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148.2.192.140
Hi
Iīm not a speaker diyer (electronics), but why not give it a try :-)
I need hi-eff speakers, but donīt have the room for big horns, so the Karlson design seems very interesting.
However, where could i read more about the theory behind the Karlson speakers?
Is the sonics from the Karlsons competing with the best, or should I see them as nice historical vintage gear?
Pix
Sweden
Follow Ups:
Hi Pix -
do you have enough room for K15? would you have acess to coaxial? P-Audio's lighter cones should work - do you have any lively 12-15" speakers?
I like the first K12 aka "Karlsonette" 1955 with 3-position damping strip and K15 (late 1951) pretty well and had a full-size blueprint for K12 but think my kid threw it away (?)
K15 are built in France with Altec Duplex
Karlson are intended for coaxial but will work ok with horn or maybe better yet a slotted waveguide pipe on top. The concept adds a type of acoustic "reverb" which can sweeten dry recordings and enhances guitar, plucked strings such as harpsichord - on some recordings there can be a bit of funkyness. I had an Altec 604 in one of my K15 with series network and overall it was glorious on Garry Karr's bowed bass -- the little K12 Karlsonette would render the bass tone well too only down a bit in "scale"
LF distortion and cone movement on transients with strong motor and low mass cone is good and "may" outperform some compromised horn of similar bulk - I put a 103g 18" in a K15 size coupler and although its half-space response was down ~8dB at 50Hz, distortion was at ~1% for 20vrms and 2% for 30vrms input.
the effect and process isn't perfect but can add live quality plus cone motion seems damped - it can also sound odd on some recordings- I think K15 plays about as loud of drum as Klipschorn but sounds "faster" - or less confused.
a coupler added to just a tweeter horn might get some of the effect (?)
K12 with 27-30 degree baffle and flat port board sound "sweeter" than 25 degree K12 with 10 degree port board
If you don't have a coaxial, a 1 inch format K-tube sounds very good and can set on top of a coupler and be made from
a 5.5" section of pvc or abs pipe
************************************************
Some large horn sound good on top of K15 such as "big radial type" and low-mass low inductance woofesr are to my taste but I've heard K15 play "pretty" with EV SP15B whizzer cone wideband which had Qts ~1.05
************************************************
K-builder Carl says the following about K15
Fred,
The Fh behaves different for the UF compared to a horn.
Fhm = factor * EBP
For a horn the factor is 2. This is why you can't get a horn to have an extended high end.
The UF 's advantage is that it is essentially "open" at MF and has extended band width comparred to a horn.
If you make the UF less "open" the upper MF reduces. If you tighten it enough, the Fh is severly restricted, much like a bandpass.
Wayne, says the design of the box is a 4 deg of freedom system. The tapered slot requires complex mathematics to represent. To understand the UF remember the horn of the Altec is essentially "open" to the enviornment with some box reverb.BTW:without reverb, electronic or mechanically induced to a critical minimum level, the reproduced sound will not sound real. Now the low end. The port output is driving the Karlson coupler. You don't want high frequency tube resonances coloring the sound. Therefor no tubes. Starting with the backwave, a low pass filter, and padding to kill a lot of MF/HF going to the port. The port mass is set to provide LF drive to the coupler. The mass loading of the coupler lowers the f3 while the coupler provides the gain. The front shelf blocks significant MF/HF from the top chamber. The rear volume is made small because a sealed coupler at LF loads similar to a horn. Likewise the ported volume can be lower like ported horns.
Remember, you can't be an expert on the UF without building and testing them.
Same goes for horns, sealed and ported boxes etc.
Carl
*******************
Here's exceprts from Karlson's first "Acoustic Transducers" patent
J.E. (John Edward) Karlson “Acoustic Transducers” US 2816619 filed Dec. 1951
"----Basically my invention consists of a pipe or elongated chamber closed at one end and open at the other. The size and shape of the opening are controlled to give the desired acoustic properties and differs from horns and similar devices in that the principal radiation occurs with a directiivity which is essentially normal or perpendicular to the axis of this pipe.
