Raptor's Dayton RS15' Sub Build Thread (Project:5)

[Raptor550]

Ok, so I have been dreaming of building a sub woofer for a while. Financially I could not afford A huge sub and with my NatP towers going as low as they do I could not justify building a rinky-dink 8" or 10" sub, too much overlap in capabilities. Anyways perusing the forums I saw "Zaph" was selling off a RS15 for $100. Needless to say I now have a mission to accomplish. So I will keep my latest efforts and tribulations up here.

The first tribulation I should mention is with finding an appropriate amplifier, a venture on craigslist brought me to a 1000W Velodyne amplifier. At its owners house I hooked up the only driver I had on hand to see if it would put out sound. (an RS225). It clicked allot, It was a class D amp and I imagine the clicking was do to its "D'ness" being broken, It had a few unlabeled tabs on it so assuming I had wired it wrong I tried the others, well at the first gentle brush against the accursed tab I hear what sounded like a loud gunshot behind me and the smell of "something" burning. My aluminum cone RS225 was now the first Dayton Midbass dome woofer. In horror of the carnage and in lue of (later admittedly) being electrocuted several times earlier that day by the Amp, the Craigslist seller gave me the wretched thing for free. If I could fix It I would feel less sad.

Anyways on to better things, I now have a Big Beautiful Driver and a box about half complete.



The plan is a 3.1^' internal volume box sealed with 3 inch chamfered edges and spiked feet. I will probably put some figlerglass insulation inside too. Haven't thought things much through past that so if people have porting recommendations stuffing ideas and the like its welcomed.





One question, on a sub, besides aesthetics, is surface mounting a woofer bad on sq? I know its bad on tweeters and midrange. I don't have the gear on me to flush mount.

[Hdale85]

No cross braces in the cabinet?

[Gir]

No, it's not as important to flush mount a subwoofer since the wavelengths are so high. Correct me if I'm wrong, please.

What kind of wood are you using?

Looks like it's coming along nicely! Sorry to hear about the RS225! Interesting destruction though 8O

[Hdale85]

Looks like Pine or something.

And no you don't have to flush mount a sub. It looks better though

[Gir]

Looks like Pine or something.

That's what I was thinking, which brings up a bit of an issue. I always heard that pine was a bad wood to use as far as speaker cabinets are concerned. Perhaps you should add some bracing in there to avoid any unwanted box resonances.

That being said, I do love the look of the box!

[Raptor550]

Hahaha, you guys don't miss a beat do you? I am putting a truss system inside it of twelve beams at 45 degree angles connecting all walls to each other. It should be strong enough. I have to have all the walls put together first to do this, hence why I started with a cage.

I believe it is pine but the cage inside is a different wood. I heard pine is mostly a problem in super high humidity places with big temperature shifts. so Florida or Wisconsin out doors is out. but I am sealing the box and lacquering it so it should be more rigid when I am done. Maybe pine is also bad at resonating at certain Fq undesirable for a full range speaker, but would it do this with content below 50hz? Am I missing something?

[Hdale85]

Why did you use pine anyways? And any updated pictures

[Dennis H]

Nothing wrong with pine or any other solid wood for a sub. The resonance frequency (tap the box with a coin to hear it) will be way above the sub range.

[jkrutke]

That picture of the woofer on your washing machine looks like you took a picture of a normal woofer, enlarged it 3x and photoshopped it onto the washer. :B

[Hdale85]

Probably taken with a camera phone.

[Gir]

Nothing wrong with pine or any other solid wood for a sub. The resonance frequency (tap the box with a coin to hear it) will be way above the sub range.

Good point!

That picture of the woofer on your washing machine looks like you took a picture of a normal woofer, enlarged it 3x and photoshopped it onto the washer.

Man, I was looking at that and thought it looked a little funny. Definitely hit the nail on the head! lol

Hahaha, you guys don't miss a beat do you? I am putting a truss system inside it of twelve beams at 45 degree angles connecting all walls to each other. It should be strong enough. I have to have all the walls put together first to do this, hence why I started with a cage.

Sounds like it will be nice and solid!

[Raptor550]

I'll agree, it does look like its been enlarged with photoshop, but thats the real thing baby. Actually when I set it on there I forgot that the washing machine was magnetized and it made a comical dive bomb to the poor little machine. when I took the sub off the washing machine lid went with it. :-D

[Raptor550]

Trying to get a handel on porting and dampening concepts

How do you choose a port diameter for a ported sub? one program said I needed a 6" port at like 64 inches to tune to 22hz, I looked at what a 4 inch port looked like and that was more manageable but whats the downside of a smaller diameter port? right now my internal volume is at about 3 to 3.1 cubic feet at the most. any recommendations?

