1963 Fender Bassman

The short-lived Brown-Panel/Blonde era of Fender amps were produced from 1959 through 1963. They are often considered tonally right in-between the more famous Tweed and Black-Panel circuits we are all familiar with. The Brown/Blonde era was the first time Tolex would be applied to Fender amps, and cosmetically appearing closer to the often re-issued Black-Panel and Silver-Panel models. The changes to the circuitry included the move to cleaner more hi-fi sounding tone, two preamp channels with individual tone stacks, Fixed Bias output stages, Long-Tailed Pair Phase Inverters, and the increased use of Negative Feedback. This 1963 Fender Bassman is the later revision 6G6-B circuit that comes in “piggy-back” form - which was just Fender’s terminology for a separate head and speaker cab. This was a fundamentally huge change in form and tone from the pervious Tweed era combos. With advent of the Brown/Blonde Bassman, Fender started paying a lot more attention to creating a better bass amp that could handle low frequency response with much more clarity. Hence the piggy-back format, which meant Fender could design a separate closed-back 2x12” cab made especially to meet the demands of a rapidly evolving music scene that wanted more low end definition at much larger capacity concert venues. The 6G6-B Bassman, has a number of unique circuit design choices; its Bass channel is still using a cathode-follower stage to drive the Bass control, but Fender has placed this stage immediately after the input with the Volume control after the first tone stage. The Treble control follows this but is separated again by another gain stage provided by a 7025 preamp tube. The Normal channel displayed Fender’s new preamp topology with an EQ stage sandwiched between two gain stages. This model is also unique in that it features a solid-state rectifier, and is rounded out by a 40 watt 5881/6L6GC power section. Notable users include: The Beatles, Pete Townshend, Brian Setzer, Tom Petty, and Mike Campbell.

The amp was given a partial restoration to complete the previous one from years earlier. The competency of the older restoration (parts quality/technique) was actually good - but there was some preventative maintenance and issues left unaddressed. All possible preventative maintenance was then completed. New 2 Watt Metal Oxide power dropping resistors were installed in the bias circuit for better reliability and lower noise floor. In the same circuit a new Vishay brand axial lead electrolytic capacitor was put in due to the previously installed unit being a radial lead cap with the wrong ratings for this amp. The cathode resistors for V2 and V4 were replaced with 2 Watt Metal Oxide type units due to heat damage. All plate resistors were replaced with 2 Watt Reduced Mass Metal Film type units for preventative maintenance and reliability. All screen resistors were replaced with 3 Watt Cement 470 ohm type units for same reasoning. A new 3AG 250v 3A Fuse was installed as the one present was underrated.

The original tubes did not all test good or had issues with noise. All were replaced. This was the final lineup: V1-V2 = EHX 12AX7 GOLD, V3 = JJ 12AX7S, V4 = EHX 12AX7, V5-V6= TAD 6L6WGC-STR Matched Pair. These tubes were picked for best tone, reliability, and low noise. The 6L6GC's Fixed Bias was set to %66 Class AB Plate Dissipation with a B+ of 422VDC. The tube sockets were all re-tensioned to make good contact with the vacuum tube pins and then were treated with De-Oxit to remove/prevent corrosion. The pots were sprayed out and the amp was cleaned inside and out. All hardware was tightened. Amp now functions perfectly, with that rad Brown-Panel tone and custom carved wood grill, this Bassman is a real catch for any vintage amp enthusiast.