most all my K-Lines were designed so that the total 1/4 wave length was measured from the middle of the back of the magnet to the centre of the front of the cone. In other words the length of the front coupler was included in the total line length. In the case of the karsonator the added section of line above the driver permits driver placement on a nodal point.
To bad you cannot play with damping as the single side damping will generate turbulence which will affect the impedance of the line like back pressure in a header pipe on a motor. What about shrinking the CSA of the line that ought to generate greater back pressure and so increase the impedance the line presents to the front of the speaker, can you see what that does in the program? The load of the line must go up if you want to place a greater load on the face of the driver to control motion. Well that's my theory for now. Is this possible to prove or disprove with your model? Best regards Moray James.
as an after thought what about including intentional controlled bottle necks in the line to choke it and creat more back pressure at the face of the driver? Just thinking out loud here.
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Moray James,
I am not sure how damping creates turbulence. It reduces reflections and the cavity Q and thus smooths over peaks and valleys. Damping will cause airflow to slow down and be laminar flow - opposite of turbulent flow. If you want turbulent flow you want high velocities like flow in a vent tube approaching Mach 0.1 and large gaps in the flow path.
Regarding loading the driver cone more, you will really need to reduce CSA by a lot to so it that way. The way to get loading to work is to match the impedance of the velocity at the cone surface on the back to expansion of the horn or wave guide. When this is done smoothly and with a large expansion ratio, that loads the cone. A great example is the BIB it has great impedance matching between the cone and cabinet wave guide and it is always expanding. Not a constriction of CSA in sight. So this tells me that the original Karlson works more like a horn than a TL. Hard to believe but that is sort of what the physics and behavior is telling us.
I am not sure how damping creates turbulence. It reduces reflections and the cavity Q and thus smooths over peaks and valleys. Damping will cause airflow to slow down and be laminar flow - opposite of turbulent flow. If you want turbulent flow you want high velocities like flow in a vent tube approaching Mach 0.1 and large gaps in the flow path.
Regarding loading the driver cone more, you will really need to reduce CSA by a lot to so it that way. The way to get loading to work is to match the impedance of the velocity at the cone surface on the back to expansion of the horn or wave guide. When this is done smoothly and with a large expansion ratio, that loads the cone. A great example is the BIB it has great impedance matching between the cone and cabinet wave guide and it is always expanding. Not a constriction of CSA in sight. So this tells me that the original Karlson works more like a horn than a TL. Hard to believe but that is sort of what the physics and behavior is telling us.
Ive heard of people lining horns with sandpaper to create turbulence but air actually will flow better over a rough surface in some circumstances. Really smooth surfaces cause more surface drag due to higher friction. I used to do engine machining and unpolished intake runners would flow more air than polished.
X: if you have a four sided line in which all four sides are smooth then the air flow in the line is smooth and unrestricted. If you tack a layer of lets say carpet on one of the wall of the line yes you get some damping but you will also generate turbulence within the line. That turbulence will create a back pressure. More turbulence more back pressure. At low frequencies I expect that you can get away with expansion rates which don't look so good on paper but which probably get the job done. So as I see it devices or tricks to manipulate the line back pressure will allow you to adjust the load on the front side of the driver. Best regards Moray James.
Having a rough surface like carpet or sandpaper or even enable dots trip the transition from laminar flow to turbulent flow at a lower velocity and the turbulent boundary layer is thinner than the laminar flow boundary layer. This reduces drag and back pressure. A thick layer of fiberglass damping on a wall will constrict the flow more than any boundary layer effect which is really for higher velocities like those on surface of driver cone. Golf balls use the dimples to achieve this and reduce pressure drag. Fluid mechanics was my specialty years ago. With speakers it is all oscillatory flows (no net mass flux) but that is not to say there is no net energy flux through sound or pressure wave propagation. The velocities can be quite high next to cone surface of driver.
X: can you say that in non fluid mechanics terminology? What would you suggest to generate back pressure in the line? Will the simple 1/2 inch layer of fiberglass on one or more walls do? I think that keeping the energy level of the line high is a good thing as far as output goes. what do you guess would be necessary to shift the impedance of the line? What about no stuffing directly behind the driver but lots in the front coupler section? Again I am just thinking out loud. Is any of this making sense to you? Best regards Moray James.
here's Z for 3 bifurcated horns of mine plus a pipe - the Zu style pipe is an easy build
Peavey FH1 - much like a Klipsch Belle only 6 inches deeper
Klipschorn
Ray Newman's EV Sentry IV W-bin
homemade Druid style pipe with the first Eminence B102
Peavey FH1 - much like a Klipsch Belle only 6 inches deeper
An externally hosted image should be here but it was not working when we last tested it.