If I stuff a vented box with stuffing will it actually make my box appear bigger? If I have a 3.1cu' box and I am working with WinISD and I plan to stuff my box .5-1 lb per cubic foot. Would it be appropriate to enter the box volume as oh say 3.8?

[looneybomber]

A 4" port is much too small! 6" is a better idea, but you'll need a bigger box to get that to fit...and then it causes the driver to run out of xmax with little power in the ~30hz area. Go to "plot" add in some wattage and then click on cone excursion and play around with box size and tuning freq.

Sealed may be your best bet.

[mayhem13]

Sealed may be your best bet.

How about PRs?-2 15" AEs at about 1300grams each would do nicely!

[Dennis H]

Normally, you don't stuff a ported box, just line the walls. Stuffing doesn't change the apparent box volume, it decreases Qa in the Advanced properties button of the box tab. If you were to stuff the box say half full, leaving a clear path between the driver and the port, you might try Qa=10 and see what happens.

The Dayton is a pretty short stroke driver so you might get away with a 4" port. It would be about like using a 6" port with a TC2000. Give the driver some power in the signal tab and then look at the cone excursion and rear port velocity graphs. Don't forget to add a highpass filter to keep the excursion below Xmax at low frequencies. That will also help keep port velocity down.

Edit: to model what happens when you stuff the box clear full, blocking the port, set both Qa (absorption) and Qp (port) to 5-10 depending on how dense the stuffing is.

[stangbat]

Have you tried using two ports instead of one? Maybe see what lengths and diameters you can get by doing that. Or is there a reason for avoiding this?

[Bent]

two smaller ports are just about as long, plus they eat into the interior volume even more.

[looneybomber]

two smaller ports are just about as long, plus they eat into the interior volume even more.

...and has more surface area which means more port noise given the same area and flaring.

[JonP]

In case you didn't get the port velocity graph suggestion, that's the one to watch in regards to port noise. Freq response, cone excursion and port velocity are the main ones to keep your eye on.

Up past 15-20m/S it's going to start making noise. Depending on how noisy what you're playing is, (quiet acoustic bass, war movie battle climax) how close or how directly pointed at you the port is, and at what frequency it gets that high... more or less could be tolerable. Also, larger port flares can help, to a point.

A good place to get some info is Bob Collo's subwoofer pages... check the
DIY links thread here... he's in there. Lots of good info, and handy calculators, one of which will estimate turbulence noise in a port under various conditions, and how much will flare size help.

6" port with flares would probably be nearly soundless, but unless you want to try and get away with external pipes as a design plan... ("The Power Station".. "The Smokestack Lightning Sub".. "Sub with Headers"...) it's tough to get it all in the box.

Finally, there's slot ports... but they add more woodworking to the project. Would be tough now to retrofit. And they're difficult to tune, if you need to change things.

Anyway, check it out, perhaps a 4" might not be that bad. Most of your air movement will be down at 20-30hz, so up in the "music" range it might be pretty quiet.

I built a RS315HF sub for a friend a while ago, in a 3cu ft box, tried porting about 20-22hz... Took about 28" of port, I made a giant U bend with 4 elbows and Precision Port flares... it was too much hassle, took too much volume away from the box... Finally just pulled it out and went with 3 cu ft sealed.
Didn't notice much noise, though. Of course, that's a 12" not a 15"...

Hope that helps...

[joecarrow]

I love that picture on the washing machine- it really gives scale to it! I've seen people's photos of these giant subwoofers with a CD for scale, and this is much better.

Regarding the ports- I was going to mention what JonP already said- there's no reason a port can't extend out of the box somewhat. You still need to make sure that the port isn't so long that it has pipe-organ resonance, but it could be helpful to remember that this would be allowed.

[brent_s]

Port noise is going to be related to frequency content and how loud you listen to said content.

I've got a DVC15 in 5.9 ft^3 net tuned to 17hz with a single 4" PrecisionPort. I've never noticed any port noise even when running the system up to reference level on LFE specific demo discs. I generally watch movies at -10/-15 below reference. Port is downfiring into carpet, which may help some. As they say...YMMV.

-Brent