Jubilee - D.I.Y. drawing project (work in progress)

[Neandertal]

Hello again,

I have read, I have thought, I have calculated. Here is how it MAY be with regard to the slot opening at point A. PKW's design data has the throat at .029 sq.m. The .pdf drawing measures the opening at 4.916" so lets bump it to an even 5" (the pdf drawing has been pretty darn accurate so far). The resulting half throat created by the splitter is 2.5" which is the same as the A-B flare width. This would also meet D-man's comments about having the slot opening match the following flare width. Also matches the concept of the splitter acting as a two sided reflector. With the Point A throat at .029 sq.m (for BOTH the upper and lower drivers combined...all the other measured throats have been combined numbers) which equals 44.95 sq.in. and a width of 5"....the height would be 8.99" or just about 9" if we are a touch sloppy when the slot is cut. So we now have a 5" by 9" slot split into two halves and doubled by having two drivers.

Now to the A-B flare length. By making the slot wider....the length shortens because it is measured from the center of the bifricated(sp?) slot at point A. I now calculate this to be 7.436" or .189m horizontal. We are short from the PKW design of .209m. Now remember this is in the horizontal plane. Now follow into 3-D. With the assumed LF bin at 38" tall (PKW's number)...the interior motorboard is going to be 36.5" tall. Asigning 12" to the center drone, this leaves an upper and lower 12-1/4" for the drivers. Centering a 5"x9" slot in this area gives us a Point A which is 6-1/8" from the top and bottom of the motor board. Each driver's horn is at 18-1/4" wide (2x 18.25" = 36.5"). The CENTER of EACH horn is 9-1/8" from the top or bottom. The VERTICAL distance between the 1/2 slot A CENTER and the center path of an individual horn is 3".

Now to geometry...the horizontal path is 7.436" and the vertical is 3"....the linear path is 8.018" or .204 m. This does compare well to PKW's design value of .209 m. I will draw this up if the majority agree this is a sound path to follow. Once the horn flare passes Point B the two individual half horns are full height in the body of the LF bin.

These assumptions will have the A-B flare being built with asymetrical(sp?) wings. Still need to know if the drone opens in any shape or form into the horn path. Any quesses as to how that thing works? Anyone have a clue as to what drone is used?

Will draw more soon. Keep feeding me ideas.

Bert

[arco]

Nice work Bert!

[D-MAN]

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On 3/29/2005 9:14:30 PM William F. Gil McDermott wrote:

The other potential issue is the excursion of the diaphragm when mounted to the motor board. One good fellow on the forum pointed this out years ago. I thought he was being too cautious but I took it to heart.

It may be that the K-33 woofer has an extra thick gasket so that the diaphragm excusion can't hit the motor board. I was using a Pyramid unit in the home made K-Horn. Therefore I used some hardboard to make a spacer in all my bass horns. It is a pain in the neck but it is one less thing to worry about.

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That is a good point, I always use a separate motor board to mount the drivers (ala SpeakerLab K plans) so that if needed, I can handle the problem of cone extension by using a spacer board with a full circle cutout between the driver and the slotted motor board.

However, in the case of double 12" inch woofers, the power will be split between the two and therefore less extension is needed in order to produce the same SPL as with a single 15". So that point may be rendered somewhat moot unless one likes it VERY VERY loud. This would be determined by the actual application, especially when used in a HT setup, where the dynamics sky-rocket to levels that could cause a cone in an unaltered driver mounting to slap against the baffle.

DM

[Trey Cannon]

One reminder....THe LF cabinet with the drone is under a patient...IF you sell any you would maybe steping on Klipsch toes.

The no drone unit may be different.

[D-MAN]

Based on something that Gil said previously about the throat opening size having a 10% threshold of acceptable variability, I would like to elaborate on the throat proper, not the opening to the throat, to be exact. I would tend to agree with Gil on the cavity opening as not being "particularily" critical to the overall performance, although this does not discount the fact that for each driver and each horn throat, there would be an optimum opening proportional size for the flatest and therefor "best" frequency response.

The MOUTH of the horn has the greatest amount of variablility that can be applied to its dimensions, as PWK said concerning the Khorn, the variations can be as much as 1/2" in any direction before it influences the response.

However, in every thing that I have read concerning horns design, it has been stated repeatedly that the THROAT is the area of criticality concerning the overall performance of the horn. There is less available "play" in the proportions at the throat due to the size of the waveform (i.e., an high velocity wave front) as compared to the same wave after propagating through the horn to the mouth (where it is a low velocity wave form with an expanded front). It is the throat portion of the horn where restrictions and discontinuities are to be expressly avoided, or excessive reactance (impedance) can occur usually due to reflections.

