I imagine that some folks have been wondering where I’ve been since the end of May. The truth is it’s been a very busy summer. Shortly after my last blog post, I learned that I was being transferred for the second time in less than two years. So far this summer I’ve bought a new house, moved ≈1500 miles (≈2400 km), totally packed and unpacked an entire house, a complete workshop, and an electronics lab, started a new job, and basically just tried to keep my head above water. However, in the process of unpacking things at my new house, I found something interesting.

At the bottom of a box of miscellaneous equipment I found this…This is the amplifier that “started it all”; my return to vacuum tube amplifiers almost 10 years ago. I built this amplifier in 2005 for my desk at work. It’s a simple dual LM386 based amplifier with a little three terminal power regulator and optional 9V battery. I used it to drive my noise cancelling headphones as my desk at the time was adjacent to a hallway which, at times, got rather noisy.

In my introduction on the “About Me” page, it is this amplifier to which I was referring when I say “I was listening to music through a little headphone amp based on an LM386 audio amp”. So I decided to give it a try once more and see what I thought.

I’m happy to say that the last ten years were not “all for naught“. It was just as I remembered from 10 years ago, the sound was there, but not the music. But after looking at the schematic, I tried something else. I connected the amplifier directly to a little pair of book shelf speakers which I decided long ago were totally incompatible with vacuum tube amplifiers; the Realistic Minimus-7. These little speakers really require a very low output resistance to produce any bass. This is something you won’t get out of most tube amps but is easy to get with solid state amplifiers. When I turned it on I was pleasantly surprised.

The little amp that really didn’t work well for my headphones actually produced a very pleasant sound driving the little bookshelf speakers. It’s not a lot of volume but enough to provided some nice background listening. I actually have a couple of locations which are ill suited to tube amps due to dust and such. This little amp with the pair of Minimus-7s will work in these spaces nicely.

It’s really good to know that after all this time I can put this little amplifier back to work.