Flint Acoustics: "Lil Jokers & Arthur" indoor edition

[Flint]

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:


Dry fitting the parts:


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


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

 

[Flint]

Clamping the front baffle on:


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


Dry fit of the initial subwoofer internal parts:


The finished satellite cabinets

 

[Flint]

The internal braces of the subwoofer to reduce vibrations, flexing, and adding strength while keeping the weight down as much as possible:


Opposite side of the subwoofer internals


Clamping the final two sides to the subwoofer:


Measuring the satellite coaxial driver mounted in the speaker.

 

[Flint]

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.

 

[Randy]

Even unfinished that is beautiful!

 

[Flint]

I took the clamps off the sub enclosure, and all that bracing paid off in spades. Without increasing the weight much, all the panels are dead when I knock on them. Whoop!

 

[PaulyT]

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 or does it really measurably help to reduce internal turbulence or something?

 

[Flint]

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 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.

 

[mcad64]

You must own a shitload of Bessey clamps?

 

[Flint]

You must own a shitload of Bessey clamps?

LOL!!! That last subwoofer clamp-up photo had all of my Bessey clamps in it.

 

[Wardsweb]

You never cease to impress. You sir have mad skills. You make me look like a rookie. Not an easy thing to do.

 

[Flint]

Thanks!

Today I created a blinding cloud of MDF router dust and finished the sub enclosure's milling. Now for finishing.

 

[AndySTL]

Wow these look awesome. Can’t wait to see the finished product.

 

[Flint]

A few new photos:


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.


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]

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:



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.



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

 

[Flint]

Completed the port plug I built for the subwoofer:

 

[Xgm3]

Excellent craftsmanship!

 

[team_tsp]

Very cool as usual, that internal bracing is a work of art!

 

[Flint]

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]

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.