The throat area is where distortion is mostly generated and so should be arranged in such a way as to avoid turbulence, reflectivity and obstructions of any sort to a minimum. Some people paint the inside throat and the entire horn channels with a high gloss paint in order to reduce air/wall friction. It certainly won't hurt, and might improve efficiency very slightly. We all know that a duct with a smooth interior moves air quiter and with more efficiency than an untreated one with a rougher surface, so that makes sense.

So usually the throat is the area of main concern in determining the proportions and mainly to achieve a smooth unobstructed pathway for the soundwaves to propagate through.

The "rubber throat" or a throat expansion rate that is much higher than the rest of the subsequent horn channels is used to reduce reactance at the throat. It can easily be seen that a higher expansion rate would allow for air to be moved through it than a lower expansion rate as the moving air is allowed to expand along the channel walls faster than a tighter expansion rate would, actually allowing the relatively high pressure at the throat to become lower pressure in a shorter distance of travel than a tighter expansion rate (lower frequency) would. This has the effect of reducing the resistance to air movement "seen" by the driver at the throat opening, allowing greater extension per given electrical impulse.

One point that I'd like to make is this: in my opinion, based on his previous work and the fact that PWK did not vary much in that he tended to stay with certain aspects of his designs, I would expect that the throat design of the Jubilee to be very much like that of the La Scala (except being 2 of them stacked) very much like the drawing posted above. I would add a horizontal strut (like the Khorn's vertical) between the two throats, though, if I was building it, as the front panel takes the most beating, i.e., the highest pressures in the horn occur there.

Additionally, in lieu of adding a 3rd "drone", (you ain't gonna need it), the void spaces on the front panel can be added to the overall volume of the back chamber by the use of appropriately placed baffle cutouts. Not alot, but probably a gallon or more of volume (231 cu.in per gallon), enough to account for the insertion of the two drivers anyway. It certainly won't hurt and may lower the resonance a bit, who knows. I don't know if the comnmercial version does this, but if I was building it, I would do the baffle cutouts. PWK had a tendency to slightly undersize his back chambers when trying for a small enclosure size, and did not used baffle cutouts to recover any (granted what is available is small, but WHY NOT?). Whether there is anything to actually be gained sonically, I'm not sure, but for my own edification I would build it including cutouts.

The Jubilee is more closely related to the La Scala than it is the Khorn. You can see PWK's progression in horn design when you look at all of them in a sequence, I'm talking patents and such. The Jubilee completes the circle.

Typical of PWK design features (not in any particular order):

1) exponential horns preferred, however, the LS and BELLE have a hyperbolic mouth section with an exponential throat

2) front loaded horns with sealed back chambers - this is a PWK signature (ignore the REBEL/SHORTHORN -their rear-loaded horns and PWK eventually dropped them anyway)

3) back chambers slightly undersized upto as much as 20% from theoretical volumes. This tended to raise the enclosure resonance to a degree which he found acceptable for size considerations

4) shared componentry - use the same drivers as much as possible; not always optimum so clearly an economic decision.

5) "rubber throats" - the production (modern) Khorn, the Gillum patent and the "little bastard" being the only ones (that I know of) without a rubber throat.

6) bifurcated horns - only one non-bifurcated horn design(the "little bastard")

The design of the Jubilee clearly stands as being a PWK design as it embodies most of the above, not unexpected, and not a real departure in any area. It's a shame that its not in production.

DM

[D-MAN]

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On 3/30/2005 3:43:37 PM Trey Cannon wrote:

One reminder....THe LF cabinet with the drone is under a patient...IF you sell any you would maybe steping on Klipsch toes.

The no drone unit may be different.

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What is the patent number?

DM

[sunnysal]

DM, don´t forget that "smooth" does not necessarily guarantee the best airflow performance. what one desires is not to have the air "attach" to the wall as it passes AND to ensure it detaches as it passes a change of direction. with wings and balls smooth is not the best surface, that is why many wings have venturi generators, some cars now have the same generators on the back edge of the roof, golf balls are dimpled and olympic swimsuits are textured.

however I am not convinced that air flow is the major concern here since we are talking about wave propagation and not a constant air flow, right? hard, smooth reflecting surfaces for the waves are more important than friction of air in this case, no? regards, tony

p.s. I think we are only discussing D.I.Y. jubilees here so I think trey can relax

[D-MAN]

I agree, but if it IS patented, let's see it!

I don't understand why anyone would consider the Jubilee less complicated to build than a Khorn, it's right up there in number of parts and such... seems to me that those who think its an easier build HAVEN'T built one AND haven't COUNTED the parts! Just because the design is easier to read DOESN'T mean its also easier to build! It's also guaranteed to take more wood than a Khorn which takes 2 sheet of 4x8 per.

