FalseMetal666
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Looking forward to seeing how you set up the bracing. Awesomest gift.
College dorm speakers
- Thread starter Tsingtao_1903
- Start date
When using a coaxial driver like the 328C - if you transplant the compression driver to an external horn, does the open cavity become an additional cabinet port? Does something attach to the rear of the woofer in its place like a threaded dummy horn that seals the cavity? Does this product exist?
FalseMetal666
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I think there’s little blocking plates available to seal off the compression driver hole.
Tsingtao_1903
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The 2412H is held down by a bracket using two screws.
1) Replace the 2412H with a 3D printed, dimensionally correct dummy.
2) As mentioned, use a blocking plate.
Once again, your resources meet talent
Tsingtao_1903
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Ripped some 1x1's on the table saw. Made a ripping fixture using 3D printed parts to rip the 1x1's into halves.
Tsingtao_1903
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Just about done. Zip tied and secured all the internal wiring (for the many future dorm moves). Exposed plywood corners are tough to get flushed and squared. Decided to build L & H handed speaker terminal locations.
Will likely go with the 1211 horns in the final version. Can't break those heavy cast aluminum horns right?
Will likely go with the 1211 horns in the final version. Can't break those heavy cast aluminum horns right?
gortnipper
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Hah - just read something related to this thread over the weekend. So different to my university experience, even tho I didnt live in a dorm myself but was in various shared houses and apartments.
www.theatlantic.com
How Parents Hijacked the College Dorm
The spaces were once furnished by scrappy kids. Then the adults entered the room.
www.theatlantic.com
Tsingtao_1903
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This post is for whoever wants/thinks about using the JBL 328C's for their speaker builds.
Turns out I needed to create a much more accurate model of the JBL 2412H... Below is a picture of 3 JBL 2412H's. One is from the auction website. The other two are removed from the JBL 328C's. The one from eBay is lower right. It has a bug screen. The ID of the bug screen is nearly 1". The one on the top is from a 328C. The throat piece is one-piece cast aluminum. No bug screen. The one on the left is from a different 328C. The throat piece is one-piece turned aluminum. No bug screen. There are some minor dimensional differences between the cast and turned throats. But, I suppose are within design tolerances.
Revised the model to show: 1) The bug screen, 2) the pocket where the bug screen sits, and 3} the actual throat dimension without the bug screen.
Two problems: 1) Without the bug screen, the pocket would create a gap between the driver and the horn (about 1mm). 2) The actual throat size of the JBL 2412H is 22.5mm. A sudden transition from 22.5mm opening to 25.4mm has the potential to create unwanted diffraction at the interface.
So, a special adapter is needed to be able to use the JBL 2412H on standard 25.4mm horns. The adapter has a raised boss to fill the pocket in the 2412H throat, and an added length to transition from 22.5mm driver throat to 25.4mm horn throat.
A bit more work than expected. But, all good.
Turns out I needed to create a much more accurate model of the JBL 2412H... Below is a picture of 3 JBL 2412H's. One is from the auction website. The other two are removed from the JBL 328C's. The one from eBay is lower right. It has a bug screen. The ID of the bug screen is nearly 1". The one on the top is from a 328C. The throat piece is one-piece cast aluminum. No bug screen. The one on the left is from a different 328C. The throat piece is one-piece turned aluminum. No bug screen. There are some minor dimensional differences between the cast and turned throats. But, I suppose are within design tolerances.
Revised the model to show: 1) The bug screen, 2) the pocket where the bug screen sits, and 3} the actual throat dimension without the bug screen.
Two problems: 1) Without the bug screen, the pocket would create a gap between the driver and the horn (about 1mm). 2) The actual throat size of the JBL 2412H is 22.5mm. A sudden transition from 22.5mm opening to 25.4mm has the potential to create unwanted diffraction at the interface.
So, a special adapter is needed to be able to use the JBL 2412H on standard 25.4mm horns. The adapter has a raised boss to fill the pocket in the 2412H throat, and an added length to transition from 22.5mm driver throat to 25.4mm horn throat.
A bit more work than expected. But, all good.