Klipschorn
An externally hosted image should be here but it was not working when we last tested it.
Ray Newman's EV Sentry IV W-bin
An externally hosted image should be here but it was not working when we last tested it.
homemade Druid style pipe with the first Eminence B102
An externally hosted image should be here but it was not working when we last tested it.
It will be pretty much dead flat, but the trade-off is its BW will be defined by its LF and HF corners where Fs is the mean, i.e. this will be its entire usable BW and huge.
I approximated one some years ago with MJK's original BLH software using a small TB W6-1139C to prove it to a naysayer. It's an expo, but needs to be hyperbolic to smooth out its extremes.
I didn't try to calculate its size, but obviously it will be at least small house size to accommodate single digit frequencies, so such alignments are only suitable for higher frequencies in a multi-way system.
Right, as I previously noted, all the K alignments are 4th or higher order of BP with each resonant cavity adding another order and tapped when 6th, 8th [don't recall any higher order alignments ATM]
GM
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The Karlsonator Scales Well to Smaller Drivers!
I thought I would try scaling the Karlsonator to a smaller driver to see what happens. It turns out that because it is a TL, it scales quite nicely and is very forgiving - unlike the K15.
For the first case I decided to use something small and crazy, almost anathema to a typical large Karlson: a 4 inch Tang Band W4-1320SIF bamboo cone driver. I simply scaled the width and depth by 5/15 (33%) to give the box some room to mount a 4 inch driver, and I scaled the vertical direction by 10/15 (67%). This produces quite a neat little box that is about 5 in wide x 5.5 in deep by about 20 in tall. I am looking at the response in the near field with the speaker pushed back touching a back wall. The freq response surprised me with how flat the bass shelf is. There appears to be some room suck-out at 250 Hz and 600 Hz - which may be a deal breaker but I think some stuffing and room placement may solve this. The second plot is the impedance and this looks OK I think, and the third plot shows the cone displacement, which looks well controlled given that max excursion is 4 mm on the Tang Band. I think the 40 Hz bass extension with 90 dB sensitivity is actually quite good for this enclosure given that no optimization was done for the T/S parameters.
For the second case, I am using a completely different character driver: the high sensitivity BLH special - Fostex FE166EN. Here, I scaled the cabinet by 7/15 (47%) in width and depth to accommodate a 6.5 in driver and I scaled the height by 13/15 (87%) resulting in a trim looking cabinet that is about 7 in wide by 7.5 in deep x 26 in tall. The fourth plot shows the frequency response, which also shows deep bass extension to 40 Hz and around 90+ dB sensitivity (low for the Fostex) and a big dip around 300 Hz - but the native high freq efficiency of the Fostex may sound too harsh and 'shouty' combined with the bass that is only 93 dB. Not too bad though - given that it is a completely different driver with low Qts and high Bl. The fifth plot shows the impedance for the Fostex and the sixth plot shows the cone displacement - kind of exceeding the 1 mm max.]
So in summary, I would say that the Karlsonator is great for getting pretty good deep bass with a flat bass shelf from 40 Hz to 150 Hz and is very scalable with driver size. However, given that the design does not restrict cone excursion as well as the original Karlson, I would pick drivers with higher xmax - which will give a more balanced sound as the the low Qts high Bl motor drivers will be very 'shouty' with their high frequency SPL compared to the bass that is produced. A driver with about 85 to 89 dB efficiency and Qts of 0.35 to 0.50 may work better.
I thought I would try scaling the Karlsonator to a smaller driver to see what happens. It turns out that because it is a TL, it scales quite nicely and is very forgiving - unlike the K15.
For the first case I decided to use something small and crazy, almost anathema to a typical large Karlson: a 4 inch Tang Band W4-1320SIF bamboo cone driver. I simply scaled the width and depth by 5/15 (33%) to give the box some room to mount a 4 inch driver, and I scaled the vertical direction by 10/15 (67%). This produces quite a neat little box that is about 5 in wide x 5.5 in deep by about 20 in tall. I am looking at the response in the near field with the speaker pushed back touching a back wall. The freq response surprised me with how flat the bass shelf is. There appears to be some room suck-out at 250 Hz and 600 Hz - which may be a deal breaker but I think some stuffing and room placement may solve this. The second plot is the impedance and this looks OK I think, and the third plot shows the cone displacement, which looks well controlled given that max excursion is 4 mm on the Tang Band. I think the 40 Hz bass extension with 90 dB sensitivity is actually quite good for this enclosure given that no optimization was done for the T/S parameters.
