Old Karlson speaker cab design

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Old Karlson speaker cab design

Postby EWBrown » Wed Oct 19, 2005 9:05 am

D'oh !!!!!!!!! Yellow_Light_Colorz_PDT_09 Yellow_Light_Colorz_PDT_02 These are Karlsons, from around 50 years go....

I recently got a pair of these speaker cabs just for the effort of lugging them home. If my memory serves me well, these were from a Popular Electronics project design over forty years ago. THey originally contained some Utah "Celesta" 12 inch "full range" speakers that sounded like crap,
but I figure that these cabs can be re-loaded with newer better FR speakers like the coaxials from Eminence or PAudio, or just stuff some vintage Altec 12 inch 414A woofers in them and use them with some Vintage ALtec 800 Hz compression horns and crossovers.

The Utahs look physically OK, but I'm sure that they are just plain "tired" after some 40-odd years of use and storage.

Does anyone here remember what this cabinet design was called?

The speaker was mounted on an internal angled baffle, and the top part of this has long slots cut in it to act as some form of bass reflex design. The front of the cabs have a board, with an "exponential horn" shaped cutout, with the narrow end pointed up.



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The wood is 3/4 inch plywood, and the inside surfaces are coated with some sort of hard resin or very thick varnish, and there was no sound absorbent material inside.


/ed B in NH
Last edited by EWBrown on Fri Jan 11, 2008 1:13 pm, edited 1 time in total.
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Karlsons

Postby EWBrown » Wed Oct 19, 2005 10:46 am

These are known as Karlson enclosures, apparently they are a popular box for high-efficiency speakers. Just google "Karlson Project" and use -Manager in order to eliminate the "Seagull Project" responses.

I had half the magazine's name right, they were in Popular Mechanics, not PE, and this variant is commonly referred to as the K-12. THey allegedly make great (sub)woofer cabs, and some full rangers work very well in them, if the coaxial tweeter isound egress sn't blocked by the front panel.

For speakers, I had guessed right, the Eminence Kappa 12 inch is a good choice and the Altec 414 is decent as well. There are some others from mem, Pyle and others (some of these are made by Eminence).

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

The Utahs will probably end up on the "swap" table at the local dump, er, recycling center... They may have been good 40 years ago, but they're just "poopoo" now... Yellow_Light_Colorz_PDT_07

/ed B in NH
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Postby evsentry3 » Wed Oct 19, 2005 11:36 am

Hi Ed,
I also recently picked up a Karlson cabinet. Mine is the 15" style and also came with a very tired Utah! I have not had much time to play with it yet but once I loaded a Altec 803A in it, the bass was pretty good! In that configuration is was after a LP at 300. Running full range with the same driver, the mids were much stronger than the low end. I was very surprised at the 15" having that much output that high! My cabinet has a more convential port in the top instead of the multiple small slots in the pictures. That could be a difference in the 12 from the 15 I suppose. The site you quote is the best batch of info I've found. Mine also came with a multiple page original Karlson booklet thats pretty fun too! If you PM me with a mailing, I'd be glad to make a copy and send it your way. The heavy finish inside is part of the Karlson formula, but a sound absorbing padding in a couple of places is also needed. Otherwise, I'd expect the high frequency from the back of the cone to really bounce around inside the cabinet. Mine has no finish inside and poor absorbing tiles. If you ever do buy that place in the hills you've talked about, maybe you'll come over the mountains and hear it!!
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Pyle PRO-PYM1298

Postby EWBrown » Thu Oct 20, 2005 5:14 am

One of the recommended "Karlson" cabinet woofers is the Pyle PRO-PYM1298, which is apparently (from info I've found on "the asylum") an Eminence Kappa-12 in disguise, and at a much lower price. ANd the lowest price for these that I've seen is from a place called DJTRONIX
at $70 each and includes free shipping. Part Sexpress gets nearly 95 for these and charges for shipping...