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Brilliant!
Tsingtao_1903
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So, the JBL 2412H is not a good match with the 1211 horn. Sounds nice, but, ear fatigue sets in about 30 minutes or so.
Playing with the 1510 horn and the loaner Lansing H1000. The 1510 is nice and smooth. But, the H1000 is special; Clear and musical.
Ultimately, I will be going with the 1510. The H1000 is not mine. Beside, the fabricator agrees to make another 1510 to pair with the one I have. Will be sending the one 1510 back to him. Both will be powdered coated hammertone dark grey. (If you want the paint to match, then, paint both at the same time.)
Playing with the 1510 horn and the loaner Lansing H1000. The 1510 is nice and smooth. But, the H1000 is special; Clear and musical.
Ultimately, I will be going with the 1510. The H1000 is not mine. Beside, the fabricator agrees to make another 1510 to pair with the one I have. Will be sending the one 1510 back to him. Both will be powdered coated hammertone dark grey. (If you want the paint to match, then, paint both at the same time.)
Tsingtao_1903
Site Supporter
So, I can't leave well enough alone....
Had to make my own version of the Lansing H1000. Screw mount; 10 cells; 1000hz. PLA CF printed with a baffle.
10 cells to give the horn a bit wider horizontal dispersion.
Listening now. Really nice.
Had to make my own version of the Lansing H1000. Screw mount; 10 cells; 1000hz. PLA CF printed with a baffle.
10 cells to give the horn a bit wider horizontal dispersion.
Listening now. Really nice.
Mr. Widget
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I love the look of this combo.
I know you have spent a great deal of time, effort and probably money on creating metal versions of some of your printed horns, but I am wondering if there are any acoustic differences between them.
Obviously a metal horn will be more durable, but I would think a nicely finished printed horn should sound as good as a metal horn and with tweaks to the design it could have concealed webbing to make it even more rigid and be even less prone to ringing.
Have you made any listening tests or measured comparisons?
Tsingtao_1903
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The answer is "It depends". There are so many factors affecting the acoustical performance of metal vs printed horns.
1) Horn geometries and dimensions.
2) Filament type.
3) Print resolutions.
4) Print parameters: Walls layers, infill percent, surface texture, print temp, print speed,...
5) Horn size.
6) Quality of the 3D model for printing.
I typically model much larger horns. So, high quality prints will take days (5 to 10 days.) So, I print fast and with inexpensive filaments just to validate the sounds and design features. If a horn printed this way sounds good, chances are it will sound even better casted.
Can't speak for other 3D printed horns as their materials and printing parameters are not known to me.
The H1010 horn is relatively small. So, it was designed with specific geometries and dimensions for fine resolution prints using PLA CF with 0.6 nozzle (any smaller the nozzle will clog.)
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Does the finer resolution mean smoother or less noticeable ridges between each pass?
Also, have you tried the wood based filament and with with results? (May have asked this already).
Tsingtao_1903
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Yes, finer resolution means smoother/less noticeable layer lines. However, post processing methods such as acetone honing can smooth these ridges out.
Don't care much for wood base filaments. Because of the high heat required to melt the PLA, the whole room smells of wood smoke....
My preferred filament is carbon fiber filled PLA. For smaller prints requiring fine geometries (0.04"), PLA CF has sufficient rigidity for my purposes. There are other better filaments. But, for me, 3D printing is a mean to an end. Not my core focus nor expertise.
Mr. Widget
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With care and patience it is amazing what you can do with 3D printed parts. Here are a couple of objects that we finished back when I ran a prototyping shop.
Tsingtao_1903
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So, my son will be finishing his first year at UF in a few weeks. He and his dorm mate will be moving to a near by apartment for the next school calendar year. Each will have their own room and quite a bit more space.
More space, bigger speakers....
Came up with a rough design for a cabinet using an Altec 414-16. Cabinet volume is about 3.5 ft3. Down firing port. The horn on top may change.
More space, bigger speakers....
Came up with a rough design for a cabinet using an Altec 414-16. Cabinet volume is about 3.5 ft3. Down firing port. The horn on top may change.
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