how i spent my weekend - abc enclosure

[robbyho]

I got back form vacationa and saw the pile of oak plywood that was lying against my fence from a desk I took apart. I figured, what the heck, I'll try my hand at an abc enclosure.

I'll explain it all when I get back from playing basketball, but here's a few pics.

The red is the response of my abc box, the blue is the response of the JL H.O. box.


The inside of the enclosure (2 chambers, 3 vents).



In my car for testing.


More info to come.

Rob

[robbyho]

The abc enclosure is a relatively new design that incorporates two chambers and 3 vents. To my knowledge, there is no exact formula to design one, but there is a general guideline. You design a ported enclosure for your subwoofer. Take the net volume of the ported design and divide it into 2 chambers with a 1:2 ratio. So a 1.5 cubic box would be two chambers of 1 cu ft and 0.5 cu ft. Whatever vent length you desing will be used to vent each chamber to the outside, and each chamber to each other.

The result *should be* a frequency response that has 3 peaks instead of 1 like a regular vented enclosure. The peaks will be at whatever the original vented box tuning frequency was, a 1/2 octave above and a 1/2 octave below. I chose 35 hz, so it should have had peaks at 26 hz, 35 hz, and 52 hz.

The graphs I made were from the data taken of both enclosures outside, about 5 feet from a wall facing into my yard, with the mic one yard away. I used a 200 watt plate amp, with no settings changed for both tests.


You can see the large peak at 55 hz from the abc enclosure, with a slight peak at 40 hz. This doesn't really reflect how the abc enclosure's respons should look like and I am not sure why the peaks are not easily seen.

As for in car tests, I hooked up the abc enclosure with the 10w7 to a Phoenix gold Ti400.2 bridged (400 watts rms). The bass is definitely loud, and sounds nice. Definitely louder than the J.L. H.O. box. The peak is a little high for my tastes, I would prefer it to be around 35 hz, like how I thought I designed it. Still, it adds a perfect sound for 808 booms (the hip hop bass) and it is exellent for rock bass guitars. Rock kick drums sound a little bit colored when played at high volumes, but if I turn the sub down a bit, it blends very nicely.

In conclusion, I would recommend this abc for any daily driver. It is not the ultimate sq enclosure (I still would go sealed with a lot of power for that), but it offers a smooth frequency response and a nice peak for the bass head. It is also a great enclosure if you have a smaller amp. With 400 watts, I can accomplish what would take 1000+ watts for a sealed enclosure to do. The sub is hardly moving and the bass is amplified like crazy.

Rob

[Magnum-RT-AWD]

good read-----I still love a good sounding low tuned ported enclosure alittle more so than sealed or BP-----TL(if I could fit it in the Mag would go in there) my buddy has designed a few ABC's and had good daily driver numbers from them.

[OoTLink]

Don't you trade clarity for noise in this case?

[robbyho]

Don't you trade clarity for noise in this case?

That statement is partially accurate if you substitute "loudness" for noise. Noise is not the right word. A sealed enclosure will yield the flattest frequency reponse, meaning it is the most accurate. A ported or an abc enclosure will make certain frequencies louder and thus more prominent in music. Sometimes this sounds better, sometimes it sound worse, it depends on the music and the listener.

Rob