Channel: Uncle Doug

Category: Music

Description: This video features a 1955 Fender Tweed Harvard Amp......quite rare and in very nice, original condition. As usual, we check it out cosmetically, discuss the place that it filled in the Fender line-up, and then overhaul the circuit for maximum performance with minimal disruption of originality. Despite replacement of rectifier and output tubes, filter caps, coupling caps, selenium rectifier, power cord, etc. the plate current remained quite low (6 mA), implicating the power transformer as the most likely culprit. In order to preserve originality, however, I extensively modified the bias circuit to achieve a PC of 31.5mA with a relatively low PV of 215 VDC for a PD of 6.8W.....approximately 60% of max. The audio demo seems quite acceptable with good tone and volume, but a final determination on the PT will be left up to the owner. NOTE: Although the Harvard circuit normally operates at a relatively low PV of 325VDC (compared to other Fender circuits), this circuit's PV is about 100VDC below this level. I have no idea if the seemingly-original power transformer is incorrect (for foreign use?), slightly defective, or operating properly (with no other Harvard circuits to compare). If you enjoy videos such as this, please SUBSCRIBE to our channel and consider becoming a Patreon patron at: patreon.com/uncledougsvintageamps or making a PayPal contribution to dldcam@aol.com. Thanks so much for watching :)