I don't have a clue as to why the Jubilee would need a passive in addition to two 12" drivers.

I have seen a patent for a bifurcated horn to Hook (1986?), that uses a reflex port feeding into the horn, so I have some idea.

I'd like to see the respective patent, though.

DM

[sunnysal]

I too think the passive radiator should be left out of the DIY jubilee, it will add more problems than it will solve methinks...tony

[D-MAN]

Tony, concerning painting the interior of the horn channels, yeah, but we ain't talking flight surfaces to supply a consistent trajectory or a producing a controllable flight surface.

This is concerned with reduction of simple air friction that occurs along horn walls. I probably agree that it's overkill, but then again, hey, why not - I mean why not cover all the bases even the somewhat obscure ones, if you have the time and energy, and desire? (Accent on the desire).

I read about this in Dinsdale's articles on horn building, I believe. It's evidently a British DIY approach mentioned there.

Please note that I did not take the time to do this in my horns, either. Just an option.

DM

[greg928gts]

Yes, let's see the patent.

From my point of view, the Jubilee looks to be much more straight forward of a build than a Khorn. It's easier to see the sequence of construction of it in my mind.

DIY only? I don't know?

Greg

[formica]

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On 3/30/2005 5:33:24 PM D-MAN wrote:

I probably agree that it's overkill, but then again, hey, why not - I mean why not cover all the bases even the somewhat obscure ones, if you have the time and energy, and desire? (Accent on the desire).

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And that brings me back to the PR.

The patent may reveal how these drivers and PR were squeezed into such a tight area, as well as the benefits PWK found in using it. As mentioned, he was very cost conscious in most of his designs... so I'm figuring that he must have found there was a significant enough of an improvement to justify using it. More than the "overkill" factor.

Given that most 12" drivers have slightly larger baskets (easily 1/8" to 1/4") placing three of them would fill the entire 36-1/2" height. How would the PR vent into the horn? Is it possible that the initial expansion occurs in the front to back plane rather than top to bottom (contrary to the cross section being used)? Is the PR a 10" with significantly more excursion (I doubt it)?

Rob

[D-MAN]

Hi, Greg! I was just trying to make the point that parts count is high and that's alot of cuts to make, so I don't see alot of savings there.

As far as being more INTUITIVE to build, that's a no-brainer, I agree, it would be easier to do in a sequential manner, almost intuitive in that sense, requiring very little reference work.

But overall amount of time and labor, I would guess its at best a wash, at worst, of course, more work in the long run.

Did anyone stop to consider the finish work required (now there's side panels, etc.), or are we talking spray painting them black?

DM

[D-MAN]

Hi, Rob! One possibility is that it could be inset back from the baffle connected to the baffle opening by some sort of ducting. I too wonder if it is smaller in diameter than the active drivers.

But my re-occurring question is "WHY IS IT NEEDED"?

Something smells fishy. If I remember correctly, the Daddy Dee reported that the one in the Klipsch home did not include a passive...or am I confused?

DM

[sunnysal]

since the folding takes place on one plane I assume some of the compound angles will be eliminated, at least that may make the construction easier since boards are matched with angles on only one plane. regards, tony

[greg928gts]

As far as finish goes, it looks pretty easy to me if the side grills are used.

Greg

[formica]

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On 3/30/2005 6:51:17 PM D-MAN wrote:

But my re-occurring question is "WHY IS IT NEEDED"?

Something smells fishy. If I remember correctly, the Daddy Dee reported that the one in the Klipsch home did not include a passive...or am I confused?

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Ok, DMan... you made me dig through the search function (moderators... PLEASE add the fuction of finding the actual post with the search criteria rather than just the thread!! DaddyDee's post has some 150 replies!) to find the posts which sparked my curiosity.

The drone (passive radiator, or PR) is definitely placed between the two woofers. Even Trey Cannon confirmed this in the Preparing for Jubilee build thread where he mentions:

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On 1/29/2005 9:30:24 AM Trey Cannon wrote:

When using a passive it goes between the woofers.

The ones the guys got to hear in Hope on the first "fan trip" used KLF-30 woofers. Did a fine job. The pro unit uses a 4" vc pro 12.

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I agree that can mean a lot in terms of orientation and openings... but let me mention a couple of observations. The KLF-30 woofers probably have more excursion than the K33 as well as about 30% more surface area. If the woofers were to fully extend, the PR would need more than twice the excursion of the KLF30 woofer if it's a12" PR... and even more if it drops to 10". I realise the the horn loading would minimize the woofer's excursions... but the same desire should be applied to the PR.

