies of the drawings if you could send them in dwg format. We should work together on this.

To make these look good, an Altec 511B fits almost perfectly around the "bend" of the front of the speakerlab. I plan on fabricating a gril out of aluminum and bending it in a radius to match. I will also enclose the Altec in a small top enclosure.

The other cool thing is that JBL 2404's wil fit in the front of the speakerlab cabinet (they are deep enough to clear the magnet). It should look pretty good when complete. Kind of like a JBL 4430 or 4435 where the baby cheek is exposed.

I think that the key to making the bend is to maintain the cross sectional area of the original design. I can take some measurements because I still have my old false corners. I think that if a line is drawn down teh center of the horn path, the break should be in the centerline. The problem appears to be how to do this without a compund bend (i.e. avoiding two angles).

By the way, I agree that the tail board is necessary. My False corners have a flat back that sat right behind the K Horn back board.

Email me and we can combine efforts to come up with a good design. The shape of the speakerlab realy lends itself to an exotic look when done. That's why I'd like to make the bend and have grills facing almost forward. Its my understanding that the speakerlab puts out a lot more bass than the K33. This should be a good design that doesn't need to be in a corner to have good response.

Chris

Edit - Armando - I just looked closer at your drawings. I don't think it will be a big deal to gain and lose the small area. Your drawings should work and produce good bass response.

I also see where you mention that teh exit is 4" and teh flares are 3.5". This should not be a problem because there are two sides at 3.5" which is an expansion over a single 4" gap.

[tigerwoodKhorns]

Gil,

That picture that is posted was taken at the guys home that sold them to me. They are definately built at the Speakerlab factory. He lived in Seattle when he bought them new in 1982 and Armando has sent me sales literature showing the deisgn that I have.

These do have a straight front. There is an additonal chamber in the front that holds the crossover, midrange and tweeter (actually, three small chambers).

Chris

[HarleyMo]

Thats whats great about this forum, you learn something new everyday. Thanks for the pic. Interesting take on the corner speaker design.

[D-MAN]

What a cool thread! Sorry I missed out on it when it was "fresh"!

What Armando said above is great. His drawings are also great.

The "old" Speakerlab K, like Gil said, is a virtual knockoff of a 1970's-era Klipschorn bass bin, with a couple of add-ons, which I like, such as extra reinforcing on the back chamber and a removable motorboard. When I think of SL-K's the 1970's "Klone" is what I think of.

The "new" SL-K as shown above is a modified version that occurred sometime in the 80's, with some changes, all of which are fine, technically speaking. I would make a few changes in that I would extend the top to form an enclosed exit channel, ala Khorn.

Otherwise the horn will begin to unload a bit early and its mouth becomes somwhat indeterminate, although it will still certainly "go low". See the EV Centurion for something sort of like it. The cone midrange is a great idea, although it blows the all-horn thing all to pieces; also being that it is fixed, it cannot be adjusted for position and dispersion (ala Khorn again)... That's the only thing I don't like about it, but then, that's one of my pet peeves about fixed positions for the higher frequency units.

The actual exit channels are determined by cabinet placement, that is, how far from the walls it sits. This is left entirely variable, and as Armando said, should result in an exit area approximately 8-9 inches from the wall (if the expaning lines of the side channels was extended in a straight line). What is shown in Armando's drawings is very much still a virtual Khorn, as far as the proportions, channel sizes and layout goes. Anything you can do to a Khorn, you can do to these, such as the rear-exit 45 deg. splitter add-on, etc.

I also would go with Armando's placement of the exit channel terminal angle change, ala Jubilee. Just arrange it so that the exit width is the same as before, however it can be 1/2" wider each side without any problems.

With an extended top and bottom giving the ability to add side panels, the free-standing version could be easily made, ala Jubilee.

Not a bad platform to experiment with...

I attached a beautiful pic that I would guess is a new-style SL-K without the midrange additions, that is, bass bin only.

Dana

[D-MAN]

I would add a top and bottom extension to attach a tailboard/reflector as in Armando's drawing. It isn't absolutely required, it will still work without it. Many, many horn designs of the past don't have a tailboard at all, so there is ample precedent for no tailboard at all...

For an example of a somewhat "restrained" top/bottom extension, the Pi corner horn has a tailboard (attached pic), which could easily be added to the "new" SL-K.

It depends on what you want. How much it matters remains up in the air. Depends on where you crossover - at 400Hz or below, it won't matter so much...

[D-MAN]

See where the "new" SL-K footprint came from? The original 1945 Khorn...

There is nothing new under the sun...

[Deang]

No matter how many times I see your sig -- it brings up a chuckle.

[D-MAN]

Having my speakers suck half the time is better than all the time, but there ain't no way around that disturbing little fact, is there?!

Irony can be pretty ironic sometimes!

DM

[D-MAN]

Another note on the flat 180 deg. reflector such as used on the Khorn:

I have a question of the value of a flat reflecting panel vs. a raw corner (i.e., no reflector at all) as to which actually sounds better... perhaps there is a point to not having direct opposing reflections (with tailboard) and no direct reflections (raw corner)...

I would like to hear the stock "new"-style SL-K's just to check it out. My inclination is to either leave out the reflector entirely (as in the plans), or I would employ a 45 deg. full-channel width splitter at the tailboard. One or the other, but I am not convinced that the tailboard as we know it in the modern Khorn actually has much beneficial effect.

The bottom line is whether low frequencies travel through a horn as if it were an air duct or whether the soundwave travels through as if it were a waveguide flowingon the interior surface. The two design concepts are almost unrelated at certain points, in particular, such as when making a 180 degree fold (or turn).

Personally, I base alot of my opinion on what PWK and Roy Delgado did at the rear fold of the Jubilee as being the best example of exploiting the reflective properties of the horn channels, rather than handling it like more like duct-work, such as the Khorn. It would be a frequency-specific choice, I figure, and that means that the new-style SL-K, having a fairly low crossover point the same as the Khorn, can be handled in a more "duct"-like fashion.

So in my estimation, it won't really matter a whole lot how the tailboard situation (or lack thereof) is addressed.

The new SL-K looks very interesting. Sort of funny how these things all rely on "tradition"... mostly everything "horn" that can be tried has been tried at one point or another, and it is just a "mix" of these elements in different configurations that we come up with, and each generation has to rework all these elements out again for themselves. We are re-inventing the wheel, so to speak, dicussing the value of tailboards, etc.

DM

[tigerwoodKhorns]

Dana,

I took Armando's drawing and moved the tail board 3.5" off the back of the rear outlet to match the K Horn. I also spent a few hours calculating iterations so that the bend in the horn does not interupt a constant expansion of the horn (I.e. I found the design where the area lost equals the area gained to a very close tolerance.

I am going to build the flare like my old false corners with tops and bottoms.

Do you think that I shoudl change anything?

Email me and I'll send you AutoCAD drawings to review.

Chris