3D Printed Speaker Enclosures for 3.5" Full Range Driver

[terryforsythe]

My son wants to 3D print speaker enclosures for use with his gaming computer. His requirements are as follows:

1. 3D printing is a must - he enjoys 3D printing and wants to give it a go on his newly upgraded printer.

2. The following maximum dimensions, to allow them to fit under his display:

Maximum height: 4 inches
Maximum depth: 10 inches
Maximum width: None within reason - he has an ultra-wide gaming monitor

3. Full range driver - he does not want to mess with crossovers for this project, neither active nor passive. He may apply EQ in Windows if it helps. I'll probably put a capacitor in series with the driver to protect it, though.

4. Cost - less than $100 for a pair of full range drivers. He only wants to use a spare class D amp I have laying around and not have to purchase any additional electronics. He will use a 3.5mm to stereo RCA splitter cable to connect from his computer to the amp.

After a little bit of researching, I settled on the GR Research LGK 2.0 driver for $40 each. Of the 3.5" full range drivers I came across, it had the lowest Fs and Qts, even though they are still quite high at 113Hz and 0.628, respectively. But, what do expect for a 3.5" driver. If anyone knows of a 3.5" driver that will perform better in the bass without sacrificing midrange and highs, let me know.

Attached are images of a cabinet I designed using a SBB4 QL=3 bass alignment. The internal volume is approximately 2.6L after subtracting out air volume taken up by the driver, braces, ports, etc. -3dB calculates to be around 96Hz.

I designed the cabinet to minimize the requirement for supports when printing. As it is, supports will be needed for the driver recess and the cross member behind the woofer. It is designed to be printed with the front side down on the build plate.

 

[ppataki]

This is a really cool project!!

Have you considered any Markaudio drivers?
If you can go up to 4" they offer way lower Fs and way higher xmax than the GR Research LGK 2.0

 

[terryforsythe]

Have you considered any Markaudio drivers?
If you can go up to 4" they offer way lower Fs and way higher xmax than the GR Research LGK 2.0

Thank you for the heads up on Markaudio!!!

I just checked out their full range drivers. The Alpair 5.3 (3" driver) would just fit the baffle if I remove the fillet around the driver. Or, perhaps, we could make the box 1 or 2 cm taller. A pair would be about $40 over my son's budget, but maybe he could make it work.

Using a SBB4 QL = 3 bass alignment the box would be 4.54L, as opposed to 2.6L for the LGK driver, for which the enclosure currently is designed EDIT: It also comes out to 2.6L - I input an incorrect value into my spreadsheet. But, I looked at their cabinet design and it is 3.56L, and they claim an F3 of 63Hz. That might be doable; I could make the box 31cm wide as opposed to its current width of 20cm. EDIT: 3.56L won't be doable while holding the maximum height and depth we need. It is too wide to fit on the printer's build plate unless we print it in pieces and glue it together, which we would like to avoid if we can. We'll see. I'll talk to my son about it.

Although the radiating surface area of the Alpair 5.3 is a hair smaller than the LGK (28cm^2 vs 30.8cm^2), it more than makes up for it with a longer throw (3mm vs 1mm).

In sum, I think the Markaudio driver may work better. I'll run it past my son to see if he can stretch his budget a little.

 

[ppataki]

Thank you for the heads up on Markaudio!!!

I just checked out their full range drivers. The Alpair 5.3 (3" driver) would just fit the baffle if I remove the fillet around the driver. Or, perhaps, we could make the box 1 or 2 cm taller. A pair would be about $40 over my son's budget, but maybe he could make it work.

Using a SBB4 QL = 3 bass alignment the box would be 4.54L, as opposed to 2.6L for the LGK driver, for which the enclosure currently is designed. But, I looked at their cabinet design and it is 3.56L, and they claim an F3 of 63Hz. That might be doable; I could make the box 31cm wide as opposed to its current width of 20cm.

Although the radiating surface area of the Alpair 5.3 is a hair smaller than the LGK (28cm^2 vs 30.8cm^2), it more than makes up for it with a longer throw (3mm vs 1mm).

In sum, I think the Markaudio driver may work better. I'll run it past my son to see if he can stretch his budget a little.

Just FYI the CHR-70 and the CHP-70 even have their on-axis and off-axis responses documented in their datasheets
They look a bit jagged but their shapes are almost identical, meaning that the speaker can be EQ-d very well! I think this is an important factor for a full range driver since you will need to EQ it anyway

 

[Tell]

Looks like a fun project! I have no suggestion about drivers (the only one I really know of in that size is the Vifa TC9), but I'd at least suggest placing the drivers further out on that wide baffle to get a bit more stereo width

 

[terryforsythe]

Just FYI the CHR-70 and the CHP-70 even have their on-axis and off-axis responses documented in their datasheets
They look a bit jagged but their shapes are almost identical, meaning that the speaker can be EQ-d very well! I think this is an important factor for a full range driver since you will need to EQ it anyway

I looked at those earlier. They look like really nice drivers, and they are well priced at $36 each from Madisound. Unfortunately, the boxes will be too large. I'm coming up with 7.44L for the CHP-70 and 9.38L for the CHR-70. Also, they are 4-7/8" diameter, which means the baffle would need to be a bit over 5". Maybe I could slant the baffle backward to make it fit in the 4" height constraint, but we are not going to be able to fit that much air volume under his display unless I get really creative with the box design. But, maybe. I'll take a look.

