Kornerhorns.........how to improve an old pair

[Colin]

Unlike the drivers of conventional loudspeakers, which have a lot of stressful movement and DO wear out quickly, a few large cones or many small ones do NOT move a lot. Only noisy and excessive power can wear out or ruin the diaphragms after a period of time.

What is the front-end equipment and room conditions of the Hartsfield/Lansing display? Who made it?

Unfortunately since our frigging forum profile STILL does not include our equipment list, we need some information from you about your front-end equipment, some of which might make a improvement in your home movie and music reproduction system. Solo or small groups sound better on almost all systems there doesnt seem to be enough channels, amplifiers and drivers yet to fake out our ears. RealTrap room treatments really seemed to bring my big ole horns into the audiophile league have you tried this? Old horns do not have the mid-bass punch that new speaker designs have, some intentionally turn up at the low frequencies to add that full sound. BTW 10 foot by 10 foot bedroom is 100 square foot space.

[3dzapper]

http://www.classicaudiorepro.com

Rick

[D-MAN]

Hi Guys,

I have a couple of thoughts and blatherings concerning the Khorn as compared to the Hartsfield... Please bear in mind that I have not heard a Hartsfield per se but have studied a little about it.

The Hartsfield was patented in '59 especially to compete with the plethora of horn-type encosures in vogue at the time (including the arch-rival Klipsch patented in '45).

To avoid paten infringement, it features a more complicated folding of the exponential bass horn than a Khorn which (of course) has the tendency to color and/or limit the upper-mid-bass frequencies that it can produce. It is typically operated as a two-way whereas the Khorn is typically a 3-way. Patented as a "convertible" corner horn speaker, a single back-loaded driver version was offered to allow for the end-user to "step-up" the the full 2-way front-loaded horn version at a later time and for more money. Note that the Hartsfield lasted in production for about 10 years, and the Khorn is still in production after 50; nuff said about the labor and material costs involved as the end result did not apparently justify the means in the market place.

The Hartsfield has a completely enclosed exponential horn all the way to the mouth, which the Khorn does not (it uses the walls to "approximate" the horn mouth. I say approximate because technically the Khorn begins unloading the horn as soon as the top is "cleared" by the expanding waveform which reduces the pressure and starts to unload the horn. The addition of "wings" on the top of the Khorn will serve to maintain the pressure on the expanding wave extending the horn mouth for another 8 inches (or so) on each side until the sides of the cabinet are cleared. This can be done with a single triangular sheet of plywood placed on the top of the bass bin and below the upper cabinet. This will enhance the bass response of the unit, and I believe that when done this way, the length of the Khorn exponential horn is longer (which is better) than the Hartsfield.

Another favorite tweak of the Khorn is to strengthen the back reflector with extra bracing as it is only 1/2 in thick and is liable to vibrate which absorbs accoustical output at various frequencies. This mod tend to "clarify" the bass and present a more "solid" and clean bass performance. Accurate sealing of the cabinet to the walls by using foam rubber gasketing material is also recommended.

The Hartsfield is shorter and wider than a Khorn and that does have an effect on the listening position to a certain extent. At a shorter distance from the speaker (i.e., closer than I would sit with a Khorn), I would think that a Hartsfield would probably sound better in the mid and upper freqs than a Khorn. But at an appropriate distance for the height of the Khorn upper-frequency cabinets and their dispersion characteristics, the Khorn would sound better than a Hartsfield at the same distance. So listening environment and especially listening position is of course important to the overall effect when making a comparison.

I would also imagine that the Khorn is slightly more efficient than the Hartsfield in that the Khorn bass horn has less foldings to navigate when the same drivers are used.

The Harsfield also used/uses a novel aluminum horn attachment that looked like some sort of a wave guide protruding in front of the upper frequecy horn. Note that this is no longer available; I wonder about its sonic value, but it gave the Hartsfield a distinctivly cool look.

But cool looks aside, it still went extinct for a reason.

