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In Reply to: RE: besides shellac don't forget to try sidewall refleKtors posted by freddyi on August 31, 2007 at 07:36:34
And I after I warned you bout them oversized TP rolls?Actually, the concrete forming tube is amazingly dead
for as lightweight as it is. No tendancy to ring like
a bell. And striking mine gives a percussive sound of
no particular color. Perhaps a little warm in the low.I don't think I would build anything intended to last
with one. But for experiments, can't beat the price.-----------------------------------------------------
Actually, I was thinking, if you fold the 1/4 wave
over and start cutting the narrow end of the slot
over the top and down the back over the cabinet.
Or instead to fire forward into the other half and
again once more through the wider end of the slot...
Words are useless, probably need to draw a picture.
Edits: 08/31/07Follow Ups:
when building K-type and going tall at some point, one might get a hybrid of t-line and lose some coupled-cavity hump/kick.
if the vertical divider is perpendicular then there may be less projection than using mild forwards cant(?)
most woofers in Karlson's time had low mass and more expensive examples low qes.
Carl who imo is "sekretive" with regards to sharing data (I don't think he thinks regular methods show transient response) must dump a lot of time and $ into CNC wings, etc. - - his K10 with Scan-Speak might have 3/4 or so cubic foot rear chamber
if your wood is still usable, maybe you can make some sorta funky K type which will be a bit better than the first try (?)
A picture was the only way...
Just wasn't going to get there by describing...
Anyways, its only a thought. Not a plan.
that's pretty wild - Klang & Ton (I think - ?) featured a k-t-line with two slotted apertures - - easiest build (with little path length) would be diagonal baffle holding speaker, front slot with ~1/2" gap at top and let it sailK's Fig one from ~1955
Is the back cavity part of the transmission line (smooth
continuation of the tapered Koupler at the front), or is
the back cavity severely choked, as-if a tuned port box?I see trouble if the back were extremely broadband and
allowed to mix with the frontwave out of phase. I think
this is why the resistive port may be used on the 12 or
perhaps the shelf on the 15. Acoustic low pass filter.
Doubt the front of a K15's cone is loaded nearly as much
as the back when the baffle is so near the open end.
And Karlson's design conspires to blend them only over
a transitional range where both phases are compatible.I see a tuned port. Tuned a bit low, so there is perhaps
a big peak in low bass and dip in mid bass before the
front wave takes over loading the cone. Then the Karlson
loading is a bandpass boost to restore the midbass range.
Low cutoff set by 1/4 wavelength of the guide, and high
cutoff (for the back cavity only) set by the tuned port.
There is no such high cutoff for front side K loading,
but coupling is rather weak due to the placement near
the open end. Does this make any sense? Am I missing
something?There should be no such complication with the Rocket, all
fed from the same end. And K loaded over the full bandwidth.
But it would be far more directional at highest frequency.
And thats another kind of a complication...
I'm not sure what happens - thers only so much airspace, with vented coupler a 3rd Z peak will occur around 300Hz for K8;200Hz for K12, 155Hz for K15 and a coupled cavity peak may occur depending upon parameters and coupler.Theres not much rear chamber in K12 compared to cone area. X15 and Acoustic Control's little 115BK (apparently derived from Transylvania Power"s "KHYBOE" coupler were like "widened K12" and lost ~1/2 octave LF due to only ~2 cubic foot rear chamber vs K15. Tapped horn/whatever good sub would help the little K-couplers
The first K12 with a 15/16" high vent compared to 6-slit vent model shows about 1.5dB more output from 80-200Hz. The slit vent may sound better under conditions such as repeating double-kick-drum. Vent position will alter graphs somewhat. Theres mechanical reverb.
K12 with slits has two boards which give 0.5Sd constriction- - the first K12 had a movable choke board)
slit vents lose support of sine wave and seem to push up air velocity yet may sound cleaner on transients.
K15's front shelf partially offsets a 250Hz null, adds a boundary to the vent and deflects some HF from the top of the coupler. Take the front shelf out and it will sound different in character. Theres certain angles which give less null on graphs.
Here's an 18" K without any shelf or lowpass choke at 20vrms vs a commercial front load pipehorn - - a rear lowpass might help it play transients better. Putting 18" in K15 size gave about the same response as 15 and like K of that siae theres some "wow" factor when they're hit with 60-300W peaks - theres a nice subjective shockwave
M151 in 50Hz reflex the size of K15's rear chamber had a lot more cone excursion and vent velocity at 36Hz/20vrms than M151 in K15. Beta 15CX in same reflex vs K15 had 10dB reduction of sidebands of 32Hz mixed 1:1 with 160Hz vs that reflex.
8 cubic foot (32"H x 21.5"W x 20" D)18" coupler vs Yorkville USC1 pipehorn 50Hz/20vrms sine
K15 in RCA-Fan halfhorn - direct radiator "clearer" - K15 much less cone excursion on big drums but tuned higher Fb - wise
K15 with good coax or stuff on top ain't too shabby -- I think new couplers could be built with different tonal center but due to health reasons don't have good saw setup to piddle with the things.
X15 could get hellish with its "reverb" it must be partly a matter of adjusting the partitions distance to wings
re:Rocket & asymmetric projector -- I think bulk for bulk they load "about the same" (?) - - theres not enough K-experimenters and some of those are pretty weird about sharing result and data :^) better measuring methods might be konkocted.
hell if I K now - - - - hahahahahaha
K12 propaganda 1955
rear choke 1955 K12
rear choke bar on Karlsonette K12 - I like that coupler
You may kneed a pair of sunglasses with K-tubes to kover both ears...
.
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