 

[terryforsythe]

Just FYI the CHR-70 and the CHP-70 even have their on-axis and off-axis responses documented in their datasheets
They look a bit jagged but their shapes are almost identical, meaning that the speaker can be EQ-d very well! I think this is an important factor for a full range driver since you will need to EQ it anyway

We are going to go with the Markaudio CHR-70. Thank you for the information on it!!!

My son said he can move his monitor up 1/2" or so, and I am going to slant the front baffle back 37 degrees (3,4,5 triangle). That should give me 5-1/2" for the baffle, which should be adequate for the CHR-70. Also, that will serve to point the drivers closer toward ear level.

The shape of the enclosure will go straight back a distance a little further than the thickness of the display, about 2-1/2", then expand upward from there. Essentially, the enclosure will be a backward L-shape. I also am going to try to curve the baffle to match the curvature of his display, which is 1000R.

Tomorrow I will start on Rev. A of the enclosure design. Given the size and complexity, I am planning on having two sections that will be glued together. Hopefully I'll have the revision ready to share in a couple of days.

 

[JohnnyNG]

This looks like a cool project. I'd love to try a printed enclosure but it looks like an entire hobby unto itself.

 

[terryforsythe]

OK. I came up with a box design that will work with the Markaudio CHR-70 full-range driver, with the baffle still fitting under the display, though my son is going to have to move the display up 3/4". It sure ain't pretty, but it will serve the purpose, and most of it will be somewhat hidden behind the display, which is a 49" ultra-wide (5120x1440).

The new box is 9.5L. F3 calculates to be 59.9Hz using SBB4 QL = 3 bass alignment. I haven't yet modeled it in VituixCAD, but I will do that before settling on the port length. Here are the pictures - brace yourself:

 

[terryforsythe]

It will print in 3 parts: the smaller baffle section, the larger back section, and the rear cover. The larger back section is 23cm x 23cm x 21cm, which will just fit on my son's printer.

 

[mhardy6647]

This looks like a cool project. I'd love to try a printed enclosure but it looks like an entire hobby unto itself.

Start small... print horns!

e.g., see https://www.lycan3r.com/other-materials

 

[terryforsythe]

I did some analysis in VituixCAD using the enclosure tool. I ended up changing from QL = 3 to QL = 15 for the SBB4 bass alignment. That allowed me to drop the enclosure size from 9.38L down to 6.8L, while also dropping F3 from 60Hz to 56 Hz. With QL = 3 there is about a 1.8dB boost around 100Hz. With QL = 15 the boost is about 2.9dB around 90Hz. My son probably will like that. I took the extra space from the depth of the speaker, removing 6.5cm. That saved me CAD time since I did not have to change the cover other than the port size. Also, height is less of an issue with his setup than is depth. It still has an ugly profile, but the ugly part will mostly be hidden behind the display.

 

[ppataki]

I did some analysis in VituixCAD using the enclosure tool. I ended up changing from QL = 3 to QL = 15 for the SBB4 bass alignment. That allowed me to drop the enclosure size from 9.38L down to 6.8L, while also dropping F3 from 60Hz to 56 Hz. With QL = 3 there is about a 1.8dB boost around 100Hz. With QL = 15 the boost is about 2.9dB around 90Hz. My son probably will like that. I took the extra space from the depth of the speaker, removing 6.5cm. That saved me CAD time since I did not have to change the cover other than the port size. Also, height is less of an issue with his setup than is depth. It still has an ugly profile, but the ugly part will mostly be hidden behind the display.

Just out of curiosity I just ran some simulations in BassBox Pro for the CHR-70

With a sealed design (with typical damping level) it gave me these results:

With a ported design:

 

[terryforsythe]

Here is what VituixCAD gave me for SBB4 QL=3:

Here is what VituixCAD gave me for SBB4 QL=15:

I briefly looked at the SQB3 and SC4 alignments using my spreadsheet, but the enclosure volumes were too large for our goals. VituixCAD confirmed that. SC4 QL=3 gives a flat response with f3 at 46Hz, but the enclosure volume is 27.2L.

 

[terryforsythe]

Here is what it looks like using 6.65L enclosure and a 51.1Hz port tuning frequency. F3 is at 52Hz.:

 

[terryforsythe]

This one looks good. 6.65L with a 55Hz tuning frequency.

 

[terryforsythe]

The issue with 55Hz port tuning above is that the opening of the port would be too close to the opposite enclosure wall. If I move the port lower on the panel where there is more clearance, that would put it behind the driver, which can cause some issues, though I don't know how audible they would be.

 

[ppataki]

The issue with 55Hz port tuning above is that the opening of the port would be too close to the opposite enclosure wall. If I move the port lower on the panel where there is more clearance, that would put it behind the driver, which can cause some issues, though I don't know how audible they would be.

I personally would go for the bigger cabinet with lower Fs and 'happier' port

 

[mhardy6647]

I personally would go for the bigger cabinet with lower Fs and 'happier' port

... or... perhaps... a passive radiator? One of the traditional, ahem, "use cases" for a PR is a situation where the optimal port size (i.e., volume, or length) isn't practical. Obviously, the real estate taken up by even a small-ish PR in the present case might be equally impractical, but it felt like it was at least worthy of mention.

 

[terryforsythe]

I personally would go for the bigger cabinet with lower Fs and 'happier' port

What is strange is that with the smaller box I get a slightly lower F3. But, that is how I measure F3, which is 3dB down from the nominal 85.6 dB, not the bass peak as VituixCAD dispays when the parameters are enabled. With the larger box I can get a lower bass peak, but I think my son will actually prefer the peak. I let him drive my car a while back and the next time I drove it he had turned up the bass. Anyway, I'll show him the graphs the next time he comes over and let him decide.