Twin Sundown SA6.5 SW D2 32Hz Ported 0.6ft3 in Ford Escape Box Build

[THATpurpleKUSH 5,000+ posts]

New video part 3

Nope, its because pr's work best with subs with a high ebp indicating a preference for ported boxes.

 

[Buck 5,000+ posts]

You can make a series 6th order with all passive radiators

 

[THATpurpleKUSH 5,000+ posts]

You can make a series 6th order with all passive radiators

I bet you could really dial in the tunes on a 6th order with all pr's.

 

[imsickofweed]

Man, this box design is getting way out of hand, lol. I studied up a little more on the PR and have decided against it, the disadvantages over ported start to amplify the closer it gets to 0.5 Qts, these subs are at 0.46 Qts. My box is on the long side at 21” built with true 1/2” birch giving me 19” of port length on the top plus another 3/4” rounding the tip of a single board and giving me roughly 0.6-0.63 internal net volume. That length of port tunes the box to 36-37Hz depending on where it winds up at between 0.6-0.63. Ive also read a few threads about the X6.5s because theres not much out there on the SA6.5 and theyre very close in T/S parameters just mainly a difference in power handling. During the X6.5 design process they modeled the best box (opinion of sundown test and design team) to 32Hz. Their graphs show a similar curve to the one shredder did towards the beginning of the thread and I originally thought that would be a decent frequency response curve but wouldnt get much box gain for my trouble. My comprimise is going to be the middle of the road and the design that makes it easiest for me to modify the box up or down on port length. The single board making the slotted port can be cut down with a compact router using an offset base or an orbital cutoff tool from the speaker hole or a piece can be added to extend it down the wall from the speaker hole.

A 3” PVC pipe flared with a heat gun also looks promising for ease of adjustment, but its a little smaller diameter than what 8cuin works out to be (3.2” diameter). This shortens the port length for round ports, but is still longer for that particular frequency than the slotted port and Id have to have a bend in there somewhere.

 

[THATpurpleKUSH 5,000+ posts]

Theres a lot more to it than just the shape of the curve. I still think pr's are a good fit for this build.

 

[imsickofweed]

Theres a lot more to it than just the shape of the curve. I still think pr's are a good fit for this build.

Whats the reasoning for the PR? Every how to Ive read over says that Im borderline on the Qts. Ive seen a few graphs modeling them vs ported vs sealed and they have a sharper drop off than either of the other 2, but a flatter curve over all. I like the flatter curve, but not the sharper drop off. If I could tune in the 20ish Hz area and had a lower Qts Id be all over it, but it just seems like spending more money I dont have for something I might not like. I know these drivers work well in small ported enclosures, and thats where the PR shines for subs that wouldnt normally fit in an area that small with a port. Im able to fit a port just fine and have the recommended box size. The main benefit I saw with the PR is the tightness like a sealed and the resonance like a port. If theres something Im missing please let me know.

 

[THATpurpleKUSH 5,000+ posts]

It really comes down to personal preference. I myself would do a passive radiator because of the chance of port noise and with some good tuning it might even be able to play a little lower than a ported box. The hardest part about PR's is finding a suitable PR. But if you're saying you can fit a long port then go for it. If you don't like it just rebuild the box or sell the subs and box and find something with a lower fs. I don't see a problem with the qts. As far as the steep rolloff goes both ported boxes and PRs have a -24db/octave rolloff, so they both roll off steep compared to sealed or 4th order.

 

[imsickofweed]

The PRs look interesting and by my math Id need 70g weight on a 10”, but was worried that dayton PR might not have enough Xmax. I wasnt able to find a calculation to figure PR Xmax from the drivers 11mm Xmax. Im pretty sure Im going to do the port this time, but if I get too much noise where it bothers me then I can plug the port and cut a hole for the PR and try that. It seems its a lot harder to plug a 10” diameter hole than a 1”x8” slot. Ive been documenting my progress on an Escape forum, so maybe one of them wants to buy the rough draft. Im keeping my patterns so it should be a little easier building it the 2nd time around.

 

[MattinMO]

I’ve seen less hassle for b pillars!

 

[imsickofweed]

I’ve seen less hassle for b pillars!

I really didnt think itd be much hassle, lol. Ive got a buddy with a mercury clone of the escape so Im trying to sell him on a box so I can make 2. One with the PR the other with a port, Ill keep the one I like best. Or maybe Ill put it on the other side of the back seat footwell and make them fight it out.

 

[poolman966554]

Passive radiators are like magic to me.. one or 2 subs going in while the PS goes out. Hows that not causing cancellation? In my head, its like 2 subs out of phase by 180'

Theyre over my head, but ordered 2 5" ps for my dayton nd90. Hopefully itll help fill the gap

 

[imsickofweed]

Passive radiators are like magic to me.. one or 2 subs going in while the PS goes out. Hows that not causing cancellation? In my head, its like 2 subs out of phase by 180'
Theyre over my head, but ordered 2 5" ps for my dayton nd90. Hopefully itll help fill the gap

Im obviously no expert, but from the research Ive done people put them on opposite sides of the cabinet to counterbalance each other. If I do this box in a PR version Id put the PR downfiring next to the subs and bolt it to the floor.

 

[poolman966554]

That makes sence in a way.. i wonder what the

additional pr resistance does to box rise..

 

[THATpurpleKUSH 5,000+ posts]

That makes sence in a way.. i wonder what theadditional pr resistance does to box rise..

That would be a good experiment to conduct. All enclosures are subject to impedance rise.

 

[imsickofweed]

Progress has slowed, I got 2 free routers, but theyre missing parts. The parts were cheap, but it takes a while to ship, hopefully they get here before the subs. I also ran out of the nice 9 ply scrap birch wood, and its hard to find the same wood for any decent price. Im probably going to do a single 3/4 sheet for the baffle and just screw it in for now while I do some testing and then glue everything into place and possibly a layer of fiberglass inside for good measure.

In case anyone is wondering the free routers were a Skil 1817 (missing base plate and screws) and a DeWalt DW670 (missing collet and tightener nut). I also ordered a jasper circle jig, it says it doesnt work with the 1817, but it does work with the 1830 and they both share the base plate. My guess is because the 1830 is the plunge version and 1817 is not, which will make the jig a little more dangerous. Ive seen people start the hole with a drill and then come in with the router, or keep the base loose for a sloppy plunge then tighten the base and go.