Small 2 way "in desk" speaker build suggestions

[Ceri]

I'm in the early planning stages of building myself my own desk from scratch. The plan right now is to make it a sort of "command and control center" for office, music, and computer gaming purposes, with a focus on integrating as much "techie" gear as possible.

Here's the MSPaint concept drawing I've come up with so far:


So the idea is to integrate a relatively inexpensive 2 way sealed speaker system. The front baffle will be angled however I want. I can put it dead center at the listener, upward, outward, etc. as the driver's might call for. One of the biggest concerns is a mid/woofer that's relatively small in diameter. The corner trapezoidal pieces can't dominate the desk space. Also relatively important is that they don't interfere with USBs, headphone jacks, power and reset buttons for an integrated computer, or any other electronics that may go nearby. I can shield the other plugs and switches with copper sheeting if it proves necessary.

One thing that's important to note is that I plan to mount a swivel arm monitor attachment at the same place that the left speaker is pictured. There's a small cutaway that might not be too clear. I can play with the dimensions, but it's important to note that it will be mounted in that area. It's approximately 5x4x4" and will encroach on the usable volume behind the speakers.

The plan is to power them with an existing logitech subwoofer plate amp that's capable of about 50 watts RMS x 4 channels (it started it's life as a logitech z560 HTIB type 4.1 setup). What I don't know is the rated impedence, but I'm assuming 6 or 8 ohms. I'm only going with a 2 channel stereo integrated system plus subwoofer behind the piece labeled "computer" in the drawing above. I drew in a circle for it's position. I might find some way of adding rear surrounds, but for now that's not in the equation as my desk "floats" in the middle of a rather large room. Small business. 4 workstations in one house. I'm in the middle of the living room behind a sofa staring at my big screen TV.

This will be my first DIY speaker project. I know that with my space and position constraints I'm not going to be able to get extreme SQ out of this setup, but I've got the subwoofer that's crossed relatively high (around 120 hz I'm guessing), so low end extension isn't a pressing concern. If I can get by with a 5" class mid/woofer that would be swell. I can throw out 7"+ woofers, but if there's something in the 6-6.5" class that can handle small sealed volumes I'd consider it.

I'm aware that this is a form over function design. The desk is the project, but I'm an amateur audio enthusiast (at least until I graduate).

A premade kit is a plus since it would be my first DIY speaker build. I'm a 2nd/3rd year EE undergrad so I have a sophomoric understanding of circuit diagrams and components (for the crossover).

In summation:
1. Small volume MT sealed design
2. Small mid/woofer
3. Power handling <= 50 watts RMS at 6/8 ohms
4. Shielded?
5. Subwoofer crossed at ~120 hz
6. Primary focus of imaging and clarity, not power handling
7. Computer games, high rip rate audio CDs, Netflix style movies as an afterthought.
8. Budget is <$200, but I've got some money set aside I can tap into if it's worth it.

I must admit that this logitech setup is my reference for good sounding speakers as sad as that may sound. I've got $4000+ wholesale cost in car audio gear and sound treatment in my truck (not a boom box) and this $150 logitech box set sounds better at moderate listening levels. I've had them for nearly 10 years and haven't heard better computer speakers yet.

Any help, suggestions, or links would be much appreciated!

Thanks gang!

[enigmaticEntity.]

hmmm....very interesting idea...

Have you considered looking at some small full-ranges, eg. Fountek fr88 or fr89? (one of the best 3'' full-ranges, was $29 before all this price rise) This way you won't be struggling for volume, and you also get relatively good "imaging" and no issues with woofer/tweeter spacing. Acoustic effects when the drivers are so close to the desk surface; this may effect imaging, although they are angled upwards, which helps.

Given your sub's 120Hz crossover, want of small volume and # 6.), a full range driver may suit your needs more and will be easier to implement. This is just what I think...if you want to go with a two way and larger drivers, then feel free to do/say so...

[Ceri]

I appreciate the suggestion.

I am inclined to lean toward a woofer/tweeter 2 way setup for the silly reason that it is more aesthetically pleasing to the untrained observer. Part of the build is to say "look at that! Isn't it awesome". If the consensus is that a fullrange is best, my current desktop set are full range ported. I know it can produce some really good results. Another minor nit-pick with fullrange is that I wont really have to do much DIY constructing. This is both a results and an experience build. Since it's my first build, I'm trying to familiarize myself some with the process, and a fullrange doesn't offer a whole lot of growing potential (if that makes sense).

