They are similar in the way that both are clean sounding with just one 12ax7 tube in the preamp stage (vibrato ch in bandmaster and normal channel in bassman). Let’s study the blackface Bandmaster AB763 and blackface Bassman AA864.
#1964 FENDER BANDMASTER HEAD PRO#
The Bandmaster Reverb head is therefore quite similar to the amps in the Pro Reverb and Vibrolux Reverb, just without the speakers. Not only is there more action in the preamp section, the silverface Bandmaster Reverb also has less attack and less clean headroom in the power amp section due to the tube rectifier. This is caused by the lack of gain stage in the reverb recovery circuit which contributes to tube distortion and compression in the preamp section when the amp is pushed. The reverb amps will start to break up around 4-5 on the volume knob while the non-reverb amps stay clean to approx 6-7. All these ab763 amps with reverb has the gain stage in the reverb recovery circuit which the non-reverb amps don’t have. Yes of course some have the mid knob and bright switch while others don’t. The main differences between these amps are transformer size, filter caps size and output/speaker impedance. The silverface Bandmaster Reverb is a typical ab763 amp and shares basic circuit design with the Super Reverb, Deluxe Reverb, Twin Reverb, Vibrolux Reverb, Pro Reverb and Twin Reverb. It reminds us more of a classic 80w Twin Reverb than a Bandmaster Reverb, and it shared its circuit design with the Pro Reverb and Super Reverb at that time. The 70W model from 1978 with master volume and push/pull boost had a huge power transformer and big filter caps. As usual the later silverface models were modified to become cleaner and more powerful.
Due to this the silverface Bandmaster Reverb is less powerful, has less attack and breaks up earlier than the blackface Bandmaster. The silverface Bandmaster amps got a 5U4GB tube rectifier and the vibrato channel got reverb. The blackface head had a diode recifier, one normal channel and a vibrato channel with no reverb. The Bandmaster came with many different circuits during the blackface and silverface eras.
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