1)3) Brain exercise is good, but don't turn your brain into mush over a cabinet design that has already been optimized, and can't be accurately simulated with Hornresp!
LOL, remember my original purpose was to find out why measured Fb was higher than the sim. And from the sim, it looks like mouth size vs. cabinet volume might be the key. The volume at the back of the horn is smaller than it should be, which could partly explain the smaller mouth you ended up having to use to achieve a lower Fb.
After messing around with the layout a bit, if the cabinet depth is extended to 24" and the internal panels re-arranged slightly as per diagram below, mouth size can be extended to 300 sq.in. and Fb will be about 32 Hz. Of course what the passband response looks like will be entirely dependent on the placement and shape of said mouth...
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Real world numbers for box sizes?
I'm watching but appreciate real world applications a bit more than most guys.
Yeah, I've been running a few sims on some other TH folds that I've transcribed to workbooks to see what could optimally fit in a box that's 45" x 22.5" x 26.5", and apart from one that had an Fb down at 24 Hz and could hit just under 130dB but would require 180V to do so, I haven't come across much. Art has done some horn alchemy with the KS
.I just though of a new TH fold though that might work though, and it can be KS'd too, and it places the driver at the bottom of the box which should make it slightly more stable (or a bit less prone to damage if the box is tipped). Roughly drawn out it looks like it might work, but I'll to do a bit more workbook-warrioring to see if it will work....
The screenshot below shows the raw response of the 48” tall Keystone B-Low cabinets, the B18 loaded with an 18” B&C18TBW100-4, the Key B15 loaded with a 15” Dayton PA385S-8. The “S” designation is using the “step down” exit cover plate which lowers the Fb from 32Hz to 31Hz.
The drive level was the same for both drivers, the 15” being an 8 ohm driver gets half the power as the 4 ohm 18”, therefore has been raised by 3 dB on the screenshot. The overall sensitivity of each driver is quite similar down to 35 Hz, the B&C 18 +2dB at 30Hz. The B&C driver has more excursion and power handling, so can play louder and cleaner than the Dayton, but the 15” works better than expected.
Art
The drive level was the same for both drivers, the 15” being an 8 ohm driver gets half the power as the 4 ohm 18”, therefore has been raised by 3 dB on the screenshot. The overall sensitivity of each driver is quite similar down to 35 Hz, the B&C 18 +2dB at 30Hz. The B&C driver has more excursion and power handling, so can play louder and cleaner than the Dayton, but the 15” works better than expected.
Art
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The sound is great, but have not done any high power testing since the initial listening test was stopped after a neighbor came over with complaints of her windows rattling and chest hurting.
I would like to do some high power distortion testing, but that won't be happening until I can find an alternate test site.
It appears the band pass effect from the step-down cover also reduces harmonic distortion by around 36%.
Art
I been trying a lot of different constellations with my 4 keystones, indoor and outdoor.
This weekend im going to setup in a semi open dome (15 Meters diameter)
Last time i was outdoor i put all 4 keystones together and 4 HD15 kicks om top and spread the tops around.
I felt the bass didnt spread to much.
Was extremely focused straigh forward but not to much to the sides.
So my question is:
If i want to "open" up a bit the spread of the bass
How far distance would be appropriate to have in between the subs if i kind of line them up in a curve 1 next to the other or maybe 2 and 2?
Any inputs/suggestions/ideas are welcome.
Thx
This weekend im going to setup in a semi open dome (15 Meters diameter)
Last time i was outdoor i put all 4 keystones together and 4 HD15 kicks om top and spread the tops around.
I felt the bass didnt spread to much.
Was extremely focused straigh forward but not to much to the sides.
So my question is:
If i want to "open" up a bit the spread of the bass
How far distance would be appropriate to have in between the subs if i kind of line them up in a curve 1 next to the other or maybe 2 and 2?
Any inputs/suggestions/ideas are welcome.
Thx
If you x-over at 100 hz, make it 80 cm between the cabs to follow 1/4wave rule. You can also increase horizontal dispersion by either delaying the outer pair a few mS or place them 20-40 cm behind the front pair.
I have only tried physically delaying the subs but it has been a very good cure for the "extremely focused straight forward" sound a horizontal sub stack can yield(other sub cabs tho)
I have only tried physically delaying the subs but it has been a very good cure for the "extremely focused straight forward" sound a horizontal sub stack can yield(other sub cabs tho)
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A while back (with smaller THs, indoor), we set up four subs next to each other, but with the cabs pointing slightly away from each other, back corners touching. Seemed to spread the sound around evenly, but remember it was indoors (specific room dimensions/qualities), so your results may vary.
spread sound
Hi there C: You have setup a horizontal array approximately 100 inches wide, with 3 gaps between units. Possibly adding barn doors on the outside and fills between the cabinets could improve the spread. Anyone tried laying these cabinets on their sides? This configuration would provide at least a 16 foot front before doing the curve layout with fills and wings. ...regards, Michael
Hi there C: You have setup a horizontal array approximately 100 inches wide, with 3 gaps between units. Possibly adding barn doors on the outside and fills between the cabinets could improve the spread. Anyone tried laying these cabinets on their sides? This configuration would provide at least a 16 foot front before doing the curve layout with fills and wings. ...regards, Michael
LOL, remember my original purpose was to find out why measured Fb was higher than the sim. And from the sim, it looks like mouth size vs. cabinet volume might be the key. The volume at the back of the horn is smaller than it should be, which could partly explain the smaller mouth you ended up having to use to achieve a lower Fb.
After messing around with the layout a bit, if the cabinet depth is extended to 24" and the internal panels re-arranged slightly as per diagram below, mouth size can be extended to 300 sq.in. and Fb will be about 32 Hz. Of course what the passband response looks like will be entirely dependent on the placement and shape of said mouth...
Brian this intrigues me as I would like to get a flat response as close to 30 hz as I can. 35hz Flat would be fine as well. Any idea what sort of maximum spl your revised keystone loses to a traditional keystone?
Art, do you have any guidance on getting a little more extension than your current BLow design?
Same guidance as in post #1135:
Although I am happy with the response of the Keystone B-Low for the type of music I prefer to work with, if heavy output below 40 Hz is what you are looking for, Josh Ricci’s Othorn, Gjallerhorn, or Skhorn are still the way to go if you can afford it.
Art
Art,
I was all ready to build the Othorn and did a lot of research on it. Then in my reading i found Scientifics post where he had built an xo1c, a keystone, and an othorn. He said the othorn had good extension, but was not impressed by its spl or sound. He recommended TB46's TH18Sc in the flat to 35 for $325 thread. Then i raninto some people preferring the FT-30 design. I know it comes down to personal preference and sound taste for lots of people, but i do enjoy hearing reviews from people who have heard the subs in person. I do know I love the fast response/impact/ attack of the keystone. I also love its slim profile. So i am tempted to try brians lower keystone. Eventually i will have 20 different subs and have a listening party haha.
I was all ready to build the Othorn and did a lot of research on it. Then in my reading i found Scientifics post where he had built an xo1c, a keystone, and an othorn. He said the othorn had good extension, but was not impressed by its spl or sound. He recommended TB46's TH18Sc in the flat to 35 for $325 thread. Then i raninto some people preferring the FT-30 design. I know it comes down to personal preference and sound taste for lots of people, but i do enjoy hearing reviews from people who have heard the subs in person. I do know I love the fast response/impact/ attack of the keystone. I also love its slim profile. So i am tempted to try brians lower keystone. Eventually i will have 20 different subs and have a listening party haha.