anyone ever build a cabinet with Karlson slots?


diyAudio Moderator Emeritus
2001-09-18 2:33 am
Connecticut, The Nutmeg State
It might not be a Karlson slot strictly speaking, but the author mentions the same principle-an exponentially shaped slot. There might be some variation in the slot shape.

If the Karlson slot doesn't work too well-and apparently the people on this forum who have experience with them say it doesn't-then there is no reason to suspect that this will be any better.

Since the Karlson slot is the opening of a transmission line, and not a wooden "curtain" in front of the woofer, it might work all right. If you are going to build that enclosure, I would recommend a round or square port, though. From what I can gather, transmission lines are tricky enough without worrying what resonances the Karlson shaped line opening might introduce.
Keen minds think alike :)
That's exactly what I was thinking about doing...

I will have two separate lower baffles. One with the round port and one with that slotted port AND an attached L-shaped (looking from the side of the cabinet) transmission line divider creating a TL length of 6ft which is appropriate for the Fs of 45 of the driver. So the back wave in the case of the TL will travel towards the back of the cabinet, then down, turn forward, then back up the front and out the slotted port. That whole piece will be removable and replacable with the baffle that has the bass reflex (round) port. This will allow me to swap betweeen a TL and a bass-reflex cabinet very easily.

Will let you know how it goes.

Ebay fodder of Palmsprings estate sales


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WellI have a van so I hop size is not an issue. The enclosure I have now is around 45 cubic ft and has approx 964 Sq in of port. How big do the karlson enclosures have to be? SQ is not a factor as it does not matter in this style of competition. The enclosure will be tuned to one specific note or Fq. Also how wo W loaded enclosures work? Thanks in advance
Karlson pipe

I put a karlson slot in a 2.2M high 150mm dia (6") pipe,
The slot tapers from 6" wide at the top to 0 at about 1/3 the way down.
I used a 4" driver placed about 1/3 the way up.

No measurements, but it sounds more open than the same speaker in a small BR box.
It has even bass which goes quite low, but not earth shattering; bass sounds louder when you listen close up to the top opening.

Not very practical, next iteration I'll cut the pipe in half, put the baffle down the middle of the pipe for same path length, and add another 4" driver for more punch in the bottom end.

Pete McK
>The enclosure will be tuned to one specific note or Fq. Also how wo W loaded enclosures work?


The Karlson is a double reflex loaded bandpass with a slot vent to create a wider usable BW than a typical tube vent.

When you say "W" loaded, I assume you mean a horn. For only playing a single frequency at peak efficiency you want a compression driven plane wave tube, IOW a bandpass with a vent long enough to be tuned to the specific frequency.