3D printed 6" Sub Build

[sevenmead]

Hello, I'm designing a small sub with a 2.1 plate amp and 6" sub from PE. The sub is 60 watts which is the max of the amp. I have a HUGE new printer I'm currently assembling with a build area of 19"^3. Way more than enough. I've been digging around for a couple days trying to determine how I should approach the build in terms of shape and port but the learning curve is pretty massive. I'm tempted just to make a cubic foot box because I like round numbers but how big to make the port? I can make it any shape I want so is it better to get funky and have no sharp edges?

here is the sub

https://www.parts-express.com/HiVi-D6.8B-6-Poly-Bass-Midrange-Shielded-297-444

What would you do?

[Chris Roemer]

1.0 cf seems a bit large ...
Have you run a box simulation?

Not being a true "sub" (only 5mm Xmax), this looks to hit Xmax at around 30w.

[sevenmead]

OH that's a good tip.

[sevenmead]

can you recommend a box simulator. I'm only just dipping my tow in.

[mdocod]

...

What would you do?

If I had a big (19"^3) 3D printer and wanted to do a subwoofer project around a 6" sub, I would use hornresp to model the box possibilities. I would probably just plan on using most of the ~19" X 19" printing space, with the "width" of the box being built up as the printer goes so that you can build up the interior baffles that will make up the port with nice smooth corners and transitions.

I wouldn't use that particular 6" driver for this project. For around that price you could use a Epique E150HE-44, which has more than twice as much total displacement while actually being about 3/4" smaller in diameter, with characteristics that will model well in a very compact enclosure... https://www.parts-express.com/Epique...r-Coil-295-102 -

Tune the box to around 30-40hz.

[sevenmead]

I'm going for simplicity on my first try and the amp is only 60w to the sub channel. Will there still be a noticeable increase in performance from that sub despite not having the power to drive it? I could also add a second stage amp, it that advisable?

[anunnaki]

This works well on a tighter budget. Roughly .45 Ft^3 tuned to about 35 hz. I 2nd the epique suggestion above though!

https://www.parts-express.com/Dayton-Audio-DCS165-4-6-1-2-Classic-Subwoofer-4-Ohm-295-198

[sevenmead]

I think I'll get the sub recommended by anunnaki and bulid off the dimension in the kit that uses that sub.

https://www.parts-express.com/Dayton-Audio-6-1-2-Down-Firing-Active-Mini-Subwoofer-Kit-with-2.1-Channel-Amplifier-300-7161

still have to figure out the port diameter tho since it's not listed

[mdocod]

The DCS165-4 is barely different from the originally selected Hi-Vi driver in terms of displacement.

Consider the W6: https://www.parts-express.com/Tang-B...peaker-264-919

More than double the displacement.

[sevenmead]

that's a good option but I think I'll save that for a version two with a bigger amp.

[sevenmead]

Port of ID of 1 3/8 found

[Chris Roemer]

WinISD from www.linearteam.org is all you really need.

IMO 1.375"id is a bit small for that driver. I'd go with at least 1.75"id.
For the DSC165 0.45 cu.ft. box (interior) needs a 1-3/4" port that's 8" long to tune to the upper 30s and should reach (F3) into the mid 30s.

[mdocod]

For the DCS165-4 I would suggest a ~7-8" wide box with the port exit and sub mounted on the narrow baffle side. The depth and height can be anywhere from ~10-16" as long as you get an internal volume of ~0.25-0.5ft^3 in the box portion (not including port and other stuff), and another ~0.2ft^3 for the displacement of the driver, cross bracing, and mostly, the port.

Do a 1"X(internal-box-width) slot port that "wraps" around inside the box at least completing an "L" shape and possibly beyond, depending on the tuning you desire. A smaller box with an "L" port using up the length of both sides will result in tuning frequencies up in the 40-45hz range, if you go a bit bigger and wrap that port around to the 3rd side (30+ inches long), you can tune down around 30-35hz.

