alternative designs- why go jubilee?

[Horatio]

Hello all:

I have recently joined this forum, and have made only a few posts.

In terms of background, I have designed a la scala- based horn, and cut my teeth on the issues of trying to improve an existing design, working with the Leach/Plach/Keele sources on throat and back volume, etc., etc. I have built a pair of the so-called Fostex-based two-ways (with my son, while he was in high school; they now pretty much rule his college dorm, nothing can come close, or so he says), I have built a set of University Classics (with a somewhat unconventional approach to the top end- EV CD horns), and I have wrestled with the ownership of Speakerlab K's, finally transforming them to an acoustic copy of the original Klipsch design.

I have been reading with great interest, the many posts here on Klipschorn/Belle/La Scala mods, and of the projects along the lines of classic designs. In particular, I have read about the Jubilee system, including the AES paper describing their design.

While mods can be made to the original Klipschorn, and many of these can be really efficacious (I'm thinking here of the various approaches to handling the midrange, primarily, although there's lots to do with crossovers and tweeters, too. Very few change anything on the bottom...unless they're working with a Speakerlab K, in which case, they change to a K33E and slap in a Type A crossover...), I wonder if we're off track a bit (maybe I just am not on the same page as to where this collective forum is going...). I like mod'ing as well as the next guy, but I think we are making end game refinements to a design concept whose constraints we can't avoid. I do not dispute the greatness or significance of the design; it is remarkable that a 60 year old design can put most of today's general loudspeaker product to shame. Physics is not often bought off by the next pretty face.

For example, there are countless ruminations and designs for alternate bass horns...it is really really hard to get lower than the Khorn, in any similarly sized package...build after build shows this. Even the Jubilee trades absolute low end for somewhat smoother passband and extended upper bass, relative to the Khorn.

Where I am going, is this (and it is not terribly original- those who've been to the volvotreter web site know this): What if we focus on a so-called satellite-sub design, based on a Khorn, crossed out at, say 150Hz. Then, we work on a two-way satellite that is horn-loaded. Here, I am thinking of the front lenses that DDS makes, on a healthy 10 or 12 inch driver really optimized for upper bass, for the bottom of the satellite, and a really open sounding horn on top, where we take care not only with the frequency response, but we are paying close attention to the directivity. We also have less time delay issues to work with. Finally, isn't it about time that we begin thinking about the design of such systems in conjunction with the electronics (not only in the ususal sense of loading, and so on) in the sense of active equalization? Can we not use CD horns, or horns that, in order to give the desired pattern control, must be in some way equalized? Such an equalization scheme could also potentially deal with the response of the Khorn bottom in the 50-150 Hz range, too, to smoothen this out somewhat.

Such a system would go a long way toward addressing some of the age-old issues we've been talking about with respect to the Khorn (bass response, mid-bass and lower mid-range behavior, patterning of the midrange and tweeter, and lastly, the fact that the Khorn just can't deliver that 'slap in the face' response that say, a VOT can do (again, the mid-bass, lower midrange problem).

Thoughts?

(thought I'd throw a piece of raw meat in the house!)

[Guest " "]

The sub-woofer technology used in the auto industry is pretty advanced. These sub-woofers have long excursions and can produce low frequency SPL that seems to defy the math. But their range is only 20hz-100.

Most folks are happly just by adding an amplified sub-woofer to their heritage line setup to address the bottom end.

Others address the mid-range area by moving to alternative mid horns such as the 511b or wooden tackhorns.

In terms of K-horn or Jubilee, I'm not sure that either is well suited for the typical NYC listening area which varies from 12X12 to 16X14.

I think a min-jubilee, with a partner long excursion sub-woofer would be an intresting combo.

[Horatio]

I agree that the technology in the sub market has evolved considerably. I am somewhat dubious of this, as those systems to which I have been exposed seem pretty heavy-handed and not real listenable. Maybe I need to find a credible system and give it a critical listen.

