In senior year of high school I took a speaker building class. For the final project, a pair of speakers, we could choose from a few sets of components depending on how much money we wanted to spend. We could also choose a custom design, though the teacher warned that his guy who supplied enclosures tended to procrastinate on these.

For some reason I decided I wanted one of the wedge-shaped stage monitors often seen at concerts. Probably I believed this would bring me close to my dreams of rockstardom. I used the skills I had acquired in drafting class to make a technical drawing showing the exact dimensions of the enclosure I wanted. I presented this to my teacher, who warned me again that his guy was probably going to screw me on it.

I then spent several weeks playing "Marathon" on computers in the classroom while everyone else assembled their speakers. With only a couple of weeks to go, my teacher finally relayed his guy's estimate: $200 for the enclosure alone. At the time this seemed to me like an astronomical sum intended to discourage me from pursuing it any further. Indeed, I had to say I couldn't afford it and would instead simply build a single speaker of normal proportions. When it was done, I tried it out once with Beck's "Mutations" on our home stereo, and then it sat in my closet for several years.

Earlier this year, with the speaker sitting mournfully in my bedroom studio, I decided to put an end to this sorry state of affairs. I would somehow acquire an amplifier that would allow me to at least use the damn speaker for rehearsals, plugging a synthesizer or even a laptop into it. I would buy one if I could, but if not, I would build it. I posted on the TapeOp message board my requirements:

• 8" x 10" or less, so it could either sit on top of or go inside the speaker
• about 50 watts, loud enough for rehearsals if not for shows
• $200 or less

The responses offered some helpful tips which eventually led me to another message board, diyAudio. I started reading all about chip amps, amplifiers based on tiny integrated circuits, which could purportedly offer excellent results at low cost and complexity. I eventually decided to order a kit based on the LM3886 chip from chipamp.com. These kits are made by Peter Daniel, an active contributor to diyAudio, and one is basically assured customer support by many very knowledgeable and helpful people, as well as a thorough existing knowledge base.

At the same time, I was pretty anxious about two things (besides figuring out what a "snubberized" power supply is):

1. No kit included a transformer, the biggest and most expensive single part of the amplifier, whose job is ironically to reduce the voltage coming in from the wall, rather than to amplify anything. The instructions had a page of text about how to choose a transformer, little of which I understood. My head was swimming with details about primaries and secondaries and bias voltages. Finally, I found a diyAudio thread containing a simple endorsement for a 22-Volt model available at Parts Express. It weighs 3.3 pounds and costs $42 (and it is possible to ruin it with improper assembly).

2. Enclosures. Many diyAudio contributors' projects use separate enclosures for the amplifier and the power supply to eliminate any chance of interference. I felt this practice probably wasn't necessary for me, since even commercial amplifiers rarely use it. But how small could the enclosure be before hum would become a real problem? I couldn't find any precise information. Most amplifiers are the standard big home theater size. Finally I decided to simply make what I wanted and see how it sounded, rather than risk unnecessary sacrifices.

The assembly process is one of repeated orders from Mouser and Parts Express and runs to Radio Shack for the inevitable items I forgot or ordered wrong, but I enjoyed it nonetheless. After a lot of mental juggling, I decided on a 5 x 7" enclosure from Hammond. Once I had everything assembled it was time for some moments of truth. One of the difficulties I've always had with electronics projects is testing incrementally and so as to avoid damage, the way I would always do with software that I create. I just don't know how to do this in hardware. The kit's creator offered the procedure of measuring the voltages on the output connectors at minimum and maximum volume, which went fine. The next test required a Variac transformer to gradually ramp up to 120 volts, but I wasn't prepared to buy one just for this. So finally I had to go ahead and turn it on and see what would happen.

Thankfully, nothing blew up, and it even made sound, without any hum! The only trouble I had was with wiring the volume knob backward, easily corrected. The maximum sound level is adequate, though I wouldn't mind if it could pump out a little more—keep in mind I did only build one half of the kit. As for the sound quality, I honestly don't think I can judge whether it's merely good or audiophile-ready, having only run a synthesizer through it, but I'm perfectly happy. My thanks to Peter Daniel for an excellent product.