K15 vs BIB in Open Spaces
OK, why did I just pick on the MLTL? Many folks associate a BIB with a speaker that is good for filling sound in a larger space. Well, below are sims of a Betsy K in a BIB with dimensions as prescribed by GM's BIB calculator spreadsheet (20 in wide x 28 in deep x 67 in tall, all internal dims).
The first plot shows the BIB flush against a wall with mic at 1 m away. The response actually looks very good - nice and flat with great bass extension, and boy is it loud at 1 watt!. This is just to show that on paper, the BIB can actually look good for certain cases.
Second plot: when one steps back 5 m with BIB still against a wall, the response doesn't look as good anymore - there is a big wide dip at 450 Hz.
Third plot: move the BIB to 60 inches away from a wall and listen to it at 5 meters away and you get recessed low end bass and a bass peak at 100 Hz and generally uneven response with average SPL in the mid 80 dB's.
Fourth plot: Now lets look at the Betsy K in the K15 (per Job Ullman's plan with a 21.5 square inch vent) at 5 m away and 60 in from a wall. Clearly a nice performer with nice even bass response and huge punch at 90 dB.
If you are curious what the Betsy looks like in the K15 plan with the 40 square inch vent, this is shown in the fifth plot. Still pretty good but not as tight a bass shelf as the Job Ullman variant with 21.5 sq inch vent.
So there you have it, the K15 continues to kick butt even when matched against the venerable BIB.
OK, why did I just pick on the MLTL? Many folks associate a BIB with a speaker that is good for filling sound in a larger space. Well, below are sims of a Betsy K in a BIB with dimensions as prescribed by GM's BIB calculator spreadsheet (20 in wide x 28 in deep x 67 in tall, all internal dims).
The first plot shows the BIB flush against a wall with mic at 1 m away. The response actually looks very good - nice and flat with great bass extension, and boy is it loud at 1 watt!. This is just to show that on paper, the BIB can actually look good for certain cases.
Second plot: when one steps back 5 m with BIB still against a wall, the response doesn't look as good anymore - there is a big wide dip at 450 Hz.
Third plot: move the BIB to 60 inches away from a wall and listen to it at 5 meters away and you get recessed low end bass and a bass peak at 100 Hz and generally uneven response with average SPL in the mid 80 dB's.
Fourth plot: Now lets look at the Betsy K in the K15 (per Job Ullman's plan with a 21.5 square inch vent) at 5 m away and 60 in from a wall. Clearly a nice performer with nice even bass response and huge punch at 90 dB.
If you are curious what the Betsy looks like in the K15 plan with the 40 square inch vent, this is shown in the fifth plot. Still pretty good but not as tight a bass shelf as the Job Ullman variant with 21.5 sq inch vent.
So there you have it, the K15 continues to kick butt even when matched against the venerable BIB.
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Hmm, many folk's listening experiences and occasional measurements don't line up hardly at all with these or other long distance sims you've posted, so I'm inclined to ignore all of the room modes BW of those more than a meter away.........
For sure, I wouldn't use them for tweaking a design.
GM
For sure, I wouldn't use them for tweaking a design.
GM
"....K15 continues to kick butt even when matched against the venerable BIB"
I would hope! - LOL traditionally a K's wings visually just intercept the edge of the driver with a dead-on view. The smallest driver I've run in K15 was the Nirvana Super 10 - the reduction in cone excursion was very helpful
how difficult for you is it to scale your model to 0.8 size and run for BetsyK and FE206EN?
I would hope! - LOL traditionally a K's wings visually just intercept the edge of the driver with a dead-on view. The smallest driver I've run in K15 was the Nirvana Super 10 - the reduction in cone excursion was very helpful
how difficult for you is it to scale your model to 0.8 size and run for BetsyK and FE206EN?
