ACA LJ a Amp Camp Amp mod with easy to find transistors

 Building a modified version of Nelson Pass’s famous Amp Camp Amp (ACA) was a rewarding experience, especially given the challenges I faced sourcing components. The original ACA design uses JFETs in the input stage, but importing them was prohibitively expensive due to high shipping and duties. Instead of giving up, I reached out to a friend, Mr. Liadel Joshi, to see if he could modify the circuit to work with more easily available transistors. He gladly took on the challenge, replacing the JFETs with BJTs. 

Note that the input stage has been changed to BJTs, so the sound may differ slightly from the original ACA. 

Finished PCB form fabricator 

Here is the finished Amp 

I designed the PCB layout using EasyEDA, my go-to tool for circuit design, and had it fabricated. The finished amp sounds wonderfully clear and sweet, especially when paired with high-sensitivity speakers. I tested it with Boston Acoustics full-range speakers, and the sound was excellent. However, with more demanding two-way speakers, I found the amp could use a bit more gain. Adding a simple gain stage or preamp really made a difference, boosting the output for these speakers. I powered the amp with a 20V DC linear power supply, but an SMPS is also an option.

you can find PCB  transfer pdf , BOM , layout here