Grid leak biasing

[Tomislaw]

Sure thing!!  Those old Supros can be really cool. The ones you build sound like really neat versions.  It's smart to experiment like you did because some of the Supro this sound and work great and other need some help.  One thing I've always found found with Supros it that they are really really speaker specific so I found that using lighter speaker helps get that classic Supro tone.   I'd love see pictures sometime!  

I will post some pictures later. 

I'm very curious how the new Supro's are built, but there are no schematics available I'm afraid. I watched some demos on the YT and judging by the fat tone I'd guess they are way different from the original circuits and use at least two gain stages per channel. The Black Magick combo has 4 preamp tubes but The Coronado advertised as a reissue has 4 12AX7's as well (just like my experimental build). 

Still to be determined is what speaker configuration would give the best "Supro" sound, but I've not had the chance to crank it up on my 1x12 cabinet. I added master volume pots to both amps and also hooked them up to the attenuator. More about it later