A Speaker that Kicks Butt in Large Spaces

[xrk971]

Plans here

 

[freddi]

hey X - Gazza is familiar with K15 - he's looking for a guide to a practical Karlsonator 15 - what might that be with a good modern 15" woofer?

 

[xrk971]

Sorry I did not catch that as this is a K15 thread. I am guessing a modern 15in pro driver with Qts from 0.35 to 0.45 can work. Scale it by 1.25x should work. I can run a sim but in meantime look at the MOAK thread in subwoofer forum and you can see the sort if bass extension one can get. It will probably hit 30Hz - use something like an AE TDM15. Give me a day or two and I will get a design together.

 

[freddi]

what I'd like to see is what you can come up with for a Karlsonator15 which does not exceed K15's bulk more than a few percent - say limit the cabinet's external bulk to 8 cubic feet - then compare its tradeoffs vs the original K15 cabinet. Can you pull nearly another 1/2 octave on the low end with an 8 cubic foot bulk Karlsonator loaded with decent 15?

 

[xrk971]

Ok that is a good design challenge. The Karlsonator with a 12 already reaches 40hz flat vs 60Hz for K15. It may mean just scaling width and a tad on height/depth. Going with a moderate Qts driver will get deeper bass vs a high strength low Qts motor.

 

[gazzamongo]

I'm running iconic 704-8a in my k15 , a little more extension while keeping that karlson punch and agility would be amazing

 

[xrk971]

The dynamics of the K15 and Karlsonator are very different as one is a highly efficient 8th order bandpass and the other is closer to ML TQWT with 6th order bandpass. The punch from a K15 is special and if that is important, I will work with the basic K15 box to see of more extension can be achieved.

 

[gazzamongo]

Aha ,... Hugely good of you to be so helpful to so many people on here BTW. Thanks

 

[freddi]

if not too much trouble, do the 8 cubic foot Karlsonator and see how Gazza's Iconic plus another woof or two do. Traditional K's usually seem to have LF about like their rear chamber volume vs system tuning. Considering my Karlsonator 12 has only run a Nirvana Super10 with qt ~0.41 and 12LTA, it had reasonable punch and excellent sound quality.

 

[Greg B]

Ok that is a good design challenge. The Karlsonator with a 12 already reaches 40hz flat vs 60Hz for K15. It may mean just scaling width and a tad on height/depth. Going with a moderate Qts driver will get deeper bass vs a high strength low Qts motor.

A Karlsonator 15 would probably be fine at current height, but I'd add perhaps a couple inches to the height and a bit more to width/depth - depending on driver specs.

FWIW, part of the original motivation for this design was to have something that worked with typical spec modern moderate Qts drivers. The original K15 really likes those old skool low Fs low Qts specs that hardly exist anymore -- though some odd drivers will sound good in it.

I always though the 'punch' of a K15 was mostly the result of low distortion and clean impulse. There could well be subjective differences between the original 8th order K and the Karlsonator, but it may have to do with the freq response as much as anything. I don't think anyone but Freddy is actually qualified to speak from experience here.

There was at one time an interesting big Karlson project on Job Ulfman's page made by Dirk(?) in Holland. It was a scaled up K15 loaded with an 18". I recall it had quite smooth and extended response to the mid 30s. So perhaps the trick is just to make it bigger.

 

[xrk971]

I have scaled a K15 sim up for an 18in and indeed it works well - not sure if it was 30hz though.

 

[freddi]

John Karlson had a K18 - you can figure out its size sans the upper driver/whatever compartment

Karlson 18 Console
http://imagizer.imageshack.us/a/img338/7135/foldoutpage3web.jpg

after Karlson's death, Cetec-Gauss came up with their 5181 K18
http://img72.imageshack.us/img72/825/gaussbracing.jpg

 

[freddi]

Gazza - you could try tuning K15 a bit lower with a tunnel vent keeping K15's vent's area - off hand not sure how much depth to add - maybe 2" - try it on one cabinet with cardboard and tape - it may not do anything good -

legend has it that the stock K15 has more power handling below cutoff than an equivalent LF response reflex - seemed that way when I tested with 20vrms and 36Hz - also, near-cone graph shows a null around 36Hz and two tone testing good for K15 vs reflex with a lowly Beta15cx

the first few inches of slot coming down from the top can seem pretty critical in effect.

I'm not positive but think the offset driver aspect and relatively large vent of Greg B's "Karlsonator" may avoid a deep null
which can occur in "some" traditional K-type - it would be good to have XRK971's and GM's thoughts on this matter.

 

[xrk971]

I'm running iconic 704-8a in my k15 , a little more extension while keeping that karlson punch and agility would be amazing

http://www.iconicspkrs.com/downloads/704_8a.pdf


No where is Sd given??? I will assume it is 1 in less than 16 inch diam of frame. or 1140 cm^2

 

[freddi]

I think its the same as their 604-8H version - http://www.greatplainsaudio.com/downloads/604_8H_III.pdf

 

[xrk971]

Iconic 704-8 in 1.10x by 1.05x wide K15

Gazzamongo,

I am quite impressed by this Iconic driver. It has perhaps one of the best responses simulated in my K15 model with deep smooth flat response at high sensitivity.

Here is the baseline case in a standard K15 with a slot top slit K-aperture, this gives about a 55Hz -3dB point from the nominal 100dB level (there is a bass peak overshoot that gives quite a punch but at the expense of bass extension):

Here is the standard K15 with a K-aperture that goes to a sharp cusp (-3dB point is 44Hz):

Now if we scale the height and depth by 1.10x and the width by 1.05x we get 97dB sensitivity (-3dB point is now 38Hz), this configuration will reproduce the 41Hz bass note with convincing authority:

Here is cone displacement at 2.83V:

Here is the cone displacement at 30 volts to reach xmax using a 24dB HPF @ 31Hz:

Here is the corresponding max SPL with the HPF in place:

Here is the impedance which shows the tuning freq between the two peaks as about 37Hz:

Here is the Impulse Response - doesn't get much better than that - and therein lies the magic of the K15 cabinet for convincing dynamics and percussion:

Here is the electrical power input (with HPF) - it is still below the rated 140 watts:

If you have an EQ, you may need to reduce the 200 Hz to 800 Hz region to balance out the bass, or use a coil and resistor BSC circuit.

Looks like it should be a fanstastic performer. Hope you build it!

Cheers,
X

 

[freddi]

that's pretty close to a Cetec-Gauss 5181 K18 in size. How would an 8 cubic foot bulk Karlsonator fare in comparison?

5181 plan http://img72.imageshack.us/img72/825/gaussbracing.jpg

 

[gazzamongo]

This does indeed look an interesting revision , thanks so much X . a build will take place but it'll be In a little while (tedious first world problems like a house move to deal with) , uber greatful though.

 

[freddi]

here's a pair built from the 5181 plan with JBL 18 - K18 even built at K15 size are impressive

 

[xrk971]

Freddi,
What kind of CD horn is that on top of the K18? Looks like some sort of tortuous path Paraline type?