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Old 3rd June 2012, 10:50 AM   #51
elac310 is offline elac310  France
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Quote:
Originally Posted by mige0 View Post


I've been listening to all above variants, no one is any bad.
But as said, out of reasons based on my requirements the N-shaped Deep Frame Dipole got the most attention and most extended listening so far (besides the compact Ripole that I have built some time back).

Michael

Hello Michael,

I also came on the idea to "double" a ripole sub since I need as much SPL as possible. Ended up with designing other dipole shapes due to the difficulty of accommodating 2x21". I came on your posts by doing a Web search for H, W and other designs; I'm very much interested in your deep N-frame dipole and I'm now planning bulding two of these (2+2 21" woofers).

My idea is to place the two N dipoles side by side, but laying down (i.e. the mouths would radiate horizontally as opposed to (your picture in post 7) vertically. Since the deep N-frame is the one you've mostly experimented with, have you by any chance done some comparisons between vertical and horizontal placement of these subs?

Finally, the horizontal placement would allow me to use the two subs side by side as a low table (130 cm x 130 cm).

Chris.
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Old 6th June 2012, 07:48 PM   #52
mige0 is offline mige0  Austria
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Quote:
Originally Posted by elac310 View Post
My idea is to place the two N dipoles side by side, but laying down (i.e. the mouths would radiate horizontally as opposed to (your picture in post 7) vertically.

Can you post a drawing on how you plan to arrange the n-dipoles?
You know - there is a distinct difference in "just" putting two dipoles close to each other versus to arrange it to as "a deep frame dipole"

Quote:
Originally Posted by elac310 View Post
Since the deep N-frame is the one you've mostly experimented with, have you by any chance done some comparisons between vertical and horizontal placement of these subs?

Finally, the horizontal placement would allow me to use the two subs side by side as a low table (130 cm x 130 cm).

Chris.
I guess that by "horizontal" you mean that the cone would move up/ down ?
No I haven't experimented that much in this direction, simply because the weight of the cone will force the coil to move off center - which will result in increased distortion.
Over a longer period of time the spider will sink in more and more (remember, its just some fabric after all - not a metal spring)

Hope it helps - have fun !
Michael
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Old 18th August 2012, 10:24 AM   #53
elac310 is offline elac310  France
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Quote:
Originally Posted by mige0 View Post
Next is a Dual-Ripol subwoofer with the chassis arranged one behind the other

Chassis is 2x15” with Fs = 40Hz and Qts = 0.4
(Selenium 15PW5)


This Ripole-subwoofer is roughly 30x40x80cm (WxHxD) which is about the volume of the H-frame subwooofer but housing two chassis instead.


This is how it roughly looks like (top opened):


Click the image to open in full size.




This is how it measures:
RED Trace: close mouth
BLUE Trace: close mouth measurement “dipole inverse-EQed”
GEEN Trace: dipole comb filter

Click the image to open in full size.


Michael
I completed my project a couple of days ago and built two subwoofer enclosures.
I have finally opted for this S-shape design, and I'd like to thank Michael for his excellent and inspiring drawings and measurements. I introduced a couple of variations: the two speakers are mounted not 69 but 66-wise (the front faces of the cones see the same tunnel). I have retained from the ripol principle a different load for the back and for the front and finally the two subwoofer enclosures lie "on the side", so that the speakers radiate up-down.

Each sub hosts two PDW21250 (a low cost 21" speaker from Pyle audio) and I built them as compact as possible, i.e. 124,8 cm (length) x 62 cm (width) x 50 cm (higth), using 31mm plywood. On one side the mouth is thus 56x25 cm (loading the back of the woofers), and on the other it is 56x16 cm. The bottom panel can be removed to access the speakers (which "look" at the floor).

I just added these subs to my current system, using active filtering and an additional amplifier. I'm pleased with the preliminary results and the clean bass but it's too early to be too affirmative for the rest. I also need to solve a slight buzz generated by the crossover or wiring.

For the time being, the subwoofers lie side by side in front of the sofa of the main listening position (thus looking like a low square table). In the first setting, the larger mouths were aiming at the sofa then I turned the "table" 90 so that the mouths point to the left and the right. I'll try in due course other positions in the room.

More in due course.

