Freddi,
Is your sketch to scale? If so I can use dial calipers to pull dimensions and can model or for you. Otherwise I will need a drawing with more details for each little section of flow paths where the CSA changes, I need the length of that segment and the CSA of the begining and end of the segment. If you can provide that type of info it will make a model development go much faster.
Is your sketch to scale? If so I can use dial calipers to pull dimensions and can model or for you. Otherwise I will need a drawing with more details for each little section of flow paths where the CSA changes, I need the length of that segment and the CSA of the begining and end of the segment. If you can provide that type of info it will make a model development go much faster.
Here is the link to that image - pretty cool room!
http://upload.wikimedia.org/wikipedia/commons/thumb/4/48/SPF_RATF.tif/lossy-page1-819px-SPF_RATF.tif.jpg
IG
if any readers would like to hear Mr. Karlson, here's a one-hour.40 minute radio show from 1964 - the largest file is only 470MB so would fit on a CD
Hi-Fi Workbench 3/7/64 John Karlson and Reubin Gus : Free Download & Streaming : Internet Archive
Hi-Fi Workbench 3/7/64 John Karlson and Reubin Gus : Free Download & Streaming : Internet Archive
Didn't save them since it was just an approximation to prove a point. I tried once to do it in HR, but the software's 99999.99 cm^2 CSA limit wouldn't let me, so what is AkAbak's limit?
GM
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K15 with Distributed Slit Vents
I added the option to have the distributed slit vents per the Popular Science drawing from 1955. I approximated the slit vent as a single very long one located at the middle of the top angled reflector panel rather than spread out with 1 inch C-T-C spacing. Not sure if it matters but I was too lazy to add 5 more vents. The effect of the frictional losses due to the thin aspect ratio is there though. The slit vents really suck the bass out of the speaker. I tried adding more length in increments of 7-5/8 in slots. That did not help much and I finally increased the gap from 1/8 in to 0.20 in and that helped things a lot. This will probably give a more smoother balanced sound that is less punchy.
I added the option to have the distributed slit vents per the Popular Science drawing from 1955. I approximated the slit vent as a single very long one located at the middle of the top angled reflector panel rather than spread out with 1 inch C-T-C spacing. Not sure if it matters but I was too lazy to add 5 more vents. The effect of the frictional losses due to the thin aspect ratio is there though. The slit vents really suck the bass out of the speaker. I tried adding more length in increments of 7-5/8 in slots. That did not help much and I finally increased the gap from 1/8 in to 0.20 in and that helped things a lot. This will probably give a more smoother balanced sound that is less punchy.
Attachments
I don't know, give me a number to try...
I bet it is fine as the default unit is meters.
Driver specs attached.
Flare = 10.48 Hz
M [T] = 0.488
filter chamber [Vf] = 20.893"^3
compression chamber [Vr] = theoretically infinite
throat [St] = 4.52"^2
terminus [Sm] = ~66,244.786"^2/2pi
GM
Attachments
since the Karlson enclosures for the most part were sold unloaded in the days of mix and match the cabinet with a driver, its possible he thought the distributed slit vent cabinet did better with some of the cheaper/weaker drivers (?)
each slit sees a different impedance due to the front chamber and distances. A Lafayette K12 had only 3 slots but they were spaced over the same distance as the 6 slot K12 and my 4 slot K12.4 slit
this on the right may be a 4 slit - is there room for one more?
the really narrow slits like small holes whether in a K or reflex will produce high velocities and high harmonic distortion if fed by by a sine wave in the vicinity of fb. I've run a 41Hz sine wave into a 15" driver 3.6 cubic foot bass reflex tuned with 42-3/8" holes and it felt like a good fan 8 feet away with only 12 watts input.
under dynamic conditions the really restrictive ports must cease to radiate at their small signal fb, introduce drag - and with sine - perhaps "rectify" (?) - in a reflex that can cause cone offset from center.
John Lapaire once tried a slit vent panel in a K-coupler which was between X15 and K15's size and commented he might prefer that vent IF only listening to acoustic instrument music.
changing topics for a bit, re: HAK - the following 8" K-coupler when loaded with W8-1772 had 2-5dB less output than 1772 in the old K12/Karlsonette in the 110Hz to 220Hz octave
BetsyK in the 28" tall "K8" 1/6 octave smoothed
1/24 octave resolution - effect of aperture height with BetsyK
each slit sees a different impedance due to the front chamber and distances. A Lafayette K12 had only 3 slots but they were spaced over the same distance as the 6 slot K12 and my 4 slot K12.4 slit
this on the right may be a 4 slit - is there room for one more?
