Hmm, square wave clipping sounds like a good theory. I need to pull one of the receivers out to measure it today and look at how to bypass the volume control anyway so i can slave it to the other receiver anyway. I'll just bring that one out to garage to try.
Box volume was GM's recommendation, Vas/1.44. Smaller would certainly be nicer to deal with, but it raised the f3 and raised the box q as well. Of course all the wood is already cut for both boxes... i guess i could try backfilling this one to test reducing internal volume. My insulation is supposed to be here this week, so i'll reserve judgement til then...
Thanks guys
Box volume was GM's recommendation, Vas/1.44. Smaller would certainly be nicer to deal with, but it raised the f3 and raised the box q as well. Of course all the wood is already cut for both boxes... i guess i could try backfilling this one to test reducing internal volume. My insulation is supposed to be here this week, so i'll reserve judgement til then...
Thanks guys
that's a nice looking box and aspect. Here's a rough fudge of what that 18 would do stuffed into a K15 size K-coupler. For punch on drums and bass, the K would have an output and low excursion advantage. It would not hit the low pipe organ note fundamentals. Thankfully, music isn't pure sine. Maybe I'll ask xrk971 to do an XKi sim for this woofer.
https://i.imgur.com/iijQCDc.jpg
https://i.imgur.com/iijQCDc.jpg
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Update: Swapping to one of my receivers as an amp cleaned up the sound considerably. "Braaaappp" noise is gone, thankfully. Still quite boomy, but with some thump to back it up with at least. From the house, it sounds like someone has a car subwoofer going parked on the street (testing in detached garage, maybe 30 ft from my house).
Thanks Freddy, it looks okay i think, not great though. The acoustics in the garage are certainly different than living room... thats why I'm trying to reserve judgement.
The OSB is flexing a bit on sides and front/back, definitely needs bracing.
Another interesting note, the router with 3/8 roundover works fine on OSB, no chunking on test pieces i tried, went way smoother than expected. Cutting in the normal direction worked best.
The OSB is flexing a bit on sides and front/back, definitely needs bracing.
Another interesting note, the router with 3/8 roundover works fine on OSB, no chunking on test pieces i tried, went way smoother than expected. Cutting in the normal direction worked best.
that's cool the roundover works so well 
I've just looked at PA460's graph - whomever designs that line sure can get extended highs. It would probably sound pretty clear in a K18 like mine with a slotted tube tweeter mounted inside the cabinet (or on top) http://i.imgur.com/kMwSfs1.jpg
soprano and harp - generic xover 18" woofer (EVM18B) - can't remember the compression driver - probably an old/cheap Selenium Ti- YouTube
same cut with 6 inch L. Cao fullrange YouTube
I've just looked at PA460's graph - whomever designs that line sure can get extended highs. It would probably sound pretty clear in a K18 like mine with a slotted tube tweeter mounted inside the cabinet (or on top) http://i.imgur.com/kMwSfs1.jpgsoprano and harp - generic xover 18" woofer (EVM18B) - can't remember the compression driver - probably an old/cheap Selenium Ti- YouTube
same cut with 6 inch L. Cao fullrange YouTube
as you can tell, I kinda like Karlson boxes. Once, I compared 2-18"RJ boxes (6.4CF internal) and laid on their sides as stands, bi-amped to 2-FH1 (like 6" deeper Klipsch "Belle") sitting on top of the RJ. HF horns were large Peavey, to one/old/beat K15 Karlson topped with a 511 horn. I preferred the Karlson in general - lol.
A lot to like about BP alignments when limited to their design BW, so for recordings or systems where 'bass' only extends to 80 Hz before rolling off, the K15 is hard to beat for mid-bass/lower mids shot of a very large horn.
Design one for an octave or two lower for some serious bass, but then there's no mid-bass 'punch'/'slam'. Not many 'free lunches' in audio and why large multiple driver systems or compression horns are required to get both.
GM
Design one for an octave or two lower for some serious bass, but then there's no mid-bass 'punch'/'slam'. Not many 'free lunches' in audio and why large multiple driver systems or compression horns are required to get both.
GM
Garages are normally high tuned reflexes due to door leakage, so combined with hard surfaces, tend to be boom boxes all by themselves.
