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New sub design? Constricted Transflex, simple build (series tuned 6th order)
New sub design? Constricted Transflex, simple build (series tuned 6th order)
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Old 27th August 2014, 09:27 PM   #551
sabaspeed521 is offline sabaspeed521  United States
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For those who may be interested in folding this for fun. I'm going to work on a basic fold for this beast. ~7 cu. ft. internal volume, 128 dB in the power band, 2 sws 12's HP at 30 Hz. Mouth velocity is 11.75 M/s peak at full power at 36 hz. This will be end firing most likely to avoid too much air compression at the mouth.

I realized that this driver doesn't model well unless used in pairs (in a TH or by association a pipe alignment) so this is a single cabinet with the highest output to size I've seen in a while (perhaps someone knows of something even more output to size they can link ). Usable to 30 Hz in a corner, flat to f3 at 33 freestanding. There is a 20% larger version that gets .7 dB more on average but I thought that's not enough to justify the size. This will likely be 18 inches deep ~48 tall 18 wide or something. Still haven't calculated anything so don't quote me on that. I'll aim to keep it to 48 for cheap wood cost. Removable back panel (or partial) is likely needed to mount the drivers here.


For reference, my 46 tall pipe design doubled up (2 woofers vs 2 woofers) is 2-3 dB less output from 45-85, with more output at 35 (althought that would most likely be EQ'ed down)),
This is 260 L internal (which because they are separate there two extra side panels worth of width that isn't looked at here -- internal volume reported).
The Horn is 200 L internal (30%less) and more output on average and wayyy flatter.

I may just have to buy me another driver...

Last edited by sabaspeed521; 27th August 2014 at 09:51 PM.
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Old 27th August 2014, 11:27 PM   #552
Matthew Morgan J is offline Matthew Morgan J  United States
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Exclamation FINAL VERSION OF THE ML-TRANSFLEX FOR THE LAB15(SPECIAL)! DETAILS AND COLLAGE

Here is ML-Transflex for Lab15 (special) version 3.1

The Tapped, Squeezed and refolded remix ... better than ever ...

Ready to go shopping for ply BeauB?



Path length in this box turned out better than i thought! Width had to be increased in order to offset airspace taken up by internal panels while also maintaining path area and lengths to match the HR model, but it is all worked out now

Around 7 foot of path length with the mass loading puts our FB right at 35hz ...

If i were a salesman i suppose the selling points would be much like before and they are as follows :

(for more enjoyment just imagine the following spoken by a high energy guy with an infomercial voice and a terrible suit, because it is better that way)
  • Great output and extension down to the fundamental, meets rated linear excursion of this driver right at it's thermal power rating of 600 watts! So it is very well balanced in terms of well matched mechanical and thermal limits..
  • Designed with 3/4" material in mind. Internal volume taken up by panels is compensated for, and then some (add 1/2 inch holed ply braces to the back panel and bottom panel if you like) .
  • Driver fits into this box revision easily with some additional room to spare .. Easy access to driver... No removable panel required.
  • Magnet in mouth (especially being the high velocity end of the pipe) provides superior motor cooling which results in less thermal compression, longer life and more output!
  • Group delay , velocity, and phase response are all kept within acceptable bounds throughout the working range ..
  • 32hz to 150hz useable response (3db down at 32hz with single cabinet)
  • Very easy to add or experiment with optional damping and filling materials..
  • Simple design, easy to build, reoccurring measurements throughout! , no difficult angles and no intricate woodwork involved... No wasted internal space ..Very efficient use of cabinet volume.. Thanks to Greg B and his Karlsonator for the fold inspiration ..
  • acoustically shortened path by use of a mass loading constriction, which is a long vent at 50% of the main pipe's area, velocity at the port should not ever exceed 20 m/s in worst case scenario in the real world, with full power applied.(calculated by multiplying the velocity at mouth (*2 for the 2:1 mouth/port area ratio)
  • Very affordable driver and low build cost for this class of performance


If anyone makes the mistake of sending me three easy payments of 19.95 + S & H i will probably just keep the money and refer them to this post, or maybe i will send them my used "Super Shamwow", or a used food dehydrator, or a bottle of spray paint for your bald spot ........ but i am keeping the George Foreman Grill dammit! ...

