http://photos.yahoo.com/bc/gcpeng/lst?&.dir=/AKSA+100W+(custom+Par-Metal+chassis)&.src=ph&.view=tAfter starting on my AKSA 100W at the beginning of January, I have finally completed the amp. The kit itself was pretty much done in two slow weeks after having to troubleshoot a few problems with generous help from Hugh. I created the panel/chassis designs for the amp based on the 20-series Par-Metal chassis meant for "Table Top / Amplifier Cases" (not on their website, but they have a PDF available by e-mail in the same format as PDFs for the other series).
The chassis ended up taking about a month after sending in the design drawings and descriptions before receiving the finished product. Almost all holes, cutouts, and dimensions were as I specified, except for 2 hole dimensions for the RCA jacks and half of the holes on the bottom being 0.25" too far from a central axis. I e-mailed and called in to change the RCA hole sizes a few days after sending in the order, but I guess the change wasn't implemented - I had to file the holes to a larger size to fit my RCA jacks. The 0.25" offset of the holes from my specifications didn't cause any problems, but any more of an offset and the heatsink for that channel wouldn't fit in the chassis.
While waiting for the chassis, I got bored and changed a few parts:
1) I originally bought Wima metallized polypropylene for the charge suckout caps (I needed replacements for these since I accidentally destroyed one of the SCR's Hugh provided with my soldering iron). But after Hugh recommended against these, I put these on the power supply board as bypass caps, and bout Auricaps for the charge suckouts.
2) I replaced the 100uF decoupling capacitors on the +/- of each channel with 200uF Panasonic FC's I had lying around.
3) C4 was changed to a 100uF Panasonic FC I had lying around.
4) C2 and C7 changed to 10uF Elna Cerafines I had lying around (I have a lot of parts lying around
).
5) D1 changed to a schottky.
6) C3 changed to a 100uF Black Gate Standard (FK's are quite expensive
).
7) Power supply diodes were changed with some heafty 30A Stealth series diodes from Fairchild Semiconductor.
Anyway, so a month later, the chassis arrives. It's not perfect, but I'm quite satisfied. The whole chassis is clear anodized.
Top: Has vent slots right above the heatsink fins.
Bottom: Has vent slots right below the heatsink fins. The heatsinks mount to the bottom of the chassis with 3 screws (I have provisions for 5, but 3 felt sturdy enough). Vibrapod model 4's are used as the feet.
Rear: Vampire binding posts. Vampire RCA jacks with external nuts. Fuse holder (has a 8A slow blow right now). DTDP switch rated for 10A, but with the two poles wired in parallel. Filtered IEC jack.
Front: Rackmount-type handles. 2 3mm holes for T-100 size LEDs, water blue ones, partly diffuse (looked better than clear in this setup). Bulgin vandal switch, momentary pushbutton.
Inside power switch: The DPDT switch in back is the main switch that cuts off power to the relay. The relay is a Tyco/Potter & Brumfield 1 HP bistable power relay. Pushing the vandal switch briefly sends a short burst of AC to the relay's solenoid, which mechanically moves a lever that simultaneously changes the position of 2 other microswitches. These allow or cut off AC to the transformers.
Transformers: 300VA 35-0-35 ILP (Plitron's former company).
Wiring: I tried to make it as neat as possible by being direct with the wiring, but that produced what you see in the pictures. The star ground point does indeed end up looking like a star (all the white wires leading to the power supply PCB).
How does the amp sound? Since I haven't had any experience with other high-end amplifiers, this is of course the best amp I've ever heard. I really enjoy the sound, even though I don't have high-end speakers or even a good source. My Infinity RS-3 bookshelves are being replaced by Axiom M22Ti SE bookshelves which I just paid for today and should receive next week. The source will have to wait until after I get a job
.
Cost to build this?
AKSA 100W kit pricing is on the AKSA website.
Chassis with drilling/cutouts and clear anodize was $135 + $40 (for the optional, extra thick front panel) + $10 shipping = $185.
Transformers were $70 for both through a deal through the Trading Post of diyaudio.com, where I purchased 4 for $140 shipped.
Bulgin vandal switch ~$14.
Tyco/Potter & Brumfield bistable relay ~$35.
Vampire binding posts ~$11.
Vampire RCA jacks ~$14.
Vibrapods ~$30 for 4 after shipping.
Misc parts like LEDs, DPDT switch, fuse holder, fuses, IEC jack, wire, gold-plated spade connectors, screws ~15-20.
"Upgrades" and mods probably totalled ~$60-70 after all the separate shipping costs - as Hugh pointed out before, that is quite close to the Nirvana upgrade kit.
A big thanks to Hugh, of course, for the AKSA design and technical support and to other AKSA builders and builders on diyaudio.com for building ideas and inspiration, not to mention the rave reviews that gave me the peace of mind I needed to buy the AKSA.
(Sorry about the pictures, they're from a Canon S200 in a low-light situation where flash would make the picture worse.)