Stated differently, the sound comes out of the side of the pipe rather than out of the end. The advantages of this approach and the theory thereof are explained in the following paragraphs.
When sound waves are initiated in a pipe they travel towards the ends of the this pipe. At the closed end these waves are reflected back into the pipe and at the open end another reflection occurs due to the sudden rarefaction of the wave front of these waves. At certain wavelengths reinforcements of the incident waves occur due to these reflections which create the conditions for resonance. Therefore, a pipe open at one end and closed at the other end will resonate at a frequency whose wavelength is equal to four times the length of the pipe. The strengthness of this resonance is largely dependent upon the abruptness of the discontinuities at the ends of the pipe and the losses within the pipe. thus if only minor discontinuities exist at one end of this pipe, correspondingly weak reflections occur with the result that this pipe can only be weakly resonant. Also, if the energy within the pipe were gradually dissipated before it reached the end of the pipe, resonance would be further weakened. Then these conditions hold for a wide range of frequencies then we have the essentials for a non-resonate enclosures for use as an acoustic transducer for wide band applications.
This invention relates to a practical means of accomplishing these objectives. In order to present a minimum discontinuity at the open end of said pipe, a small opening is made in the pipe near the closed end of said pipe; said opening gradually being made wider until a maximum width of the aperture thus formed is realized at the other end of the pipe. The cross section of the pipe is also narrowed so that the energy being propagated toward the open end of said pipe is gradually forced through the opening formed by this tapered aperture.
This action continues until a minimum cross section at the widest end of the tapered aperture forces the remaining energy out of the enclosure. By this means, it is therefore possible to present a minimum discontinuity at any point in the opening in said pipe while at the same time providing a means of gradually dissipating the energy in said pipe in a useful fashion.
> > > (further down)
An elongated chamber is used in all thse designs in order to take advantage of the propagation effects inherent in a sound duct whose length is not small relative to the wavelengths transmitted, The parameters associated with these structures may then be regards as distributed constants and the ensuing acton may be analogous to electrical transmission lines and antennas.
The tapered apertures used in these figures although of different dimensions and shapes present a means for gradually varying the distributed constants of said chambers so that the high impedance driving sources may be adequately matched to the low impedance of the air.
The shape of the aperture largely determines the rate of release of the energy begin propagated toward the open end of any individual chamber. In order to have a minimum pressure gradient introduced at any point of efflux, it is necessary that equal amounts of energy be released for equal increments of distance along the aperture. This is done in several embodiments of my invention by varying the width of the aperture as the square of the distance along the axis of the elongated chamber.
Other rates of release of the included energy may be realized by changing the rate of taper.
> > >
An examination of Figs 1, 2, 3, 4 will show that all of said tapered aperture coupling chambers have be designed with a diminishing interior cross section starting near the apex of each aperture and narrowing down to a minimum at each base of said aperture.
The inclined planes thus present to the energy being propagated toward the the tapered apertures end of each coupling chamber deflects said energy over the entire length of said aperture. This action ensures a more uniform release of energy over the entire length of said aperture than would be normally experienced by a uniform cross sectional area. In addition to this feature a minimum discontinuity is also presented at the open ends of said coupling chamber by this structural design.
A less obvious result of the inclined plane so created in the path of the enclosed sound waves is in its influence of the radiation pattern of said coupling chamber. Properly designed relative to the rate of taper in the aperture, a uniform distribution of energy can be realized over the entire length of said aperture, especially for the high frequencies. When this occurs a roughly semi-cylindrical wave front results. This constitutes an ideal manner of propagation of these sound waves since the high frequencies will not be sharply beamed in any one direction.
If the angle of said inclined plane makes with the plane of said tapered aperture is greatly increased, several effects may be observed. Among these are (1) lower frequency limit (2) increased reverberation time (3) poorer transient response and (4) less uniformity in the radiation pattern thoughout the frequency range. Obviously optimum results of any particular application would be subject to some trial and error tests...."