An externally hosted image should be here but it was not working when we last tested it.
the really narrow slits like small holes whether in a K or reflex will produce high velocities and high harmonic distortion if fed by by a sine wave in the vicinity of fb. I've run a 41Hz sine wave into a 15" driver 3.6 cubic foot bass reflex tuned with 42-3/8" holes and it felt like a good fan 8 feet away with only 12 watts input.
under dynamic conditions the really restrictive ports must cease to radiate at their small signal fb, introduce drag - and with sine - perhaps "rectify" (?) - in a reflex that can cause cone offset from center.
John Lapaire once tried a slit vent panel in a K-coupler which was between X15 and K15's size and commented he might prefer that vent IF only listening to acoustic instrument music.
changing topics for a bit, re: HAK - the following 8" K-coupler when loaded with W8-1772 had 2-5dB less output than 1772 in the old K12/Karlsonette in the 110Hz to 220Hz octave
An externally hosted image should be here but it was not working when we last tested it.
BetsyK in the 28" tall "K8" 1/6 octave smoothed
An externally hosted image should be here but it was not working when we last tested it.
1/24 octave resolution - effect of aperture height with BetsyK
An externally hosted image should be here but it was not working when we last tested it.
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regarding K15's 30.5 sq.in. vent, I compared a reflex the size of K15's rear chamber and same "apparent tuning" as K15 (~48Hz or so) to K15 - each cabinet had a JBL M151. The reflex was tuned with two 4" ID pvc ducts. At 36Hz sine and 20vrms, the reflex had a lot more cone movement, a lot more air velocity and perhaps some cone offset from center while K15 and its vent had very little air velocity, perhaps 1/3 the cone excursion. Why did K15 have so much less cone movement vs the "equivalent" reflex? K15's port would be hard to overload/
The K15 has low cone movement due to excellent coupling between the cone and air mass via horn like behavior. The good coupling is same as good impedance match, and Karlson himself said in the audio clip that his cabinet is like a gear train in a car to enable the matching of the speed of the engine with the speed of the wheels on the road. Somehow, he did all this without computers - probably with slide rules and microwave horn theory. He design is indeed very good and time tested.
Seriously?! After all that's been repeatedly exposed about tapped pipes, horns, high order B0$3 'sub' designs by me and many others that you still haven't grasped the fact/concept that such alignments compression load the driver over some portion of its BW same as coupling a horn to it to allow it to make more SPL/W? Seriously?!
Correct, since it's being compression loaded also to some extent.
GM
BLH. Last time I checked infinite meant, well, infinite.
In a real world app then, the driver would radiate to the outside world and some form of EQ would roll it off while the horn would radiate into the sealed building. IOW, it's theoretically the widest BW reactance annulled compression horn the driver's specs allow.
GM
re: distortion - some front loaded horns I've measured have not been as clean as K15 or a K15 size coupler loaded with 18" - a Yorkville, a set of diy horns using JBL12s, Peavey FH1. Bruce's Monolith measures pretty well.
115BK is something like 1 cubic foot larger than K12 - it does well as it has a big vent - slit vents measure poorly but as music is (or used to be) transient in nature does well enough subjectively and does not distort with bass guitar to one's ears.
115BK is something like 1 cubic foot larger than K12 - it does well as it has a big vent - slit vents measure poorly but as music is (or used to be) transient in nature does well enough subjectively and does not distort with bass guitar to one's ears.
re: the Karlsonator, I have a 6.5" speaker version whose tuning is around 60Hz - its loaded with GB's old de-whizzered FE164 and sounds mellow/dark without a helper tweeter even with it elevated pretty high from the floor. It seems to "go low" and without a helper tweeter , the bass sounds "soft" - I think an internal K-tube tweeter would be good - maybe driven with a piezo element - FE166EN probably would make it present more impact than the 164. Are there appropriate 6.5" woofers at a low cost to substitute for a 166?
GB's K6.5 and the old 164 sound pretty good with a cheap Goldwood piezo put on top. 90 degrees off axis there's still mid-highs. Bass seems deep even with the speaker elevated and away from walls. It once ran FE166EN but I never got to hear that driver. The top vent is sizable. There is not a lot of cone excursion.
An externally hosted image should be here but it was not working when we last tested it.
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Do you have a link to a K6.5 plan? If the 6.5 doesn't need a high BL motor there are substitutes, but I don't know off hand.
you can download it under "more" here - I bought a 166 for it but it got trashed in a basement flood at Lapaire's - since it seems to go
pretty deep, I would not mind having a pair
https://plus.google.com/photos/1005...5578916065853178818&oid=100545049816297868412
pretty deep, I would not mind having a pair
https://plus.google.com/photos/1005...5578916065853178818&oid=100545049816297868412