Hi there. I have a lot of experience with building tube amps, but little experience with the Dumble world. I couldn't find much information on the Gen3 circuit. Do you have a brief summary of what the purported sonic differences are between the 102, 124, 183 and Gen3 are? I see that they are all very similar circuits (of course). My build will be "low" power, eg 2x6V6 or 2x5881.
Regards from snowy Maryland. Chris.
As far as i know Gen3s where made around 78-79 and serials 60-75.
Search for Dumble 3rd Gen and you will find some info