X15 versus K12 ?
which makes the most sense in a system which uses a separate subwoofer?
X15 is about one cubic foot larger in bulk than the Karlson Twelve. They can exhibit similar LF cutoff. I think in general, the 15" speaker will have less excursion on a bass transient. That said, K12 with a strong speaker, is quite punchy.
Its not out of the question to employ K15 (re-tuned) as a subwoofer per Exemplar. Two right angle 3 inch inside diameter pvc elbows are mounted on a plate to fit over K15's regular port. That tunes K15 to around 28Hz. Apply boost in fb area and enjoy.
X15 Size
K12 Size - K12 1956 style (as appeared in Popular Mechanics July 1958) has
a ten degree slant port panel. That would work to convert to an "X10" with one inch format K-tube
This is an estimation by GregB from a 1960's kit brochure of K12's basic dimensions - this version brought back the full width rear shelf/lowpass gap.
1954 K12 plan
http://i.imgur.com/ZMGQve3.png
which makes the most sense in a system which uses a separate subwoofer?
X15 is about one cubic foot larger in bulk than the Karlson Twelve. They can exhibit similar LF cutoff. I think in general, the 15" speaker will have less excursion on a bass transient. That said, K12 with a strong speaker, is quite punchy.
Its not out of the question to employ K15 (re-tuned) as a subwoofer per Exemplar. Two right angle 3 inch inside diameter pvc elbows are mounted on a plate to fit over K15's regular port. That tunes K15 to around 28Hz. Apply boost in fb area and enjoy.
X15 Size
K12 Size - K12 1956 style (as appeared in Popular Mechanics July 1958) has
a ten degree slant port panel. That would work to convert to an "X10" with one inch format K-tube
This is an estimation by GregB from a 1960's kit brochure of K12's basic dimensions - this version brought back the full width rear shelf/lowpass gap.
1954 K12 plan
http://i.imgur.com/ZMGQve3.png
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- that could be a good solution if one prefers a particular woofer or can't afford/source a good coax. Regarding "K10" - it might be best overall to simply use a 10" to 12" adapter ring and stock Karlson 12. I am pretty sure some good K10 size can be made.Conversation with Carl about Karlsons
I said that I would try to contact Mike Bates and Carl Neuser about Karlsons. I could not reach Mike (phone number and old e-mail address did not work), but I did eventually reach Carl and had a great conversation with him.
He was very gracious with his time.
He said that he has been working with the Karlson design since the 1950s.
He stated from the start that unless if you figure in the transient response(or amplitude) and decay of the reproduced sound relative to the original signal, that you are not accounting for a significant amount of the distortion of most speakers. And it isn't just the primary sound, but of the harmonics too. The point is that Karlsons are excellent at transient response. The other important point is that since Karlsons are used as wide bandwidth speakers, that the cone control of the Karlson design is important to reduce doppler distortion, which is a problem with many wide range designs.
Carl has worked with K15, X15 and Klams (maybe others?) Karlson designs, and all can be made to work well. To help optimize the Karlson design he uses the recommended dowels to stiffen the front wings and the back panel, and use some dampening inside the speaker. But he also adjusts the front and back volume, changes the angle of the baffle that the driver is mounted to, changes the location of the front and back shelves, and also changes the size of the slot between the front and back of the speaker as well as the front wings. He does this to optimize the frequency response to flatten out resonances and to improve the accuracy of reproduction of specific instruments. I thought that this was fascinating since how many of us actually fool around that much with a speaker box to adjust its performance (obviously the DIY crowd does to some degree, but most not to the degree that Carl has takes it to).
He reinforced Freddi's recommendation for the right type of woofer to use, which is a light/stiff cone 15 inch driver with a high BL. He said that a BL of 17 or higher is fine. He thought that a cone with a mass under 70 grams would be fine, although when I eventually stated that I might use a front horn for midrange and higher, he backed off the necessity of using such a light cone. We did not discuss specific drivers too much - he has used electrovoice, Cetec Gause and University drivers, but he did not speak so favorably about Eminence drivers - he said to get some good drivers.... He did speak briefly about using the Karlson design for 8 inch drivers, and while it can work OK, he thought that it never seemed to be optimized enough. I did not ask him about Karlsons for larger drivers, like 10 and 12 inch drivers.
I asked about the one fairly frequent criticism that I have heard about the Karlson, which is the coloration in the midrange. He admitted that the Karlson's do color the midrange, but it does avoid the beaming that some experience in the higher frequencies, and does have great transient response which is lacking in other designs. He also pointed out that other speakers color the midrange as well, in a variety of different ways - thus it is a matter of tradeoffs. This intrigued me to at least want to try out the Karlson midrange.
Carl raved about the quality of sound from the Transylvania tube, once it was optimized and coupled with good tweeter drivers. In fact, he said that there was no other means of high frequency reproduction that was better. I found this very fascinating. He named a few good tweeters, such as the EV T-35, TAD and Eminence.
We talked further about using the Karlson for lower frequency reproduction and only up to 200 hz or so. He said that a light cone 18 inch driver could be coupled with a modified Karlson to handle both low frequency (below 50 hz) and higher frequency (up to 200 hz or so) bass. He talked a little about a subwoofer-style Karlson that his son put together, which was quite different, but he would not reveal too many details about this. He said that if redesigning the Karlson enclosure, then one could look at a total redesign, such as a cylindrical design, which would have less flexing in the cabinet walls. This got me thinking about redesigning a conventional K15 Karlson to be based on a cylindrical design. We shall see.
I said that I would try to contact Mike Bates and Carl Neuser about Karlsons. I could not reach Mike (phone number and old e-mail address did not work), but I did eventually reach Carl and had a great conversation with him.
He was very gracious with his time.
He said that he has been working with the Karlson design since the 1950s.
He stated from the start that unless if you figure in the transient response(or amplitude) and decay of the reproduced sound relative to the original signal, that you are not accounting for a significant amount of the distortion of most speakers. And it isn't just the primary sound, but of the harmonics too. The point is that Karlsons are excellent at transient response. The other important point is that since Karlsons are used as wide bandwidth speakers, that the cone control of the Karlson design is important to reduce doppler distortion, which is a problem with many wide range designs.
Carl has worked with K15, X15 and Klams (maybe others?) Karlson designs, and all can be made to work well. To help optimize the Karlson design he uses the recommended dowels to stiffen the front wings and the back panel, and use some dampening inside the speaker. But he also adjusts the front and back volume, changes the angle of the baffle that the driver is mounted to, changes the location of the front and back shelves, and also changes the size of the slot between the front and back of the speaker as well as the front wings. He does this to optimize the frequency response to flatten out resonances and to improve the accuracy of reproduction of specific instruments. I thought that this was fascinating since how many of us actually fool around that much with a speaker box to adjust its performance (obviously the DIY crowd does to some degree, but most not to the degree that Carl has takes it to).
He reinforced Freddi's recommendation for the right type of woofer to use, which is a light/stiff cone 15 inch driver with a high BL. He said that a BL of 17 or higher is fine. He thought that a cone with a mass under 70 grams would be fine, although when I eventually stated that I might use a front horn for midrange and higher, he backed off the necessity of using such a light cone. We did not discuss specific drivers too much - he has used electrovoice, Cetec Gause and University drivers, but he did not speak so favorably about Eminence drivers - he said to get some good drivers.... He did speak briefly about using the Karlson design for 8 inch drivers, and while it can work OK, he thought that it never seemed to be optimized enough. I did not ask him about Karlsons for larger drivers, like 10 and 12 inch drivers.
I asked about the one fairly frequent criticism that I have heard about the Karlson, which is the coloration in the midrange. He admitted that the Karlson's do color the midrange, but it does avoid the beaming that some experience in the higher frequencies, and does have great transient response which is lacking in other designs. He also pointed out that other speakers color the midrange as well, in a variety of different ways - thus it is a matter of tradeoffs. This intrigued me to at least want to try out the Karlson midrange.
Carl raved about the quality of sound from the Transylvania tube, once it was optimized and coupled with good tweeter drivers. In fact, he said that there was no other means of high frequency reproduction that was better. I found this very fascinating. He named a few good tweeters, such as the EV T-35, TAD and Eminence.
We talked further about using the Karlson for lower frequency reproduction and only up to 200 hz or so. He said that a light cone 18 inch driver could be coupled with a modified Karlson to handle both low frequency (below 50 hz) and higher frequency (up to 200 hz or so) bass. He talked a little about a subwoofer-style Karlson that his son put together, which was quite different, but he would not reveal too many details about this. He said that if redesigning the Karlson enclosure, then one could look at a total redesign, such as a cylindrical design, which would have less flexing in the cabinet walls. This got me thinking about redesigning a conventional K15 Karlson to be based on a cylindrical design. We shall see.
K15's wings, due to its front "shelf" is easy to brace with two 3.5" long pieces of dowel rod.
A cylindrical K might work with little speakers for someone good at cutting elliptical baffles. GregB's "Karlsonator" has proven a way to get reasonable LF with K-type in small packages.
I've had 18" speakers play up to ~1K2 with very nice sound. One coupler, on Youtube was good from the beginning - thankfully as the wings are glued.
YouTube
A smaller coupler loaded with an 18 sounded "congested" with a 5/8" starting gap. As the radial arc wings just screwed to large cleats, I swiveled the wings to get about a 1.25" top gap. This had no significant effect on microphone plots, but subjectively gave a very even and good sounding response - better than a direct radiator with the same speaker. I ran two different Eminence 18's in it with the old Smith Distributed Source Horn on top. It was made like a "big K12", two ~4"x4" ports (to allow an internal K-tube) and about 6 cubic foot external bulk. Below is a picture of that cabinet with an Altec 421 on adapter ring.
I don't know how much influence a change in flare can exert upon frequency response. It can affect the outcome as a microphone only picks up a tiny bit of what comes out of a larger tapered aperture and whatever is delayed.
I'm very fond of the K12 with strong motor.
Eminence makes some decent 15 - perhaps they don't sound "as pretty" as vintage drivers which had paper voice coil formers.
Regarding cone mass, two drivers I've used in recent history are the Peavey HE 15 with ~53 grams moving mass and the discontinued Eminence Beta15cx that was about the same. My Peavey has the neo magnet (discontinued - the ferrite version still seems available) - the Peavey is a tiny bit less efficient than an EV15B.
Karlson type have adjustments available: front chamber volume - front chamber aspect - front chamber reflector size and shape - ( in K with deep front chambers, K15's front shelf may be of use) rear chamber volume - rear chamber aspect - aperture flare - aperture area - internal port area - internal port placement - de-Q-ing ports - rear lowpass gap. The first K12 had an adjustable rear lowpass gap comprised of a wood bar which had 3 positions that varied its proximity to the rear shelf.
Carl likes curved reflectors. I gather he never uses damping material in the front chamber or on the wings, but rather has several coats of varnish in the chamber and on the rear surface of the wings.
"small K18" - -excellent sound quality- shown here with Altec 421
IIRC the baffle laid back ~25 degrees and the port panel canted forwards ~10 degrees. There was no upper reflector. Later I added a 20 liter top chamber connected to the top of the front chamber. That brought down a mild cavity peak, and gave a big more output on the bottom.
If I can find a piece of paper, I'll try to copy a DOS routine which has a two variable input for wings - can't figure out a way to get a screenshot on an old
pc in command prompt
A cylindrical K might work with little speakers for someone good at cutting elliptical baffles. GregB's "Karlsonator" has proven a way to get reasonable LF with K-type in small packages.
I've had 18" speakers play up to ~1K2 with very nice sound. One coupler, on Youtube was good from the beginning - thankfully as the wings are glued.
YouTube
A smaller coupler loaded with an 18 sounded "congested" with a 5/8" starting gap. As the radial arc wings just screwed to large cleats, I swiveled the wings to get about a 1.25" top gap. This had no significant effect on microphone plots, but subjectively gave a very even and good sounding response - better than a direct radiator with the same speaker. I ran two different Eminence 18's in it with the old Smith Distributed Source Horn on top. It was made like a "big K12", two ~4"x4" ports (to allow an internal K-tube) and about 6 cubic foot external bulk. Below is a picture of that cabinet with an Altec 421 on adapter ring.
I don't know how much influence a change in flare can exert upon frequency response. It can affect the outcome as a microphone only picks up a tiny bit of what comes out of a larger tapered aperture and whatever is delayed.
I'm very fond of the K12 with strong motor.
Eminence makes some decent 15 - perhaps they don't sound "as pretty" as vintage drivers which had paper voice coil formers.
Regarding cone mass, two drivers I've used in recent history are the Peavey HE 15 with ~53 grams moving mass and the discontinued Eminence Beta15cx that was about the same. My Peavey has the neo magnet (discontinued - the ferrite version still seems available) - the Peavey is a tiny bit less efficient than an EV15B.
Karlson type have adjustments available: front chamber volume - front chamber aspect - front chamber reflector size and shape - ( in K with deep front chambers, K15's front shelf may be of use) rear chamber volume - rear chamber aspect - aperture flare - aperture area - internal port area - internal port placement - de-Q-ing ports - rear lowpass gap. The first K12 had an adjustable rear lowpass gap comprised of a wood bar which had 3 positions that varied its proximity to the rear shelf.
Carl likes curved reflectors. I gather he never uses damping material in the front chamber or on the wings, but rather has several coats of varnish in the chamber and on the rear surface of the wings.
"small K18" - -excellent sound quality- shown here with Altec 421
IIRC the baffle laid back ~25 degrees and the port panel canted forwards ~10 degrees. There was no upper reflector. Later I added a 20 liter top chamber connected to the top of the front chamber. That brought down a mild cavity peak, and gave a big more output on the bottom.
If I can find a piece of paper, I'll try to copy a DOS routine which has a two variable input for wings - can't figure out a way to get a screenshot on an old
pc in command prompt
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Questions -
Hi Retsel - -I hope you get to hear some of Carl's Karlson stuff and make a report for this forum. Take note of the drivers.
Hi xrk971 - - what are your thoughts on K15 (and the old K12) rear shelf? (sometimes viewed as a lowpass filter in conjunction with damping material) When is it useful? What does it do?
Hi Retsel - -I hope you get to hear some of Carl's Karlson stuff and make a report for this forum. Take note of the drivers.
Hi xrk971 - - what are your thoughts on K15 (and the old K12) rear shelf? (sometimes viewed as a lowpass filter in conjunction with damping material) When is it useful? What does it do?
I'm very tempted to mount an Audio Nirvana stamped frame 10 in my tiny "K10" cabinet - I think the mids would be "ok" - might even sound pretty good - will have to look up the parameters - IIRC qt was ~0.41 and fs ~49 - its a matter of drilling 4 small holes in the baffle. (It has 8-t-nuts in a circle for regular 10" frames). I really don't want to mar the baffle if I stick with round basket 10s. The smallest cabinet I've run AN10 was the Karlsonator12 where it played deep. (OH - I remember now having AN10 in an X15 copy). K10, in contrast, has only about 1 cubic foot back chamber.
I'm pretty sure AN10 would be nice in a regular Karlson 12 - its tough to mount due to the frame.
it would certainly look very nice - I suspect if not peaking too bad on the bottom, that it would be more lively in the mids than Beta10cx. I'll probably try a hot 10" and put a K-tube on top. A redesign like the 1956 K12 with its 10 degree panel would ease mounting an internal K-tube.
(I wish Fostex made a 10" version of FE206EN ...)
I'm pretty sure AN10 would be nice in a regular Karlson 12 - its tough to mount due to the frame.
it would certainly look very nice - I suspect if not peaking too bad on the bottom, that it would be more lively in the mids than Beta10cx. I'll probably try a hot 10" and put a K-tube on top. A redesign like the 1956 K12 with its 10 degree panel would ease mounting an internal K-tube.
(I wish Fostex made a 10" version of FE206EN ...)
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Hi Freddi,
Those params look ideal for a K, although my personal preference is not to use a traditional K scaled below 12in. Just doesn't have enough bass for me.
This is not so easy to answer without running some sims while adjusting the shelf.
So I am running some sims with the rear shelf area set at 0.25x a nominal K15 shelf and one at 2.25x the CSA of a nominal shelf. These areas may not be practical in reality but we are looking at trends. (note that files show 0.5x and 1.5x but that is scaling applied to both dimensions).
The effect on frequency response is very subtle, the location of the first dip extends higher up for a larger CSA (smaller shelf). There is also a decrease in air velocity through that shelf so less audible chuffing noise. I am running sims with standard K15 and EV SP15A driver.
0.25x CSA shelf:
1.0x CSA shelf:
2.25x CSA shelf:
Velocity with 2.25x CSA shelf:
Velocity with 0.25x CSA shelf:
I even looked at impulse response to see if it affects dynamics - not visible in graphs. So, in conclusion, I see no benefit of having that rear shelf. It actually reduces bandwidth and causes chuffing.
Those params look ideal for a K, although my personal preference is not to use a traditional K scaled below 12in. Just doesn't have enough bass for me.
This is not so easy to answer without running some sims while adjusting the shelf.
So I am running some sims with the rear shelf area set at 0.25x a nominal K15 shelf and one at 2.25x the CSA of a nominal shelf. These areas may not be practical in reality but we are looking at trends. (note that files show 0.5x and 1.5x but that is scaling applied to both dimensions).
The effect on frequency response is very subtle, the location of the first dip extends higher up for a larger CSA (smaller shelf). There is also a decrease in air velocity through that shelf so less audible chuffing noise. I am running sims with standard K15 and EV SP15A driver.
0.25x CSA shelf:
1.0x CSA shelf:
2.25x CSA shelf:
Velocity with 2.25x CSA shelf:
Velocity with 0.25x CSA shelf:
I even looked at impulse response to see if it affects dynamics - not visible in graphs. So, in conclusion, I see no benefit of having that rear shelf. It actually reduces bandwidth and causes chuffing.
Attachments
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Dear X - those are interesting simulations
The only coupler I can mount AN10 easily is an X15 copy - I think the vent area needs to be opened up and the cabinet has some leeway for that to be done. I had it in there once and it actually had some impact (totally lacking with BR) I think a regular aspect K might work better than X15 - its just a bit too wide imo for a 10" or 12" driver.
K15 as normally used has almost no chuffing vs a reflex the size of its rear chamber tuned similar (fb upper 40's) with two 4" ID vents at a rather low input of 20VRMS/37Hz sinewave - I only tested with JBL M151. I can see the rear shelf being an extra problem in little K-coupler.
The original K12 had a movable tuning "bar" adjacent to its rear shelf - fwiw, that allowed subtle changes in Fb.
The next K12 (~1956 and published in the july 1958 issue of Popular Mechanics) had a distributed slit port. (Distributed ports were a rage in that period and perhaps useful with weak motor drivers) - under sine conditions, it exhibits extremely high harmonic distortion and air velocity. Under most music conditions, I'm not sure if the distortion is fully excited - it probably would not be noticed with an electric bass guitar plugged in (of course, modern electric bass with round wound strings, have harmonics usually stronger than fundamental)
Acoustic Control, KK-Audio, and others followed the Transylvania Power Company's "X15 size" K-coupler. It has a nominal 2 inch by 19" gap, small center chamber, and is a good player with nearly 30 sq.in. of vent area and ~53Hz fb.
Does the 115BK layout work any smoother than K15's? - it seems to graph pretty smooth without any damping material whatsoever.
I forgot to mention, I have the KK-audio version of this cabinet - it has a rear shelf right above the driver - that makes the response
less smooth than leaving that feature out as in the 115VK sketch below
I'll have to look for the placement of the KK-"shelf"
The only coupler I can mount AN10 easily is an X15 copy - I think the vent area needs to be opened up and the cabinet has some leeway for that to be done. I had it in there once and it actually had some impact (totally lacking with BR) I think a regular aspect K might work better than X15 - its just a bit too wide imo for a 10" or 12" driver.
K15 as normally used has almost no chuffing vs a reflex the size of its rear chamber tuned similar (fb upper 40's) with two 4" ID vents at a rather low input of 20VRMS/37Hz sinewave - I only tested with JBL M151. I can see the rear shelf being an extra problem in little K-coupler.
The original K12 had a movable tuning "bar" adjacent to its rear shelf - fwiw, that allowed subtle changes in Fb.
The next K12 (~1956 and published in the july 1958 issue of Popular Mechanics) had a distributed slit port. (Distributed ports were a rage in that period and perhaps useful with weak motor drivers) - under sine conditions, it exhibits extremely high harmonic distortion and air velocity. Under most music conditions, I'm not sure if the distortion is fully excited - it probably would not be noticed with an electric bass guitar plugged in (of course, modern electric bass with round wound strings, have harmonics usually stronger than fundamental)
Acoustic Control, KK-Audio, and others followed the Transylvania Power Company's "X15 size" K-coupler. It has a nominal 2 inch by 19" gap, small center chamber, and is a good player with nearly 30 sq.in. of vent area and ~53Hz fb.
Does the 115BK layout work any smoother than K15's? - it seems to graph pretty smooth without any damping material whatsoever.
I forgot to mention, I have the KK-audio version of this cabinet - it has a rear shelf right above the driver - that makes the response
less smooth than leaving that feature out as in the 115VK sketch below
I'll have to look for the placement of the KK-"shelf"
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- mounted a 10 inch Eminence woofer with 2" coil, 56oz magnet and Qts ~0.23. I did not remove the back panel to check or muck with the rear shelf. It is gapped pretty tight - probably no more than 1.5" gap from the back panel giving a maximum of ~18 sq.in. lowpass gap area. (I can remove a certain amount of the rear shelf)
The cabinet was laid on its back, and sitting up off the floor on another K for input impedance measurements - driver bolted in - - wings just laying on their cleats. I will try this with either IG's brass K-tube or a Transylvania Power Company K-tube. The woofer may peak on top like a Delta10a - just don't know yet as the other one in the pair is in my baby Classic horn.
hopefully this 10 with its low Q will be stronger in the midrange than the Beta10cx. I have an old spec B102 in an ancient
and rough "Pioneer K12" for comparison.
Does the 3rd Z peak with wings "on" generally coincide or not with the position of the cavity peak?
The cabinet was laid on its back, and sitting up off the floor on another K for input impedance measurements - driver bolted in - - wings just laying on their cleats. I will try this with either IG's brass K-tube or a Transylvania Power Company K-tube. The woofer may peak on top like a Delta10a - just don't know yet as the other one in the pair is in my baby Classic horn.
hopefully this 10 with its low Q will be stronger in the midrange than the Beta10cx. I have an old spec B102 in an ancient
and rough "Pioneer K12" for comparison.
Does the 3rd Z peak with wings "on" generally coincide or not with the position of the cavity peak?
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dunno - here's a rather rough 1/24 octave graph of FE206EN in the 0.62 scale K15. IIRC, the cabinet was off the floor by around 18" and a number of feet from a "back wall" - it was within a few feet of a side wall.
when working with K of this size, could one front chamber shape be more optimum than another for a fixed
front chamber volume? A text box with movable parts might help sort things.
it played smoother with Beta10cx but the 100-200Hz "hit" octave elevated enough where I think it could play
outdoors on a tripod and sound "balanced".
when working with K of this size, could one front chamber shape be more optimum than another for a fixed
front chamber volume? A text box with movable parts might help sort things.
it played smoother with Beta10cx but the 100-200Hz "hit" octave elevated enough where I think it could play
outdoors on a tripod and sound "balanced".
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Altec A7 components for K15?
I've just started researching using my Altec A7 components in K15s (with horns mounted exterior on top). I just received a set consisting of Altec 416A woofers (16 ohm), 802D HF drivers (16 ohm), 511B horns with N-500-E XOs- all original from 1966.
But, I have a small listening room, so it would be pretty difficult to use large 9 - 12 cu ft BR enclosures- and might be a problem accoustically in the small space. My Fostex 168FE Sigma in Madisound BK-16 Nagaokas and Altec 604-8H's in JEL open baffles work well. So when I realized that the K15 boosts the output with a small foot print, sounded like a win-win situation. Also, since my components were designed to work with a horn loaded LF setup (Altec VOTT/A7 large enclosures), the amplification of LF output I think is helpful to match the horns. I have read the Exemplar article, and my components are close to those used in their Karlson project- although I'm not sure what horn they used. They did mention use of woofer cone with Fs 25Hz.
The only down side I'm seeing so far is that there are claims that this would not be ideal in small space. Also, might need different XO setup and my woofer not "25Hz type". T-S parameters are hard to find for Altec 416As, but so far I have:
*Xmax: 0.14" *Re: 12.4 *Fs: 21.4Hz *Qts: 0.272 *Qms: 4 *Qes: 0.292 *eff.dia: 12.6".
I know I need to start going thru this thread in detail- just was hoping someone had a moment for an opinion. Thanks, Kip........
