Pretty neat design XRK971!
The form-factor reminds me of something I was working on a couple of years back, which was basically a shorter SK8, dubbed mini-SK8 (originality!). It was also meant for pro 8" woofers or coax. Depth is 12" and width 13.5", as with SK8; I forget height, probably ~16" or so. Proportions are correct on the below draft in any case.
I went for simplification of most involved principles - as I could see them, thus the venting scheme "driving" the same point as the driver in the front stub "air column". I had also thought of rear venting the top-shelf much like you did here, but not quite as long. I wasn't going so much for bass extension as efficiency above ~80Hz. IIRC, sims looked decent for FF225WK, Beta 8cx and 8A as well as various B&C units. I noticed how SK8 was too big for many pro 8", so reduced the rear Vb, but folded the stub back to try and keep the ~200Hz front tuning. I never built a prototype.
I did try a long-vent modification in my actual SK8, but it turned out disastrous IMO.
The form-factor reminds me of something I was working on a couple of years back, which was basically a shorter SK8, dubbed mini-SK8 (originality!). It was also meant for pro 8" woofers or coax. Depth is 12" and width 13.5", as with SK8; I forget height, probably ~16" or so. Proportions are correct on the below draft in any case.
I went for simplification of most involved principles - as I could see them, thus the venting scheme "driving" the same point as the driver in the front stub "air column". I had also thought of rear venting the top-shelf much like you did here, but not quite as long. I wasn't going so much for bass extension as efficiency above ~80Hz. IIRC, sims looked decent for FF225WK, Beta 8cx and 8A as well as various B&C units. I noticed how SK8 was too big for many pro 8", so reduced the rear Vb, but folded the stub back to try and keep the ~200Hz front tuning. I never built a prototype.
I did try a long-vent modification in my actual SK8, but it turned out disastrous IMO.
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hey X - hope there's some readers who open those clips = "very nice" on Fick, Wagoner - I like the "reference speaker" (?) and the Beta8cx XKi does nicely against it - that track is unfamiliar and not dead "dry" sounding. Both slap bass examples are very good for recording from a loudspeaker and sound dynamic/forceful and without obvious smearing or distortion. Slapped bass is a good metric for judging loudspeakers as is bowed bass. Some speakers will just "drone" one-note-ish on bowed bass.
there is good extension from this little Beta8cx box - far better than Karlson's similar bulk K, better than the "SK8", probably better than typical K12 and possibly deeper in reach than K15. Would a Beta10cx version be as good? I know the fullrange crowd are scared of coaxial and also of Karlson.
a comparison of how speakers fare on the Fick track could be interesting. I've not heard reflexes nor my only example of a blh fare very well vs a decent K. (K15 can be very good) The blh sounds "delayed" as if the direct radiator contribution is not in phase with the mouth.
Between GregB's Karlsonator and XRK971's work, we're getting some new mileage from K-tech.
hey IG81 - good to "see you" - that squat box was close in form factor. Hopefully some more will spawn from XRK971's pioneering work.
SK81 was pretty good sounding - it had a typical behavior. The XKi family seems to have another with little "W" in the mid pass band. It would be interesting to see a larger example of the XKi with a deeper cavity to get more idea what may happen.
there is good extension from this little Beta8cx box - far better than Karlson's similar bulk K, better than the "SK8", probably better than typical K12 and possibly deeper in reach than K15. Would a Beta10cx version be as good? I know the fullrange crowd are scared of coaxial and also of Karlson.
a comparison of how speakers fare on the Fick track could be interesting. I've not heard reflexes nor my only example of a blh fare very well vs a decent K. (K15 can be very good) The blh sounds "delayed" as if the direct radiator contribution is not in phase with the mouth.
Between GregB's Karlsonator and XRK971's work, we're getting some new mileage from K-tech.
hey IG81 - good to "see you" - that squat box was close in form factor. Hopefully some more will spawn from XRK971's pioneering work.
SK81 was pretty good sounding - it had a typical behavior. The XKi family seems to have another with little "W" in the mid pass band. It would be interesting to see a larger example of the XKi with a deeper cavity to get more idea what may happen.
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Hi IG81,
Thanks for the kind words! You look like you were about to go down the same path as me. In your drawing there is a stub in the upper outer chanber. Would that not cause a echoing effect? Your two side by side vents are similar though - just not as long. In a way both resemble an RJ in some respects.
I found out the hard way that a long vent on the larger 8in causes a massive cancellation dip. So the trick is to keep it 6in or under. Unless you are using as just a bass or sub then vent can be extended for best bass performance below upper cutoff notch.
You have foam core and built a great BLH for the FF85WK. Give your K creations a try!
I was surprised how well it stands up against the reference speaker (which has way more dynamic range if you look at the sound on a graph in Audacity). But it sounds amazingly similar - not as loud and percussions are not quite as clean, but a very good performance compared to a 30in wide synergy sitting on top of a large folded bass horn in a 3 way system.
Same here!
Hi IG81,
Thanks for the kind words! You look like you were about to go down the same path as me. In your drawing there is a stub in the upper outer chanber. Would that not cause a echoing effect? Your two side by side vents are similar though - just not as long. In a way both resemble an RJ in some respects.
I found out the hard way that a long vent on the larger 8in causes a massive cancellation dip. So the trick is to keep it 6in or under. Unless you are using as just a bass or sub then vent can be extended for best bass performance below upper cutoff notch.
You have foam core and built a great BLH for the FF85WK. Give your K creations a try!
The fold-back may make for some funky effects higher in the midrange, an actual implementation would best confirm that I suppose. I was hoping to conserve the full vertical height as seen by lower frequencies, which would not care about the bend.
If that little stubby XKi of yours can do some useful bass, that is indeed cool!
