37" x 25.5" x 93" - what could I put in it...?

[MemX]

Hey all,

I thought I'd start this thread because I always like to have a project to think about, even if I don't ultimately follow it through (story of my life… ).

So, to go into more detail…


I have an alcove that is 37" wide by 25.5" deep by 93" tall.

In it currently are several Ikea DVD/CD shelving racks and my SVS PB12-Plus/2 in front of them, but due to the fact that my TV is somewhat larger in-room than I thought it would be and the fact it resides in front of the alcove, I struggle to get to the shelves now.

I therefore think I should put something large and sub-like in the alcove and move the shelves forward in front of them so I can reach them lol


I have been looking at the Josh Ricci XXX Ported box with the patented port technology applied to the port:
http://www.data-bass.com/data?page=system&id=8
because I have to say that I do love the proper ground-shaking stuff at the very bottom end of the scale, and this box apparently gives something like 114dB at 12.5Hz, even 2m away while outside in a field

I have been playing with the box dimensions and I think I can probably just about fit the 25 cu ft box into the alcove.


The issues I'm having are several:
- I have no tools and no working area available so couldn't build something myself, therefore box construction (or at least box-part cutting) would have to be given to someone like the ebay bloke or a similar place, at whatever cost they would charge.
- The Re XXX 18” D2 is now getting rare and is something ridiculous like $700-850 + shipping ($200+) + import tax + VAT, or over £900 from the UK link that someone kindly posted on here to my request asking if any are available in the UK.
- I believe the currently available XXX is the (revised) Overhung version (http://www.data-bass.com/data?page=driver&id=50) and has a different response to the original XXX (http://www.data-bass.com/data?page=driver&id=6) so I'm not sure it would work as well.
- I'm skint (but this will never change so I'm thinking I will just sort the project plan out then get it moving when I find some money )


Given the difficulty in getting hold of the XXX, and the fact it is probably not the most ‘musical' sub, I was wondering if I could perhaps use the same box but instead install two Fi SP4 18s powered by a nu6000dsp to get, what, about 60mm combined Xmax? which would match/better the 54mm XXX Xmax and therefore shift an equivalent amount of air to give the same sort of depth?

Does it work like that? Or would they each ‘see' the whole 25 cuft box rather than 12.5 cuft each, and therefore be over-extending?


I have to admit that I've not been able to play with WinISD or unibox or REW or any other software because this stupid work laptop is locked down and I haven't sorted out my own yet (see the last point in the list above&#8230 so I've not been able to even get my head round what I could/should think about.


It would seem sensible to think about a couple/several sealed subs in the space, or even just a plain old LLT box ported really low (low teens?) because the box build would be (a lot) easier and it would also give that mid-bass punch and tightness, but the low distortion and crazy output at <20hz of the LLT Ricci box is calling me&#8230;


So, what do all you forum experts think??

All advice / discussions / recommendations would be very gratefully received!!

 

[m4ccam]

Have a look at page three on my build thread. Sorry I can't seem to do links on the iPad.

You have around 100 or so litres less than I had so you should be able to model something similar. I'd been messing with winisd for weeks trying to get something working but I was doing it as one box, Dan ended up doing the design and said it would be better as two separate subs. The output is mental, [email protected] 13hz or thereabouts.

After reading a bit about the sp4 driver, I had a brief moment and thought about swapping my Q's for a pair of sp418's but it would take too much work altering the boxes and adding more power and tbh, there is nothing wrong with what I have, in fact far from it.

 

[scottthehat]

Can't you just line the alcove and make some sort of front panel that fits over the hole alcove.

 

[IronGiant]

Have a look at page three on my build thread. Sorry I can't seem to do links on the iPad.

This one? http://www.avforums.com/forums/diy-subwoofer-build/1689784-third-time-lucky-3.html

 

[MemX]

Have a look at page three on my build thread. Sorry I can't seem to do links on the iPad.

You have around 100 or so litres less than I had so you should be able to model something similar. I'd been messing with winisd for weeks trying to get something working but I was doing it as one box, Dan ended up doing the design and said it would be better as two separate subs. The output is mental, [email protected] 13hz or thereabouts.

After reading a bit about the sp4 driver, I had a brief moment and thought about swapping my Q's for a pair of sp418's but it would take too much work altering the boxes and adding more power and tbh, there is nothing wrong with what I have, in fact far from it.

Thanks for thread that's an amazing build that's far outside of my skill level or tools and space availability!

I think I have a total of 50 cu ft (93 x 37 x 25.5) which seems to work out around 1438 litres, going from the HTS calculator:
Enclosure Volume Calculator - Subwoofer Box Calculator


The Ricci box build is 25 cu ft, which works out at 708 litres? so I would appear to have plenty of room, but by the time I have factored in
- materials thicknesses
- the mounting depth of the XXX (14.75" )
- the large port at the bottom of the box
- the max hypoteneuse length (the longest dimension) so I can still tilt it over and get it in and out of the building while horizontal...

...I come out at overall external dimensions options of:
37" x 17" x 89.03571"
37" x 18" x 83.89286"
37" x 19" x 79.35504"
(w x d x h)

I may even need to add an inch to the depth measurements if I double-layer the front baffle.


