3D Printed Speaker Enclosures for 3.5" Full Range Driver

[terryforsythe]

... 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.

That is a good idea, but it will blow the $100 budget.

 

[terryforsythe]

I had texted my son the SBB4 QL=15 graph last night showing the bigger bass peak, along with the smaller dimensions. He just texted me back and stated "Yea, I usually like more low-end vs flat response." So the smaller box it is.

 

[mhardy6647]

That is a good idea, but it will blow the $100 budget.

Thanks for noting the budget -- I forgot about that!

 

[terryforsythe]

Here are the dimensions of the 6.8L box:

 

[terryforsythe]

Here are the parts to be printed individually. The baffle section and larger section will be glued together.

 

[mhardy6647]

I just had a Dick Sequerra flashback!

 

[terryforsythe]

I much prefer the look of my original design using the smaller driver over the L-shaped monstrosity, but the bass would be way too weak for my son, even just for gaming. From the front, though, the large section will be hidden behind the display, and I curved the sides of the baffle to match the curve of his display. So, it shouldn't look too bad. Also, his gaming setup is on a workbench in his lab, which already is a little cluttered with all of his electronics gear. So, even looking at the speakers from the side, they may fit the motiff.

 

[terryforsythe]

My son ordered the CHR-70 Gen. 3 drivers from Madisound. He paid a little extra to get the Champagne colored cones, $41.30 each, though with tax and shipping it did put him a little over $100. As I type this I am printing a prototype enclosure on my printer to check fitment. For the prototype, I am using thin walls and low infill to save on filament.

In total the final units will take nearly 9kg of filament. The baffle is 1.5cm thick, and the rest of the walls are 1cm thick. I think it should be good with 100% infill and all of the bracing I added. If not we'll spray the inside with rubberized undercoating to help dampen the enclosure. Also, we'll line the insides with some damping material I have left over from another project, 1" Sonic Barrier Acousta-Blue.

I'll try to remember to post pictures as we make progress, and post some frequency response measurements.

For parametric EQ in Windows, we are going to try EqualizerAPO. If anyone is using that, I am curious as to how you like it and whether there are any caveats we should know about.

Here is the beginning of the print of the large section for the prototype:

 

[somebodyelse]

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.

Since you're 3d printing it's relatively easy to add a bend or curve to your port.

 

[terryforsythe]

Since you're 3d printing it's relatively easy to add a bend or curve to your port.

I thought about that. Nonetheless, after investigating various options, I discussed it with my son and he said he would prefer the bass boost provided by the SBB4 QL=15 alignment, for which the port has adequate clearance.

 

[terryforsythe]

I tried printing the prototype large section with a 0.8mm nozzle, but it kept warping. I switched back to a 0.4mm nozzle and slowed down the print speed and acceleration. I am now printing a prototype of the baffle section. There is a little spaghetti due to one of the tree supports falling over, but otherwise it looks good. I think this one will make it to the end. I'll run out of the yellow filament before it finishes, so I'll have to switch in a different filament. No big deal, I'm only printing the prototypes with light infill to check fitment. Still, they take a long time to print. This one has been going over a day and is 63% complete.

 

[ppataki]

I tried printing the prototype large section with a 0.8mm nozzle, but it kept warping. I switched back to a 0.4mm nozzle and slowed down the print speed and acceleration. I am now printing a prototype of the baffle section. There is a little spaghetti due to one of the tree supports falling over, but otherwise it looks good. I think this one will make it to the end. I'll run out of the yellow filament before it finishes, so I'll have to switch in a different filament. No big deal, I'm only printing the prototypes with light infill to check fitment. Still, they take a long time to print. This one has been going over a day and is 63% complete.

View attachment 479610

I personally use 15% gyroid infill all the time + use a modifier shape of 60% infill where the screws go
And then I use vibrodamping sheets (4mm butyl for mass loading + vibration damping) and felt (10mm) on the inside walls

I think 100% infill is an overkill; I would not go above 45% in any case

EDIT: I also limited the speed to 100 (it made a huge difference in terms of print quality)

 

[terryforsythe]

I think 100% infill is an overkill; I would not go above 45% in any case

Thanks for the heads up. I agree that 100% is not optimal. I came across that same video sometime after my post. 60% infill density looks like the sweet spot based on his tests, but 30% wasn't bad.

And then I use vibrodamping sheets (4mm butyl for mass loading + vibration damping) and felt (10mm) on the inside walls

I also looked at using butyl rubber; I also recommend that to my son. I also am giving him my left over 1" Sonic Barrier Acousta-Blue to line the box over the rubber. I think that should be good.

Now we need to find good filament to use. I tried Elegoo and Overture PLA for the large section prototype, but they both warped quite a bit. I ended up using GST3D PLA+ filament I had left over from a few years ago, and that worked very well. But, I used the last of it printing the prototypes and GST3D no longer is in business. If you have a suggestion for good PLA or PLA+ to use, please let me know. In the past I have had good luck with Hatchbox PETG, but I have not tried their PLA.

 

[ppataki]

Thanks for the heads up. I agree that 100% is not optimal. I came across that same video sometime after my post. 60% infill density looks like the sweet spot based on his tests, but 30% wasn't bad.


I also looked at using butyl rubber; I also recommend that to my son. I also am giving him my left over 1" Sonic Barrier Acousta-Blue to line the box over the rubber. I think that should be good.

