I have always been super interested in stereo equipment. I had the stereotypical“stack” of random stuff that most 80s and 90s kids had. Big tuner of questionable quality, 5 CD carousel changer, a dual-cassette deck for making mix tapes, and eventually a turntable — something from the thrift store with a setting for 78s. Even back then I knew that some day I wanted to be able to build myself a stereo completely from scratch.

I’m not sure what the first record I ever bought was, but the first record that left a mark on me was Talking Heads, Speaking in Tongues. My mom and dad were recently divorced and I remember playing Burning Down the House in one of my dad’s rented bachelor pads and loving it. Still an amazing song. I can’t get enough early Talking Heads.

Those early experiences solidified my love of the technological magic of records — literally the physical manifestation of music scratched into a circle. I was ready to build my system, but I had no idea how the hell all the transistors and amplifiers and all that stuff worked. Record player no problem — groove wiggles needle and music comes out. Speakers no problem — cone wiggles air and music comes out. But how the hell do you wiggle electrons to make the music come out?

Enter my friend and mentor Marty Piltch — a legit genius who invents laser technology for a living. Marty is a dude who expresses himself best with a whiteboard and plenty of profanity. Marty also went to school at a time when you got to learn about vacuum tubes, and is a physicist so he can explain them in a pure and simple way — how they actually work, not abstractly via datasheets or math. He explained vacuum tubes to me in a single marathon whiteboard session in which he completely filled the whiteboard in diagrams in green marker, then instead of erasing it, went right over the top of the green in red and filled it a second time. It was all about how the load lines describe the way the electrons fly across space from the cathode to the anode at various operating points. Super raw. Magic. Finally I had a vague notion of how to wiggle the electrons to make the music come out.

I started by building a Fender Champ clone guitar amp. Stuff designed in the 40s and 50s, when capacitors and inductors were expensive, necessarily uses very few of both, so the circuits are super simple. When you can work through a schematic and know at least roughly why each part is there and what it does, it is not too long before you want to try to make your own design, which is what I eventually did. I designed a bunch of guitar amps and hi fi amps, eventually getting to what I thought were pretty creative designs. I’m really proud of a guitar amp I designed that uses a choke on the cathodes of the phase inverter tubes to keep things nice and balanced and drive the output tubes hard without using a solid state current sink or a big resistor from a negative supply. Plus it sounded pretty great.

My most technically fun design was a hi fi amp using a 2a3 driven by a 6c45 in what is called a “monkey” configuration where the tubes are directly coupled to each other and fed from the same point in the power supply. I was proud of the mathematic gymnastics needed to get everything biased and working right. Amazingly it worked. Sounded OK, but not very engaging. Eventually I disassembled it to sell the very nice transformers it was built with.

The amp I liked the best and still have today is a push-pull 6c45 amp using transformer coupling. I built it with about 60 pounds of surplus transformers left over from the Atomic Energy Commission. Wanting to go way over the top, I used a bunch of voltage regulator tubes — the kind that glow bright orange and purple. It’s awesome. I’m working on a simplified kit version that also sounds great.

The part of the system that might be least suited to vacuum tubes is the phono preamp. This is the part that takes the output of the phono cartridge and converts it to a line level signal that can be fed into an amplifier. It also has a pair of RC filters that remove the equalization used when cutting a record to keep the grooves nice and small so they can fit more music on a side. This makes it hard to implement with unknown or changing tube output impedances, and the signal level is so low that it can be hard to keep things quiet in a tube circuit.

The old “Le Pacific” phono stage circuit for some reason was the first time I looked at a JFET circuit and thought holy crap I can just replace the tubes with these transistors and it will work. I scrounged some parts and soldered up a crusty prototype and it worked. I knew I was on to something.

Designing with discrete JFETs instead of op amps is a lot like designing with tubes. Lots of compromises to deal with, but you can pursue the simplicity and super low parts count of a tube circuit.

In searching for parts, I kept coming back to the amazing sounding Russian K40y-9 capacitors. I love the smoothness of a paper in oil cap. Fortunately there are a lot of these avaiable in the surplus market, but they are getting increasingly rare.

So that is what I consider the BHL recipe — super simple circuit, PIO caps, and JFETs.

I’ll admit that the site has been pretty stagnant for the last few years. I have been letting it run on autopilot. I still ship all the orders, and answer all questions and comments, but I haven’t released anything new for a while. Now that I am no longer at my 9 to 5 job I will have the time and motivation to spend more time developing kits. I’m really looking forward to digging back in.

I’m not sure what the future holds. I have a million idea on where to go next, but I’m still waiting for that one idea that sticks. If anyone has any suggestions, please let me know.