I haven't had a mind to do much audio experimentation for some time, but I'm sure it'll come back and I may yet try a few stashed ideas. The Nagaoka-inspired 3/4-wave pipe for FF85WK seemed promising enough when I foame-cored a cruder implementation then what last drafted.
a small wad of polyfil in the foldback portion would probably kill any tendency to honk plus can aid to smooth ripple. Metro's T15 stub (if made like their depiction) has a vent smack in the middle of the length so may behave differently.
An externally hosted image should be here but it was not working when we last tested it.
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if there are any older readers, some of this might be nick-named in honor of a once-well known actor Stubby Kaye - Wikipedia, the free encyclopedia
Stubby Kaye - Wikipedia, the free encyclopedia
XRK, could you post a quick drawing of the changes you made to the Eminence 8CX beta box to improve the sound?
As I understand it, effectively you shortened by cutting some holes in the back vertical part of the port, and halved the size of the front port with some foam, and also put behind the speaker some foam pieces. (but I'm not sure where)
As I understand it, effectively you shortened by cutting some holes in the back vertical part of the port, and halved the size of the front port with some foam, and also put behind the speaker some foam pieces. (but I'm not sure where)
I basically cut out pieces of FC and stacked to match vent gap and put one to each side of vent at the top to reduce cross sectional area by factor of two. Then I cut rectangles about width of remaining vent (5in wide) x 2in tall total cross sectional area on back vent wall. I could barely reach through driver cutout to do this. The idea is to reduce area by 2 and length by 2. If built from scratch just make vent about 10in wide x 0.375in high x 6in long. Or 5in wide x 0.75in high x 6in long.
Here is sketch (not to scale) showing where foam was added and where window was cut.
Attachments
Did it work?? It seems like you are fighting an anomaly of the driver primarily, but by an unfortunate coincidence the SKi has a small dip at the same spot.
A reflection from a surface ~3.25" away would cause a null at 1khz. Any likely suspects? Could it be the wings, or the sidewalls?
Hey IG! Did you decide to finally take a break from fishing?
It's funny how modest differences in folding/geometry really matter in these things. I recently found my original Karlsonator folding sims, which looked a lot worse than your long vent modification. It took a few tries...
The SK8 -- for those of you that did not hang out in the Karlson subsection of the old fullrangedriver.com forum -- was a modestly stretched modification of the original Karlson 8 design of the 60's. It was more or less designed by committee when we all realized the original had a 'stub' that was too short.
Yes, back on post 147 I discussed improvement. I dealt with reflection (if that was part of the problem) from sidewall with foam on back chamber. The vent length reduced dip by ahout 8dB. I suspect it was not sidewall and will check by removing foam at some point. Interestingly, the added foam increased harmonic distortion so I want to get rid of it if not needed.
Here is result from post 147. Sounds great now.
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Hey IG! Did you decide to finally take a break from fishing?
Already looking forward to next season! I've been more into winemaking than audio so far this fall/winter and having moved into a house has that tendency to keep one busy as well.
I hope a wood version works as well and sounds as good ! - am starting to think FC is where "its at" (less reflective and resonant problems) how come the bass goes so low on this tiny cabinet??? At 10dB per vertical division, the adjusted cabinet is doing very well graph-wise. A bigger brother could be cool if could just play louder/cleaner and not go any lower.
here are two reasonably well known direct radiators outdoors and on axis with speaker elevated but near a "back wall" - the Nirvana sounds like a mix of its on and off axis graph - about as listenable as a direct radiator as a circular saw. (to me Super10 was better in K15 and Karlsonator12 with the latter winning for bass neutrality) The Advent is mellow but has a decent tweeter. I've got a 12PE32 in a K12 built by GregB with a K-tube on top - must be 13 dB louder than the Advent plus the little Karlson sounds pretty good.
(less reflective and resonant problems) how come the bass goes so low on this tiny cabinet??? At 10dB per vertical division, the adjusted cabinet is doing very well graph-wise. A bigger brother could be cool if could just play louder/cleaner and not go any lower.here are two reasonably well known direct radiators outdoors and on axis with speaker elevated but near a "back wall" - the Nirvana sounds like a mix of its on and off axis graph - about as listenable as a direct radiator as a circular saw. (to me Super10 was better in K15 and Karlsonator12 with the latter winning for bass neutrality) The Advent is mellow but has a decent tweeter. I've got a 12PE32 in a K12 built by GregB with a K-tube on top - must be 13 dB louder than the Advent plus the little Karlson sounds pretty good.
An externally hosted image should be here but it was not working when we last tested it.
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Freddi,
You may have pointed out a great advantage of foam core is its self damping abilities. It may be why I was able to use a very high Qts Vifa TC9FD in so many non high Qts alignments like a BLH, FLH, DCR, MLTL, TQWT, etc they all work and don't sound peaky. One neat thing is to use as a re-radiator on the K-aperture - it can smooth out an otherwise jagged response.
You may have pointed out a great advantage of foam core is its self damping abilities. It may be why I was able to use a very high Qts Vifa TC9FD in so many non high Qts alignments like a BLH, FLH, DCR, MLTL, TQWT, etc they all work and don't sound peaky. One neat thing is to use as a re-radiator on the K-aperture - it can smooth out an otherwise jagged response.
Ah, obviously I missed that one.
This thread has grown fast. Yeah, there's something to be said for lossy panel construction in some cases.
Another interesting phenomenon to explore is the effect of grill cloth over the slots of K variants. I wonder if it acts as a semi transparent passive radiator? After lots of tweaking, I ended up with grill cloth on the front of my mini karlsonators. It really cleared up the midrange, and required very minimal felt in the interior front chamber, compared to what was in there earlier. How it seems to subjectively get rid of reverby coloration inside is unclear.