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re: BetsyK - she probably likes a minimum rear chamber volume of around (qts*fs*vas)/50
when I compared an extended height K8 size coupler with 1772 to 1772 in the Karlsonette, the skinny K had 2 to 5dB less output in the 110-220Hz octave.
here's a graph of BetsyK in the skinny coupler - I think the downwards trend between 110 and 220 is partly room mode where the speaker and mic were placed - so if measured outdoors it might be rather flat versus the regular Karlson rise/"hit".
bass was "soft" in this little K - mids were good and I preferred BetsyK in this particular coupler to 1772, It will probably eventually run a Sammi with ST324 on top.
when I compared an extended height K8 size coupler with 1772 to 1772 in the Karlsonette, the skinny K had 2 to 5dB less output in the 110-220Hz octave.
here's a graph of BetsyK in the skinny coupler - I think the downwards trend between 110 and 220 is partly room mode where the speaker and mic were placed - so if measured outdoors it might be rather flat versus the regular Karlson rise/"hit".
bass was "soft" in this little K - mids were good and I preferred BetsyK in this particular coupler to 1772, It will probably eventually run a Sammi with ST324 on top.
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An externally hosted image should be here but it was not working when we last tested it.
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You are probably right about room modes being dominant. What I have here is a large room meaning it is "infinite" in extent beyond the floor and one wall that forms a boundary. So if you can imagine a room being a box, only two sides to the box are present, and these sides extend infinitely (no ceiling and no 3 other walls). So when a BIB is placed in a larger room with all 6 walls, there will be reinforcement from room modes for sure. I am basically talking auditorium/outdoor stage with a back and floor.
here's the size of the high aspect K next to a factory Karlson 12 from the 1960's
that Eminence coax has over 4mm xmax, a 109oz magnet slug, and a 4 inch voice coil
that Eminence coax has over 4mm xmax, a 109oz magnet slug, and a 4 inch voice coil
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I have an overall scaling factor that I can tweak and I tried the 0.8 factor which is same as scaling it for a 12 in driver (12/15). The simulation is 60 in from back wall and mic at 2 m away. Second plot is for the FE206EN. It doesn't look too bad actually.
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That's the TSG coax right?
I always get mixed up with the terminology, but this 8" HAK is pretty much a stretched SK8 isn't it? 13.5" wide and 12" deep? Did you prefer W8-1772 in this or SK8? I would have liked to give this TB driver a try if it weren't for the price, which is even worse here in Canada.
IG
yeah - that's the TSG with the yellow spider/dustcap - -in the tall SK8, I think 1772 was pretty good. That coupler may be a bit too tall or not the best front chamber shape. Lapaire seemed to like GB's scheme better than the Karlsonette/SK8 version. 1772 seemed happy in the little SK8. The coaxials can "beat" the fullrange in some ways.
hey XRK971 - K12 can work well with some 8 inch speakers as noted all the way back to 1955 by Julian Hirsch. Once you're into the 0.8 mode, can you easily reduce just the back chamber?
hey XRK971 - K12 can work well with some 8 inch speakers as noted all the way back to 1955 by Julian Hirsch. Once you're into the 0.8 mode, can you easily reduce just the back chamber?
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hey IG81 - - sometime make one set of the fast flare wings suggested by Carl as an upper boundary and give a listen - I liked those with 1772 in the little SK8. K12's rear chamber seemed too large for 1772.
Fast taper parameters, 131.9 square inch aperture
Gap Slope p q Area Length Wmax
0.5 2.9 1.08 9.5 131.9 18.5 12
Aperture
x w
0 0.50
1 0.78
2 1.10
3 1.43
4 1.76
5 2.11
6 2.46
7 2.81
8 3.17
9 3.54
10 3.91
11 4.30
12 4.72
13 5.18
14 5.73
15 6.43
16 7.38
17 8.72
18 10.69
18.5 12.00
Fast taper parameters, 131.9 square inch aperture
Gap Slope p q Area Length Wmax
0.5 2.9 1.08 9.5 131.9 18.5 12
Aperture
x w
0 0.50
1 0.78
2 1.10
3 1.43
4 1.76
5 2.11
6 2.46
7 2.81
8 3.17
9 3.54
10 3.91
11 4.30
12 4.72
13 5.18
14 5.73
15 6.43
16 7.38
17 8.72
18 10.69
18.5 12.00
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I'll most likely test my current-drive chip-amp on the FF225WK in SK8, as it's my second lowest Qms driver around. This faster aperture might be friendlier to it and should avoid excessive peaking at ~220Hz.
