The Amiga is a boutique HiFi killer. Although the components used here are relatively inexpensive, when properly executed will sound and look like they cost several times that much.
The Amigas are available as a kit from Parts Express, either as a knock-down kit, or with a pre-routed baffle. Or, if you like to roll your own, you can choose to purchase the items yourself from a variety of worldwide distributors.
Left: Amigas built by [Josh]. Gorgeous.
The enclosures for the Amiga are exactly the same as the Core 2-way. The cabinet dimensions and overall look of the speaker were borrowed from a well-known audiophile loudspeaker company. At 34" tall and 8" wide, they have an understated-yet-classy appearance. With a quality finish, they would easily pass for fine furniture. The Amiga should be constructed with 3/4 stock (MDF or Baltic Birch plywood), and absolutely must be braced inside the cabinet. I would recommend the use of at least one "windowpane" brace, as well as some standard "shelf" braces tying the sides of the enclosure together. I made a detailed cutaway diagram in both standard and metric.
The interior walls of the enclosure need to be lined with some sort of convoluted foam or BlackHole (honestly, I use mattress topper from Wal Mart). There is also a wad of stuffing resting in the bottom 1/4 portion of the cabinet.
The cabinet is about 30 Liters internally, and is tuned to 39 Hz. This gives an F3 of 34 Hz (ooh, yeah!). The vent is 2" diameter and is 3.5" inches long. You could build these sealed into a cabinet of 8-11 liters, if you wanted to pair them up with a sub.
The DX25 tweeter was a new one for me. It's been toyed with around the DIY community, but mostly it's been passed-over for more-popular tweeters. Its reputation is basically: "It's high sensitivity, and has a pretty low Fs, and it sounds OK I guess." The first few days of working with the tweeter, I was thinking the same thing. It wasn't terrible, but it had this sort of nasally-yet-breathy hash it would inject into the music. For a while, I thought maybe this was just an artifact of a cheap tweeter diaphragm, but then I realized it was caused by an excitation in the rather large impedance spike around the tweeter's resonant frequency... exactly the same problem that plagues its sibling, the XT25. The solution was simple: forget the low Fs, cross higher and out of the way of the Fs,and use some sort of Impedance Compensation (in the case of the Amiga, resistor R2 is helping accomplish this, though sometimes a full-blown LCR shunt filter is needed). Once I solved the Fs spike issue, the DX25 were actually very pleasant tweeters to listen to. They do their job, don't bring any attention to themselves, and don't introduce any odd-order harmonic distortion as cheap tweeters often do. Their Frequency Response is sort of lumpy, but this actually doesn't seem to pose any audible problems (ie: noticeable dips or peaks) when used in a final speaker system.
I'm out of verbosity. Basically, if you like the Overnight Sensations, you'll like this. The tonal balance is similar; the voicing is slightly relaxed to make for long listening sessions. However, the quality of the drivers will definitely showcase fine details in a recording. The imaging puts on a good "dog and pony show" like a quality monopole speaker should, with a very tight center image, and sounds seeming to appear around and behind the speakers. The bass extension should definitely surprise; with an F3 of 34 Hz, there's a good chance you can leave the subwoofer turned off. The overall sound is big; it's a 2-way that pretends to be a 3-way. The drawbacks of this design are that the speaker is not very sensitive (about 83-84 dB, after baffle step loss), and the RS180 only has so much excursion. My own experience is that the RS180 runs out of xmax somewhere around 96-98 dB, depending on the music, and modeling confirms this.
But gosh, for a HiFi boutique sound on a pawn shop budget, the Amiga is hard to beat. These are speakers I would have wanted to own, back before I was sucked into the world of DIY. I can just see myself: auditioning them at several HiFi dealers, then scouring the net for weeks before finding a good deal, which still would have been several times more than the cost of DIY!
These were built by [numberoneoppa] from HTGuide. He did a nice build log as he went along. You can read it here.
[tombond] showed off his finishing skills in this stunning build.
This build was done by HTGuide member [Anderton]. The baffles are solid eucalyptus, and the rest of the cabinet is veneered in Flame Birch. He gives additional details here. Who wouldn't want a pair of these in their living room?