Use WinISD per Chris's suggestion to model the transfer functions, [email protected], etc.

Go larger and lower tuning if you want deeper but lower maximum output. Go for higher tuning if you want louder, but less bottom end extension. Keep in mind that if you tune high, the driver will go "unloaded" with very low frequency content. It's best not to do a "high" tuning frequency for a sub that will be used with very low frequency content like movies, unless you put a high-pass filter on the sub to protect it. With that said, the DCS series are pretty "rugged" drivers that will probably handle being abused pretty well.

60W is a good match for this sub if tuned up around 40hz. For lower tuning's you'll run out of Xmax at about 20-30W, but that's really not a big deal. having 3dB of amplification headroom above Xmax won't hurt anything.

[DeZZar]

You might find this video of interest.
​​​​​​https://youtu.be/q1HIhQywMPE
This channel has multiple 3d printed speakers/subwoofers that you can get some tips from.

[sevenmead]

Hexibase is the primary reason I'm here!!

[sevenmead]

Any suggestions on wall width?

[sevenmead]

I'm going with 15 mm wall width for the time being. using mdcod's example I have a box that 210mmx 210 x 355 and a full width port . The resulting volume is .55 ft^3 not taking into account the driver.

I downloaded the driver profile from here...

http://www.loudspeakerdatabase.com/Dayton/DCS165-4

and loaded it into WinISD and the numbers are looking about what I would expect from the comments so far but the only thing that is strange is that the XMax is about 50% and I can't get it to change much. Any thoughts about that?

for ease of printing I'm looking at not doing and "L" port and just having it move toward the back... but given that I'm not maxing out the xmax a full width port of 210mm only needs 9mm width at 200mm depth to meet the 30hz tuning criteria. Can someone verify my math?

this is the basic idea so far.

[mdocod]

Adjust the signal level in WinISD to see Xmax for a given power input.

At only 9x180mm, the total cross section of the port is pretty small. When driven hard, you might experience some compression and chuffing, but perhaps not with good flares on the port. Keep an eye on port velocity for a given power input (winISD can model that, but won't necessarily be accurate for a flared port). The lower the better. Around 10m/s or less is really ideal but with good flaring 20-30m/s can also work.

AN "L" shape port can be very easy to print if you turn the print job on its side and let the printer to the work of drawing the "L"

I would personally make that box a little narrower, maybe shave 10-30mm off the width.

[anunnaki]

Your wall thickness is fine, just be sure to brace the enclosure effectively.

[Chris Roemer]

Hopefully your dims are all INternal (otherwise I don't get YOUR intended volume), and you can't count the area taken up by the slot structure as internal volume either.

You don't really care about excursion down at 10Hz (WinISD's "default" plot).
Given 60wRMS, the driver should stay below Xmax below its F3.

9mm is AWFULly "narrow" for a slot. The walls of the slot have greater drag than most models can predict (throwing off the tuning).
You'd be way better off w/a slot that's 18mm x 105 (or 27 x 70 would be better yet). Slots much less than 25mm wide (thick?) can get kinda wonky.

[sevenmead]

yah, the signal level was super low and I had not found it yet. I was just moving all the parameters around trying to get cone excision to move at all. Jut figured that out and am re assessing

[sevenmead]

Ok so reworked the design for easier printing. internal volume is .55 ft^3. port is 24mm x 200mm and length is 555. Tuning frequency comes out to 39 hz.

I like it. now i just need to fancy it up.

[mdocod]

That looks more like it! Keep in mind that if you make the box "taller" rather than "deeper" you can achieve the same internal volume but with a smaller footprint.

[sevenmead]

Well I finally have my 500mm^3 printer built and functioning...

And I'm polishing up my first sub print... but I'm wondering how everyone decides on internal support? I'm not using a particularly powerful sub so I wonder if its even necessary.