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moray james 6th November 2010 03:29 AM

Klipsch Horn Woofer designs....
There have been a couple of interesting threads here of late pertaining to conventional front loaded horns. I have been reading up on Klipsch speakers as I recently purchased a set of Klipsch speakers at a price which was too good to pass up. I was of the impression that the Klipsch horn woofers such as used in the Belle and the La Scalla were too small to really be taken seriously as modern high efficiency designs. However after reading I think that I was mistaken. While these cabinets do not extend much below 50 Hz. with out room gain though they are very compact and very efficient and would seem to have reasonable response.
I am curious to to know if any here have ever run either the Belle or the La Scalla cabinet design through Horn Response to see if Paul got it right the first time all those years ago? From what I can see they both represent a good compromise as a commercial product which has consistently stood the test of time in the market place. Both design are very similar with the Belle being a shallower cabinet with a wider mouth. Many owners consider the two versions to be pretty much the same in terms of performance. I have included a link to the AES paper which Paul Klipsch wrote many decades ago for reference. Thanks for any comments or thoughts. Best regards Moray James.

TerryO 6th November 2010 04:21 AM

You probably already know about the LaScala modification where the bass horn's back chamber is opened into the subsequently enclosed (sealed) top hat. Another variation is to add a sealed plinth under the horn which uses an opening from the bottom of the woofer's back chamber and is sometimes also ported.
Either modification seems to allow a fair amount of extension to the bass frequency range.

Best Regards,

bentoronto 6th November 2010 10:20 AM

It is great fun to experiment and explore the bass. But ultimately, hard to fill a gallon jug from a quart pitcher (or some old cliche like that). Even the Klipschorn has big compromises.

There's a lot of excessive hoopla about bass below, say 40 Hz. Sure not audible on music. Just feelable on rare recordings... and movies. And, without going all mystical here, there are qualities to woofing not fully accounted for by freq response, that your speakers may exemplify.

Are the drivers the same as in the Klipschorn?

In the AES paper, I think he is sniping at the Altec Voice of the Theater. Great guy. Love my "true" bass horn.

WithTarragon 6th November 2010 11:49 AM

I also agree with the above about going down to 40 Hz. If you can do that honestly, then you are probably covered for most music.

The drivers are not the problem. They can still be purchased, and at a reasonable price. Of course you can always spend more if you want.

An alternative to using the single 15inch driver is to use a pair of 12 inch drivers. Such a bass bin was outlined in a JAES article by Delgado & Klipsch (2000). This is the "Jubilee" bass bin and when compared to the Klipschorn it has 1) better efficiency (lower distortion) and greater bandwidth (so it could be used in a two-way configuration).

It is an easier build for a DIYer and it can also be purchased from their commercial division (go to the Klispch forum and ask how to do this - it is not a simple matter of calling up a dealer).

Good luck

moray james 6th November 2010 03:50 PM

Hey Terry: yes I am familiar with that mod (but it had fallen of my radar) so thank you for reminding me. Just for clarity I did not purchase one of the Klipsch horn designs rather a set of Forte ll.

The KHorn and the Belle and the La Scalla all use the K33 woofer I believe. I have T/S data in a file. I am not looking so much to get deeper bass from these designs as they pretty much are maxed out in the bandwidth department. I was more interested to know how modern day simulation programs compare to PW with a slide rule pencil and a pad of paper.. I realize that these designs have compromises but that is to be expected. I am interested to find out how reasonable those compromises are.
The Jubilee is a nice horn but like the Khorn requires two solid corners while the Belle and La Scalla will get by with a wall behind them. JBell's two foot cube is a nice bass tapped horn but is limited in bandwidth (upper). I wonder how much bulk could be shaved off of a Belle or La Scalla if its bottom end response was limited to 100 Hz or so?

bentoronto 6th November 2010 04:15 PM

moray james - I'd appreciate getting a copy of the T/S K33 parameters. Also, if anybody can help me with the SpeakerLab clone driver parameters* too.

PWK was a practical guy with a good ear.

WithTarragon - my Klipschorn bass box is a built-in, unfinished, "industrial" model from the early '50s, I believe. (But I've had it only since 1968.) Piece of cake to finish the flat front panel in a nice hardwood veneer. But also needs a top, stretching from wall to wall. Also a piece of cake to make a heavy, sealed top piece and to glue veneer on its flat surface too.

Little question: It is correct to call the whole 3-driver speaker "a Klipschorn" but then what is the proper name for the bass horn alone? I usually just call it "a Klipschorn" too. Well, like "cannon" and "cannon."

*one experiment too many with motional feedback.... which, by the way, seems suitable for true horns within their passband, esp. with sealed boxes behind the driver.

WithTarragon 6th November 2010 04:38 PM

A few comments to the above.

1. The Jubilee does not require a corner, although the very deep bass will benefit from a corner (as will all cabinets).

2. The Speaker lab plans are not the best - there is more then one version, and some have errors.

3. The bandwidth with a K-33 is not maximized in the designs mentioned. The upper range is a function of the cabinet folding. IOW, the K-33 in a straight horn has greater bandwidth.

4. The Jubilee is an easier build then the K-Horn, since there are no double bevels. For folks like me, there are a surprising number of ways to mess up.

5. Have look at the graphs in the JAES article, before you build the Klipschorn. You will get a notion of the performance differences between it and the Jubilee. I have owned both, the Jubilee has several advantages. Incidentally, you can buy a factory version of the Jubilee and there might be someone in your locale that would let you listen to theirs ahead of time.

moray james 6th November 2010 06:49 PM

Thank you With Tarragon for the info and correction regarding the Jubilee
room loading. I had made the assumption as a result of pictures on line I have seen, that's good to know. Regards Moray James.

Old K33E specs:

Name: 15162
Type: Standard one-way driver
Company: Eminence Speaker LLC
Comment: K33E
No. of Drivers = 1
Fs = 34.46 Hz
Qms = 7.39
Vas = 301.7 liters
Cms = 0.268 mm/N
Mms = 79.47 g
Rms = 2.328 kg/s
Xmax = 8.2 mm
Xmech = 12.3 mm
P-Dia = 336.6 mm
Sd = 889.6
P-Vd = 0.729 liters
Qes = 0.41
Re = 3.39 ohms
Le = 0.96 mH
Z = 4 ohms
BL = 11.93 Tm
Pe = 150 watts
Qts = 0.388
no = 2.903 %
1-W SPL = 96.78 dB
2.83-V SPL = 100.5 dB

Frode 6th November 2010 07:47 PM


Originally Posted by moray james (
I wonder how much bulk could be shaved off of a Belle or La Scalla if its bottom end response was limited to 100 Hz or so?

From what I understand, the LS basicly works as a sealed box below 100Hz. It's mouth supports down to 125Hz and the length supports down to 100Hz. So I guess you can't make it much smaller if you want it to act as a horn all the way down.


tb46 7th November 2010 02:12 AM

Jubilee v. LaScala
1 Attachment(s)
Hi Y'all,

I looked at these a while back, and entered then into Hornresp. For the LaScala I used the T/S parameters provided by moray james, and recalculated the values with Hornresp. From the literature I am under the impression that Paul Klipsch considered the Jubilees as his finest, sadly I never had a chance to hear them. Obviously, both designs could today be tweaked with Hornresp and AkAbak.


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