Pocket amplifier punches up headphones.
By Warren Young
Headphone amps make portable listening good Prepare the Protoboard
and loud. Commercial audiophile models can cost Start with a small prototyping board such as
$200+, or you can build a great-sounding amp RadioShack’s model #276-150 — anything that
inside a mint tin for around $30, following Chu has at least 12 rows of holes and fits into your
Moy’s popular design. Powered by a 9-volt battery, case. Larger protoboards can be cut down to size
this amp drives high-impedance headphones to with an X-Acto knife. Then solder nine jumper
thunderous volumes from even weak sources. wires as shown in Fig. 1 on page 133.
Photography by Warren Young
To make one, you need an op-amp chip (like The jumpers lower down along the edges are
the TI/Burr-Brown OPA132), capacitors, resistors, what I call “M-jumpers.” They tie three two-hole
an LED, and a small prototyping board, plus pads together to form a single pad with three free
optional knobs, switches, and other bits, all holes. You can make these by taking a one-inch
easily obtained. And, of course, you also need piece of stiff wire, folding it in half, pinching the
a pocket-sized box, like a Penguin or Altoids kink tight with pliers,
tin. See the website listed at the end for a full and then bowing the two
parts list, along with layout diagrams and more ends over. You may also
detailed instructions. need pliers to stuff the
thick middle bit into the
Your MP3 player’s music
will sound minty fresh
when played through
this li’l headphone amp.