Freddi,
When you say reduce back chamber volume, do you want me to do it to driver chamber only below the shelf or overall below and above shelf? Still keep the shelf gap constant though right?
below and above = "overall" - maybe one-third to a half cubic foot reduction total on the 12" version run with 8 inch driver. you might not have to increase the rear shelf gap. A K12's rear chamber sometimes seems a bit large for some 8 inch drivers. I have a "K10" size coupler loaded with Delta 10B which seems pretty punchy (there's no front shelf nor would it likely help in a "K10" package) I picked the Delta 10s up on sale and think they can do the job
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little shed has one klam 18 - one 8 cubic foot coupler cut for 18 - one Karlsonette copy a single diy K15. Indoors = two Weiss klam8, two klam8 copies in plywood, two beat factory X15, two almost right X15 copies in plywood, two factory K12 with 4 - slot vent from the middle 1960's, 1-K8 from the mid 60s, two blonde K15 from the 1950's - two beat factory K15's , a pair of K15's from Martin Needleman (say G'nite Gracie - LOL) - one klam 15 try, two klam 10, one k8 in bad shape from the 1950's, one factory Karlsonette from ~1955, two factory K12 with 6-slit vent, two nice K12 copies, two more K12 copies with 6-slit vent, one tall and rather slender K18 , K-tubes. two tall SK8, one SK8, Art's dad's 8 inch couplers,
then there's a few horns and other junk. I need more Ks for sure (no kidding .. )
then there's a few horns and other junk. I need more Ks for sure (no kidding .. )
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From one of Freddi's old posts...
Smaller than K15, three angle upper chamber, extra holes, no front shelf...
I gather there is some kind of stubby KTube hidden inside the bigger one.
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Smaller than K15, three angle upper chamber, extra holes, no front shelf...
I gather there is some kind of stubby KTube hidden inside the bigger one.
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that would have been a pretty accurate copy but my kutter accidentally put the driver center 7/8" higher than spec. My factory X15 are IIRC, 19.25" wide, ~14" deep and about 28" tall. Acoustic Control's little 115BK with the large vent is 27" tall, 20.5" wide and 15" deep - but it's wings are inset about 1.5" so a 115BK copy without wings inset would be 13.5" deep. This family has about the same LF cutoff as factory K12 but I think cone excursion is less due to a lot more cone area.
Kenpeter is correct on that particular K-tube. Another set of X15 owned by Johny Holiday has tubes smaller in diameter and likely no internal gizmo.
here's Carl's clone of the 1.875" x 7.25" (overall length) K-tube from my set of X15 showing the internal scattering piece.
Kenpeter is correct on that particular K-tube. Another set of X15 owned by Johny Holiday has tubes smaller in diameter and likely no internal gizmo.
here's Carl's clone of the 1.875" x 7.25" (overall length) K-tube from my set of X15 showing the internal scattering piece.
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Carl, without access to the original X15 internal details made an X15 interpretation using the advertised dimensions of 15"D x 20"W x 28" high and also made a 9 inch long tube based on the tube that was used in my beat-up set of factory X15. For tuning and research, Carl's coupler had adjustable vent s and adjustable rear lowpass shelf-gap. In more recent builds he says a fully curved reflector improved the sound quality. Here's his early X15 build - the K-tube is mounted on the upper reflector board and tilted 30 degrees downwards.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
