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Flint Acoustics: "Lil Jokers & Arthur" indoor edition

Flint

"Do you know who I am?"
Superstar
#1
A friend of my son asked me to build him a set of the Flint Acoustics Lil Jokers coaxial speakers and The Arthur sub but intended for high fidelity indoor use. The original versions of this system were designed for outdoor applications which called for sealed enclosures and a brighter, sharper sound.

After much design work, I came up with a system which is functionally similar and priced about the same, but should provide better fidelity. All of the enclosures are vented, but they can be sealed if it makes sense.

They are still under construction, but here's some photos.

The MDF panels cut for the speakers:
Ethan_Coax_20190929_115501.jpg

Dry fitting the parts:
Ethan_Coax_20190929_122356.jpg

Dry fitting, showing the bracing to reduce vibrations and breakup the acoustic reflections:
Ethan_Coax_20190929_122412.jpg

Clamping the sides, back, and braces together after glue-up
Ethan_Coax_20190930_121216.jpg
 

Flint

"Do you know who I am?"
Superstar
#2
Clamping the front baffle on:
Ethan_Coax_20191001_130017.jpg

The baffle for the subwoofer with the port glued in place and backer blocks for the speaker mounting screws.
Ethan_Coax_20191001_130020.jpg

Dry fit of the initial subwoofer internal parts:
Ethan_Coax_20191001_193025.jpg

The finished satellite cabinets
Ethan_Coax_20191002_121021.jpg
 

Flint

"Do you know who I am?"
Superstar
#3
The internal braces of the subwoofer to reduce vibrations, flexing, and adding strength while keeping the weight down as much as possible:
Ethan_Coax_20191002_124919.jpg

Opposite side of the subwoofer internals
Ethan_Coax_20191002_124939.jpg

Clamping the final two sides to the subwoofer:
Ethan_Coax_20191002_131356.jpg

Measuring the satellite coaxial driver mounted in the speaker.
Ethan_Coax_20191002_133840.jpg
 

Flint

"Do you know who I am?"
Superstar
#4
The next step is using the measured performance of the coaxial speaker in the enclosure to design a passive crossover. Then I'll finish the work on the subwoofer enclosure and measure its performance.
 

PaulyT

Behind the Curtain
Staff member
Administrator
Moderator
Superstar
#7
I notice that you round off all the edges in the holes cut in the internal bracing. Is that just because you have a fetish with routers :laughing: or does it really measurably help to reduce internal turbulence or something?
 

Flint

"Do you know who I am?"
Superstar
#8
I notice that you round off all the edges in the holes cut in the internal bracing. Is that just because you have a fetish with routers :laughing: or does it really measurably help to reduce internal turbulence or something?
For a fullrange speaker, the rounding off reduces turbulence at higher frequencies which can technically reduce internal noise which could reflect back through the cone of the woofer/midrange. It also reduces weight.

For the subwoofer it doesn't have any benefit other than reducing the weight of the brace. I had the router table setup for the satellites and just did the two larger braces since they were ready. The smaller sub braces did not get any fancy rounding over.
 

Flint

"Do you know who I am?"
Superstar
#14
A few new photos:

Ethan_Coax_20191006_104728.jpg
Here's the sub enclosure after the second application of a sealant. I think one more is necessary before I can apply a faux wood finish using wood stain.

Ethan_Coax_20191006_110147.jpg
I designed the subwoofer with a port which is tuned to produce the highest output in the 30Hz to 60Hz range. The trade off is a bit if ringing and less than ideal transient response - though it will be boomy as hell. So, I also designed into the enclosure a really solid way to block the port and convert the sub into a sealed unit which will be tighter sounding, but less deep or loud. This photo is the plate which blocks the port and a heavy wooden plug which slides into the port to enhance the level of blocking. Four machine bolts will hold this in place and when not in use the machine bolts will have to be screwed into the receiving nuts to prevent any pressure losses. .
 

Flint

"Do you know who I am?"
Superstar
#15
Update!

I've fully sealed then sanded the subwoofer enclosure and have applied the primer and paint for the downward facing baffle side. Once that completely dies in two days, I'll start on the faux woodgrain finish with wood stain:
Ethan_Coax_20191010_132929.jpg


I've build a plug for the port from some scrap MDF hole cutouts and several pieces of 1/8 inch plywood and am finishing it simply with spray paint.
Ethan_Coax_20191010_132939.jpg


The satellite enclosures are still being sealed. They'll be dry enough to sand and apply what I hope is the final coat tonight.
Ethan_Coax_20191010_132948.jpg
 

Flint

"Do you know who I am?"
Superstar
#19
Very cool as usual, that internal bracing is a work of art!
Thanks! The satellites were designed that way. The sub was designed with the two large braces and the rest of the smaller braces were just scrap pieces I fit into place to randomize the vibrating areas of each panel so no two resonate at the same frequency.
 

Flint

"Do you know who I am?"
Superstar
#20
The buyer liked the demo speakers I have where I made a faux woodgrain using stain on the sealed MDF. So, after he did some research asked for a mahogany looking finish.

Today I started applying the stain with the first coat. Once this fully dries, I'll apply at least one more coat.

Ethan_Coax_20191013_154722.jpg
 
Last edited:
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