Help Needed. Optimal Cabinet Design for Fountek FE87 2" Full Range Driver 8 Ohm

[slipperybidness]

I recently picked up a pair of these drivers, I paid $6 each so it seemed like a good deal.
https://www.parts-express.com/fountek-fe87-2-full-range-driver-8-ohm--299-022

My original plan is to use those drivers as the speakers for my bar top arcade machine build. Here is the thread on that build. The cabinet is set up for a biy marquee, but I think that will be my speaker area instead (no marquee)
http://forums.audioholics.com/forums/threads/speakers-and-amp-for-tabletop-arcade-ideas-etc.94731/

I also bought a Lepai LP2020 to power them.
https://www.parts-express.com/lepai-lp-2020a-tripath-class-t-hi-fi-audio-mini-amplifier-with-power-supply--310-300

My thought right now is to set up the bar top arcade with these speakers, and I might even use the other input on the Lepai to run a little background music off my phone from time to time. Whether or not I will be able to use these drivers on this arcade project is a little bit iffy right now due to size and space constraints. I *think* that I can make it work and look good, but I need to get a little farther into the build before I can be 100% certain on this.

Now, on to my questions and where i could use some help! Could one of you experts use the T/S parameters to model an ideal box for these drivers? 1 driver per box. And, would it be sealed or ported? I know absolutely nothing in that area of this hobby!

Here is a link to the spec sheet as supplied by PE, and it has the T/S parameters.
https://www.parts-express.com/pedocs/specs/299-022--fountek-fe87-spec-sheet.pdf

I also see that PE has a flat pack cab that "seems about the right size", but that is simply looking at physical dimensions of the speaker vs. the cab. Would this cab work out well? Sealed or ported?
https://www.parts-express.com/denovo-audio-knock-down-mdf-004-cu-ft-micro-bookshelf-speaker-cabinet-pair--300-7060

Obviously, Sound Quality is not the end goal on this project. However, I would still like to do what I can to get the most out of these speakers and get them sounding as good as can be expected.

Any help for the AH community would be greatly appreciated! Pics coming soon!

 

[Swerd]

On that driver's page, PE suggested both sealed & ported cabinets.
Ask PE what port dimensions they suggest for the vented cabinet.

Optimum Cabinet Size (determined using BassBox 6 Pro High Fidelity suggestion)

• Sealed Volume 0.1 ft.³
• Sealed F3 118 Hz
• Vented Volume 0.14 ft.³
• Vented F3 63 Hz

Scroll down further to the Q & A section. The first question is about port size.

Use a 2" long × ¾" diameter port.

PE doesn't seem to carry a port that narrow. Get ¾" PVC drain pipe at Home Depot and cut it to length.

 

[slipperybidness]

On that driver's page, PE suggested both sealed & ported cabinets.
Ask PE what port dimensions they suggest for the vented cabinet.

Optimum Cabinet Size (determined using BassBox 6 Pro High Fidelity suggestion)

• Sealed Volume 0.1 ft.³
• Sealed F3 118 Hz
• Vented Volume 0.14 ft.³
• Vented F3 63 Hz

Dang! I don't know how I missed that, but you are correct on that point!

I'm not sure that I could get a 0.1 ft3 cab to fit in the allotted space (probably not). Maybe I can if I get a bit creative on the cabinet shape.

Any idea what to expect if I was forced to shove these into a 0.04 ft3 cabinet instead? How bad would that be?

I may end up building these as a little pair of speakers, and go a different direction on my arcade build audio.

 

[Swerd]

A sealed 0.1 ft³ cabinet has an F3 of 118 Hz.

Going to a 0.04 ft³ sealed cabinet will increase the F3.

 

[slipperybidness]

A sealed 0.1 ft³ cabinet has an F3 of 118 Hz.

Going to a 0.04 ft³ sealed cabinet will increase the F3.

Thanks. That may be acceptable for this application. I'll have to dig around a little more.

Perhaps some more AH members will help out here.

 

[Swerd]

Look for 6" diameter plastic drain pipe. That ought to provide enough space to mount that driver on one end.

0.1 ft³ = 172.8 in³

172.8/3.14×3² = 6.1" length

Cut the pipe and cut some wooden circles to plug either end.

That's probably as small a cabinet as I can imagine for 0.1 ft³.

If you can find larger diameter drain pipe, or thick cardboard tubes (used for mounting fence posts in concrete) you could use a shorter tube. The only limit is the driver depth.

 

[slipperybidness]

Look for 6" diameter plastic drain pipe. That ought to provide enough space to mount that driver on one end.

0.1 ft³ = 172.8 in³

172.8/3.14×3² = 6.1" length

Cut the pipe and cut some wooden circles to plug either end.

That's probably as small a cabinet as I can imagine for 0.1 ft³.

Good Idea! I've seen this type of setup before, but didn't even think about that option!

That still might be pushing it a little on my allotted space, but with the pipes, I might be able to do a little trim out, painting, and finishing and still make it look professional! Another option may be to let the pipes stick out the back a couple of inches.

