first DIY, subwoofer. need advise with components.

[doors666]

Hi Guys,

Finally i got rid of my laziness and got hold of a carpenter and started the build of my subwoofer. Here are a few pictures of the work done so far. Stay tuned, more to come later.:licklips:


the external dimensions are 2x2x2, excluding the feet.

PS - dont they make any damn thing to specs. The damn 5" pipe is not 5", the internal dia of pipe is 5.27". The MDF is supposed to be 19mm, but its only 17mm.

 

[suri]

Hi Guys,

Finally i got rid of my laziness and got hold of a carpenter and started the build of my subwoofer. Here are a few pictures of the work done so far. Stay tuned, more to come later.:licklips:


the external dimensions are 2x2x2, excluding the feet.

PS - dont they make any damn thing to specs. The damn 5" pipe is not 5", the internal dia of pipe is 5.27". The MDF is supposed to be 19mm, but its only 17mm.

that is going to be one hell offa poseidon sub with six radiating surfaces!

 

[doors666]

what do I do the internal sealing with. Is silicone good enough, any other alternatives?

 

[doors666]

Silicone or hot melt is good enough to seal air gaps. For joining the box together, wood glue works. Please use enough bracing. Those toothpicks in the pictures aren't going to be able to hold it together.

there will be a central vertical brace panel with some cutouts. I will also be adding more "toothpicks" running around all the edges, screwed on both the sides.

 

[1000w]

Not sure if you already have the amp, did you have a look at the Dayton 1000W rack mountable amp. Its got pretty good reviews. Check out partsexpress.com for detail. I had almost pulled the plug on this one 2 years back when it was on sale for 250$ and dollar value at Rs40. I still regret not getting it, and yes it does 220V
-Manish

 

[doors666]

Not sure if you already have the amp, did you have a look at the Dayton 1000W rack mountable amp. Its got pretty good reviews. Check out partsexpress.com for detail. I had almost pulled the plug on this one 2 years back when it was on sale for 250$ and dollar value at Rs40. I still regret not getting it, and yes it does 220V
-Manish

I already got the dayton HPSA 500W amp. Its a little less for this sub as the driver can easily handle 1000w as per the specs and winisd shows no issues till about 1400-1500w. I thought of going for the 1000w plate amps but the price was too high and i can always upgrade later. Also, this being my first sub, wanted to see what I get from a 500w and if its enough, no need to sink in another 200$ for the bigger amp.
Another issues with the rack amps was that most of them didnt have a hpf (or an eq for that matter), which works fine in a sealed box, but will kill a ported one. Extra HPF was costing another 100$.

Cranky:

the bracing looks awesome in the design you sent, I wish I had a CNC machine!! Mine wont be as extensive as the one in the diagram as already the sub internal volume is down to about 5.5 cuft despite using a 2x2x2 external size. I had a tough time figuring out how to fit a 5.5"x23" external size port into the box. WAF also played a major factor in where to fit the port. Wife didnt want me to increase the height (if downfiring) or depth (distance from back wall goes up for down firing port).

 

[suri]

Eminence Lab12, ported box - Page 3 - diyAudio

:x

hi cranky -

saw the pictures and design - will not work!

will end up with something like a SOOMOKU-
http://soomoku.com/products.htm

looked again - (and layertone) apart from his CNC skills - i do not think that the man/woman has really thought about the function of a subwoofer and how to translate that into good working practice (sounds like i)
that kind of design might result in resonant panels.

 

[doors666]

Elbow joint.

I am using that!! even then its tough as the opening of the port should be atleast a diameter away from the inside walls. I had other restrictions also. front wasnt big enough to have the port. top, bottom and back was ruled out due to WAF. That left only sides. There too I had to put it at the bottom going up, just in case kids choose to drop a ball inside.

I also need to make a grill for the driver. Any good ideas? I could put the metal grill as in those ahuja speakers, but since I plan to make a nice finish, it wont look very good.

 

[suri]

And anyway, the fundamental mode of a 18" square panel is about 750Hz without bracing. The sub would drop off well below that

hi cranky - the fundamental mode = resonance mode = of a particular material?

apart from that - there are 5 of those panels + one panel cut to accept the driver = and if those panels are well jointed = consider that those panels appear to the driver (as far as resonance and excitation is concerned) as an amalgamated (x five one-fourths) whole = the situation is complex.

and yes = i think i have a much better way of doing this - will post hand-drawn diagrams tomorrow.

some insights here -

http://www.speakerbuilding.com/content/1011/page_9.php

 

[doors666]

I'm sorry, I don't understand I like my speakers naked!

Anyway you could run a large ring of MDF on a turning machine to create a big fat ring (BFR). Stick grill cloth of your choice over the BFR, and hammer in a bunch of these magnets into the back of the BFR and the area surrounding the driver frame. Four should do it, one stick of these will be fine:

DealExtreme: $2.36 Super-Strong Rare-Earth RE Magnets (8mm 20-Pack)

Good idea, thanx.

If I have the speakers naked, the driver wont last a week. 2 small kids at home.