This speaker is listed at

http://www.djtronics.com/djtronix/pylepropym1298.html

Of course this isn't a "full range" speaker, but covers 40Hz-4KHz, around 101 dB SPL, which would match up well with the Altec horn or perhaps one of the "Selenium" tweeters (from PE) crossed over around 3KHz.

/ed B in NH
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Pyle Drivers, aka the Karlson Sequel

Postby EWBrown » Thu Oct 27, 2005 7:43 am

I posted this on Bottlehead, as well:

The aforementioned "Karlson" home made cabs with the original Utah "Celestra" speakers really did sound like, er, poopoo, but now that they have some decent woofers in them, the sound is totally amazing.

I bought a pair of Pyle PRO-PYM1298s from Part Sexpress, and threw 'em in last night. The speakers went from sounding weak, thin and watery to becoming sonic earth-movers! I went against the original design concept of using a full range or coaxial speaker, and just went with the woofers, and used a pair of vintage (I bought back in 1973) Altec 811B horns, with 806-8A compression drivers and N801-8A "divider networks", sitting on top of the cabs. It is as if that these woofers and the Altec horns were meant for each other, as they play very well together, indeed. Sort of a mini Voice of the Theater system...

I initially hooked them up to the 10WPC 6EM7 homebrew amp, fed by a cheapo CD player into my stock FPII, and was quite literally blown away, both by the quality of the sound, and the level and the depth of the bass response. The Karlson cabs are reputed to extend the lower frequency response, by up to an octave and a half, so perhaps my "Pyle Drivers" which go down to 40 Hz may have been reaching downas low as 20 or even 16 Hz. This was more "felt" than "heard", and at relatively modest power levels (approx 3 Watts) I could literally feel the bass travelling through my concrete cellar floor, and all over the house! I later hooked them up to a DIY35, and the sound was even better - better output iron and a more "perfected" amplifier circuit makes a real difference here.

These "Pyle Drivers" are rated up to 600 Watts, and at that sort of power levels, I'd be wary of cracking concrete, blowing out windows and bleeding eardrums... The maximum tube "firepower" that I have available (currently) are the KT88 equipped Ikes, and a still-yet-to be-finished MKIII dyna-clone. One could develop approximately 120 dB SPL with that combo. Yellow_Light_Colorz_PDT_10

I've had those Altecs for 32 years, and they definitely sound far better when fed by tubes, than by a 1970 vintage Sansui 5000A "sand amp".

My next test will be to run them from the SET amplifier, and see how they sound (better, I'm willing to bet)...

I also intend to try out the Selenium DT150 horn tweeters crossed over at 3 KHz, just for comparison to the vintage Altecs. It ain't over until the proverbial "weight-challenged person of the female gender" sings...

The adventure continues...

/ed B in NH
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Postby Shannon Parks » Mon Jul 16, 2007 6:26 am

Ed, did you add any dampening material? I think I'll do a Karlson project after my TQWT speakers are done (and they ARE almost done :) ). I like this design. Seems like you still love this speaker after almost two years, which is good enough for me. I dig these baby VOT-type setups.
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My Karma ran just over my Dogma

Postby EWBrown » Thu Jan 10, 2008 12:44 pm

Hmmm, I just ran into myself over at the Karlson Forum:

http://gainclone.com/Karlson/index.php?topic=30.0


Of course it links back to DIY35 land, in a sort of circuituous path through Bottlehead land! Yellow_Light_Colorz_PDT_06 Yellow_Light_Colorz_PDT_03 Yellow_Light_Colorz_PDT_01 Yellow_Light_Colorz_PDT_06

/ed B in NH
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8 inch / 200 mm Karlsons ?

Postby EWBrown » Thu Jan 10, 2008 12:54 pm

I've often thought about attempting an 8-incher Karlson for use with FE206Es, looks like I'm not the only one, here are some basic plans and drawings:


http://gainclone.com/Karlson/index.php?topic=27.0

Apparently Karlson did sell 8 inch enclosure as well as the 15s and 12s and some oddball 5 inchers called "Rockets".