*******************
Hear the inventor speak in 1964 courtesy of Roger Russell
Workbench WNCN-FM 3/7/64
Speakers 100min
Eric Towline-moderator
John Karlson (KRC Electronics)
Reuben Guss (Argos-X Electronics)
Clip Introduction
Clip Efficiency
Clip Karlson's start with 3 dollar speaker
Clip 8 Hz story
Clip Karlson briefly explains K15
Clip Karlson speaks about Consumer Reports and AR
Clip Reuben Guss
Clip Prices 1964
Clip Karlson matching to wide variety of speakers
Clip Karlson cone excursion
*****************************************
K15 PLANS
*************************
KARLSON AND KARLSON-RELATED SPEAKER PATENTS
RELATED:
W.O Swinyard US 2020166 filed 1935 “Sound Reproduction Apparatus” - a wedge-shaped 20 degree coupler with “V” deflector having non-parallel walls “Proto-Karlson”!
N.C. Fulmer US 2787332 filed 1952 “Loud-Speaker System” - a folded 1/4 wave pipe with last section broadbanded with tapered slot - Fulmer’s patent apparently competeted with Karlson’s 1st “Acoustic Transducers” and an RCA patent delaying grants on both.
R-J Enclosure:
(1) "The R-J Speaker Enclosure" by William Joseph and Franklin Robbins. Published in Audio Engineering Magazine December 1951.
(2) "Practical Aspects of the R-J Speaker Enclosure" by William Joseph and Franklin Robbins. Published in Audio Engineering Magazine January 1953.
"Acoustic System for Loud-Speaker" US# 2694463; Robbins et al filed April 17, 1952 granted 11/54
J.J. Baruch US2766839 "Loudspeaker System" Filed March 16th 1953, granted Oct. 16th 1956 - deals with math of distributive resistive vents using round holes
John A. McKenzie US 3590941 filed 1969 “Speaker Enclosure” - a dual mouth K-coupler like stacked “Asymmetric-Projector” having a final deflector at each mouth
Robert W. Reams US 4196790 filed 1978 “Acoustic Transducer having Multiple Frequency Resonance” - novel use of Karlson’s slot to create a broad-banded throat in a PA-application quasi-scoop horn
Rodden, M. Raymond US 4313521 filed Feb. 2 1982 "Speaker Housing"
Sapkowski September 3, 1996 "Exponential multi-ported acoustic enclosure" United States Patent 5,552,569
Weiss et al US 5943431 August 24, 1999 “Loudspeaker With Tapered Slot Coupler And Sound Reproduction System” - basically a wedge-whaped asymmetric projector waveguide for 1” compression driver
KARLSON PATENTS:
J.E. Karlson US 2586827 “Directive Radiating System” Filed March 31 1945 - Parabolic dish microwave antenna with what appeared to be a variable directivity pattern
J.E. Karlson “Acoustic Transducers” US 2816619 filed Dec. 1951, granted 6 years later - deals with broadbanding slot both in loudspeakers and musical instruments and concurrent with K15
J.E Karlson “Acoustic System” US 2896736 filed Aug. 1955 - use of a modified Karlson laying on its back using either corner or wall to create a diffused sound image - HiFi Lit’s website shows a K12/Karlsonette used in this fashion (laid on back) on the 1955 Karlson brochure page
J.E. Karlson “Open End Waveguide Antenna” US 3445852 filed 1968 - essentially analogous with the K-tube waveguide used in Karlson’s X15 2-way speaker ~1966.
J.E. Karlson “Acoustic Transducers” - US 3540544 filed 1968 - concurrent with X15 and described Karlson’s use of ellipse based reflectors to improve the Ultra-Fidlety type via Fig.6 and Fig 8’s reflctors (Fig6 upper reflector was used in the X15) and introduced the Asymmetric Projector with tapered elipse profile which appeared commercially as the AP-9C ceiling speaker - also- slotted mirocphones were
discussed.
J.E. Karlson “Jet Engine Silencer Nozzle...) US 3543876 filed 1968 - jet engine muffler and rocket nozzles.
LIST OF INVENTIONS 4/24/50
J.E. (Edward) Karlson
1. ELECTRONIC POTENTIOMETER. A variable element which is capable of linear variations of resistances with infinitesimal mechanical motion yet also have capabilities of broad variations in resistance.