If OSB is obviously flexing, the driver is pressurizing the cab enough to probably be flexing too, so a double 'whammy' of conflicting amplitude modulation distortions.
Hopefully, stiffening the cab/mass loading the driver and properly placed in a decent room will smooth it out to perform as well as the sim implies.
Good to know, thanks!
GM
oh yeah - K live in the punch region. I think K15 is awfully ingenious to be made in 1951. K12 (with adequate power) can compete with smaller midbass horn. I like K12 better than my Klipschorns, although the K-horn can go an octave lower. Its certainly a matter of balance how one perceives "punch". A good 2-15 cabinet tuned 40 is one good way to have some usable bass. Try an electric bass with 1-15 vs 2. For whatever reason, or synergy with Altec 15s, K15 makes an excellent subwoofer tuned to ~30Hz and boosted at fb per Exemplar. (-got usable output to ~22Hz - sensitivity was high enough as was using one channel of a 25wpc JC Penny junk receiver)
at the time of Sound Practices, John Tucker said the re-tuned Karlson box was the only sub of modest size which could keep up with his Exemplar 2-way horn system. http://www.6moons.com/industryfeatures/vsac20082/exemplar2.jpg
at the time of Sound Practices, John Tucker said the re-tuned Karlson box was the only sub of modest size which could keep up with his Exemplar 2-way horn system. http://www.6moons.com/industryfeatures/vsac20082/exemplar2.jpg
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Thanks fellas, I'll be working on the bracing and insulation on the test cabinet this week and hopefully will get the cabinet into the house after that for some real testing with it in-room and on the active xo.
Freddy, I know I need to build one of your Karlsons someday... even if it's just so I can hear it and compare it!
Freddy, I know I need to build one of your Karlsons someday... even if it's just so I can hear it and compare it!
Hmmmm.
Punch to me is pressure.
Especially 250hz down.
Think of a bass guitar where fundamental under 100hz is like 20db down compared to first harmonic, other wise bass guitar players would lug around 20ft3 monster bass subwoofer cabs (maybe a bad example).
Larger cone area or smaller the room, the more punch you "feel".
My 10" has a bit of punch 4' away, while double 15's seem to punch 20' away in my big letter L shaped room.
I'm still wrestling with getting a good description.
Punch to me is pressure.
Especially 250hz down.
Think of a bass guitar where fundamental under 100hz is like 20db down compared to first harmonic, other wise bass guitar players would lug around 20ft3 monster bass subwoofer cabs (maybe a bad example).
Larger cone area or smaller the room, the more punch you "feel".
My 10" has a bit of punch 4' away, while double 15's seem to punch 20' away in my big letter L shaped room.
I'm still wrestling with getting a good description.
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my two different K18, although not going "low", seemed to have some punch. One ~42 inches tall, one 32". The tall cabinet has no front shelf - the shorter box probably had too deep a front cavity, so benefited a bit from a front shelf. Even at low levels, there's some feeling of power. A taiko drum whack at 300W or more was fun for guests.
I think 8 cubic foot external bulk is just enough to get a punchy little K18 (18" have been stuffed into K15 whihc is 7.3CF external) xrk971 will sometime work out an :XKi" alignment for PA460-8. That will probably go deeper than a traditional K as there will be more back chamber and less front chamber for a given bulk.
I think 8 cubic foot external bulk is just enough to get a punchy little K18 (18" have been stuffed into K15 whihc is 7.3CF external) xrk971 will sometime work out an :XKi" alignment for PA460-8. That will probably go deeper than a traditional K as there will be more back chamber and less front chamber for a given bulk.
Right, boost in the ~100-160 Hz BW to enhance/compensate for source and/or in room speaker response deficiencies. Boosting higher increases 'warmth' out to ~250 Hz, so BL, mid-bass horns, K15 or similar or just multiple low Qt prosound woofers are good choices.
For 'kick' when room gain isn't helping [enough], center the boost around 50 Hz.
GM
I know its not the correct thing to do, but sometimes its helpful with a vented cabinet to be able to adjust box or system tuning "to taste" (within limits of what can really be done) - this can sometimes "voice" a speaker without significantly changing the low end shape or cutoff.
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