Help with designing pair of 1 cubic foot HT subs

[c]

I need more coronavirus projects and so I've come up with a goal to build a pair of 12"x12"x12" (external dims) home theater subs.

I could really use some design help. For this project I'm recalling the old Sunfire MKII 1 cu ft sub, which was cute but packed a wallop, and so I'm going for this small pair-o-subs design concept for my living room setup. I have a full on big sub for the "home theater" but for the living room I'd like to see how much solid quasi-deep bass I could get with a pair of these little 1 cubic foot subs. I've set the 12" cube dimensions to be a design requirement.

I've identified the price friendly Dayton RSS265HF-8 10" as a nice sub to start (open to others near this price point) and thought about trying something new for me which is using a passive radiator with it (ala Sunfire!). However I'm a bit stuck using WinISD with a PR and I think I am into territories unknown to me as I can't seem to understand what I should be looking at and looking for in WinISD with a PR. I never was great overall at this program anyhow.

Once the design is figured out I'd like to pick a plate amp to keep this all self contained. I think the Carver used a crazy 2700W amp with some major tweaks to current and voltage shifts. I'd think for this a standard plate amp is fine, but of what wattage?

Are there some existing 1ft sub/PR designs, or anyone who'd be up for sharing some insights or ideas on what I've presented? I've seen the Continuum, and I like it, however the 14" cube size breaks my 12" cube design goal.

I've included my WinISD modeling using a 1 cu ft box with the RSS265HF-8 10" sub and the Dayton DSA270-PR 10". I'm just not sure what this is telling me and if it's a doable thing to do, or if there is something better, both with driver, PR or WinISD modeling. I've plotted my trusty 3L 12" Adire Shiva for my reference.




Thanks!
c

[wogg]

A few quick thoughts:

That woofer will wallop that PR. You'll need 2 of the RSS radiators to keep up. Sd x Xmax needs to be double on the PR(s).

You'll need the 4 ohm model to get the most out of a plate amp, unless you're intending to drive both in parallel from 1 amp.

A small sealed with a DSP amp to tune boost may work better. Going ported or PR in that tiny box is going to be a challenge.

[tvrgeek]

Add in your LP filter and see if the hump in the response is to your advantage. Sometimes it can be, sometimes it is too low and when combined with room gain, not a good solution. Sometimes you can rely on DSP to knock it down and actually get lower distortion. Sometimes not

Don't forget to put in the amp power into the displacement simulator and look at excursion. That Dayton ( nice, I have one, used it for my office) is not going to take hundreds of watts. It is also not a 20 hz sub. Great driver for music, but if you are looking for extreme movie special effects, it cant push enough air. Again, the simulator will tell you that. You may find it quite advantageous to add a 20 Hz second order HP to control the excursion and let you use more power where the music actually is.

I used it in a sealed box. One of my next projects is to try in in a BP-4. With proper tuning, one can get a nice peak in efficiency right in the pass-band if you don't want to get too low and your mains get low enough.

You seem to think just picking a driver and PR off the shelf will clone the old Sunfire distortion generators. They were custom designed drivers and PR to work in that volume. I have not run the sim recently, but seems to me they take about a foot and a half in a sealed box, bigger in ported. I was modeling around 2 cu ft in BP-4.

They call it a 10. It is a small 10, so a 12 inch PR should be sufficient. They do save space as they don't take up as much room as a long 4 inch pipe does.

Lastly, that is more of a 30 Hz driver than a 20.

[Chris Roemer]

Your box is too small. Your driver is too big. A box w/a PR is VERY similar (in size and extension) to a vented box.
A closed box is typically half the size of a vented box, and loses about an octave of extension.
THAT driver wants a closed box about twice the volume you're providing. 1.0cf (external) box, made w/ 3/4" stuff only yields about 0.67cf.

The closest driver to that Sunfire was the HiVi SP10 (NLA).
I put one in about 0.9cf (net), but w/a 4 ft. long slot port folded in there it was over 2.2cf (external).

[dwigle]

I built the sealed Drake (http://projectgallery.parts-express....cts/the-drake/) in a 13" cube with a net of .65 cubic ft as designed. Note: Darren's design calls for .65' but he used a 15" cube because he used a 2" thick baffle and 1" thick throughout. It also used an enclosure mounted amp that is no longer available (took up .25 cubic ft of interior volume).

