Left side is the first gain stage for a bright and normal inputsinput volume controls and summing resistors (bright one with 200pF across herinput tube circuit ECC83output transformer.. 16 Ohm tap onlyChecking a 12″ speaker can fit.. She is running but without a baffle sounds a bit thin 😉Side speaker positions filled to try to impriove bottom endChassis with power supply in place and sides blockedBaffle and speaker in positionSounding sweet with my SG… lovely breakup and never too loud but also not too quiet!Original case lid still fits!Vents at the back stil open so semi open back cab..Baffle pained and grill applied. Great Studio Amp!