Yes, the midrange issues are rife with mods like the 311/511/811, and the trachorn. I don't know about the sound of the Altec horns, but it's got to be an improvement, if for no other reason than the mouth size lends itself to fewer reflections. Since they are expontial horns, they undoubtedly still suffer from the polar response issue. The trachorn, and the Voight tractrix family in general can potentially do a better job, but, we have design technology that ought to enable us to render horn shapes that are part waveguide that, with equalized drivers, should give great frequency response AND excellent, stable patterns (and concomittent imaging). These approaches come up over and over because they either a) rely on the use of existing, better designed exponential horns, or they rely on keeping a horn that permits 'drop in' insertion to an existing system (that is, they might require minor crossover tweaks, but not much else). Very few are willing to brave the use of, say, a CD horn, which will require active equalization in order to achieve its objective, but which would yield an entirely new level of performance.

My point is, we keep trying to appeal to those classical approaches, and we keep ending up in more or less the same place. We need to think differently if we are going to arrive at another, better, place.

The automotive situation offers good insight: I have a friend who works for Bose, and we often get into discussions about the active equalization that is done for automotive audio systems. These systems know, for example, if the convertible top has been lowered, and change the system response accordingly. They self-calibrate. This kind of technology will be extremely helpful to rendering a new solution to an old problem. I will admit alot of ignorance on this area, as, I am still rather old school in my home setup: Hafler pre-amp and a bank of B&K (English) monoblock MOSFET amps. There is, I'm sure, already technology of this general type making its presence known in the consumer market. The pro sound guys have some fantastic tools available.

The apartment case is a real problem; these spaces are always going to be a struggle for full horn systems, in the sense of wide range systems. Although, along these lines, the 'Fostex-style' two-ways (German design running around on the web) can do a really really nice job, in a compact package (again, my son and I built a pair of these and they work stunningly well in his very compact dorm room). I have also seen another design that is very unusual, but workable for this case: imagine two, four foot square sheets separated by about 6 inches, with the full range driver in the middle of one of the sheets, and the driver back-loaded with a horn that radiates from the periphery of the 6" thick edges. The 6" space is divided into four tracks that exponentially expand from the center, one track to each side. THAT is a design that could be mounted on a wall, or hung from the ceiling, or...many possibilities for small spaces...

Still, a more conventional design, with say, a mid-bass driver with a short front horn in a vented box, and a tractrix-style or CD or waveguide top with a good quality compression driver, paying attention to the polar response behavior during design, ought to be doable in a box of reasonable size when one curtails the low end to around 150 Hz. Paired with a conventional sub, this could be pretty good...

[seti]

For me it was hearing the jubilee that made it my dream speaker. If you have the opportunity listen to the jubilee do it and then form an opinion.

[Horatio]

Excellent point. I have not heard a Jubilee, but have just read the AES paper, and of course, read in this forum about listening experiences. This is the nub of it, though: the mods we make to our Khorns, La Scalas, Belles, are made in a direction that that Jubilee went, esp. with respect to the midrange. We try to address the issues latent in the original design, however good the original design was.

Please understand, I am not saying the Jubilee is not worth hearing, not at all. My point was more that, our mods to the classic designs have become somewhat circular. We need to break out of that. Jubilee shows significant, step-wise refinement of a classical concept- that is what the title of the AES article intends to state, I would submit.

These designs will almost always be considered competent reproducers. I am trying to poke at us to prod us to think beyond this. I myself have built copies of these excellent, old designs. They work very very well. Perhaps I'm pushing to solve that ancient Greek geometry problem of squaring the circle...

[Daddy Dee]

I agree that the Jubilee is a step up from the Khorn. It could not be achieved through modding the Khorn.

[Duke Spinner]

, the fact that the Khorn just can't deliver that 'slap in the face' response that say, a VOT can do (again, the mid-bass, lower midrange problem).

Aaaaah ....

I can see we'll get along fine, Horatio .......

I like to refer to that " slap in yer face " ...

as .........THWACK .....!!

and , yes, x-over the KH bass bin, say at 120 hz ....

to a 10"

[Duke Spinner]

and ...

don't forget the VitaVox designs ...