I then remembered a member mentioning he had looked down into the woofer enclosure... and after some more ($%@±¤!#) searching... Andy (HDBRbuilder) posted some pretty revealing info in his post in the Jubilee thread

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On 5/30/2002 11:47:00 AM HDBRbuilder wrote:

... Jubilee set up for me to listen to. It was the same bass bin as the home version will be, but the high-end horn was fiberglass (or something similar), not wood. .... Looking down into the bass bin, through the "door in the top" you see that it is lined with foam rubber at the rear, and from top to bottom you see one active 12" woofer, one 12" passive radiator in the middle, and one active 12" woofer at the bottom...all firing forward through chokes where the sound hits a vertical splitter sending the sound to each side instead of a horizontal splitter as on the k-horn, which sends the sound upwards and downwards....

.... I was allowed to check out the interior of the bass bins on not only the home version, but some of the earlier prototypes. The original prototype versions had just the two 12" woofers powering them, but a 12" passive radiator(drone) was added to the final version for the home.

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I'm quite confident HDBRbuilder auditioned the same unit which is now in PWK's home. I seem to remember Trey mentioning that there were two working prototypes of the home version... the one in "the" famous picture with the wood horn (at Klipsch's facilities) and the one in PWK's home with the composite horn.

Perhaps there are no ramps (angled horizontal pieces) in the first horn section... and just the vertical splitter. Can the splitter be increased in size to produce the desired expansion? The fact that the PR's were added, and patented, leads me to believe there was something to gain from them.

You mentioned another article (patent) which discussed adding a port to the woofer chamber. Was this also fed into the horn's mouth? What were the described advantages?

Rob

[D-MAN]

Thanks, Rob. That clears it up.

3x12" drivers means that practically every inch is used vertically.

However, that is going to change the throat design from what was previously discussed, if the use of a passive is to be included.

DM

[Neandertal]

Hello again,

I have been working on the drawings this weekend and have several updates that will follow. I would first like to address Trey's comments.

1) This effort is for D.I.Y. usage. I have no intend to build and sell any speakers. I also do not have any interest in is selling a drawing set (this is a group effort in an open forum). This project is to educate ourselves in what may be the best home sized speaker Paul Klipsch ever designed. Since it has been made very clear that Klipsch Inc. will not build them....let us who have the some skill and time try to best honor the man and the design which Paul worked on as his last/best effort. He had a need to design it....some of us have a need to hear it.

2) I have searched and do not find a patent on the "Jubilee" design. I checked back to 1978 and find only 4 patents awarded to Paul between 1978 and his death:

#4,138,594 The LB-78 speaker (Little Bastard)

#4,210,223 Low-freguancy folded horn (Looks to be the commercial KPT-MWM prototype)

#4,237,340 Crossover network for the "Little Bastard"

#4,387,786 Anechoic Chamber Arrangement

3) I am aware Klipsch is selling the commercial LF bin from the Jubilee. What we would like to see is the design that does include the drone (for home use) as may be considered to be the "ultimate" Klipsch speaker. Also need to see if we can develope the two-way design by determining the HF horn design and network details. Maybe we can help generate a sales market for the available LF bin if we could match it with the remainder of the Jubilee design for home use.

4) Trey...any offer of data from your end to support what is an attempt to promote the legacy of Paul Klipsch? As noted above....maybe we can help you sell a few more LF bins without cutting Klipsch out of sales of a speaker you admitt won't be sold.

Bert

[Neandertal]

An open answer as to what I am trying to achieve with this design effort. A few points are:

1) Attached is a drawing of what I believe may be the greatest benefit of an avaliable Jubilee for the unwashed masses. The beast need not be perfectly fit into a 4' deeep corner to work. The attached drawing shows how if would be easier to use than a Khorn for the same (better?) sound. Khorn quality sound without the need for corners....i'm interested.

2) I would like to generate a set of plans for THE speaker Paul was interested enough in to spend his retirement days designing. This would be the 2-way design with a drone in the LF bin.

3) A 2-way design without the drone in the LF bin This would be the bin currntly available from Klipsch but we would also have the data of the HF horn and 2 way crossover.

4) A 3-way design with or without the drone in the LF bin. I have a personal interest in a 3-way design using the best LF bin design we can come up with and the squawker/tweeter upper combo from a Heresy to top it out (the Jubilee bin would allow a 700hz crossover and hence a K-700 horn from the Heresy). This would give me Khorn that I could use on the wall in which I lack the proper corner for a Khorn and have a best tone match with my Heresy surround speakers in a 5.1 setup. Maybe not a purest intent...but one which best matches may current needs.

5) Any other combo any of you may have a need for.

P.S. Anyone inform as to how I may place a drawing in the text?

Thanks,

Bert