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Outdo B&C 21DS115 and upgrade to modular subs

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Crashpc View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Crashpc Quote  Post ReplyReply Direct Link To This Post Posted: 28 December 2018 at 11:14pm
Interesting approach. I will think about it. I like the snap-on part...
Nikon and Canon people should not be married to each other. Why did you let this happen?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 4AC Quote  Post ReplyReply Direct Link To This Post Posted: 02 January 2019 at 12:05pm
To my knowledge, most manufacturers use a 'catch plate' on the subwoofer itself:

And then use a regular latch on the wheelboard:


There are plenty of other solutions, but this one is relatively easy to build. Also, the concept is proven to work fine.

Maybe another tip: experiment with the position of the handles, and also the type.
I personally very much like this type: https://www.penn-elcom.com/default.asp?PN=H1028&LG=EN


Good luck

uǝɿɿɐʌǝ6ɯo sı ʇsʞǝʇ ǝzǝp
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Crashpc Quote  Post ReplyReply Direct Link To This Post Posted: 03 January 2019 at 8:22am
Hey. Thanks for recommendation. I´m still little skeptical about the clip-on wheel solutions, as it requires additional tooling and such. That is exactly what could make me not want to move that box so often.
I re-modeled my original box so the 100mm wheels would now fit. And I will make a serious try on that. That would really solve everything (or I think it would), if it worked
For the handles, the design is appealing. How does medium hand fit in there?
 
Nikon and Canon people should not be married to each other. Why did you let this happen?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rayrainx Quote  Post ReplyReply Direct Link To This Post Posted: 03 January 2019 at 11:58am
please somebody advice me.. Are these line array plans a GO. or is it just a bunch of crap? Happens to be the only available line array plan on the internet I have seen on sale.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JonB67 Quote  Post ReplyReply Direct Link To This Post Posted: 03 January 2019 at 12:11pm
Youre posting in the wrong place.  Start a new thread so it doesn't derail this one.  

People can help you there. 


Edited by JonB67 - 03 January 2019 at 12:11pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote simo69 Quote  Post ReplyReply Direct Link To This Post Posted: 03 January 2019 at 4:05pm
Originally posted by Crashpc Crashpc wrote:

gen0me and others:
This is how it looks like now:



It is 175l (netto) box, four triangular bassreflex ports with 18*18cm sides.
Box size is about 62*64*76 cm. That is over 300l of volume.

Works well down to 31Hz. Still does something under, down to 11Hz, even over the bassreflex port accoustical short, but that is nothing much to write about...

I cut it with tops using "Pro" sound card and PC DSP (EqualizerAPO). 70-100Hz on the upper side, depending on needs,  9-26Hz subsonic, depending on usage and needs. Slight EQ at 27Hz, and some "cut-out" at 63Hz, as the room does mess here. Kept it nearly flat outside.

I picked this driver deliberately for purpose of making compact powerful box. And it is compact and powerful box. Works extremely well. Yet it is not compact enough when you need to lug around with it.

I´m pretty sure I want a lot, or maybe too much, but I´m after "nicer solutions", rather then ordinary stuff. Wanting power and compactness at once from it is troublesome. Of course, power and compactness is greatly payed by driver price and amps price, and maybe more. I´m looking to find fine balance... Those guys in B&C obviously found it. Anyone else? :-)

Now I´m thinking along the lines:
The 21DS115/8 has normalized motor force of 326 ((Bl*BL) / Re).
It has displacement volume of 2770 cubic cm.
And Cone area 1680cm squared.

For better system it either needs to be both better, or at least the force factor must be higher, and displacement area same, and assisted by greater accoustical impedance than what bassreflex box provides. To go deeper or louder, can be interchanged for each other to a point...

I´m basically close to knowing what I´m doing. there is just not that much connection with real products, and not many ideas to what to pick first, for sims and tests.

My first shot was Dayton Audio RSS265HO-4    - 10" driver, 6 pieces.
Summed to motor force at 530
Displacement volume 2580 cubic cm
Cone area over 2000cm sq.
So that one would need to be put in TML, TH, or FLH.

For bassreflex box, the displacement volume is not enough.
Four 15"s woud do, but it would be less efficient for weaker motor force. That smells like trouble and burned coils for usable bandwidth to up to 100Hz.




HI
Do you have the drawings for this 21" cabinet design - as I am after four cabinets?


Edited by simo69 - 03 January 2019 at 4:06pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote simo69 Quote  Post ReplyReply Direct Link To This Post Posted: 03 January 2019 at 4:16pm
Originally posted by Crashpc Crashpc wrote:

So, I did some sims and thinking, got help from some forum members here (thanks) and elsewhere, and so I decided to take some action and try.
 
The resulting concept is this:
 
Not what I firstly expected and demanded. But still, this design shaves over 50l off, of the original compact enclosure. So this one is indeed very compact for 21" and hopefully with new shape, handles, sledge and wheel, I will be more likely to move it more often.
I plan to build one piece from waste wood to see how it handles and how it measures.
 