2. CAPLESS DISPENSING TUBE. This device permits the use of toothpaste tubes, etc. without the necessity and bother of removing and replacing the cap after each usage.
3. GEOLOGICAL PROSPECTING SYSTEM. A system for use in the prospecting for oil, minerals, etc. This system may also be used for radar applications.
4. RADAR ANTENNA WITH AUTOMATICALLY VARIABLE BEAM PATTERN. This invention provides a simple means of automatically changing the beam pattern of a radar antenna from a pencil beam to a cosecant beam.
5. DIELECTRIC ANTENNA. This invention provides a technique for designing commercial and military antennas which will have overall dimensions than conventional antennae, and yet have equivalent gain and directivity characteristics.
6. BRUSHLESS DC MOTOR
7. ASHTRAY. An extremely simple design for an ash tray which quickly extinguishes cigarettes.
8. PRECISION DELAY CIRCUIT. This circuit provides a delayed pulse at a precise interval following an initial pulse.
9. CHATTERLESS CONTACTS FOR RELAYS
10. TELEVISION ANTENNA. This invention provides a simple, low cost antenna which can be readily hidden or obscured in the average room and is suitable for both F.M. and television.
11. SLOT ANTENNA. This design provides a slot antenna with broad band matching possibilities.
12. HYBRID WAVEGUIDE JUNCTION. This is a wave guide section which has variable propagation characteristics dependant upon the direction of propagation.
13. R.F. TUNER. a simplified tuner for F.M. and television use.
14. ADVERTISING SIGN. Novel electric sigh with quick change possibilities.
15. LIGHT VALVE FOR TELEVISION PROJECTION AND PICKUP TUBE.
16. ACOUSTIC TRANSDUCER. A novel loudspeaker enclosure with improved matching characteristics and controlled reverberation.
17. FISHING DEVICE
18. TELEPHONE AMPLIFIER WITH SPECIAL ACOUSTIC CHARACTERISTICS
Thanks Freddyi
I think I need some days to melt all this, some questions will follow.
But to answer your questions,
do you have enough room for K15?
Yes, but only close in the front corners (0-1 meter out from back wall). Will this work with K12 or K15?
would you have acess to coaxial? P-Audio's lighter cones should work -
do you have any lively 12-15" speakers?
Actually I use a pair of Zu Cable Druids right now.
Is the K12 or K15 configuration good used in a separate bass woofer to complement nu recent main speakers?
Regards
Pix
Sweden
Hi Pix -
K12 with 5% effiency speaker only goes to about 80Hz flat outdoors and K15 will go about a half-octave lower
K15 can be tuned lower (like Exemplar does) using woofer like Altec 416 using 2-3"ID pvc elbows and boosted around 30Hz to make a pretty good subwoofer
my K15 have almost been always in cramped room and up against the back wall and the corners - might be better if they had some breathing room but I don't have the space.
I'd expect P-Audio 15" coaxial which sell in US for $231 to be pretty good in K15
here's a cellist's K15 and room
btw - I had some older Eminence B102 and tried to fake a Druid without ever seeing or hearing one - do you think Zu's custom woofer is any stronger than the new model Emiennce B102? (it looks the same other than phase plug)
Low frequency 1/12 octave outdoors graph
Effect of 3/4" gap versus 3/8" gap vs no gap graph
On and 20 degrees off horizontal of B102 relative to its whizzer graph
On and 20 off with 0.23mH/2uF series network and no pad
with microphone at tweeter height graph
Hi Freedyi
I get the feeling that Karlsons should be built as a complete speaker and not as a sub-woofer to my Druids.
I guess the low rol-off is about the same, so perhapps in my case an alternative design would serve me better.
However, I should keep an eye open if any suitable speaker cross my way.
I donīt think I could get any P-Audio speakers in Sweden, but old Altec is up for sale ones in a while.
Regarding your Druid look alikes, As I mentioned earlyer, I am a speker diyer (just electronics) and dont have the knowledge to comment your graphs (perhapps someone else here at AA could do that). I can just tell you about my own Druid reflections.
