Vox V-1 Tube Pathfinder Amplifier
"A Look Under the Hood"




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© 1998 - 2017 The Vox Showroom, all rights reserved. No use on online auctions, eBay or Reverb.

The V-1 Pathfinder tube amplifier was manufactured in 1966 by the Thomas Organ Company of Sepulveda, CA under license to Jennings Musical Industries of Dartford, Kent UK.

Point-to-Point Hand Wired Chassis
The Vox V-1 Pathfinder chassis featured point-to-point hand wired construction. Point-to-point construction implies that the electrical components (resistors, capacitors, etc) are installed and soldered by hand to terminal strips. Additional hand soldered wires would connect the components installed on the terminal strips to the transformers, tube sockets and filter capacitors. No printed circuit boards would be used on these amplifiers.

The quality of the point-to-point hand wired construction found in JMI Vox amps built in the UK was tidy and masterful (see photo at left). Compare this to the view of the open Pathfinder chassis shown above. It is my opinion that the design and workmanship of the hand wired Vox amps built by Thomas Organ does not approach the quality one would find in a JMI Vox amp.

Chassis
The chassis of the Vox V-1 Pathfinder amp was composed of two parts: the steel chassis pan and the folded steel control panel.

The stamped and formed steel chassis pan (Thomas Organ p/n 30-5068-2) served as the backbone of the chassis. The T1 power transformer, T2 output transformer, C14 filter cap and four tube sockets were mounted to the outside of the chassis pan. The preamp circuitry was constructed on terminal strips mounted to the inside of the chassis pan. Locating the high gain preamp circuitry inside the grounded chassis pan shielded it from stray electronic fields eminating from the transformers.

This basic steel chassis pan was also shared with the Vox V-2 Pacemaker, V-3 Cambridge Reverb and V-8 Berkeley Super Reverb amplifiers and was later incorporated into the solid state versions of the Pacemaker, Pathfinder, Cambridge Reverb and Berkeley amps produced from 1966 through 1970.

The folded steel V-1 Pathfinder control panel included the rotary controls, jacks and switches. It was fastened to the top of the chassis pan with two machine screws.

Preamp Circuitry
Please refer to the chassis diagram at the top of this page when reading this section.

A 12AX7 tube labeled "V2" powered the preamp stage of the V-2 Pacemaker amplifier. The first section on the tube, V2a, increased the signal coming from the input jacks. The second half, V2b, was used for gain recovery after the tone control stack. This preamp circuit was shared with the V-1 Pathfinder, V-3 Cambridge Reverb and V-8 Berkeley Super Reverb.

A second 12AX7 tube, labeled "V3" powered the tremolo circuit.

Power Supply
An EZ80 (V1) tube recifier served to rectify the AC output of the HT secondary of the power transformer (T1). The pulsed DC output from the EZ-80 was filtered and smoothed by a vertical twist lock style filter capacitor (C14). This 350 volt electrolytic filter capacitor had three sections, 40uf, 30uf and 10 uf. The V-1 Pathfinder schematic publishes the power supply output voltages at 300 VDC, 290 VDC and 260 VDC.

Power Amplifier
A single ended, EL84 (V4) powered output stage provided about 8 watts RMS power to an 8" "Gold Bulldog" speaker.



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Photos and editorial content courtesy Gary Hahlbeck, North Coast Music


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