I really need to get my monitor so that I can figure out exactly how much space I have to work with on the audio. Even if I can't end up using these drivers on this project, I might do the drain pipe cabinet idea anyway and use them like that, and build some little stands. That could be a cool little industrial design!

 

[Swerd]

Good Idea! I've seen this type of setup before, but didn't even think about that option!

That still might be pushing it a little on my allotted space, but with the pipes, I might be able to do a little trim out, painting, and finishing and still make it look professional! Another option may be to let the pipes stick out the back a couple of inches.

I really need to get my monitor so that I can figure out exactly how much space I have to work with on the audio. Even if I can't end up using these drivers on this project, I might do the drain pipe cabinet idea anyway and use them like that, and build some little stands. That could be a cool little industrial design!

Browse the Parts Express Project Gallery for ideas. These two might be adaptable for you

http://projectgallery.parts-express.com/speaker-projects/totally-tubular/

http://projectgallery.parts-express.com/speaker-projects/sdss-1-1-single-driver-tube-speakers/

 

[DukeL]

That little 2" Fountek cone only has 1 mm of linear excursion. To put things in perspective, so does the Dayton Audio 2" dome midrange. Frankly if I was going to the trouble to build an enclosure, I'd want to use a more capable driver so that it would be worth my build time.

That being said, you can tune a .04 cubic foot box (that's the net internal volume, accounting for the driver's big magnet and the port) to about 65 Hz by using 3/4" diameter tube 6" long. Also get a solid rubber cork to plug the port, in case you get distortion on bass notes because of that tiny x-max. In sealed mode you'd have less low end but be less prone to distortion due to over-excursion. You'd theoretically be -3 dB at 103 Hz vented and 122 Hz sealed, but in vented mode you'd have a 2 dB bump from about 150 to 250 Hz, which would probably be desirable in this application.

If you know in advance what the lowest frequency is that the speaker will be trying to play, and/or how much power it will see, we may be able to tailor the design accordingly.

 

[slipperybidness]

Thanks for all the info and ideas!

I have a couple of monitors scoped out on ebay, so I should have that taken care of by early next week.

Then, I'll know exactly how much room I have to work with on the audio side. It's gonna be tight, I know that for sure.

 

[slipperybidness]

That little 2" Fountek cone only has 1 mm of linear excursion. To put things in perspective, so does the Dayton Audio 2" dome midrange. Frankly if I was going to the trouble to build an enclosure, I'd want to use a more capable driver so that it would be worth my build time.

That being said, you can tune a .04 cubic foot box (that's the net internal volume, accounting for the driver's big magnet and the port) to about 65 Hz by using 3/4" diameter tube 6" long. Also get a solid rubber cork to plug the port, in case you get distortion on bass notes because of that tiny x-max. In sealed mode you'd have less low end but be less prone to distortion due to over-excursion. You'd theoretically be -3 dB at 103 Hz vented and 122 Hz sealed, but in vented mode you'd have a 2 dB bump from about 150 to 250 Hz, which would probably be desirable in this application.

If you know in advance what the lowest frequency is that the speaker will be trying to play, and/or how much power it will see, we may be able to tailor the design accordingly.

Well, after poking, prodding, measuring, cursing, etc, I think that I have to abandon the idea of using these Founteks on my arcade cab build. The box that they need will just be too large for this project!

DukeL, do you think it's worth doing anything with these Founteks? At $6 each, it will cost me almost as much to ship them back to PE for a refund as they would be worth (ie spend $8 or so in shipping for a $12 refund). So, it seems to me that these will go into my "future project bin" for now. How about building something like this, it's a rugged portable "speaker tube". I think that might be kind of neat to build, not too much work and maybe not a lot of $. Any other ideas on easy ways to put these to use and get decent sound out of them?
http://www.amazon.com/BOSS-Audio-ATV20-All-Terrain-Powersports/dp/B004S50WZG/ref=sr_1_1?ie=UTF8&qid=1446558263&sr=8-1&keywords=speaker+tube

As far as my "plan B" for the arcade cab, I have 2 ideas in mind.
1) I went ahead and ordered a pair of the Dayton Cube Speakers (ie Minx knockoffs). I think that these will be just about the perfect size to do what I want. If not, then these may end up getting mounted in the garage.
http://www.parts-express.com/dayton-audio-sat3b-3-cube-speaker-pair-black--300-675

2) The used Dell monitor that I bought off ebay will be coming with one of those Dell sound bars that clips onto the bottom. That will likely work, but if possible I would prefer to flip the monitor around so that the sound bar is at the top. May not be possible though.

I'll start posting back in the main thread again on build progress.
http://forums.audioholics.com/forums/threads/speakers-and-amp-for-tabletop-arcade-ideas-etc.94731/

 

[DukeL]

DukeL, do you think it's worth doing anything with these Founteks?

A use for the Founteks may come along some day... maybe as a present for kids or grandkids, in a little primed-white wooden enclosure that they can color, paint, or decorate as they see fit. Get 'em hooked now, and they'll be audioholics when they grow up.

 

[lsiberian]

I'd say you'd be fine with the 172 cu inches suggested box is, but I also think 120 cu inches per driver would work if you filled the back of the box with miner wool.