The Druid are a very fast speaker. High impact ("slam" as someone call it). The sonics are very direct and close to the listener.
I would say that some people judge them as to "direct", and you have to get a bit used if you have lived with "ordinary <90dB speakers" earlyer.
In my case, I use the soft touch of a 300B amp, and I would say the mid and heights works very fine.
The only really problem in my opinion (not really a problem, but something that could be better) is the weak bottom.
Listening to vocal and soft jazz -no problem, but when the Rock albums is spinning, I would like something more below.
The Druids heights is seldom mentioned, and I think that is sad, because in my opinion thats one proppery that I really appreciate. Very natural, very close to real. Not that fire-cracker wooow!! first time impression that many speakers give you, but something I start to appreciate after a long time listening. No sharp s-sounds but still very airy.
I compared the data from the B102 with the Zu speakers and they seems like quite similar.
Not exactly, but similar.
The sensitivity of the B102 is a bit lower, but that is as a radiator, It might be the same put in a box like the Druids.
The X-over point in the Druids are 15KHx (-3dB) and from your graphs I guess you are using a lower point.
To bad you live 1/4 turn around the globe, otherwise you would be very welcome to bring your speakers to a comparison.
Regards
Pix Sweden
Hi Pix - - K15 with low fs Altec would probably make a "pretty good" sounding sub - by tuning lower there would be ~6-7dB more output vs stock tuning at 32Hz and more at 20-22Hz. It would be futher boosted with a bandpass circuit or underdamped 2nd order highpass circuit as used in the old EV Interface speakers. Exemplar likes K15 for sub-duty. I think it would behave on the bottom about like a 6th order reflex but there would be some gain vs reflex on top and better damping - might be happy-accident.my Druid clone with 1uF cap would be ~15KHz "xover" - it had good dynamics and slam fot a little speaker - its midbass didn't sound as open as open baffle but I didn't play much with the stuffing (might you tell me how Druid is "stuffed"?) - Being larger, K15 could have more slam, but perhaps colorations which you might not like :^)
Best,
Freddy
Hi Freddyi
I peeked inside the Druids trough the bottom vent, and they are stuffed with some syntetic wool behind the WB radiator.
From topp down to the tweeter magnet (all filled).
Below this -nothing.
BTW I helped a friend today with tube swap and bias adjustment at his EL34 PP stage.
I was amazed how good they worked with the Druids.
I just wanted to mentioned that the speaker character is very much determend by the amplifier match.
Perhaps this PP amp didīnt had the "glow" and pressence as my SET amp. but the missing bottom was almost all what I could ask for.
A very versatile speaker
Regards
Pix
Sweden
thank you very much Pix - - I'll put my fake-D back togehter and try that damping - I ran 250W solid state so may have been a bit "hard" or "lean" in bass. Is there cloth on your Druid's vents? - if so, wonder if its mainly to keep mice away? I still wonder if theres much motor differce vs various B102.
Best,
Freddy
Freddyi,
Well there are a fine-meshed net over the vent, and I honestlly donīt know why.
Perhapps to keep meddlesome diyers out :-)
As for your questions about the similareties to the B102 radiator, I just dont have the knowledge about the Zu radiator to answer your question, Perahapps anyone else here at AA could answer that question.
When you menthioned your hi power amp I recall about some advise I got from Zu regarding the Druids, many people (like me) use the Druids together vith low power SET amps because of their high sensitivity.
However, the Druids are rated 300 Watts and many SET users never get them breaken in at all. The cone movement is so low...
That are really sad, because when breaken in, its a total different speaker.
I used a 50W PP amp, playing them front to front (one out of phase) about two weeks before listening.
Now I have own them about 1,5 years and still hear improvements !
So, for other Druid/SET users, my best advise for improvement of the Druids are, borrow a high power SS amp and let them play at high volume for weeks and weeks.
Or better borrow a house at the countryside, because whem using 50-100 Watts they play extremely loud!
Iīve never came across a speaker needing so much heavy duty burn-in.
When speaking with Sean at Zu about this, I understand that it is possible to get breaken in Druids for delivery (at least this was possible a year ago).
Regards
Pix
Sweden
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