Chris.
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Last edited by elac310; 18th August 2012 at 10:27 AM.
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Old 20th January 2013, 01:34 AM   #54
elac310 is offline elac310  France
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Default Subwoofers with dual 21" in ripole mode

Here are a few pics, finally:

[IMG]Click the image to open in full size. Photo0028 par elac310, sur Flickr[/IMG]

[IMG]Click the image to open in full size. Photo0030 par elac310, sur Flickr[/IMG]

Click the image to open in full size.
Photo0031 par elac310, sur Flickr

and a schematic (sorry, comments are in French but you get the "picture" of the structure):

[IMG]Click the image to open in full size. Numériser 1 par elac310, sur Flickr[/IMG]
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Old 30th January 2013, 03:12 AM   #55
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Those frames and magnets look much like the MCM 21" Cast Frame drivers that I'm using in my OB setup. The build looks absolutely huge! I'll be following for your listening impressions.
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Old 30th January 2013, 08:48 PM   #56
elac310 is offline elac310  France
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Quote:
Originally Posted by siruis815 View Post
Those frames and magnets look much like the MCM 21" Cast Frame drivers that I'm using in my OB setup. The build looks absolutely huge! I'll be following for your listening impressions.
Ca you post a link to this MCM brand/woofer ? never heard of them.
Probably some other OEM production by the same manufacturer.

Don't be fooled by the pictures: yes the double magnets are quite large but the basket is stamped steel (no molded massive aluminium) even for those apparently large basked branches. Nonetheless, bulding was OK on this batch, no inverted connections, no decentered / rattling voice coil, clean gluing of surrounding and dustcap etc. On one woofer, the double magnets are not 100% perfectly aligned but we're talking of something like half a milimeter here.

The ripoles hold their promises. Extremely tight bass, nothing comparable with most bass reflex or closed boxes I've heard so far. Maybe I would dare a comparison with a (good) bass horn... But to go that far down with horns, they'd need to be extra-large size, I guess. There is also some inertia with those heavy cones and they need a few volts to become alive. Not too much of an issue in multiamping mode, of course.

Sensitivity is on the low side, compared to the rest of my system, at least.

Overall, very pleased with the "experiment". My conclusion: there isn't much below 50Hz on the majority of commercial records, but several well recorded ones do have life at those depths too, though.
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Old 30th January 2013, 11:50 PM   #57
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Here's the MCM: MCM Audio Select 21'' Die Cast Professional Woofer - 800W RMS | 55-2985 (552985) | MCM Audio Select
vs
the Pyle: Pyle Performance Optimized 21'' Pro Audio Die Cast Woofer | PDW21250 | Pyle

My sensitivity is low as well - but then again we are doing OB woofers. I'm currently using a 50Hz Lowpass as my "EQ", yielding pretty good results.
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Old 31st January 2013, 08:42 PM   #58
elac310 is offline elac310  France
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Thanks ! Another nice baby !
Have you done your own T/S measurements or have you heard anything about the trustworthyness of those published by the manufacturer?

My subs are managed for the time being (until I find a suitable equivalent pro-tool) via a little cheap thingy called Reckhorn S1. Xover ist at 45-50Hz (the pots are not very precise), no subsonic limit applied and I give some extra boost/equ at around 25 Hz or so.
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Old 31st January 2013, 08:56 PM   #59
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I have not done T/S measurements - but I have heard that the ones posted are not very accurate. Being that I went with the OB route (24x48" panel) the specs didn't quite matter as much - especially just applying a line level filter. Future investments in things such as the minidsp are planned. I'm not running subsonic filters either unless I want to go deaf - then I'll apply a 40Hz xover to the 2 12" subwoofers ported to ~20Hz.
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Old 31st January 2013, 09:21 PM   #60
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Quote:
Originally Posted by elac310 View Post
Overall, very pleased with the "experiment". My conclusion: there isn't much below 50Hz on the majority of commercial records, but several well recorded ones do have life at those depths too, though.
Most pop stuff is aimed at making maximum boom, pretty easy to do 50-100Hz.

Try "Raising Sand" by Robert Plant & Alison Krauss.
Many of the cuts have as much peak level at 25 Hz as at 50 Hz.
Sounds really big even at moderate level with speakers flat to 20 Hz.
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