[Duke Spinner]

and ...

don't forget the VitaVox designs ...

on the Direct Radiator issue, it seems to me

that all common subwoof's suffer from that "underdamped" sound

unlike KH

[Guest " "]

Horatio:

I think we are a couple decades to late.

There is a production speaker system that uses the k-horn bass bin, a large wooden horn, a mid horn and a hf horn.

It's was the Patrician IV sold by Electro-Voice, under license from Klipsch.

[Duke Spinner]

nothin' new ....

in Audio ...[]

[jwc]

and ...

don't forget the VitaVox designs ...

Hey Dukey,

You don't happen to have a copy of any of those VitaVox Plans do you?

jc

[Duke Spinner]

You stop sniffin' 'round all these speaker designs, JC ...[]

you cut yer index finger off ... you can' t work ....[] [] []

there is a VitaVox website w/ plan's ..

i'll try to find it in my mess of saved places

VitaVox ... look's remarkably....

.......like a Jubilee... Eh ..??

[Duke Spinner]

to continue your education , JC .....

you should build a VOTT, and a JBL scoop....

both have likeable attributes ....

there is no perfect speaker, alas ...[]

[jwc]

Yes, there is a VitaVox that looks similar to the jub. However, I don't think I could ever find those particular plans.

I have debated the jbl scoopes a few times. The VOTTS are freakin Huge.

Typically if I build it, I have to keep in mind that I would have to be able to sell it one day or find room in my house. This last venture was an attempt to get something with about the same footprint and sound as good or better than the dbb's.

Of course....many egged me on to make the jub.

Heaven sake......I hope I keep all my fingers.

[Daddy Dee]

I think that's the design that the bentwood horn builder from Canada used. It does look like a jubilee bass bin. He has his stuff on Ebay from time to time.

[Duke Spinner]

I think that's the design that the bentwood horn builder from Canada used. It does look like a jubilee bass bin. He has his stuff on Ebay from time to time.

First Octave audio... is selling an upscaled Vitavox Volunteer ... using an 18"

[sheltie dave]

Everyone keeps missing the boat on the tophat mid/tweet design. Just drop a pair of Bose 901s on the basebin. They are relatively linear in the 200 to 20K range, only needing 2 dB of boost at 200 Hz and 30 dB at 15kHz. [8-|]

[boom3]

A crossroad decision in this quest is: Do we cut off the bass at say 150Hz and have a nice Big mid, possibly going to a 4 way design, or: do we try to extend the bass bin down to the grail of 20 Hz and keep a reasonable size mid---or some of each? The manuevers required to upsize the K-horn to 20 Hz have been discussed here, and I recall one example from the web-name escapes me-that upsized the K-horn by about 1/3rd. This was a DIY project, not a commercial example.

There's something else here that a few threads have touched on. What do bass horns do below cutoff? Paul's writings on the subject are vague. The graphs indicate they drop like a rock, so few want to try to equalize them in their last octave. Some conjecture that a horn below cut off acts as a direct radiator-albeit not a very good one...and can be EQ'd with proper high-pass filtering to kill subsonic problems.

Then of course there's been healthy discussion about porting the LaScala. So the logical question is: port a K-horn? Both the K-horn and the LS use the back volume for reactance annuling, so it seems that porting-if it works as some believe in this case-might be a valid way to go to increase last-octave response.

[DizRotus]

Sheltie Dave-

"Just drop a pair of Bose 901s on the basebin. They are relatively linear in the 200 to 20K range, only needing 2 dB of boost at 200 Hz and 30 dB at 15kHz."

I sense sarcasm. Nevertheless, I recall seeing a mimeographed ad for just such a combination from some DIY entrepreneur decades ago. I never actually heard, or even saw, the finished result. The builder/seller was probably infringing the Bose patent (the Klipschorn patent had probably expired by that time).

I've owned Khorns and 901s. Such miscegenation should not be allowed. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />