Front shelf turned sideways (gap on sides) can double as a wing brace.
Angled plate is mostly to keep the front upper chamber from being too
parallel. Reflect sound out front slot before it bounces too many times...
Shelf is probably important enough to model, I don't know if I'd bother
worrying about the small volume under the angle plate.
This is not an ultimate upper chamber for minimum midrange reverb.
Just a transition from horn to Karlson, with intent to produce bass...
the 40.5 sq.in. vent should have Zmin just about at 50Hz - narrowing the vent may lessen output a bit in the "w" region a bit but have little effect on the bottom. I'm guessing a really little vent will have a big hole in the response.
the 1954 Radio & TV News article was the first to publish the plan - it seemed strange to me that Karlson gave away the plan - K15's introductory article was in Audio Engineering magazine in 1952.
for those without good coaxial, a K15 size coupler could be made something like a big K12 or the X15 system so an internal K-tube could be mounted.
the 1954 Radio & TV News article was the first to publish the plan - it seemed strange to me that Karlson gave away the plan - K15's introductory article was in Audio Engineering magazine in 1952.
for those without good coaxial, a K15 size coupler could be made something like a big K12 or the X15 system so an internal K-tube could be mounted.
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Effect of more Karlson holes and back wall
I went in and added 5 more (14 total) rectangular holes to approximate the Karlson slot more accurately. The effect was minimal - smoothed out a peak or two in higher frequencies. For practical purposes, 9 seems to be just as good. Below is the simulation with original 9 and then 14. I also moved the back wall from 5 ft away to 3 ft away and see that it makes the bass shelf sloped in a way that resembles Freddi's measurement. Even the little kink in the slope if there. However, the "W" now goes away, but the middle of the W if it were there appears to be at 200 Hz.
First plot is original 9 holes 5 ft from wall, 14 holes 5 ft from wall, then 14 holes 3 ft from wall.
I went in and added 5 more (14 total) rectangular holes to approximate the Karlson slot more accurately. The effect was minimal - smoothed out a peak or two in higher frequencies. For practical purposes, 9 seems to be just as good. Below is the simulation with original 9 and then 14. I also moved the back wall from 5 ft away to 3 ft away and see that it makes the bass shelf sloped in a way that resembles Freddi's measurement. Even the little kink in the slope if there. However, the "W" now goes away, but the middle of the W if it were there appears to be at 200 Hz.
First plot is original 9 holes 5 ft from wall, 14 holes 5 ft from wall, then 14 holes 3 ft from wall.
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I've done a few near-cone measurements of K15 and a K15 size coupler without any front shelf and even tho they tuned in the high 40's, there appeared to be a cone null around 36-37Hz. A woofer in the Karlson would move much less than in a reflex the size of the K's rear chamber and same apparent tuning. Imageshack has lost many of my images - I'll have to dig up one for a K the size of K15 loaded with an 18". The ~450Hz centered dip might be a sidewall cancellation.
An externally hosted image should be here but it was not working when we last tested it.
FWIW, near-cone measurements I've done mysteriously had shifting dips depending on where the mic was on the cone. Spread might have been somewhere between 5-10Hz, IIRC, that was a good while ago.
I'm wondering if the Akabak model is seeing the front chamber's semi-trapped air as a mass that loads the internal vent, it should really tune lower than that. Ditto for the front chamber Fb, but that one's kinda more complicated.
It's cool you're doing this xrk971, not many folks care about the Karlson and that's when they are not outright hostile on the subject!
IG
I'm wondering if the Akabak model is seeing the front chamber's semi-trapped air as a mass that loads the internal vent, it should really tune lower than that. Ditto for the front chamber Fb, but that one's kinda more complicated.
It's cool you're doing this xrk971, not many folks care about the Karlson and that's when they are not outright hostile on the subject!
IG
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Why Karlson's Kick Butt for Large Spaces
I posted a new thread here: http://www.diyaudio.com/forums/full-range/237948-speaker-kicks-butt-large-spaces.html
detailing my study of why the Karlson is special for large rooms when compared to a very 'flat freq response' MLTL using same driver.
I posted a new thread here: http://www.diyaudio.com/forums/full-range/237948-speaker-kicks-butt-large-spaces.html
detailing my study of why the Karlson is special for large rooms when compared to a very 'flat freq response' MLTL using same driver.
I learned to gain a lot of respect for K15 and K12 - - K15 with an Altec 604 doesn't go "deep" but it has an agile and effortless bass quality whether delivering rap or whether Gary Karr's bass viola and beauty on vocals/harpsichord/ guitar/whatever. I've measured K15 vs reflex to have 1/10 the reflex modulation distortion. I've compared a K15 size diy coupler loaded with 18" and less refined than K15 to perform cleaner than several horns. An adventuresome builder could come up with new couplers.
one thing talked about for years but not proven is making the aspect taller so the coupler section can have more and lower pipe action - - if this makes a coupler system tune lower and flatten the typical cavity peak then could be useful if in general predictable.
Karlson's claims of low cone excursion were and are true. His slotted pipe waveguide simple/elegant and useful too.
In his January 1954 Radio and Television News article, John Karlson stated that scaling K15 to make a 12" cabinet had some problems - I tend to disagree - the front shelf might be made shorter - its good to experiment with the listener being the final judge.
Some of the last commercial K-couplers were the Transylvania Power Company product and others such as Acoustic Control's 115BK. Those were about the size of Karlson's X15 so lost around 1/2 octave on the bottom compared to K15 -- they did have a a diagonal baffle arrangement which could be useful on some new K-couplers.
FE206EN on "The Spirit Of The Chinese Drum" album "Falling Leaves" when mounted in the old Karlsonette/ first K12, produced bass on drums which sounded better in quality than my Klipschorns.
Here's John Lapaire's K15's doing sound reinforcement duty for a band
one thing talked about for years but not proven is making the aspect taller so the coupler section can have more and lower pipe action - - if this makes a coupler system tune lower and flatten the typical cavity peak then could be useful if in general predictable.
Karlson's claims of low cone excursion were and are true. His slotted pipe waveguide simple/elegant and useful too.
In his January 1954 Radio and Television News article, John Karlson stated that scaling K15 to make a 12" cabinet had some problems - I tend to disagree - the front shelf might be made shorter - its good to experiment with the listener being the final judge.
Some of the last commercial K-couplers were the Transylvania Power Company product and others such as Acoustic Control's 115BK. Those were about the size of Karlson's X15 so lost around 1/2 octave on the bottom compared to K15 -- they did have a a diagonal baffle arrangement which could be useful on some new K-couplers.
FE206EN on "The Spirit Of The Chinese Drum" album "Falling Leaves" when mounted in the old Karlsonette/ first K12, produced bass on drums which sounded better in quality than my Klipschorns.
Here's John Lapaire's K15's doing sound reinforcement duty for a band
An externally hosted image should be here but it was not working when we last tested it.
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The picture shows them paired with a CD-Horn mid/tweeter which I think is the perfect combo given how high the bass efficiency of the K15 is and its great spatial dispersion uniformity in order to achieve a balanced speaker.
I have not yet had the opportunity to listen to a Karlson but look forward to hearing one one day given your glowing praise of it rendition of drums being better than a Klipschorn.
simimalarfor horns on top of K15 - I tried
Emilar "bowtie" - thick casting - rather refined sounding - it probably needed a baffle due to the small dimension at its center.
SFW radial horn - about 30 inches wide and 28" deep - quite good on vocals using an Altec Symbiotic driver and ring radiator on top - probably had to get back somewhat for the drivers to merge
250Hz Edgar rectangular tractrix with JBL LE5 topped with ring radiator - didn't like it a lot
Altec 811 - ok - perhaps not the best pattern match
Altec 511 -similar but more dynamic than the 811
Smith distributed source horn - quite interesting sound overall
for conventional helper tweeters I liked the slot lens Selenium ST324 and 320
fwiw , with higher crossovers a simple K-slotted pipe would probably sound better than most horns including CD type. If you have a compression driver laying around you could make an almost instant K-tube with a rolled up sheet of paper, scissors and tape.
Emilar "bowtie" - thick casting - rather refined sounding - it probably needed a baffle due to the small dimension at its center.
SFW radial horn - about 30 inches wide and 28" deep - quite good on vocals using an Altec Symbiotic driver and ring radiator on top - probably had to get back somewhat for the drivers to merge
250Hz Edgar rectangular tractrix with JBL LE5 topped with ring radiator - didn't like it a lot
Altec 811 - ok - perhaps not the best pattern match
Altec 511 -similar but more dynamic than the 811
Smith distributed source horn - quite interesting sound overall
for conventional helper tweeters I liked the slot lens Selenium ST324 and 320
fwiw , with higher crossovers a simple K-slotted pipe would probably sound better than most horns including CD type. If you have a compression driver laying around you could make an almost instant K-tube with a rolled up sheet of paper, scissors and tape.
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Hey Freddy: feel like I have turned the corner and am on the mend, thanks. That is with the nose cup on so you are looking at a sideways look at my EV DH1A that is a two inch paper tube you are looking which provide scale to see just how large the DH1A really is 9" in dia over 5" deep and 23.5 lbs of motor capable of outputting a continuous 10 acoustical watts across its full bandwidth 500Hz to 20KHz that three watts more continuous that a JBL 2226 fifteen inch woofer. Will try the driver with the nose cup off as a 1.4 inch exit. I am totally impressed with this driver and ruined for less I am sure.
In the snap shot the tubes are running wit a Heresy 3 (very very modified) woofer crossover is at 750 Hz and I am using a CF3 network to run the DH1A. You would have to experience the visceral impact to believe what this combination can do. You never heard a Cornwall do this. The tubes are at ear level pointing directly at the sweet spot and the K-slot cross fire toward each other so there is no tube radiation toward the two outside walls. Plan to get back at playing with these in a few weeks from now have to concentrate on walking on the new hip and building new muscle tissue. Best regards Moray James.
In the snap shot the tubes are running wit a Heresy 3 (very very modified) woofer crossover is at 750 Hz and I am using a CF3 network to run the DH1A. You would have to experience the visceral impact to believe what this combination can do. You never heard a Cornwall do this. The tubes are at ear level pointing directly at the sweet spot and the K-slot cross fire toward each other so there is no tube radiation toward the two outside walls. Plan to get back at playing with these in a few weeks from now have to concentrate on walking on the new hip and building new muscle tissue. Best regards Moray James.
Well, I want to talk for moment about the removable bottom concept.
And sideways shelving. Neither built yet, just the thought experiment.
Even with K15 built traditionally in every other way, bottom seems a
far easier access than through the front or back. There is no room for
tools at the inside bottom or under the frontside shelf. If you take the
bottom off, then tool access for inside mounting is easy allway around.
The bottom panel involves fewer furniture bolts than wings or back,
and it on the bottom, so less pretty screws are an option here too.
If you go in through the bottom, then there is no access penalty for
added bracing to the wings or back. I think front and back shelves can
easily be turned sideways to double duty as bracing... By "sideways"
I mean gaps of same area relocated to the sides, rather than gaps of
no bracing value across the front and back.
When midrange sound comes up around sides of the front shelf,
it crashes back together in a vertical stripe behind the front slot.
I think this may give an exit in fewer passes, for less reverb.
And sideways shelving. Neither built yet, just the thought experiment.
Even with K15 built traditionally in every other way, bottom seems a
far easier access than through the front or back. There is no room for
tools at the inside bottom or under the frontside shelf. If you take the
bottom off, then tool access for inside mounting is easy allway around.
The bottom panel involves fewer furniture bolts than wings or back,
and it on the bottom, so less pretty screws are an option here too.
If you go in through the bottom, then there is no access penalty for
added bracing to the wings or back. I think front and back shelves can
easily be turned sideways to double duty as bracing... By "sideways"
I mean gaps of same area relocated to the sides, rather than gaps of
no bracing value across the front and back.
When midrange sound comes up around sides of the front shelf,
it crashes back together in a vertical stripe behind the front slot.
I think this may give an exit in fewer passes, for less reverb.
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Freddie,
I love the idea of a K tube made of paper and tape. I have a soft spot for easy to make speakers that can be cobbled together from common household items. My love of foam core speaker builds is related to this. Do you think a K15 can be made from the pink XPS foam sheets from Home Depot? Perhaps with some strategic use of reinforcement with thin 0.25 or even 0.125 thick plywood on front K aperture and driver mounting panel. I am getting such good sims with the Betsy K and you are saying BG20 works well too I may give it a try one day.