Now we need to find good filament to use. I tried Elegoo and Overture PLA for the large section prototype, but they both warped quite a bit. I ended up using GST3D PLA+ filament I had left over from a few years ago, and that worked very well. But, I used the last of it printing the prototypes and GST3D no longer is in business. If you have a suggestion for good PLA or PLA+ to use, please let me know. In the past I have had good luck with Hatchbox PETG, but I have not tried their PLA.

Yes I do but unfortunately it will not help since it is Europe specific. I use this filament for all my prints:

https://www.alza.hu/alzament-hyper-pla-1kg-white-d12717989.htm?kampan=adw1_alza_pla_all_hidden-gems_all_c_9063010___751236987982_~180961880844~&gad_source=1&gad_campaignid=22541136418&gbraid=0AAAAAD2xsm6QFCuD1MO_2LAKsb1VnlwVO&gclid=Cj0KCQjw0Y3HBhCxARIsAN7931VWp8jTnlj3FAEz9EzXTYTxUyiOCMo4I3gBNARtY5QNwv9nHVVxp_gaAm0PEALw_wcB

I think the point is that it shall be PLA+ (instead of regular PLA)

 

[JohnnyNG]

I also looked at using butyl rubber; I also recommend that to my son.

I've used this 4mm butyl and it seems to work really well:

https://www.amazon.com/dp/B01IWCMN1G?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1

 

[terryforsythe]

I've used this 4mm butyl and it seems to work really well:

https://www.amazon.com/dp/B01IWCMN1G?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1

That deadening material has great reviews. It is 4mm. At $105.04 for 10 sq. ft., it works out to $10.08/sq. ft., and my son is on a tight budget for this project.

I just found this Vevor sound deadening material on Amazon at $45.99 for 25 sq. ft. ($1.83/sq. ft.) It is 80mil (2mm) butyl rubber, with a layer of foil and a 3mm layer of what they call high density foam:

https://www.amazon.com/dp/B0CPY1XWXN/?coliid=I385NRPUVBM25Q&colid=2WZ7CMFC3FDJO&ref_=list_c_wl_lv_ov_lig_dp_it&th=1

I'll keep looking to see if I can find something that has thicker butyl rubber while still being cost effective.

 

[a4eaudio]

That deadening material has great reviews. It is 4mm. At $105.04 for 10 sq. ft., it works out to $10.08/sq. ft., and my son is on a tight budget for this project....

Amazon now has "Amazon Basics" sound deadening material. It seems to be about 2.5mm thick, so you might need to double it up - I don't know if it comes out economical at that point or not.

 

[terryforsythe]

I've used this 4mm butyl and it seems to work really well:

https://www.amazon.com/dp/B01IWCMN1G?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1

10 sq. ft. is overkill for these small speakers, as well as the price for that amount. BUT, I went to Design Engineering Inc.'s website and they sell 4 sq. ft. of the Boom Mat for $41. That is enough material for the project and more along the lines with this being a very low budget build.

I also found this on Amazon:

https://a.co/d/jbVhQon

I sent links of both to my son and I'll let him choose.

 

[terryforsythe]

Here is a picture of the prototype. I used up numerous old rolls of filament printing it. It sounds OK but, definitely, the enclosures need to be printed with more wall lines and infill density, and lining the inside with butyl rubber and damping material will help.

I need to play with the port tuning. The various braces I added appear to have created some air flow restriction - the port tuning ended up being about 10Hz lower than that predicted by VituixCAD, as well as my spreadsheet calculations. I revised the braces in the CAD model to reduce some of the restriction. Also, I modified the port to be in two pieces that slip together. That way we can print one of the tubes in various lengths and select the optimal length based on measurements. I'll do that with one of the final enclosures my son prints. Once we determine the optimal port length, we can glue the two pieces together. The seams will be inside the enclsoures, and thus not visible.

My son is waiting for some more parts to come in for his printer, as well as time to finish his modifications. So, it probably will be after the new year before he gets the enclosures printed. I offered to print them on my printer, but he wants to do it on his, which I understand. That was his motivation for starting the project in the first place.

 

[terryforsythe]

Here is my other current speaker related project using 3D printing. The enclosure and lid for the controller board are on my printer now:

It will come in handy for doing a sweep of frequency response measurements with the speaker at various angles. I'll use it not only to measure my son's speaker, but also for my other speaker project.

I can control the swivel on the same computer I use to run the frequency response sweeps, and set the presice angle I want. It will save a lot of time running a suite of frequency response sweeps. I still need to cut the board to size and radius its corners, and I need to figure a way to mount the whole thing to my ladder, which I will use to get the speaker well off of the ground when doing outdoor measurements.

I also plan on building a wedge shaped contraption to put on the ground to mitigate ground reflections. Ground reflections were an issue the last time I ran outdoor measurements, which ended up only being useful above 400Hz once I applied an IR window to clean up the data. Also, last time I used an 8 ft. ladder to hold the speaker. This time I am going to use my Little Giant ladder for the speaker, and the 8 ft. latter for my microphone stand, the mounting mechanism for which is my next 3D print. That should put the speaker round 14-15 ft. off the ground. If I had a taller microphone stand I would be able to get the speaker up to 19 ft. with my Little Giant ladder.