In other words, I'd like to have to assemble a passive crossover.

But definitely thanks for the suggestion!

[mayhem13]

Try a pair of the 5" SEAS coaxials
Seas Prestige L12RE/XFC (H1602) 5" Alum/Fabric Coaxial: Madisound Speaker Store

Will save some space and provides all you requested...including the desire to build some XO's.......There's a published XO from seas linked at the bottom if it makes life any easier. Coax's in the nearfield are really a thing to behold.

[Ceri]

Originally Posted by mayhem13

Try a pair of the 5" SEAS coaxials
Seas Prestige L12RE/XFC (H1602) 5" Alum/Fabric Coaxial: Madisound Speaker Store

Will save some space and provides all you requested...including the desire to build some XO's.......There's a published XO from seas linked at the bottom if it makes life any easier. Coax's in the nearfield are really a thing to behold.

Those appear to be 4 ohm drivers? I'm not sure my logitech plate amp can handle them for long term usage.

[mayhem13]

The cones are 4, tweeters six. Follow the impedance plots and expect an avg impedance of 5 ohms.......avg not nominal. Most 'nominal' 8ohm systems are substantially lower at some point in the FR.

[Ceri]

Originally Posted by mayhem13

Try a pair of the 5" SEAS coaxials
Seas Prestige L12RE/XFC (H1602) 5" Alum/Fabric Coaxial: Madisound Speaker Store

Will save some space and provides all you requested...including the desire to build some XO's.......There's a published XO from seas linked at the bottom if it makes life any easier. Coax's in the nearfield are really a thing to behold.

I appreciate the suggestion, but I'm fairly set on a 2 way woofer/tweeter configuration simply for the visual appeal, though two of you have now told me a full-range or coaxial point source sort of arrangement is best.

Also, please help me understand this. My understanding is a good metric for determining a good sealed woofer is to take Fs and divide by Qes. If the result falls under 50, it's a good sealed woofer. 50-100 is decent at both, and north of 100 is best ported. That Seas comes up around 166 using that formula. I like the Vas, but I'm not sure that setup will work for me. Again, I may not be getting the concept so feel free to correct me.

edit: Or have I switched it entirely?

[joe58]

Make sure the PC tower is isolated/ or the cabinet is very dense as the subwoofer vibrations won't do it any good. So it may be a better idea to move the tower to the other side where the rubbish (English please :P ) is. Just to make sure.

[Nanook]

please do yourself a favour and check
ApexJr. out. The M&K coaxials are inexpensive ($14.95 ea.) and very good (and not bad looking either). I have 2 pairs of these drivers: one pair retrofitted to a small pair of "Teac" loudspeakers (the ones that came with the Reference 100 mini system of about 12-14 years ago). and one pair in a set of Pluto inspired loudspeakers.

The "Pluto (Siegfried Linkwitz design) loudspeaker wannabe" project that uses the recommended cross-over in a 39" long tube, and very little stuffing. Sounds too good to be true, but it is. Dirt simple to make.

Crossovers should be inexpensive to make (or buy a "bag of crossovers" from Steve at Apex Jr.). He is a small business and is a diyaudio.com sponsor. Only thing to be concerned at all about is that these drivers have no screw holes in the flanges, but some could easily be drilled.

Don't be put off by the lack of sensitivity of 87dB (2.83V/1m), you'll probably end up sitting at about 1 meter (39") away. 87dB is louder than you think. Add an inexpensive (but good) T-amp, kit or an integrated amp (hopefully a good one) that you may so have on hand, and you are a long ways along to good desktop performance.

The Teac enclosures are very small, at only 4-1/2" X 6-1/2" X 7-3/4" (outside dimensions). The walls are only 1/4" thick "hardboard" with a shiny laminate over top. They are a ported design, using a 1" diameter X 2" long rear port. I do not use them with a subwoofer at all and do not miss the bass. There is a strong sense of bass even if it doesn't measure very well.

Personally I would suggest building simple boxes, that way you can move them as desired, on your desktop or some Pluto inspired "tube" loudspeakers so they can be placed almost anywhere in the room.

Hope that helps.

[joe58]

You say you want 'wow' factor so what about attempting a Ikea bowl enclosure. Stick them in the corners on a stand of your choice and people should love them.