Karlson Enclosure

A have built many Karlson enclosures about 15 years ago in different sizes and also experimented with various drivers.
At that time I found them good because somehow I liked the "fast", tight bass and the high output, though I always felt there was something strange in sound.
Another reason why I have been attracted to build this (I have to admit) is the unusual design which looks really cool.
With increasing experience, more investigations over time and better measurement equipment , I figured what has me disturbed.
The Karlson has some serious resonances upwards around 100Hz or so, with severe frequency and phase response deviations.
Also it does not produce really deep bass.
I consider this design being good for PA purposes only (high output) but would NOT recommend it for serious Hifi.
As I did not want to scrap all the enclosures I produced, meanwhile I changed them to simply closed boxes by closing the upper part behind the exponential shaped front (I always called them "curtains") and added an active EQ with
the Linkwitz circuit. This is far better now, though the "curtain" and the remaining volume in front of the driver still produce some strange frequency response in the upper bass. Because I use them only as subwoofers anymore with a steep 80Hz lowpass cutoff, this does not disturb too much.

Christoph
 
I have to disagree with the Karlson Trashing

I have an original pair of Karlson Ultra Fidelity enclosures loaded with a pair of Stromberg Carlson coax's and personally, I think the sound is wonderful.
True, the resonances and phase shifts are a drawback, but the determined DIY'er can overcome the majority of those problems if they simply design their cabinets correctly. The problem, I think, was that the enclosure was designed to accomodate a wide range of drivers from Altec 604's to Allied or Knight coax's. That's a pretty big difference in performance and parameters.

Nowadays, speaker designers would never design a box with more than one speaker in mind. There are also tweaks written into one of John Karlson's patents "Acoustic Transducers" (patent 3540544) that place focusing elements into the front chamber which aim all of the sound out the flared opening. This reduces the resonances significantly, as sound doesn't have a chance to bounce all around inside the chamber before finding it's way out.

There were also port and shelf mods that further smoothed the response of the cabinets. All of this information can be found at the aforementioned webpage

http://home.planet.nl/~ulfman/

Personally, I prefer the challenge of using all the available info to build a Karlson design cabinet well for a specific driver (like an 8" Fostex FE206E for instance) and reap the benefits of the design instead of avoiding the cabinet altogether because of it's tarnished image. It's kind of like the DeLorean of the speaker cab world. It was a work in progress that never had time to develop into the butterfly it could've been. Nothing really wrong with it that can't be fixed except for it's reputation.

-Erik.
 

Ron E

Member
2002-06-27 10:41 pm
USA, MN
The slot is based on a method for slotting a resonant tube (whistle) to make its output more like white noise than centered on a particular frequency.

The slot doesn't do anything at bass frequencies. Karlson's are just really big vented boxes for high efficiency woofers, and they excel at making lots of 40+Hz bass.

Paul Klipsch measured these (investigation of a competitor at the time) and he had a couple funny quotes about them.... These measurements are out on the net somewhere.

The cavity resonances at ~200Hz+ created by the slot and the space behind are really bad: like +/-10+ dB

There is a guy on the Audio Asylum sites named Freddyi who seems to love these things if you want another opinion about them...;)
 
cocolino said:
The Karlson has some serious resonances upwards around 100Hz or so, with severe frequency and phase response deviations.
Also it does not produce really deep bass.

Christoph [/B]

I've seen Cocolino around a good bit and would give careful consideration to his comments -

And then on the other hand we have a bona fide poster from the karlson Page. Hi E.Lectronic.

freddyi who hangs around High Efficiency at AA, and over at the Full range driver forum has made a number of posts on Karlsons - I don't know how many he has actually built -

I guess you're going to have to take your best shot and let us know - but if it were me looking at it, I would want to be sure of solutions to the frequency deviation and phasing problems before starting construction -
 
I know Freddyi

Yeah, Freddy knows more about Karlsons than I do by a far stretch, and he owns several different pair of them of varying size -I believe 8" up to 15" (driver size).

I'm in the process of building my first pair of K-8 cabs modified with the tweaks I mentioned in my earlier post. It's definitely a challenge to attempt to correct it's shortcomings, but I believe it can be done. I mean if you break it down into it's basic components its just a bass reflex box (easy) with an exponential coupler front chamber for the higher frequencies. When you look at it that way, it's really easy to conceptualize design.

About the Karlson not producing really deep bass, that has not been my experience at all. The 15" Ultra Fidelity Karlsons I own put out some of the best, most effortless and "alive" bass I've ever heard from a speaker and that includes those soffit mounted TADs in the recording studio I interned at many years ago. Don't get me wrong, it isn't that I'm saying the TADs aren't way better speakers, but there's something about the Karlson that makes the response of the driver very fast and punchy. It takes me one step closer to feeling like I'm in the same room with the musicians. Now, granted, Ron E. is correct about the slot not doing much for deep bass. The way I understand it, physics dictates that the slot would have to flare out to a width that would accomodate the wavelength of the lowest frequency produced in order to be useful. But, the perceived bass is different because of the slot's effect on harmonics of the bass frequencies. The actual bass frequencies are affected by the bass reflex design of the rear chamber. Thus the bass can go as low as any other vented enclosure, and K15's are pretty big, so they can produce some impressive lows. And who knows, maybe there is an advantage to the extra loading of the front chamber? Freddyi might have some ideas about that.

