SUBi - repurposing a trashed subwoofer

[Ond]

Project SUBi!   

Walking the dog the other day I found this lying amongst a pile of hard rubbish on someones lawn.

It's a Home Theater subby from the late 90's!  As I scurried away with my treasure I wondered "does it work?".  "What would be wrong with it?"  I'm sure the original owner peered through the blinds as I made off with it, chuckling to himself "heh, wait till he fires that piece of crap up, boy will he get a surprise".

So of course I plugged it in and ran tests.  Horrendous humming and buzzing ensured    What is kaput here?  I replaced the standard things that don't age well over the years.  Capacitors all new (cost about $12).  Then had a closer look at the input side of things.  The RCA sockets were so worn that my input cable was not making ground contact.  Thus the buzzing.  Removed sockets and replaced with new shiny gold ones.

Re-ran tests.   Ahhh thumpin clean Danish designed BASS.  Who's laughing now neighbor?

So this hardware is destined for a subby to compliment a pair of bookshelf speakers I'm building.  It will be sealed unlike the ported original enclosure.  I'm only interested in a frequency output that fills the gap just below these speakers.  More punch and not so much rumble if you know what I mean.

The real value in this is the 90watt Jamo amp.  The rest can go in my hard rubbish.  I'm going to build a new sexy enclosure for an 8" driver to go with the amp.  I won't be using wood or MDF at all to make that...

Stay tuned.

[wp34]

Nice!  Jamo is good stuff.  Great find.

[bobbyb13]

Curious to see what this box build will become!

[Ond]

Here is the sketch-up design for the new enclosure, grey is cast concrete 2" thick, yellow is MDF.

I bought this new 8" driver (but not expensive), better specs than the old stock one.

[bobbyb13]

2" ...
Of concrete.....?!?

So in design phase you have already outrun my rather wild expectation for this one.
 

Solid obviously, and quite damp harmonically also I imagine?

Very fun choice.

[jennifer]

2" of concrete?...This just got very fun. 😜

[Ond]

Yeah, I've been wanting to make a sub-woofer enclosure cast from concrete for years.  This was as good of an excuse as any!  As you say bobbyb13 great material for damping out vibration, at 2" thick, very stiff support for the driver with no internal bracing needed.  The concrete will be a mix of glass fiber and cement - No Rocks 

@jennifer - yes should be fun, especially things like making proper release molds and mixing the concrete to the right ratio of ingredients.  The enclosures will still be surface finished in a traditional looking way.  The only giveaway that they are mainly concrete will be the weight...

Here are the finished concept renders I will work toward:

As you can see, very simple lines, a mesh at the rear will allow the plate amp to breathe a little with some cool blue illumination to let you know SUBi is on. The light will not strobe with the beat cos that would get annoying real fast!

[bobbyb13]

This is so much fun.

There is a gentleman out here who worked on nuclear power plant structures and was inspired to design two homes built on the beach here on the NorthShore.

Foundation, walls, ceilings/floors are entirely of poured concrete (like a high rise structure) except that instead of rebar the reinforcement is 1/2" thick fiberglass rod.  2 stories, pilings that run to the bed reef (about 20' deep in this spot I bet), no spalling need apply.

I don't know how thick the walls actually are but I imagine those houses could potentially withstand even a sizeable tsunami- never mind your ol run of the mill sea level rise- for quite some time.

The boat I lived on in the Ala Wai harbor for 8 years was a ferro-cement hull.
Done well it's brilliant stuff really.

3 generations on will be enjoying the thump of your creation!