/ed B in NH
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Postby EWBrown » Thu Jan 10, 2008 1:46 pm

To answer an old question, I briefly tried a little dampener (1 inch thick foam panels on the internal horizontal surfaces only) in one cab, but eventually ended up taking it out, as it made it sound just plain "weird" Yellow_Light_Colorz_PDT_09 . The specified hard coating covering all of the inside of the cab must have had a good reason, so I didn't wanna screw with mother nature Yellow_Light_Colorz_PDT_08 Yellow_Light_Colorz_PDT_04 Yellow_Light_Colorz_PDT_02

I'm sure that a swept tone freq response curve of these things would look like a seismograph taken just before Krakatoa blew its top :o
However, all that aside, these things still continue to sound good and amaze me. The true test will be when I get 'em down into NC and fire them up in the 56 X 28 foot cellar :o with some REAL power... :o Yellow_Light_Colorz_PDT_02

Another interesting "feature" of this design, is that the cabs can be stood vertically in the normal configuration, , or laid on their sides or back and still work well! I still find that the normal vertical orientation seems to couple the LF better to the rest of the real world, and might give better deep bass response, as it makes the floor and surroundings a "virtual extension" of the enclosure.

The external multi-cellular horn will still have to face forward, and be positioned at least 30 inches off the floor, in any case.

/ed B in NH
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Postby EWBrown » Mon May 24, 2010 2:31 pm

It has been recommended that Karlsons have no dampening material insode the cab, just the "hard" finish coating inside the cabs. I know, this
flies in the face of most conventional wisdom, commonly accepted practices. Using a separate HF driver, whether multicellular horns or a simple horn tweeter, crossed over around 800 to 1200 Hz gets around the Karlsons' bad reputation for shoutiness and harsh mids. I suppose that
with the 1950s vintage of modest-priced paper coned FR or coaxial speakers, the "shoutiness" probably enhanced the orhtrwise lifeless mids
and highs of typical lower cost FR / coaxial speakers of the era.
I suppose that some Stephenson Trusonics would be stellar in the Karlsons, if these can indeed be found any more.

I had one 15 inch version, with the 8 cell horn, and it was SWEET... It would have been easier to find an honest politician or a pound bag full of of turtle fur, than to find a mate for this epeaker... I ended up swapping it to Mark Hardy, back in NE, for a pair of nice EV HF compression drivers. He had an enpty 15 inch Karlson cab in need of a suitable speaker.

/ed B in NC
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Karlson

Postby msmpe » Sun Aug 08, 2010 10:44 pm

I remember something like that way back, but can't place it. I picked up a Hammond M2 specifically for the amp and speaker and wood to build a "sub" woofer speaker. The Karlson would be fun to try. Is there a source for plans for the 15"?
8>) Mike

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Karlson

Postby msmpe » Tue Aug 10, 2010 10:16 am

Plans and alot more are on the Ulfman site noted above.
8>) Mike

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Postby dhuebert » Sun Nov 21, 2010 9:56 am

I want to build one of these but I can't find a drawing of the curve for the front baffle. Ed, could you measure yours, say the width of one panel in one inch increments?

Never mind, found it.

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Postby nyazzip » Sun Dec 19, 2010 2:35 pm

that interior finish looks a lot like shellac...very shiny/stiff finish, soluable in isopropyl alcohol, great for acoustic instruments, necks, etcetera.
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Postby EWBrown » Sun Dec 19, 2010 7:38 pm

The internal finish looks like shellac, but feels more like some form of hard coating, perhaps a thick aplication of shellac would do. It could be some form of epoxy resin, too (???) :/

These cabs will never win any beauty contests, but they definitely deliver the sonic goods in a VERY BIG way... At least I didn't have to do the dirty work just re-stuff them with new speakers, and put more modern binging posts on the bottoms of the cabs, as they have a 2 inch "footer" around the bottom. Originally they had cheap and cheezy L Pad attenuators, and the zip cord entered through a drilled hole on the back of the cabs. I wanted to be able to lay these flat on their backs, or flush against a wall, so I could use no rear binding posts, and I figured that using "cups" would compromise the original design.

/ed B
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