 
Sensitivity sim:
 
 
 
 
If I like the box, and it plays and measures well, I would like to have two of these:
 
 
can you send me the full drawing with all dimension on this box..?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Crashpc Quote  Post ReplyReply Direct Link To This Post Posted: 03 January 2019 at 7:35pm
Hey. I don´t really have plans for any of these. I don´t care that much about past developments.
But here is drawing of the original box:


Full size drawing: http://www.picfront.org/d/9QyD

620x640x780mm box, triangular ports 180x180mm ending 130mm before back wall. The speaker back flange is 45mm far from the front edge of the enclosure, giving it about 25mm clearance for cone excursion before hitting the grille. With sane usage, that is okay, but with lots of power, the cone actually could touch or hit the grille if you go crazy at it. I would recommend another ~5mm of clearance if you plan to run the sub really hot. 508mm is baffle cutout, 548mm is for second "front baffle wall" as it is doubled (yet only one wall is used to hold the speaker).
It is built from 15mm high quality ply/birch.
The grille holder obstructs the bassreflex port a little bit, but didn´t cause any trouble in real world usage. If you mind, you might add some bracing to the back wall (I used triangles cut from the front wall, making the entrance of the bassreflex ports).
The raw tuning is about 33-34Hz I think, which is very usable for PA usage. You could make bassreflex ports 5-10cm shorter if you wanted maximum SPL and less low extension.
The box is suited for 21SW152 and 21DS115. Maybe RCF 21N451 and 551. some fast Voids or 18Sounds. Not good for lower motor force drivers with less than normalized motor force of 200 ((Bl * Bl)/Re). This box really worked for me, output wise.  Yet I need to dowsize and upgrade the ergonomics. Therefore, more compact box is in development.

You can make out the rest, if you want that box I guess. It is straight forward.


For the second, smaller and taller box with bassreflex ports on the bottom and back side, this is matter of ongoing evolution. There are no static plans yet, until I really solve the enclosure in real world. Until it handles and measures as expected. Only then I will release plans.
Current plan changed a bit, for accomodating 100mm rear wheels for the box.
The final box size should be 580x600x730mm, bassreflex port is 115mm high on the horizontal side, 105mm on the vertical side. Very little, but variable port area. Back side wood piece is 32cm "long".

The newest plan with greater cut-out area for the wheels differs at this part, and the port is touch longer. Raw tuning should hang around 29-30Hz, then possibly pushed down to 28Hz with slight padding.

For this box, only speakers with greatest motor force (over 300) are suited, because the enclosure is really small and demanding. Final box volume for the driver will be like 122-128l. I´m hesitant to recommend IPAL drivers for these boxes, as 15mm ply might finally be too weak for this kind of drivers, and also those speakers displace awfull amount of air with their cones, and would do the same via bassreflex ports. Those beasts require at least 50% of the cone area for bassreflex port, to work towards the maximum power rating without serious limitations.
My compact boxes do not supply this kind of "resources" to the speaker, so only speakers made for mortals are usable in there. I.E.: 21DS115 and direct equivalents.

I tried to simulate and compare the plan with 18" drivers, as 125l might sound too low for 21" driver. It is for ordinary conventional drivers, but with enough motor force, one will still profit from the efficiency and sensitivity of the large cone, and also total amount of cone displacement. The driver still drives the bassreflex port to the usable extent. In the first 135l box, there was cca 2,5db bump in the 30Hz region where the port is tuned. In steadily falling response curve towards low bass, it is welcome. So the driver still could drive the port easily. I am not afraid to cut the box for another 5-10l because of that, to make it super compact, versatile and easy to handle.
I´m super busy with family now, so I expect to finish this compact development box not sooner than by the end of next week or the other one. BUT, I´m surprised by myself, that I´m rather holding onto these plans. I was very likely to build something smaller, using 18IPALs, but due to the demands of the driver, the box volume savings would be negligible, and price would rise, while performance bump would not really be there. So, 21DS115 for the win!

//Edit: repaired some mistakes in my text...



Edited by Crashpc - 03 January 2019 at 9:26pm
Nikon and Canon people should not be married to each other. Why did you let this happen?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Crashpc Quote  Post ReplyReply Direct Link To This Post Posted: 29 January 2019 at 9:34am

New prototype of the box has been made, with 100mm wheels that fit in.
Welp, Not exactly as I expected - the box really needs to be angled a lot to go safely (balanced) above the ground. One really needs to get down to it, to pull it well.
It has been pointed to me, yet I didn´t think it´s a biggie. Once things got real, it is not so easy.

So the "corner" handle is not very ergonomic for rolling around, yet straight handle cannot be put and used on the top desk, as the box would not be balanced well for pulling.
I´m now considering something like a suitcase handle and other solutions.
What a drag, to get just simple box easy to lug around...

Nikon and Canon people should not be married to each other. Why did you let this happen?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote smitske96 Quote  Post ReplyReply Direct Link To This Post Posted: 02 April 2019 at 11:40am
@Crashpc

L'acoustics have brought out the new KS21 (very similar dimensions to your design) main difference is their "L vent"
I would suspect they also use the 21DS115, or an altered version of it.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Crashpc Quote  Post ReplyReply Direct Link To This Post Posted: 02 April 2019 at 1:42pm
Including legs, mine will be 580x600x750mm. L´acoustics  571x602x762. That´s a funny coincidence.
I think they will have different tuning and different approach though.  I also wonder how did they put 21" in, as their "L-vent" doesn´t allow for vertical mounting of the driver. 
Nikon and Canon people should not be married to each other. Why did you let this happen?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote smitske96 Quote  Post ReplyReply Direct Link To This Post Posted: 02 April 2019 at 1:51pm
Probably use 15mm wood, remove a bit above and below the driver. the L vent reaches a bit in front of the driver just like the KS28 but maybe a bit more extreme.
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