SVS 12.2 Sonosub DIY Virgin!

Shoot, I'd get this.

http://www.thrilleraudio.com/detail.aspx?ID=478

Its about the perfect size for a net of 3.5ft. I'd tune it to somewhere between 18-20Hz using this:

http://www.thrilleraudio.com/detail.aspx?ID=43 + http://www.thrilleraudio.com/detail.aspx?ID=428 +
http://www.thrilleraudio.com/detail.aspx?ID=427

I use my 12.2 SVS 2039 CS-Plus with a 250w mono amp, and I run the sub in the 16Hz tune mode. Based on my experience, I would recommend the lowest tuning you could fit in the tube. Also, twice the power would be nice, but I have way more things that I want to get than I have the money for, so a new amp is not in the cards for a while. It is satisfying with only the 250w I have. It could be a bit more satisfying with the extra power, however


The 16" stuff is the same diameter SVS uses. Mine is just over 35" tall in internal height, as near as I can tell with out disassembing it. It uses three 3" ports, however. That means that the same "net" volume can be achieved with a smaller internal height if you use a single 4" powerport kit, plus a 12" extension tube and connecting ring, as suggested.

You should tune it as low as possible, based on what length tube will fit in the enclosure. For example, lets assume a 35" height. You can add the depth of the top plate the port goes through (1.5") to the available length (36.5" at that point), then subtract the top-mounting depth of the driver (maybe 5", for 31.5" remaining now) and subtract the 4" of minimum allowed clearence between the driver and the port tube (~27.5" it seems). That turns out to be just higher than 18Hz tuning with the extra inch needed for the powerport kit. It seems Willd took that into account in his recommendation.

There are good threads around the net of (bigger, but who cares) sonotube construction processes. Check here and at the HTGuide forums, to start.

Unconsciously, yes.

Learning about building subs is never a waste of money. I have have close to 30 subs ranging from 8" to 15" that I'm building boxes, cylinders and IB manifolds for. It's just learning and testing for me. I'll keep a few, sell a few and give some to family and friends. Plus it's just fun to build stuff that's loud.

-Robert

Chris - What else would you do with this 12.2 driver? It won't cost you that much to build, you'll learn like Robert pointed out, and you'll end up with a pretty good sub in the end.

Well, yeah, for a room that big you'll certainly want something that has much more output capability.

You mentioned IB...I'd certainly go the 4x15 or 4x18 route for a room that big, at the least.

I have a ~5000ft^3 room, that is open to the rest of the house. I am currently using two SVS 16-46PC+ subwoofers, sitting about 11' away from them. They are not co-located, but instead stereo. Once level matched and EQ'ed, they are good enough for the frequency range speced. I can hit, at the listening position, ~105dB <20Hz, and ~110dB >20Hz. That may be good enough for you. Be aware that there is of course distortion at these extremes.

Since they're ported and the FR is very flat anechoic, room size and consequently gain is not going to be needed as much. In fact, my room gain starting at <18Hz or so bumps the low end up and I have to EQ it down.

The 16-46 enclosure is 4.5 cubic feet, in case you wanted to go with a larger enclosure than the smaller SVS cylinder subs to get a lower tuning at the sacrifice of some >20Hz SPL. It still uses the same 500W BASH amp.

I also happen to have two db12.2 drivers available since I upgraded to the Plus 12.3 drivers. If you're interested, send me a PM.

i've got an extra 12.2 driver as well. this will be my first diy sub so i thought the easiest thing to do would be to duplicate my 20-39 pc plus's dimensions and ports (a 16" x 39" sonotube with the three ports). besides, i believe the driver parameters are somewhat of an unknown, (not that i would know what to do with the actual paramters anyway ). i haven't been able to find a place where i can get ~39" of 16" sonotube, so the thriller audio link posted above caught my eye. i asked them about longer lengths but they said they only have the 36" long tubes. should i worry about the 3" difference in length? if i do not mount the plate amp in the tube do you think the volume that the amp would have taken up will offset the volume lost by using the shorter tube?

richh- I wouldn't worry too much about the 3" difference.

Sonotube is usually in really, really long lengths. Like 12' or 15' long. And they cut them to length. You should be able to find a place to cut it to exactly the length you want by looking up concrete suppliers in the phone book.

But yeah, I wouldn't worry about 3" less since you're not playing with the T/S parameters anyway. I would worry about how you're going to mount the amp in the tube, unless it's on an endcap. If you cut a hole into the side of the tube, you need to do what you can to make sure it is air-tight and still retains its rigidity.

i called a couple places and they said they'll cut it to any length i want, but i still needed to buy the whole 12ft length.

as for the amp, i'm leaning towards building a passive sub with an outboard amp; either a behringer type or a plate amp in a simple wooden enclosure. that 500w bash plate amp at parts express looks like a good deal (on sale for $159).

anyone know what SVS does in their 20-39 CS and their 20-39 powered subs? they're both 39" tall but one has an amp and one doesn't. doesn't that change the volume?

edit: well all the worrying about length differences was for naught. i just measured my 20-39 and the overall (including legs) height is 39". the actual tube is about 35.5". so i'm good to go with the killer audion tube .