I've just started researching using my Altec A7 components in K15s (with horns mounted exterior on top). I just received a set consisting of Altec 416A woofers (16 ohm), 802D HF drivers (16 ohm), 511B horns with N-500-E XOs- all original from 1966.
But, I have a small listening room, so it would be pretty difficult to use large 9 - 12 cu ft BR enclosures- and might be a problem accoustically in the small space. My Fostex 168FE Sigma in Madisound BK-16 Nagaokas and Altec 604-8H's in JEL open baffles work well. So when I realized that the K15 boosts the output with a small foot print, sounded like a win-win situation. Also, since my components were designed to work with a horn loaded LF setup (Altec VOTT/A7 large enclosures), the amplification of LF output I think is helpful to match the horns. I have read the Exemplar article, and my components are close to those used in their Karlson project- although I'm not sure what horn they used. They did mention use of woofer cone with Fs 25Hz.
The only down side I'm seeing so far is that there are claims that this would not be ideal in small space. Also, might need different XO setup and my woofer not "25Hz type". T-S parameters are hard to find for Altec 416As, but so far I have:
*Xmax: 0.14" *Re: 12.4 *Fs: 21.4Hz *Qts: 0.272 *Qms: 4 *Qes: 0.292 *eff.dia: 12.6".
I know I need to start going thru this thread in detail- just was hoping someone had a moment for an opinion. Thanks, Kip........
K15 re-tuned per Exemplar (and boosted at fb) will make a nice subwoofer - I think it will play well in a relatively small space and that one cabinet would suffice. John Tucker and Jeff Markwart used their K15 subwoofer to augment their updated Voice of the Theater tyep system which had a tractrix treble horn and 135Hz or so tractrix horn for its 15 inch woofer.
I briefly ran a 416 in a beat-up K15 with 2-3"ID right angle pvc ducts and an 80Hz crossover to a little Karlson 12 with wimpy
Allied-Knight (Jensen?) coax - it was really great on theater organ recordings and more articulate than another woofer run
as assisted 6th order reflex. (I ran this bi-amped test setup with a 25 watt per channel junk receiver !!) It still doesn't
add up to me why K15 would work so well vs a simple B6 reflex in subwoofer duty. Perhaps xrk971 would have some ideas.
(I think the Altec drivers, with resoanbly low mass and underhung (I think??) motor are cleaner sounding than some heavier cones
with large overhang)
image from 6 Moons http://www.6moons.com/industryfeatures/vsac20082/exemplar2.jpg
I briefly ran a 416 in a beat-up K15 with 2-3"ID right angle pvc ducts and an 80Hz crossover to a little Karlson 12 with wimpy
Allied-Knight (Jensen?) coax - it was really great on theater organ recordings and more articulate than another woofer run
as assisted 6th order reflex. (I ran this bi-amped test setup with a 25 watt per channel junk receiver !!) It still doesn't
add up to me why K15 would work so well vs a simple B6 reflex in subwoofer duty. Perhaps xrk971 would have some ideas.
(I think the Altec drivers, with resoanbly low mass and underhung (I think??) motor are cleaner sounding than some heavier cones
with large overhang)
image from 6 Moons http://www.6moons.com/industryfeatures/vsac20082/exemplar2.jpg
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a strong 10 inch speaker in the little 0.62X scale K15 produces graphs as so - these are relatively close, in a cramped room and one is away from room ways and elevated 28" from the floor. (Some of these have the mic below central axis) i think at this size, the K-coupler needs to be against at least one boundary with an ~98dB rated 10" speaker.
I'll try a K-tube on top and hear how it subjectively fares. The object with this tiny size is to see how it competes with typical front loaded "midbass" horns.
I'll try a K-tube on top and hear how it subjectively fares. The object with this tiny size is to see how it competes with typical front loaded "midbass" horns.
X- should i attempt to tune my 0.62X K15 with 10" speaker a few Hz lower by extending its port boundary? Closing off the port on the other 0.62X cabinet loaded with Beta10cx didn't seem to sound good.
btw, when running low level sine into the cabinet with the strong motor 10, I used an aperture plate off a little XKi to partially block the inner vent. I had this plate so the "V" was sideways - interestingly, this partial inner vent blockage produced a number of overtones from the inner vent - I'm not sure why but know the slit vent K12 when driven with sine around Fb does the same. (???)
