At first glance, Scott’s amp looks like an SE-5a, but inside is a modified 18W circuit. Using the same transformers and chassis as used in the PP-18, Scott used the SuperLite circuit which has enough gain to allow Treble, Middle and Bass tone controls.
“Amazingly it even worked first go!” Scott wasn’t the only one wanting the 18W with tone controls, and after he built his amp, I added the SL-18 SuperLite TMB amp kit (since discontinued).