I thought you'd be ok with that tube, Rich.

So are you gonna go ahead and order it? Are you going to tune this new sub to around 20Hz?

I was able to buy just two 4' lengths from the concrete supply company near me. They were very nice and helpful. A different supply company that I called first wasn't as helpful.

SVS has a wooden "frame/brace" that is where their in-cylinder amps go. IIRC, it was a lot of plywood or some other sort of layered wood. It does change the internal volume a little. If I stuck my head inside one of the SVS subs to look more closely, I might feel comfortable sticking a plate amp on a tube also. But right now I only feel comfortable building a passive sub.

yep, going to order the tube plus some ports. regarding tuning, if i have two sonotube subs, is it best to have them tune to the same frequency or one high and one low (or should i say one low and one lower)?

is it best to just duplicate the (3) 3" x ~20" ports on the 20-39? or, for a given tune would there be an equivalent single port configuration.

You want to tune them to the same frequency, if you will be using them together (IMO).

If this DIY 12.2 sub will be in another room, then I'd tune it lower than 20Hz...closer to 18Hz, like Jonathan suggested.

In that case I'd use a single 4" flared port, from Thriller audio, with an extra 12" tube and an extra connecting ring....so you want two flares, two 12" tubes, and three connecting rings. Once you receive the stuff, you'd about 1.5" off one of the 12" tubes, then glue everything up.

both the diy sub and my 20-39 pc+ will be in my ht which is about 3200 cu ft. if i stuck with the 20hz tune to match the svs and did not need the tuning adjustability that the svs 3 x3" porting gives, is there a another porting configuration that would work?

Yeah, using the single 4" flared port @ 17" long would be close enough.

ok, got my tube on order from thriller. also have the 500w bash plate amp on order from parts express though it's on backorder til 12/4. ended up getting the dayton 4" inner and outer flares plus the 15 3/4" staright tube as well.

so for the endcaps, i figure two layers of 3/4" ply or mdf (is there a preference?) glued together for the top and bottom. on both ends the inner layer is cut to fit inside the tube and the outer layer is cut to the same dia as the OD of the tube (or slightly bigger for asthetics). some questions...

for the outer flare on top and the driver on the bottom should i just route a pocket in the outer layer of plywood so they sit flush?

i know there was a thread about this a week or so ago, but being this is an SVS clone, any problems with adding the parts express steel mesh grille to the top to cover the port like SVS does?

what's the best way of attaching the fiberglass to the inside of the tube. hot glue gun?

You want at least three 3/4" layers for the endcap assembly, IMO. Two layers for the plug and one for the cap.

For mounting the driver flush, it is easier to just cut the hole in the outer layer larger than the inner two. You can mount the port flush with the top, if you want.

Their shouldn't be, but make sure you get a larger grille (I think an 8" grille would be ideal for this particular port).

Hot glue would work fine.

Are you finished your 20-39 clone yet? I am just finishing up my two 20-39 clones with Samson sx1200 amp. Let me know how it sounds when you're up and running. I used 3M spray on adhesive for the insulation, as per Tom V.'s (SVS) recommendation. If you aren't finished and have any more questions, ask here or fire me a pm. Tom was an amazing help with my diy and steered me in the right direction on several occasions. One more reason SVS has the reputation it has.
Derek

Unfortunately, I've put that on the back burner for now. I'm trying to see if I can finish up the theater in time for my daughter's birthday, so all my time and energy has been spent there. It's a shame too, as I have all the parts on hand. As soon as I free up some time, I'll be cutting some mdf.

Family commitments slowing you down a little, I can relate. Nothing more important than your children though. I'll post some pics when I'm finished my subs, probably later on this week.

Willd... I hope you're still watiching this thread. I finally had some time to get my sonotube going. I have the endplates cut and glued, driver and port are attached, just need to add the insulation to the inside walls, cut the port to length, and then glue the caps on. One question on the 17" port length. Is this the total length of the port including the inner and outer flares, or is this the length of just the straight tube?

Also, what's the best glue for gluing the endcaps to the tube?

The 17" is the effective port length, so it is taking both port flares into account.

Some people don't use any glue at all and just dry fit, but I used liquid nails. Works like a charm, of course.

So just how tight is the fit of the endcaps into the tube supposed to be? Mine are snug but they are nowhere tight enough to go without glue. How do I know this? After assembling the sub (dry fit) I did a test run with the Darla scene and the top endcap came out .

Do you think I need to redo the endcaps or with the glue suffice?