One more element of comparison; the back chamber area of the Hartsfield is substancially smaller than the Khorn (I am assuming a 15 in. driver). This would indicate a higher Fc than perhaps one would expect in such a case (read that in a Klipsch patent).

I would guess that pound-for-pound a fully tweaked Khorn can successfully compete with the best there is and do it for a lot less wallet.

DM

[HDBRbuilder]

In my previous post here, I gave a link for JBL Hartsfield plans. Please note that these plans are for the 1959 redesign of the basshorn, which is essentially two side-by-side "S" horns, bifurcated at the beginning of the soundpathway. The Klipsch Jubilee basshorn is also primarily two "S" horns bifurcated at the point of soundpathway origin, and laid out in a similar manner...but with less severe constraints on its construction process...with the basshorn being pushed by two 12" drivers (with the later adoption of an additional 12" passive radiator in the planned home version), and with the HF horn NOT included in the lower cabinetry of the basshorn, as it was in BOTH of the Hartsfield versions.

The original Hartsfield basshorn of 1954 was not laid out in the above manner. For more info on just how the original model's basshorn was laid out, AND a really GOOD pic of its soundpathway, you can go to the following website:

http://www.audioheritage.org/html/profiles/jbl/hartsfield.htm

The above site also gives a brief history of the Hartsfield development and such...but the pictures there of the internal workings of Bill Hartsfield's original version of this speaker are worth a thousand words! Right, Q-man?

As of yet, I have NOT been able to find a FREE downloadable set of the plans anywhere on the internet for the ORIGINAL VERSION JBL Hartsfield of 1954...If I find them, I will certainly post them for you all!

One of the things I find interesting is that JBL was able to take full advantage of FREE publicity found in NON-AUDIOPHILE journals of the day, such as LIFE magazine's article on the Hartsfield, in which it was touted as the "finest home loudspeaker anywhere in the world" at the time. It seems that this free advertising of the Hartsfield speaker within the pages of journals that were highly distributed during those years (Life magazine was one of the MOST-read magazines in this country at the time!) was directly responsible for increasing JBL's "name-brand household recognition" with the "average common man" in this country to a point where JBL was able to drastically increase its sales in the mid-to-late 1950's, which kept it from teetering on the verge of bankruptcy as it had done prior to this. Klipsch, on the other hand, relied primarily on "word-of-mouth" advertising and articles published in audio, engineering, and scientific journals to spread the word of its speakers during this same time frame...thereby keeping its name in the minds of the "audiophiles" of that time, but NOT getting anywhere near the same level of "name-brand household recognition" that was heaped onto JBL back then! Yet Klipsch still survived, began to prosper and expand, and the Klipschorn is still in manufacture!

Can you think of any current speaker brand that PRIMARILY aims its advertising at the "common man" in order to increase/continue its level of "household name-brand recognition" today? I'll give you a hint...Paul Harvey!

[Al Klappenberger]

JWPATE

James,

I am very courious about the Hartsfiled too. I think it looks like a real fine speaker. I think, in the time it takes you to put the kit together, you might try the 1 uFd bridging cap idea on your AA networks. This is the mod posted under Ods and Mods by "Different" describing extended highs for the AA. My tests show it to be a real good and inexpensive improvement. You definitly need a larger cap than initially proposed though. 1 uF looks good.

Al K.

[ZAKO]

QMAN.......NO the SMITH milti septa design mouth opening is 2"x30" like a big pie slice.

[JWPATE]

Sorry HDBRbuilder,

The Hartsfield speakers being built at CLASSIC AUDIO REPRODUCTIONS are, as you probably expect, the later, JBL design and not the originals.

[JWPATE]

No Al,

I am not using the AA crossovers........I am using those wonderful ALK crossovers, which you sent last month!!

James

[JWPATE]

Thanks Colin,

You have asked for a description of my front end, and I provided that in a previous post. It is still there. The room conditions of the Hartsfield experience were a motel room here at The Home Entertainment Show in Las Vegas. My listening room is roughly 21 feet square, while that motel room was about 20 by 25. The ceilings in both cases were 10 feet, but my ceiling is actually broken by architectural features into three different levels, the lowest level being 10 feet.

