Dating blackface fender bassman 60
Tung Sol 12AX7 for the V1 and V2 position as it has such low microphonics and a rich tone One Tung Sol 12AT7W for the reverb drive circuit and again with low microphonics maintains a rich warm reverb sound. This is the pre-amp valve that has the most load on it due to driving the reverb tank and the 12AT7W handles this with no issues.
One JJ Electronic 12AT7 for the phase splitter and this is a matched / balanced Three JJ Electronic ECC83S ( the British 12AX7). One is matched / balanced for the splitter position before the output valves Two Electro-Harmonix 6V6GT matched output valves.
The blackface Bandmaster is therefore ideal for those who look for a pure Fender clean sound without making ones ears bleed.
The blackface and silverface Bandmasters are medium/big sounding amps with a flexible speaker impedance of 4 ohm, allowing anything between one and four speakers (8 ohm each) to be connected via the main and/or external speaker jack.
The vibrato channel in the Bandmaster is even more clean than the Bassman because of the vibrato circuitry loading the signal chain and reducing the gain level in the premp section.
Hence, the AA864 Bassman normal channel has more preamp “juice” and reaches the sweet spot at an earlier volume knob setting.
The Bassman has a slightly bigger output transformer resulting in a firmer tone and more attack.
A smaller output transformer will introduce sag and compression in the power amp section.
The Bandmaster Reverb head is therefore quite similar to the amps in the Pro Reverb and Vibrolux Reverb, just without the speakers.
All are chosen for their own special merits for each valve position in the amp.
Nothing makes your Fender Deluxe Reverb Re Issue sound like new than a complete new set of valve/tubes for your amp.
Summary The Bandmaster came with many different circuits during the blackface and silverface eras.
The blackface head had a diode recifier, one normal channel and a vibrato channel with no reverb.