Last edited by Matthew Morgan J; 27th August 2014 at 11:47 PM.
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Old 28th August 2014, 12:05 AM   #553
zettairyouiki is offline zettairyouiki  United States
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You're simming with an Le of 3.00. The Eminence spec sheet says it's 1.60. Oversight or intentional?
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Old 28th August 2014, 12:29 AM   #554
GM is offline GM  United States
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I'm confused, plugging these specs into HR = ~63.297 L with a very narrow under-damped alignment centered at ~147 Hz.

GM
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Old 28th August 2014, 02:04 AM   #555
Matthew Morgan J is offline Matthew Morgan J  United States
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Quote:
Originally Posted by zettairyouiki View Post
You're simming with an Le of 3.00. The Eminence spec sheet says it's 1.60. Oversight or intentional?

Zetta ,
It is intentional .... I read about it for a while here on DIYaudio ...
It has been used by others as a way to get a better idea of what the real world measured response will be.... Many folks including myself have observed that if an alignment in HR sim looks underdamped (peak at FB and a saddle shaped response), then the box built from that same exact design will often not show that characteristic saddle curve when the cabinet is actually measured, it may be due to losses, or something about the way LE has more influence on damping down low.. I have heard a few theories about why the measured response looks smoother in these cases and i have no idea which theory is correct, maybe some combination , or maybe something else altogether *shrug*... Some folks were as much as doubling the LE figure to simulate the phenomenon with success...... So i use it .... Seems to help approximate real life , but like my RE method, its not a perfect solution , just something that helps ..

Luckily with this box ( the version 3.1 cabinet in the sketch) if more damping is needed based on the measurement it is convenient enough to add or remove some stuffing to the first third of the path just by pulling the driver out (which should be easy enough to access with this design's rather shallow mouth , its only about 7 inches deep, if it were any shallower the magnet would stick out!) ...
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Old 28th August 2014, 02:27 AM   #556
Matthew Morgan J is offline Matthew Morgan J  United States
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Quote:
Originally Posted by GM View Post
I'm confused, plugging these specs into HR = ~63.297 L with a very narrow under-damped alignment centered at ~147 Hz.

GM
GM ,
Make sure HR is using "throat chamber" which you can find by going to main input-page / tools / chamber type ...

Also be sure to enter the Ap1 , Lpt, Vtc and Atc values ... This box relies heavily upon a large throat chamber with a long pipe-like aspect ratio (60+ cm @ 824 cm sq) connected to a long port with half the sq cm area, then it opens back up where the tap and mouth are (S1 through S5) ... ....The use of the large throat chamber in HR re-purposed like a pipe was just a workaround in order to create the shape and sections that were needed , otherwise it is not possible in HR .... The chamber/pipe , port , and final pipe sections strung together in series work well as a resonant system ... Although admittedly the "schematic" view does look really weird...

In Akabak (which i understand is more configurable) I am sure that this first section could just be simmed with just regular pipe segments before the squeezed down section , our port (412 cm sq @ 50cm) and then after that it feeds a larger area at the tap/mouth .....

Last edited by Matthew Morgan J; 28th August 2014 at 02:39 AM.
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Old 28th August 2014, 02:36 AM   #557
Brian Steele is offline Brian Steele  Grenada
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Quote:
Originally Posted by Matthew Morgan J View Post
it may be due to losses, or something about the way LE has more influence on damping down low.. ...
I don't think HornResp takes losses into consideration. Combine that with inadequately-braced construction and...

If the impact of Le is too low in the model, this should show up as a significant difference between the measured Vs predicted impedance curves at higher frequencies.
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Old 28th August 2014, 04:06 AM   #558
Matthew Morgan J is offline Matthew Morgan J  United States
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Correction in the text of my reply for GM ^^^
Should read:

"a large throat chamber with a long pipe-like aspect ratio (around 120 cm @ 824 cm sq) connected to a long port with half the sq cm area"

Last edited by Matthew Morgan J; 28th August 2014 at 04:30 AM.
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Old 28th August 2014, 04:12 AM   #559
GM is offline GM  United States
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I inputted exactly what's shown and used the 'throat ported’ option, but if you total up all the volumes, it's only 63.2974 L, not 150 L, nor is there a L45/S5 length, so seems like you’ve posted the wrong HR record.

GM
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Old 28th August 2014, 04:46 AM   #560
freddi is offline freddi  United States
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Default g]

at 150l its the same volume as my old 1-fold tapered pipe

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