Dating blackface amps
More power and punch than Fender, less ruggedness than Marshall.I'd say its closer to a Vox type sound, but if you want Vox sound, this will not suffice.
i stuck a master volume on the back, jumped the channels, and cranked both channels to 7-8, plugged in my custom shop '61 reissue sg, and it kicks so much ass [through 4x12 25w greenbacks] its indescribable i bought both a 1971 yba-1 and a 1972(? [...] the yba-1a is currently beating the snot out of an old mesa 4x12 with 90 watters in it. this would make sense to me considering how very crushing it is and yet chimey. The only real problem was it seemed to be blowing fuses.
One [channel] sounds kind of like a "bright" channel and one sounds regular Two 6CA7/EL34 power tubes, three or four 12ax7s, solid state rectifier; hand wired, very high quality work, simple easy-to-modify circuit; larger [than the ones used in the Bass-Master YBA-1] 50-watt Hammond transformer (7 lbs.); Often operated with 4 ohm loads; best used with an eight ohms cab Runs on 540 volts, weights 54 pounds - bigger transformers [than the YBA-1] Dimensions: 8"x18"x10" (HWD); weight: 40 lbs.? (source: Catalog) Early [Bass-Master] Mark IIs have the (noisy) fan mounted on the end [in the cabinet side], later [Bass-Master] Mark IIs (with lift-off top, and the reflector 'Traynor' logo) have it mounted in the back [center]; Silvery grey grille cloth; Can exceed 600 volts on plate; expect about 550 volts, if you're lucky (one has eported 537 volts on plate) Early models are identical in appearance to the Voice Master/Signature.
I have swapped out the 4M volume pots for 1M, and put a 47K resistor in the NFB loop.
A 1967 YBA-1 is reported to feature a diode rectifier.
The used tubes are, as indicated in the amp: Two 6CA7s (replaceable by EL34s) and three 12AX7As (also called 7025s or ECC83s); plate voltages have always been a question on these units, but I think this may be largely because of confusion with the YBA-1A models that run VERY high plate voltages; most of the YBA-1 models probably come in somewhere /-450 volts (one has reported 425 volts on plate, another one ca.They feature a 'flip-top' design that allowes the top of the head to open like a lid.