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In Reply to: RE: Electro-Voice 12TRXB triaxial speaker in cabinet posted by mjcmt on March 07, 2016 at 15:36:41
FWIW, using the attached specs:
A 60" h x [w x d] = 117.96"^2 [not much bigger than the driver] sealed tower with the driver down 25.2" sims +/- 2 dB [with typical internal damping] from 50 Hz - up in the cab's pass-band in half space, so up against a wall will easily get down another half octave.
All dims inside [i.d.] and approximate. Due to its high aspect ratio, use [heavy] adjustable base to dial in the tweeter/seated ear height. Adding a heavy top or potted plant is a good plan too.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
Follow Ups:
Based on the theil small parameters you gave me and this enclosed link for a 1/4 wave flared vent cabinet...http://dbdynamixaudio.com/quarter-wave-flared-vent-t-line-horn-bass-reflex-enclosure-calculator/
...I was able to calculate a 36"h x 14"w x 16.5"d folded horn cabinet with 34hz tuning point. The port is on the bottom and driver on the top. (Their drawing shows it laying on it's side.)
What do you think?
I do have one question, which theil small paramater is the driver displacement? I plugged in Qes in their calculator.
Edits: 03/20/16 03/20/16
Dunno, post the worksheet results if it doesn't closely match what I simmed in Hornresp.
Historically, driver displacement [Vd] = Sd*Xmax = 535 cm^2*0.33 cm = 176.55 cm^3, but it appears he means driver volume displacement [Vid], so best guess is same period 12" Altec's ~0.15 ft^3/4.25 L.
Qes is the motor's effective motor strength: http://www.eminence.com/support/understanding-loudspeaker-data/
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
thanks for the dictionary
The ported cabinet that came with the speaker is 6 cu ft, which corresponds to the 167 liter vas of your Theil specs.
Could I just build a new tower cabinet with the same internal volume and same port volume that the cabinet now has? But with the slotted port at the bottom of the cabinet and the driver mounted higher at ear level.
Sure! 'Bigger is Better' [BIB] :^)
Due to its 1/4 WL pipe loading though, the vent probably can be a bit smaller; with the existing 60" height, but with a [w x d] = ~170", Hornresp sims a 83"^2 x 3/4" long [baffle thickness] vent for a ~Fs tuning.
This may be too much bass if near/at a wall or corner so may need to close it up to as little as 7"^2 [3" dia.] if there's much floor loading with a bottom firing vent.
Another consideration is that with the driver up high and the vent out the bottom, this will cause a fairly big notch in the lower mids, so might want to put it on the baffle centered in the 48" - 51.5" [i.d.] range down the pipe.
BTW, what is the [average] tweeter/seated ear height or is my guess good enough for you to make work?
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
Another solution is to build an angled front, tilting backward from the bottom to the top. This would allow you to mount the driver lower, but still be more-or-less on the axis of the tweeter output. My current speakers use E-V T350 tweeters. I have the boxes tipped backward against the wall, about 25 degrees. The center of the tweeter is about 22" from the floor. This provides great direct sound, as well as providing a better ambient sound since more of the HF energy gets around the room rather than being immediately absorbed by the carpeting and furniture. My next speakers will have tilted front baffles.:)
Edits: 03/15/16
Agreed; my preference for point source drivers and use to recommend it, but I finally gave up years ago as no one TTBOMK would 'go the extra mile' woodworking wise.
Ditto building triangular shaped cabs, even when corner loaded was planned [with one notable exception]!
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
What the heck is TTBOMK?
:)
One of the first net lingo acronyms I was confronted with when I got on-line in '96:
TTBOMK - To The Best Of My Knowledge
Online jargon, also known as text message shorthand, used primarily in texting, online... - See more at: http://www.netlingo.com/search.php#sthash.sw6YRHzD.dpuf
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
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