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RE: besides shellac don't forget to try sidewall refleKtors -- LOADING

Posted by freddyi (A) on September 1, 2007 at 07:42:05

In Reply to: RE: besides shellac don't forget to try sidewall refleKtors posted by kenpeter on August 31, 2007 at 20:41:35:

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 Know - - - - hahahahahaha

K12 propaganda 1955

rear choke 1955 K12

rear choke bar on Karlsonette K12 - I like that coupler

Edits: 09/01/07 09/01/07

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