I am afraid I do not take your meaning, when you point out that a 10ft X10ft bedroom is 100 square feet. That is, of course correct; but so is a 5ft X 20ft bedroom equal to 100 sq feet the acoustical possibilities however would be quite different. I had given the room dimensions because someone asked for them. Surely you are not suggesting that square footage would have been an appropriate response. Or are you?

James

[WMcD]

I looked into the Hartsfield a few years ago.

The original one can be found under the patent number if you go to the USPTO site with the number. You'll need to download a special .tiff viewer.

My recall is that the original one included an adapter so that a "starter" 8 or 10 inch drive unit could be used. Then it could be upgraded to a larger unit. This may have been the patented aspect of it.

It was a nightmare of construction, even by the demanding standard of the K-Horn. The revised one had more simple construction; still more complex than a K-Horn, and took the larger bass driver.

I don't recall that the treble horn was ever an option. It was used in both.

The louvers on the treble horn was an effort to delay the propagation at the center so the longer path lenght long the sides of the horn would come out even. Someone had a concern over delay induced phase and directivity. Was a tweeter added to some other ones?

Such is my recall. Maybe I'm off in some of this.

Gil

[Al Klappenberger]

James,

OOPS! Sorry. I should have remembered you since you have the latest set I built. I got a rotten memory!

Al K.

[D-MAN]

Yeah, Gil.

The highlights of the patent were that a single full range driver was available that used a metal horn "adaptor" to mate with the bass horn mouth as a rear-loaded lower cost version that could be upgraded by the owner at a later time by purchasing the midrange/tweeter driver and horn along with the larger woofer to be monted directly in the bass bin.

The patent also specified that damping material was installed inside of the metal adapting horn to prevent upper frequencies from being transmitted. This was a major point, but only effected the rear-loaded version.

The patent-version Hartsfield looked like a nightmare to build, but it is an exceptional example of ingenuity and market savy. I took some of these qualities to heart when I did my design.

I ended up with a top-loading Khorn (more or less) that could do the same thing so I could experiment and tweak.

Don't know of anyone else that has them! Hell, I would have bought a Khorn flat kit, but couldn't find one. I don't think that I'd want to try a Hartsfield flat kit...

But a Khorn flat kit - Why aren't any of you guys selling those?!

DM

[3dzapper]

D-MAN,

There was a thread recently about a German corner horn copied from the Klipschorn that is availiable in the form of a kit. The kit still cost more than a good pair of used Khorns.

Rick

[ZAKO]

Gill....The 075 tweeter was added to the later Hartsfields. The 375 mid hf driver never went mutch above 9K hz. The slant plate infront of driver & horn is called a ACOUSTIC SERPENTINE LENS. IT helps to spread high frequincies horizontaly through the room.

[ZAKO]

KLIPSCH LLC.....I want the Klipsch company to note this was an oppertunity missed in NOT to haveing the JUBILEE. Even having the cinema Jubilee bass bin available would stop the bleeding off of customers. The Hartsfield buyer will not be back.

[khorn58]

Q-Mann said "The first Klipschorns were built with backs that completed the folding of the basshorn and had a top on the basshorn. This top came out to the front of the speaker and was below the midrange horn, just like the Hartsfield. Another words it was also a complete basshorn. I don't know the reasons why Paul changed this design"

I just wondering were you got this info on a khorn with built in back flares instead od walls?

I have seen what I think is all of the proto type khorns as well as many or the early 40,s ones. all look basicly like the modern khorn. There is one on the horn site with sides but I 100% sure they were add buy a owner yeras ago.

[Q-Man]

I have a set of some original Klipschorn plans signed by Paul that he sent out for bids. These plans have a back and a top.

[Q-Man]

I was wrong. I just pulled out the plans to take another look at them. They have a full top like the Hartsfield, but use the walls for the back. When I last looked at them I must have mistaken the full top measurements to include a back.

[D-MAN]

Oops. Messed up; the Hartsfield patent was 1957, not '59 as I stated previously.

Sorry.