The left is now much quieter than the right and is lacking bass, so I assume the driver handling the bottom end has died. Luckily, I have an old pair of ER-6i to fall back on, but this leaves me with a dilema. Do I pay to have my out of waranty UM2 repaired (I was fairly happy with them), or...

When I first started working on my amp over the holdiays I got 3 of the EVJ 10k pots to evaluate (they are cheap, so why not). They all used most of their +-20% range and had large differences between the two elements. The best was 1.5k apart at 10K and the worst was 8.6k for one element and...

Finished moving it over. I like this much more than the plastic Pactec case I was using before. Although it is a little wider and longer, the thinness (0.75") makes it more pocketable. The complete amp (with quarter for scale): Full res pic Innards: full res pic Before...

Although I got my "cranky opamp" CMOY working, there was more hiss than I liked. I use Westone UM-2, which are low impedance (27 ohm) and high sensitivity (119 dB/mW) in-ear monitors similar to the Sure E5. They are notorious for bringing out hiss in almost anything. My 4G iPod that is quiet...

Needing a holiday project, I thought I would build an amp. I had some LM6172 dual opamps around from doing some rolling in a Marchand electronic crossover. I used the "cranky opamp" desing from Tangent (http://www.tangentsoft.net/audio/hs-opamp.html). All values are as listed in the schematic on...