 

[suri]

Well it just said vertical brace, which this is but done a little differently - I'll wait for your drawings

hi cranky - here are the drawings-

By witchesofsound, shot with DMC-FZ7 at 2010-03-10

note that the width of MDF left intact after the centre of the board has been "cavitated" becomes the thickness of the four sides of the subwoofer (not considering the front and back)

the front and back become as thick as the number of boards that are stuck and placed at the two ends of the "cavity" MDF - all ports, apertures, cable openings can be planned and cut before the MDF boards are glued.

finally - from front to back at the four corners - stainless steel rods (which are threaded at ends) are passed through drilled holes - nuts are applied over stainless steel washers and tightened with a wrench - the heads are recessed into the MDF (say half of 3/4") and concealed with putty, or veneered over.

using a flat panel to form the sides of a subwoofer cabinet is sub-optimal IMO.

and using bracing -is trying to correct a mistake - IMO

another example - this, a vandersteen-

By witchesofsound at 2010-02-14

 

[suri]

Translam?

yup, translam - and look at what i found - jkrutke actually posting on a forum -

(HTGuide Forum)-

"Hello,

Interesting project. You all may see a laminated construction project at Zaph Audio someday. Then again, you may not. We'll see how it turns out. It's obvious a lot of this is inspired by the Magico Mini. Personally, I think stacked plywood is beautiful, but the Magico Mini is flawed by inefficient use of material and less than optimal enclosure design.

I've found a local CNC wood cutter to do it for me relatively cheap.

I've come up with a 2-piece design with the following improvements:

* Better managed internal reflections
* Much more efficient material usage
* Interlocking pieces for easy alignment
* Sexier looks. Yeah, baby!

Most important is the efficient material usage. This will allow "nesting" of pieces to get a lot more out of a single sheet of plywood. Construction of a Magico mini will result in 90% waste of plywood. With better design, the waste can be closer to 50%. With nesting of the pieces, all the parts are cut out of a single sheet on the CNC machine with the pattern properly spaced to make the most of it. This keeps things cheap, as it's all about setup time."
__________________
Zaph|Audio

hehehe!! - and when a passionate sculptor was asked - "how did you carve that lion in marble?" - he answered - " took off everything that did not look like the lion".

i do not suppose that one should consider the unused material/discarded material as waste - should be thought of as cost for the project.

 

[doors666]

I'm sorry, I don't understand I like my speakers naked!

Anyway you could run a large ring of MDF on a turning machine to create a big fat ring (BFR). Stick grill cloth of your choice over the BFR, and hammer in a bunch of these magnets into the back of the BFR and the area surrounding the driver frame. Four should do it, one stick of these will be fine:

DealExtreme: $2.36 Super-Strong Rare-Earth RE Magnets (8mm 20-Pack)

how do i make sure that the grill cloth stays flat in the front of the ring.

the dimensions of the ones you mentioned is 8mm dia and 0.8mm thick (thickness is mentioned in the comment section by someone) and people are saying it easily breaks. I was thinking of going for a bigger one, 18mm dia and 2mm thick.
how do u hammer this thing into the wood. wont it stick to the hammer.

I would also like to get some sturdy grill cloth, possibly here in bangalore. many times a very flimsy fabric is used for the cloth which could be easily torn. has anyone used the one available from corrson.

 

[doors666]

Hi Guys,

I managed to get the neodymium magnets from SP road

Industrial Supplies Store, #55 SP Road. Ph - 22231011. This guy had all sorts of magnets in various sizes and shapes. The ones I got costed 31/- a pop.

How do I embed a magnet in the grill. Hammering is ruled out as the magnets are supposedly really brittle. In the cabinet I can probably put a nut.

I also need to figure out what to use for the feet. The options are castor wheels, spikes and wooden feet. I dont know where to get the spikes if I decide to go that way.

For the grill cloth, will a mosquito window mesh work. What about a sheer curtain. What are the characteristics that I am looking for in a grill cloth. I saw one on SP road costing 60/- pm and it looked like it will tear if someone even sneezes near it.

I also got the t-nuts from SP road (JC Gupta & sons 7/A SP road ph - 22237659). How do I use these. Drill a hole and hammer the nut from the inside and use the screw?

 

[doors666]

Here are some more pics of the sub under construction.

Amp


View attachment 2065

View attachment 2066

Driver

View attachment 2067

Cabinet

View attachment 2068

View attachment 2069

 

[doors666]

After putting everything together:

View attachment 2070

View attachment 2071

I am yet to do the spikes, grill, painting and finishing.... Stay tuned for the final pics.

 

[musicmypassion]

Nice work there... I am sure you are a person with a lot of patience . Waiting for the final pics.

 

[grubyhalo]

Looking good there! Congrats!

 

[GeorgeO]

I went across and saw it and can attest that it is going to be a real performer once it is completed!

George

 

[doors666]

I went across and saw it and can attest that it is going to be a real performer once it is completed!

George

thanx george.

i am going to test it for a week or two and then do the finishing work, just to make sure I dont want to change anything....

I like the bass so far, nice and tight, no boominess, there are no spikes on this and its kept on the floor directly, so once I add that, there will be a definite improvement in sound. Tried with music and movies both.