The Drake uses the RSS315HO-4 driver and a lot of boost to get low. The boost causes the power required to escalate especially during movies, granted in a large room (4000 cubic ft) I can push the Dayton Audio SA1000 to it's limits. I would think the rack mount version or plate or even the 500 watt version with dsp would work well.

For a very small cube, this thing is really a beast. Great for music, good for HT in a smaller room. (<250sqft).

[LOUT]

The RSS HO subs are better for ported or PassiveRadiator builds, the RSS HF and FA subs are usually better for sealed or IB builds.
I don't think there's a big price difference between the HO and HF versions, so go with an RSS265 HO or RSS210 HO if you're aiming for lows under 40hz in a small box.

[a4eaudio]

A couple of comments...

• IF you are determined to stick to the 12" cube design requirement then your plan turns into finding the right driver taking into account many of the comments above. Maybe the RSS HO drivers per dwigle and LOUT, look at the CSS 10" driver and model it, etc. (You never stated your budget limit).
• HT subs usually aim to go much lower than music subs (low 20Hz or below). Ported and passive radiator subs drop of QUICKLY below box tuning and with a 12" cube, with port /PR and a plate amp taking up space, you are going to really struggle to get really low. Consider DSP with a sealed sub to get low. The sealed sub allows better cone excursion control but needs lots of power and DSP to reach low. If you can get an external amp (I think the old Behringer iNukes have changed names) you can have a LOT of power with DSP to dual subs AND not have to take up any interior box volume.

[Wolf]

Look up my Overdrive10 project, as it's close to your goals. Price of admission is not cheap though.

Later,
Wolf

[Chris Roemer]

to OP:

You stated that you weren't a "WinISD expert" (and no one can fault you for that). To model a "buildable" PR box, what I do is FIRST model an "acceptable" (to me) ported box, dialing in a box size and tuning I can live with. THEN I try to model a PR (based on the example below, I'd choose the 12" RSS315PR - which isn't "quite" up to the "2X" rule, but it's close - NEARLY 1.9X). THAT one can take about 450g I think.

General ROT for PRs is to have twice the "swept volume" of the active driver.
The RSS315HFA lists a stroke (Xmax) of 14(+)mm and an area (or "bore") of over 500 sq.cm. (500 x 14 = 7000)
The DSA270PR you picked has a stroke of 11mm, and an area of 350 cm^2 (350 x 11 = 3850)
Using the "2X" rule, you'll want your PR capacity to be around 14000 (or more).
14000 / 3850 = 3.6, meaning you'd need FOUR of those PRs to handle that 12" sub.

Also, PRs can only take so much added mass. 500g (1/2 kg) is roughly 1 pound. Don't know of ANY PR that could take that weight w/out damage (except possibly the very largest, like a 15" or 18" PR)? I've not use that PR (and "added mass limit"s aren't always published for PRs), but I'd think about 100g could be its limit (POSSIBLY up to 200g? - anyone know?).

also, also, I could not get a rolloff curve to look ANYthing like your curves for the 12" HFA driver in 0.67cf, OR EVEN 1.0cf - but MAYbe could if I upped the box vol. to 2cf or so.

[Wolf]

I would say about 300g for the 270, as the 215 is limited to 200g. Seems reasonable...
Wolf

[djg]

Jeff Bagby designed the "Baby Boomer" sub with a 10" Dayton woofer, either ported or dual PRs. SD300-6 plate amp. Kit available from the Michigan based kit supplier. The writeup doesn't really give the external dims, but a picture showing the 10" driver in the cab extrapolates to around a foot square.

[a4eaudio]

Jeff Bagby designed the "Baby Boomer" sub with a 10" Dayton woofer, either ported or dual PRs. SD300 plate amp. Kit available from the Michigan based kit supplier. The writeup doesn't really give the external dims, but a picture showing the 10" driver in the cab extrapolates to around a foot square.

Yes, see posts 13 and 14 here to confirm djg's extrapolation

Also, Jeff says in post #5 that it is flat to 28Hz which is pretty sick!