1971 NEWCOMB PATHFINDER E-40

 This is a 1971 Newcomb Pathfinder E-40 that I restored and converted to work better for guitar input impedance and frequency range. The Newcomb E-40 started it's life as a PA owned probably by a church or military base and was originally designed for microphones and turntables. This isn’t the first conversion I have done on these Newcomb Pathfinder amps - I love them - They sound as good or better than any vintage amp out there.

This amp boasts an all tube signal path that is completely hand wired point-to-point with no circuit boards of any kind. It goes from a clean chime at lower settings, to an unbelievable British sounding overdrive at half volume, which then turns into a full on distortion/fuzz meltdown when cranked to 3/4 volume and above. Overall this amp reminds me of early Vox AC-15/AC30's that contained the sought after EF-86 tube pentode in the front end.

The power-amp puts out a full 45 watts provided by 4 cathode biased JJ EL-84's in push-pull. The preamp section consists of a JJ 12AX7 as the input stage and a fairly rare NOS GE 6BR8A that contains both a pentode line driver and a triode phase splitter in the same glass envelope. The tube compliment is rounded out by a NOS RCA 5U4 tube rectifier. The Cathode Bias was set to %95 Class AB Plate Dissipation with a B+ of 375VDC.

All the electrolytic caps are new (including the CE cap can), all signal caps have been replaced with Mallory 150 film type, power resistors have been upgraded to 2 watt metal oxide and 1 watt carbon film, and all potential problematic carbon comp resistors have been replaced with modern 1/2watt carbon film type. A Trainwreck style Type-3 Master volume was put in to replace the “Phono” knob/pot, and the pentode line driver was cathode bypassed with 50uf 100v electrolytic capacitor to give fuller frequency response.

“Mike 1” and “Mike 2” each have a push pull pot to change them into a “Bright” channel - “Mike 1” was converted into a Vox style cathode bias preamp that was modded to my liking, with “Mike 2” remaining the original grid leak bias type preamp. The tone stack was modified to have tighter bass response. A speaker jack was also added for convenience. Much of the rest of the circuit design was left intact as it sounded great as is. This was for a customer who mailed it in all the way from Colorado.