This amplifier is based on the amplifier section of a 1949 E H Scott amplifier-receiver, probably model 500. It features separate bass and treble controls, and a line level input. The B+ voltage is approx. 380 volts
| Resistor ID | Value | Function, notes |
| R1 | 500K Audio taper | Volume Control |
| R2 | 560 ohms metal oxide 1 watt 5% | V1 Cathode |
| R3 | 47K 1/2 watt 5% | V1 Plate load |
| R4 | 150K 1/2 watt 5% | V1 Screen decoupling |
| R5 | 47K 1/2 watt 5% | Tone compensation network |
| R6 | 500K Linear taper | Bass tone control |
| R7 | 500K Linear taper | Treble tone control |
| R8 | 22K 1/2 watt 5% | Tone comp. |
| R9 | 100K 1/2 watt 5% | AF load |
| R10 | 220K 1/2 watt 5% | V2 Grid leak |
| R11 | 2.4K 1/2 watt 5% | V2 Cathode |
| R12 | 56 ohms 1/2 watt 5% | V2 Cathode |
| R13 | 47K 1/2 watt 5% | V2 Plate load |
| R14 | 220K 1/2 watt 5% | Grid leak |
| R15 | 6.8K 1/2 watt 5% | Grid leak |
| R16 | 680 ohms 1/2 watt 5% | Inverter cathode follower |
| R17 | 7.5K 1/2 watt 5% | V3 Plate load |
| R18 | 47K 1/2 watt 5% | Output grid |
| R19 | 47K 1/2 watt 5% | Output grid |
| R20 | 210 ohms Wire-Wound 10 watts 5% | Output cathode |
| R21 | 560 ohms 1/2 watt 5% | Feedback isolation |
| R22 | 300 ohms W.W. 10 watts 10% | Power supply filter |
| R23 | 750 ohms W.W. 20 watts 10% | Power supply filter |
| R24 | 2K W.W. 10 watts 5% | Voltage divider |
| R25 | 10K W.W. 10 watts 5% | Voltage divider |
Unless noted, resistors are carbon composition.
| Capacitor ID | Value | Function, notes |
| C1 | 25mF electrolytic 25 volts | V1 Cathode bypass |
| C2 | .25mF metalized polyester 630V | V1 Screen bypass, may also be .22mF |
| C3 | .1mF metalized polyester 630V | DC blocking |
| C4 | .01mF metalized polyester 630V | Treble tone comp |
| C5 | .0047mF metalized polyester 630V | Treble tone comp |
| C6 | .0047mF metalized polyester 630V | Bass tone comp |
| C7 | .022mF metalized polyester 630V | Bass tone comp |
| C8 | .047mF metalized polyester 630V | AF coupling |
| C9 | 25mF electrolytic 25 volts | V2 Cathode |
| C10 | .047mF metalized polyester 630V | DC blocking |
| C11 | .22mF metalized polyester 630V | DC blocking |
| C12 | .22mF metalized polyester 630V | AF coupling |
| C13 | 25mF electrolytic 50 volts | Output cathode bypass |
| C14 | .01mF ceramic 1400 volts | Line bypass |
| C15 | 10mF electrolytic 450 volts | Filter |
| C16 | 10mF electrolytic 450 volts | Filter |
| C17 | 10mF electrolytic 450 volts | Filter |
| C18 | 10mF electrolytic 450 volts | Filter |
| C19 | 10mF electrolytic 450 volts | Filter |
| C20 | 10mF electrolytic 450 volts | Filter |
| Filter Choke | Inductance (henries @ 1000cps, 0 current) | Current, notes |
| L1 | 5 Henries | 180ma |
| L2 | 5 Henries | 80ma |
| Power Transformer T1 | |||
| Primary | Secondary 1 | Secondary 2 | Secondary 3 |
| 117V AC 60cps 1.45A | 760V, CT @ 260mADC | 5 volts @ 3 Amps | 6.3 volts @ 4.5 Amps |
| Output Transformer T2 | |
| Primary Impedance @ 400cps | Secondary Impedance @ 400cps |
| 5600 ohms, Center-Tapped | Match to speaker. Tap at 4 ohms for feedback connection. |
At this writing, I am thinking about adapting the design for two channels. In doing so I would want to loose the 6J5 and replace it with another dual triode tube type 6SN7-GT. Each triode unit of the 6SN7-GT is identical to the 6J5.
If you don't like tubes with top connections, use a 6SJ7 in place of the 6J7.
For stereo conversion, another 5U4-G tube would also most likely be needed. The 5Z3 tube is suggested because it is less expensive and not in very great demand.
Note: Use twisted pair for all heater wiring.
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