an australian client has ordered this stereo MB1 chassis – versus – my sweet lady tube 2 way EQ . a great combo . he has supplied a beaut old ‘skin’ tolex covered ferrograph tape recorder case for it . so im going to make this stereo mic/di/eq amplifier into that – complete with on board 5 watt tube amp and the original 9X6 inch goodmans monitor speaker. the new dual pultec MB1 tube mic amp will have variable input impedance. 30.150.600 ohms . alex has some real old ribbon mics . and wants extra tonal front end augmentisation capability in general. the big old meter switches between the two preamp outputs. as does the EL84 single ended tube P.A. amp. the 2 way tube equalizer features as the MB1 alternative input source. reverse engineered design from an american roberts (or rogers) stereo system. a unit that i repaired once really impressed me. the eq sound was so fat and deep. a very particular circuit built around the feedback of a single valve amplifier stage. ive added a preamp stage to it to enable an effective rumble filter, and hi/lo frequency switches to the bass and treble stages to complete this massive sounding 2 way eq adjustment scope of this ferral graffa transportable 2 channel studio preamp unit .
- gyrator ten8tor tested
- commando design preamp