Why Fold the Horn?

[ooteedee]

So if a typical Klipsch folded horn limits bass response to 400hz, why bother with the horn?

Doesn't that put too much emphasis on the mid and high speakers?

And secondly....were the Klipsch speaker design's based on the limits of 40's-60's amplifier technology?

[ricktate]

Im not as good at some who will reply but,,,the Folded horn 400hz limit is the high limit and it is folded to lower distortion.Some of the older amps are actully better than new ones. When you can get 104 DB with one watt you dont need to much amp...Most speakers wont even get to 104DB with hundreds of watts of power and if they do distortion would be so great it would sound bad.Rick

[Marvel]

The horn is folded to reduce the physical size of the speaker cabinet. If it were not folded, it would be far too big to fit into most rooms. The KHorn, by design, utilizes the corner of the room it is placed in to increase the horn size, giving it the ability to produce lower frequencies with higher efficiency.

[Tom Mobley]

I think the Khorn sound path is like 12 feet long, not many people are going to be willing or able to a 12 foot long horn in their living rooms.

[J.4knee]

IF you did not fold the bass horn you would be using your back wall for a baffle (motor board) into your next room for a K-Horn. It greatly reduces the size of your cabinet and as others have indicated it reduces distortion.

[j-malotky]

First - PWK designed the folded horn bass bin to match the performance of the midrange horns he loved to listen too. Midrange horns are what set apart the Heritage line from the modern Klipsch speakers.

Second, what limitations of the amps are you refering too. Most vintage amps, both tube and SS, equal or easily outperform the majority of modern "high end" amps.

JM

[boom3]

Most of the questions you are asking really would be answered by a good grounding in the basics of acoustics. Here's a short list of stuff that would help you:

"Loudspeakers" by Badiemaff and Davis. Some of the stuff is outdated, but the essentials are still correct. Don't think it's in print, but it was reprinted beaucoup times and should be easy to find.

"Acoustics" by Harry F. Olsen. A peer of Paul's, Olsen was the technical guru of RCA's audio business for decades.

"High Performance Loudspeakers" by Martin Colloms. Colloms is indeed an expert, even though I don't agree with him on every point. He's also one of those that tends to sniff at horns, particularly bass horns.

Back issues of "Speaker Builder", available from AudioXpress. Although not published anymore, SB was a valuable pre-Web forum and in the back issues one can trace the development of Bruce Edgar's horn designs.

If you have a university with an electrical engineering department nearby, they should have most of these references

The papers of Paul Klipsch (of course). K&A used to sell these in a binder. He also issued a newsletter called "Dope from Hope". A few years ago, someone on this forum was offering a copy for a modest fee.

[Dylanl]

Why fold the horn? Here is why: A straight, exponential horn for use down to 30 Hz will exceed 16 ft in length, and terminate in a mouth with the man-size dimensions of 11 ft x 11ft. All of this, of course, will have to be ridgid, nonresonant, and open into an area allowing development of 37 ft wavelengths. You will not see many of these in the home audio system.

[edwinr]

Check out Avantgarde's US website. You'll see a picture of the 'subwoofer' which is virtually the size of a small room.

www.avantgarde-usa.com

[WMcD]

Two issues.

One is that the exponential horn is sort of like a French horn or trumptet. It tends to be long and big at one end. The geometry just is not compact. So folding or curving makes a lot of sense.

The path length of the LaScala is three feet, but folding can get it in a two-foot square box. The K-Horn path length is about 60 inches and its actual depth is closer to 30 inches (depending on where you measure).

If you have a corner, it can serve as the final flare of the horn, so you make up a lot of length and bulk there too.

You see comments that horn loading was needed with low power amps in the old days. None the less, there is much to be said for their benefits of low distortion regardless of amp power.

Best,

Gil

[JJkizak]

I remember reading PWK's notes on the horn and I believe he said the mouth of the horn would be 66 feet for a 15" driver. So he did the next best thing and used the room walls. I was originally going to build a house around his design recommendations in 1976 but the cost would be about 3 million bucks that I did not have.

JJK

[ooteedee]

Ok, great responses. I now understand why you fold the horn.

Maybe my question should have been:

Why HAVE a horn speaker if it limits bass response to 400hz?

[ricktate]

HUH....did you read the above?,,,,Rick

[WMcD]

Why use a horn if the high frequency response is limited to 400 Hz.

Fair question.

The driver sees more of a resistive load and that resistive load is fairly constant even up above 400 Hz. That is converting the force generated by the motor into real sound at good effeciency.

The problem is that the driver has limited force available and as frequency goes up, more and more of the force is taken up moving the mass of the diaphragm. So response drops. (Higher frequency means higher accelleration and F=MA.)

But, where the driver is working well, you get better results.

It does mean that now you need a big midrange horn which works down to 400 Hz. That has its own problem in that it has the same problem at its high end. So you need a horn loaded tweeter.

Tom Brennan had alluded to all this in another thread where he pointed out "efficency bandwidth product". You can have efficency, or bandwidth, but not both. This BTW refers to the driver, not the horn.

Gil

[JohnA]

I think I see where this is going. The answer to "why bother with the horn" is that they are more efficient, lower distortion and have greater transient response.

The bass horns are "folded" to make them smaller and fit into a room. Making them smaller requires compromises that reduce deep bass output, but the result is acceptable.

High frequencies do not go around corners well. The corners in the Klipsch folded bass horns limit HF response in the K-horn Bass horn to about 500 Hz. The La Scala's bass horn HF limit is almost 1000 Hz; it is not folded as many times as the K-horn.

To get good response curves, a horn should have good response at least an octave beyond the crossover point. Thus, the La Scala should not be crossed above 500 Hz. Mr. Paul used 400 Hz and K-horn parts in the La Scala because they were available and that was cheaper than designing and building new parts. So, the La Scala has forever had a 400 Hz crossover to the squawker.

It couls be comfortably raised 2 or 3 notes to 500 Hz, no problem, but why bother?

[Dylanl]

What shocks me is the amount of viable music that comes out of the bass bin alone. If you have never done it, disconnect everything but the bass bin and play some music. I think you will be amazed. I thought it may sound like a sub. initially because I have heard of people using the bin as a sub in their systems. It does not sound like that at all. Try it for yourself.

[LarryC]

The current K-horn crossover point, 450 Hz, is just above the 440 Hz "A" used to tune an orchestra. That's well up in the middle range.

[ooteedee]

Ok then!

I guess I'll just give it a whirl...and build my LaScalastein.

Even though I've got a whacked out crossover for it and all the wrong components, I'll build it anyway....and see how it sounds.

At least I'll have a well made cabinet.

I can always improve it later on with the right horns and drivers.

Perhaps then I may appreciate the La Scalas unique sound even better.

Let the experiment begin!

Thanks everybody.