I love the idea of a K tube made of paper and tape. I have a soft spot for easy to make speakers that can be cobbled together from common household items. My love of foam core speaker builds is related to this. Do you think a K15 can be made from the pink XPS foam sheets from Home Depot? Perhaps with some strategic use of reinforcement with thin 0.25 or even 0.125 thick plywood on front K aperture and driver mounting panel. I am getting such good sims with the Betsy K and you are saying BG20 works well too I may give it a try one day.
Hi Moray James and welcome back!
As for a foam Karlson, it would probably be very colored. There is a lot of pressure going on in these. Even 18mm BB-ply wings in the K12 really need bracing and I'm certain I can get an improvement on the tiny SK8 if I do so. Still, it's an easy experiment and I have not always let technical details and certain flaw detract me from trying stuff.
Smith horns are indeed fun on a Karlson. After the K-Tube, they were second best for me, in front of some CD-waveguides, DIY conical horn and tiny tweeter horn such as EV TW-35, APT:80 or FT17H.
IG
As for a foam Karlson, it would probably be very colored. There is a lot of pressure going on in these. Even 18mm BB-ply wings in the K12 really need bracing and I'm certain I can get an improvement on the tiny SK8 if I do so. Still, it's an easy experiment and I have not always let technical details and certain flaw detract me from trying stuff.
Smith horns are indeed fun on a Karlson. After the K-Tube, they were second best for me, in front of some CD-waveguides, DIY conical horn and tiny tweeter horn such as EV TW-35, APT:80 or FT17H.
An externally hosted image should be here but it was not working when we last tested it.
IG
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Styrofoam Smith horn of the same material you suggest for K15, I've built.
I can say from experience that it looked very cool, but didn't work too well.
Probably just too soft to contain the wave...
I might still build a styroK for a neodymium 12" or 15", but bracing will be
an issue for sure...
http://www.diyaudio.com/forums/multi-way/153831-styrofoam-smith-horn.html#post1958688
I can say from experience that it looked very cool, but didn't work too well.
Probably just too soft to contain the wave...
I might still build a styroK for a neodymium 12" or 15", but bracing will be
an issue for sure...
http://www.diyaudio.com/forums/multi-way/153831-styrofoam-smith-horn.html#post1958688
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Replaceable baffle
This is far more pain than it looks. The wings, back, and driver all
have to be out first, and the bolt locations offer no access for tools.
Yet another reason I think a removable bottom panel makes more
sense than removable wings and back. I could pull the driver and
baffle out in one piece, and tool access would be much improved.
No bolts hidden inside an angle with barely enough headroom to
remove the bolt, much less figure how you get the wrench on it.
I'm saying, never do what you see in this picture! Ain't worth it.
Make the bottom removable first, then maybe this makes sense.
Pics were during conversion from 12 to 18, and I don't recommend
shoehorning SigmaPro18-A2 into K15 either. Barely fit with lots of
grinding, and kick in the chest retained very little Karlson impact.
DeltaPro12 was a better match to this cabinet. I've not yet tried 15.
This is far more pain than it looks. The wings, back, and driver all
have to be out first, and the bolt locations offer no access for tools.
Yet another reason I think a removable bottom panel makes more
sense than removable wings and back. I could pull the driver and
baffle out in one piece, and tool access would be much improved.
No bolts hidden inside an angle with barely enough headroom to
remove the bolt, much less figure how you get the wrench on it.
I'm saying, never do what you see in this picture! Ain't worth it.
Make the bottom removable first, then maybe this makes sense.
Pics were during conversion from 12 to 18, and I don't recommend
shoehorning SigmaPro18-A2 into K15 either. Barely fit with lots of
grinding, and kick in the chest retained very little Karlson impact.
DeltaPro12 was a better match to this cabinet. I've not yet tried 15.
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speaking of 12s, a 12pe32 is nice for a K12 - I don't know if that combo would be considered to kick in the chest but its pretty lively
its interesting to hear the tradeoffs between the little K and an Advent
its interesting to hear the tradeoffs between the little K and an Advent
An externally hosted image should be here but it was not working when we last tested it.
one combo which I think is interesting is Eminence's current Beta10cx and a K12 - its somewhat less sensitive than the big motor 12cx/woofers so may give the impression of going a bit lower and there's a sense of power. Beta 10cx is relatively inexpensive at full price. I paid ~$40 each at a sale. Inexpensive compression drivers such as the PRV 280ti work well.