I think at first, I was just amazed that it worked. The fact is that with a few well spaced metal pieces and a little magnetism, you can create an amplifier. It turns out, electricity is every bit as natural as air and water. How could it be that I had a smart phone, but I had never realized this? I was hooked.
The first amplifier that I built from scratch was a 5 watt, Single Ended, combo based on the 5E1 Tweed Champ. Once the circuit was optimized and running as designed, I began to experiment.
The only detail that differentiates a 5E1 Champ circuit its successor, the 5F1, lies in the power supply. The 5E1 uses an Iron-Core Choke coil as the first component in the path of the high voltage power supply. This choke serves to resist changes in the DC voltage rail, which helps to reduce hum in the amplifier. The 5F1, however, uses a resistor in place of the 5E1's choke. This performs the equivalent voltage drop to the choke, while lowering the cost of manufacturing considerably. I took this as an opportunity to hear the difference between the two circuit options. In the end, the choke coil remained in the circuit. I have since included this style of filtering choke in nearly every amplifier that I design.
Further experimentation involved additional gain stages, redirecting the signal path, and altering the frequency characteristics of each stage. LSD901 now travels the United States accompanying the incredible Dax Riggs. www.daxriggs.com/
Nearly as soon as I finished LSD901, I began my second amplifier; an 18 watt model based on the 5E3 Tweed Deluxe design in 1957. I had recently heard Neil Young's Are You Passionate? and was blown away by his guitar's tone. A little research led me to the 5E3. I built LSD1101 from scratch using pure 16 gauge copper plate and solid planks of Black Walnut lumber.
Once optimized to the 5E3 ideal, I began to alter crucial circuit elements one by one. Each time, I made careful observations of the performance of the amplifier. My obsession with LSD1101 focused around the frequency response characteristics as each amplifier stage was coupled to the next.
By the time I had settled on its voice, it was nowhere near the thick, and massive voice of the 5E3. In its place was a sweet and silky tone with no perceivable distortion. However, the amplified signal was thoroughly embellished by harmonic content and voiced for natural acoustic clarity. I have used LSD1101 to amplify my acoustic guitar since 2012. In 2014, I added transformer coupled, balanced output.
Here, I am playing my J200 through LSD1101, while Lucas Broussard runs his 70's Les Paul through LSD1502; a 10 Watt single ended amplifier employing a single 6L6 power tube.
to be continued ....