The above also doesn't take into account any internal bracing, which going from the Ricci box dimensions (41.5" x 22" x 66") and working back (losing 2" in width for materials, 3" in depth for materials, and 1"+3.25"+ 2" for bottom plate+port gap+materials) gives 39.5" x 19" x 59.25" = 44467.13 cu inches = 25.73329 cu ft, 0.73329 cu ft bigger than the stated 25 cu ft, which must be taken up by the port volume and bracing volume.

With a 36.5" length port @ 9.38" effective diameter (taken from post 2 of the build thread), that gives 342.37 cu inches for port volume, which means internal bracing takes up 0.535159 cu ft. (Does that sound about right??)


Re-working the dimensions above to add in the port volume and internal bracing volume to the overall dimensions, my final external dimensions could be:

37" x 17" x 91.44929" (scraping the ceiling when tilting it over lol)
37" x 18" x 86.15558"
37" x 19" x 81.48466"
(w x d x h)

which then gives me between 8 and 5 inches of depth to use to allow cone excursion and also put my shelves in front of it and be in line with the overall 25.5" alcove depth, depending on if I double-baffle the entire front panel.


Does that all make sense??

Can't you just line the alcove and make some sort of front panel that fits over the hole alcove.

It would indeed make it easier but it's not a perfect square and I also have plug and aerial sockets in it that I need to allow for!

The back wall of the alcove is shared with next door, but fortunately that's the only bit of the living space apart from the small bathroom wall that is shared with next door, I have a stairwell between the majority of the two flats and the construction is also solid concrete block, fortunately


Hope that all makes sense!

 

[m4ccam]

Wow that's some calcs going on there.

I must admit mine did take quite a lot of planning and working out the best way to assemble it. At first I thought it would be quite easy and all I had to do was build a wall which I do for a living but it wasn't that simple and it ended up as a big box split in two.

I started with around 1030 litres, I could have got more but Dan designed it and suggested making it not quite as deep so as not to protrude into the room as much. I also spoke with Am from blade ice and he said to not go above 1000 litres for two q18 drivers. I finished up with around 430l each. I then added a bit more bracing and I made a small duct to hide cables so I probably ended up with approx, 410l for each driver.

I think Scott has a good point. Can you put some pics on? And we should be able to see what you have.

 

[MemX]

Ok, rubbish pics!

Excuse the mess, I was playing with furniture placement/heights before buying some new cupboards, and badly needed to tidy everything up as well lol

It's changed quite a lot since then but you can see how the old 36" CRT TV fitted in the alcove nicely and reduced the depth in-room, whereas the flatscreen now sits pretty much flat, carrying on the line of the wall on the left across the alcove but about 10 inches away from the wall due to the stand/shelves it's on.

The sub now hides behind the flatscreen telly, in front of the shelving in the alcove, so my thoughts were to put the LLT where the shelving is and move the cabinets forward, in front of it, and move the current sub elsewhere (or flog it lol). The front of the shelves would then (using my measurements above) be in line with the wall on the left.


You can also see the weird square bit that sticks out in the corner of the alcove. I'd only want to to up to where it sticks out (that's the 37" width dimension) because the plugs and sockets are in the wall on the right hand side behind the TV, so the gap between them and the line that would exist if you drew one into the room from where the square sticky-out bit starts would enable easy access to the plugs. (I guess it could also increase port length / flatten the response if I aimed the actual driver at the right hand wall?)


Your thoughts are welcome!

 

[m4ccam]

I would extend the the sockets and bring them out of the alcove or just plug a an extension cable in. What are the walls and floor built out of? If your DIY skills are not the best I would go with Scott's suggestion and wall across the whole alcove with two layers of 25mm mdf or Baltic birch if you've loads of money. On the inside. You only need to work out the cc you need and put a shelf in at the correct height set back from the existing wall 52 mm to take the baffle and couple of mm of filler to blend in. I would set it it back enough to take a plasterboard and skim the whole wall. I would then mount the tv the sub. The port will give some strength I don't think you would need to add too much more bracing. Mine has minimal bracing and Dan didn't show any on the drawing but I added some to where I had to join the mdf together. I was a little concerned about the tv vibrating but it doesn't until I had dredd on at -4 albeit not for long.

I think this would be far easier than building a box then trying to manoeuvre it into place just to be able to get to plug sockets.

You will also need more tools of a decent quality to be accurate enough to build a big cabinet, also you need to have room to build it and move it about.

If your any good with sketchup it is worth playing with that.

I hope my thoughts are of some help and not put you off in any way.

Whatever you decide if I can be of any help I will.

Good luck

 

[MemX]

Thank you for the suggestions!

The walls are the usual board but over concrete block, and the floor is a concrete skim over what I presume are normal timber joists and insulation, so it has a decent vibration deadening mass (although not quite as deadening as I'd like lol).

I hadn't thought about walling it off - it could work as I could create shelving for the various electronics boxes and the media, mount the TV to it, and create a slot for the mid speaker that's in the loft because it's too big. I guess the box wouldn't have to be an exact cube either, so I could work round the plugs issue somehow. All of which is more woodwork and hassle, of course...

I will have to play with the figures more!


I may also start a thread on the american forum I visit sometimes, just to see what crazy TH / IB / multi-driver-madness ideas they come up with...