For the second case, I am using a completely different character driver: the high sensitivity BLH special - Fostex FE166EN. Here, I scaled the cabinet by 7/15 (47%) in width and depth to accommodate a 6.5 in driver and I scaled the height by 13/15 (87%) resulting in a trim looking cabinet that is about 7 in wide by 7.5 in deep x 26 in tall. The fourth plot shows the frequency response, which also shows deep bass extension to 40 Hz and around 90+ dB sensitivity (low for the Fostex) and a big dip around 300 Hz - but the native high freq efficiency of the Fostex may sound too harsh and 'shouty' combined with the bass that is only 93 dB. Not too bad though - given that it is a completely different driver with low Qts and high Bl. The fifth plot shows the impedance for the Fostex and the sixth plot shows the cone displacement - kind of exceeding the 1 mm max.]
So in summary, I would say that the Karlsonator is great for getting pretty good deep bass with a flat bass shelf from 40 Hz to 150 Hz and is very scalable with driver size. However, given that the design does not restrict cone excursion as well as the original Karlson, I would pick drivers with higher xmax - which will give a more balanced sound as the the low Qts high Bl motor drivers will be very 'shouty' with their high frequency SPL compared to the bass that is produced. A driver with about 85 to 89 dB efficiency and Qts of 0.35 to 0.50 may work better.
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Back pressure can easily be accomplished by restricting the passages or terminus (if there isn't too much volume between driver and terminus to compress air). However, this method of generating back pressure is inefficient as you are throwing away the acoustic energy as a pressure loss which is converted to heat. That is what stuffing and damping materials do as well as tight constrictions. What is desired is a way to provide a resistance to driver cone by coupling a column of air so that the energy in the driver is efficiently transferred to the air. A well designed horn will achieve this and have minimal losses due to pressure drops imposed by either constrictions or lots of stuffing which give back pressure but do so through permanent and irrecoverable pressure losses.
GM,
What are the dimensions of the horn that you simulated to produce this wonderful frequency response? (Throat, Mouth, length, curve exponential and driver parameters ) just curious what it looks like if one could build it.
I have seen one of the largest spacecraft acoustic pressure testing facilities in the world capable of producing 163 dB of sound in a room the size of a 5 story house. It is fed by about two dozen huge nitrogen driven horns some of which are part of the room and made of concrete.
An externally hosted image should be here but it was not working when we last tested it.
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yeah - Acoustic Control's 115BK was a Karlson roughly the size of the X15, part of Acoustic's "Collaboration Series" - here's some info (my graphs used EVM15L) including my sketch of its internals
Acoustic's 115BK and Transylvania's K (Page 1) / Karlson / Fullrangedriver Forum
The Transylvania Power Company, KK-Audio, Westwood. and another company produced this size Karlson. 115BK, KK and Westwood were pretty much the same inside - I'm not sure about the Transylvania cabinet
Karlson's X15 and the later 115BK used CTS 15s with a square 54oz magnet.
here's one of my KK - Audio cabinets - it has a 3 panel reflector plus a rear lowpass choke but otherwise is like the 115BK
I'd like to know how 115BK and cousins sim and scale.
Acoustic Control 115BK side view - its internal width was 19 inches. Its wings were radial arc with a 1/4" starting gap on some of the cabinets.
Acoustic's 115BK and Transylvania's K (Page 1) / Karlson / Fullrangedriver Forum
The Transylvania Power Company, KK-Audio, Westwood. and another company produced this size Karlson. 115BK, KK and Westwood were pretty much the same inside - I'm not sure about the Transylvania cabinet
Karlson's X15 and the later 115BK used CTS 15s with a square 54oz magnet.
here's one of my KK - Audio cabinets - it has a 3 panel reflector plus a rear lowpass choke but otherwise is like the 115BK
I'd like to know how 115BK and cousins sim and scale.
An externally hosted image should be here but it was not working when we last tested it.
Acoustic Control 115BK side view - its internal width was 19 inches. Its wings were radial arc with a 1/4" starting gap on some of the cabinets.
An externally hosted image should be here but it was not working when we last tested it.
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