SK8 with Delta pro 8A tuning - regular aperture vs "fast" aperture. for all practical purposes, this cabinet is almost the size of the 0.62X K15.
0.62 scale K15 with strong motor 10 tuning - perhaps it would be a bit better with Fb ~70 (?) Also, there's only some carpet felt for damping - the 3 traditional pads. Do you think a pad on the back chamber and a thick piece of bonded Dacron under the rear shelf could provide clearer sound?
btw, when running low level sine into the cabinet with the strong motor 10, I used an aperture plate off a little XKi to partially block the inner vent. I had this plate so the "V" was sideways - interestingly, this partial inner vent blockage produced a number of overtones from the inner vent - I'm not sure why but know the slit vent K12 when driven with sine around Fb does the same. (???)
SK8 with Delta pro 8A tuning - regular aperture vs "fast" aperture. for all practical purposes, this cabinet is almost the size of the 0.62X K15.
0.62 scale K15 with strong motor 10 tuning - perhaps it would be a bit better with Fb ~70 (?) Also, there's only some carpet felt for damping - the 3 traditional pads. Do you think a pad on the back chamber and a thick piece of bonded Dacron under the rear shelf could provide clearer sound?
Wings OFF - Near-cone and Near-port graph of 0.62X K15
speaker is a low Q 10 (Qts ~0.23, fs ~53) - there is a rear shelf with a tight gap spacing of about 1.5" or so. When the wings are added, the prominent peak is around 232Hz.
I should have added some resistance to modify Qes and will do to check effects of a weaker motor when get appropriate resistors or can get an L-pad to read consistently in one spot.
The rear shelf can be shortened somewhat to check effects upon tuning and port output.
At 0.62 scale, the rear chamber is around 0.86 or so cubic feet. A regular K12 will probably provide some useful LF extension in a manageable package.
Could the Acoustic Control 115BK layout which just extends the baffle up near the top of the cabinet provide a better behavior? - or would that be the same?
There's no damping in this enclosure other than 3 thin carpet felt pads placed
in traditional K15 manner. (Cabinet bottom, bottom of rear shelf, top of cabinet).
Karlson's K12, X15 and K8 of the 1960's had both sidewalls treated with
Kimsul" or fiberglass.
I'll pull the back panel and try a thick bonded Dacron pad under the rear shelf.
note - the null in the near cone response ` coincides with the port peak up towards 300
speaker is a low Q 10 (Qts ~0.23, fs ~53) - there is a rear shelf with a tight gap spacing of about 1.5" or so. When the wings are added, the prominent peak is around 232Hz.
I should have added some resistance to modify Qes and will do to check effects of a weaker motor when get appropriate resistors or can get an L-pad to read consistently in one spot.
The rear shelf can be shortened somewhat to check effects upon tuning and port output.
At 0.62 scale, the rear chamber is around 0.86 or so cubic feet. A regular K12 will probably provide some useful LF extension in a manageable package.
Could the Acoustic Control 115BK layout which just extends the baffle up near the top of the cabinet provide a better behavior? - or would that be the same?
There's no damping in this enclosure other than 3 thin carpet felt pads placed
in traditional K15 manner. (Cabinet bottom, bottom of rear shelf, top of cabinet).
Karlson's K12, X15 and K8 of the 1960's had both sidewalls treated with
Kimsul" or fiberglass.
I'll pull the back panel and try a thick bonded Dacron pad under the rear shelf.
note - the null in the near cone response ` coincides with the port peak up towards 300
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X- when I get around to it, I'll try shortening the rear shelf and see if that has any effect on that peak. The back needs to be pulled anyhow to experiment with damping material. Karlson's small enclosures of the 1960's (X15, K12 & K8) had Kimsul or fiberglass pads covering both sidewalls and extending a bit into the top and bottom. I don't know if rear pads were used nor if they had pads under the rear "shelf". Could that peak be a Helmholtz resonance formed by the rear chamber(s) and shelf gap ? I don't want to damp this cabinet too much as its lean already from the low Q, low mass 10 - would like to try a different ("more open") aperture although that's certain to raise Fb further. Using that 2-variable input formula in a different post, a P=1, Q=1.7 aperture would open a bit faster during the last half of travel from top to bottom and have minimal impact on system tuning.
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