As far as measurements go, many of the "Karlsonites" -as we call ourselves on that page- have measured their cabs to pretty low and impressive frequencies at very good SPLs. I'll have to ask Freddyi. He's the real number man. The fact that many people use their Ks as subwoofers or Bass guitar cabs speaks highly for their bass response.

I'll see what info I can dredge up from some of the others on these issues and get back to you. In the meantime, I recommend to anyone interested to visit the Karlson Speaker Project, read some of the posts and articles and chat with the locals. If nothing else, it's a design that I believe was ahead of it's time in many ways and is worth investigating just for it's curiosity.

-Erik (slightly Krazy "Karlsonite"):clown:
 

Cortez

Member
2002-12-26 9:45 am
Hungary
Karlson review

Hi all !

Karlson is a very intresting enclosure type and an acoustic tool for us.
Here is a great Karlson-site (maybe the best in this subject):
http://home.planet.nl/~ulfman/

And here is the theory:
http://home.planet.nl/~ulfman/theory.htm

It is basically a TL, an air column resonator, but it is not a regular
simple-TL, cause it have a special exponential cut on it, and
therefore it acts like a broadband-resonator cause it works like
a lot of TL pipe paralell with different lengths and opening areas.

Have somebody own experiences from practice with this ?
Not with the conventional reflex-Karlson with the "curtain",
but a normal TL with an axponential cut like on the figure.

Theoretically everything that improves something, should have some drawbacks too.
Now then, what could be the penalty to use this kind of smoothing ?
Maybe the overall output level decreases related to the regular straight TL at the same
time, cause the karlson cut increases the acoustic shortcut at low freqs a little bit ?

Waiting for your comments ! Thanks ! Regards ! :)
 
Yep, I've done it...

with 150mm plastic pipe about 1.2 meters tall, baffle down the middle, so it's folded, & 4" drivers,
it worked really well for me, but I haven't measured the result.
Plenty of low end
(I bi-amped with chip amplifiers, xover @ 150 Hz)
I'll post a pic when I get back to my usual computer...
I'd like to try again with good drivers and bigger pipe,
but too many other projects at present....
Pete McK
 
nah...

All my drivers are on the baffle, which is down the middle of the pipe. The top of the pipe behind the baffle is closed off. The baffle goes all the way down the middle except for a gap of 150mm at the bottom, so essentially its a folded pipe, loading the rear of the drivers.
The K slot is cut down one side of the pipe opposite the fronts of the drivers, so they can radiate into the room.

How do they sound...well, not having measured, this is subjective, but they sound very different from my stereo speakers (I'm using them for TV/HT sound - got 100% SAF :) (even though i think they could be made to look a lot better). Plenty of lows for such small drivers & 5W amp; the pipes seem to have a gradual roll off which gives the impression of more bass
when augmented by the pipe resonances. I don't know how the transient response of these would measure, (for TV it doesn't matter to me), and I'm sure the slot has an effect on the radiation pattern. Of necessity, I have placed on either side of the room, (not ideal) and seem to sound best when aimed to cross over in front of the listening position by quite a bit.

The drivers I used were just odd 'no-name' units I had lying around, that's why I'd like to try again with better & bigger drivers, the sound is good enough that I'm convinced the approach has merit. I've got a pair of high q 10" drivers which might be good, however, I've been seduced by OBs in the meantime....Pete McK
 
pic

here ya go.... I'd do the slot a bit different next time though...
 

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Ron E said:
The slot is based on a method for slotting a resonant tube (whistle) to make its output more like white noise than centered on a particular frequency.

The slot doesn't do anything at bass frequencies. Karlson's are just really big vented boxes for high efficiency woofers, and they excel at making lots of 40+Hz bass.

Paul Klipsch measured these (investigation of a competitor at the time) and he had a couple funny quotes about them.... These measurements are out on the net somewhere.

The cavity resonances at ~200Hz+ created by the slot and the space behind are really bad: like +/-10+ dB

There is a guy on the Audio Asylum sites named Freddyi who seems to love these things if you want another opinion about them...;)



The slot when used properly with a tuned front and back chamber will give you a 3-6 db gain 50-250 Hz. It also eliminates floor dip and baffle step which in turn will give you much stronger and linear bass response with higher efficiency and lower distortion over reflex, sealed, open baffle, transmission line designs. For midbass I have yet to find a configuration that sounds better - straight expo and hypex horns are close but are not as linear and take up much more room. In my experiance my Karlson type Klams will easily outperform Klipschorns in the bass - no +-10 db dips here even with 1/16 octave resolution. Klipsch was one of the first great bullshitters of audio.