SOHA II Parts List


Amplifier - Both Channels

Part Quantity Description
Circuit Board
- 1 SOHA II Two Channel + PS Board
Potentiometers
Volume 1 Alps RK27 Dual Audio Taper
P1L, P1R  2 200Ω Trimpot - Bourns 3296W
Not needed for Fixed CCS
P2L, P2R 2 10Ω Trimpot - Bourns 3296W
Resistors
R1L, R1R 2 1/8W 1% Metal Film Resistor 300Ω
R2L, R2R, R3L, R3R 4 1/8W 1% Metal Film Resistor 220Ω
R4L, R4R, R16L, R16R 4 1/8W 1% Metal Film Resistor 18kΩ
R5L, R5R, R11L, R11R 4 1/8W 1% Metal Film Resistor 3.3kΩ
R6L, R6R 2 1/8W 1% Metal Film Resistor 200Ω
R7L, R7R 2 1/8W 1% Metal Film Resistor 620Ω
R8L, R8R 2 1/8W 1% Metal Film Resistor 10kΩ
R9L, R9R 2 1/8W 1% Metal Film Resistor 820Ω
R10L, R10R 2 1/8W 1% Metal Film Resistor 2.2Ω
R12L, R12R 2 1/8W 1% Metal Film Resistor 4.99Ω
R13L, R13R, R14L,
R14R, R15L, R15R
6 1/8W 1% Metal Film Resistor 1MΩ - See Resistor Tweaks
RLED1, RLED2, RLED3 3 1/8W 1% Metal Film Resistor - See Notes for Value
Capacitors
C1L C1R 2 Metalized Polyester/Polypropylene Film Capacitor 220n 100V
C2L, C2R 2 Metalized Polyester/Polypropylene Film Capacitor 1μ 63V
C3L, C3R, C4L, C4R 4 Metalized Polyester/Polypropylene Film Capacitor 100n 63V
C5L, C5R 2 Aluminum Electrolytic 470u 25V
C6L, C6R 2 Metalized Polyester/Polypropylene Film Capacitor 1μ 63V
Diodes
Z1L, Z1R 2 1/2W Zener 18V - See Zener Tweaks
LED 3 1.2V - 5.2V LED
Transistors
Q1L, Q1R, Q2L, Q2R 4 BC560C - See Transistor Tweaks
Q3L, Q3R, Q4L, Q4R,
Q5L, Q5R, Q8L, Q8R
8 BC550C - See Transistor Tweaks
Q6L, Q6R, Q7L, Q7R 4 BD139 - See Transistor Tweaks
Integrated Circuits
ICL, ICR 2 High Beta, Jfet Input Single Opamp - OPA134
Vacuum Tubes
V1L, V1R 2 Dual Triode 12AU7 or 6922 - See Tube Tweaks
Miscellaneous
Heatsinks 4 1" Tall TO-220 Vertical
Heatsink Mounting Kit 4 TO-220
Sockets 2 9 Pin PCB Mount Tube Socket
Connector 2 or 3 3 Pin Phoenix 651-1729131

 

Resistors

  • All resistors are 1/8W 1% Metal Film type - 7mm lead spacing.
  • RLED1, RLED2, and RLED3 set the current in the LEDs. Calculate RLED
    using the forumla RLED = ( 12.6 - VLED ) / ILED.
  • Calculate RLED power with the formula PRLED = ILED x ILED x RLED.

Trimpots

  • P1L, P1R, P2L, P2R are 3/8" multi turn cermet - 0.100" lead spacing inline (e.g., Bournes 3296W).

Capacitors

  • C1L, C1R are Polyester/Polypropylene - 5mm lead spacing 7.2mm width.
  • C2L, C2R are Polyester/Polypropylene Film - 5mm lead spacing 5mm width.
  • C3L, C3R, C4L, C4R are Polyester/Polypropylene Film -5mm lead spacing 3.5mm width.
  • C5L, C5R are Aluminum Electrolytic - 5mm lead spacing 10mm diameter.
  • C6L, C6R are Polyester/Polypropylene - 5mm lead spacing 7.2mm width.
  • C1L, C1R Alternate are Polyester/Polypropylene Film - 7.5mm lead spacing 6.0mm width

Diodes

  • LEDs can be either 3mm or 5mm.

Transistors

  • Q1L, Q1R, Q2L, and Q2R are BC560C series.
  • Q3L, Q3R, Q4L, Q4R, Q5L, Q5R, Q8L, and Q8R are BC550C series.
  • Other small signal or audio transistors may be substituted, such as 2N5086/2N5087 and 2N5088/2N5089, but these devices have different pinouts and will need to be rotated before being inserted into the pads. See Small Signal Transistor Tweaks section.
  • Q6L, Q6R, Q7L, and Q7L are BD139 TO126 power transistors. Other types with the same pinout and similar characteristics can be used, such as MJE243. Output bias point may or may not adjust to 100mA.
  • BD139 are ECB pinouts. The board supports power transistors with BCE pinouts. See Device Mounting section.

Heatsinks

  • Heatsinks are 1.0"H x 1.38"L x 0.5"W - Aavid 513002B02500G.

Integrated Circuits

  • ICL, ICR are OPA134 single opamp, but any high β, jfet input opamp with the same pinout can be substituted.
  • WARNING: Do not use BJT input opamps as they will not satisfactorily zero the offset.

Tubes

  • The design center is the 12AU7 tube. But, because of the flexible front end design, many other tube types are possible. See the Tube Tweaks section.

 

Power Supply - Low Voltage, High Voltage, and Heater

Part Quantity Description
Resistors
R1P, R2P, R3P 3 1/8W 1% Metal Film Resistor 100kΩ
R1H 1 1/8W 1% Metal Film Resistor 9.31kΩ
R2H 1 1/8W 1% Metal Film Resistor 1kΩ
R3H 1 1/8W 1% Metal Film Resistor 6.98kΩ
Capacitors
C1P 1 Aluminum Electrolytic 100u 50V
C2P, C4P 2 Aluminum Electrolytic 10u 50V
C3P 1 Metalized Polyester/Polypropylene Film Capacitor 100n 60V
C5P 1 Aluminum Electrolytic 1000u 50V
C6P, C7P 2 Aluminum Electrolytic 100u 50V
C8P, C9P 2 Aluminum Electrolytic 100u 100V
C10P 1 Aluminum Electrolytic 100u 160V
C11P, C12P 2 Aluminum Electrolytic 22u 100V
C13P, C14P 2 Metalized Polyester/Polypropylene Film Capacitor 100n 100V
C1H, C2H 2 Low Impedance Aluminum Electrolytic 100u 25V
C3HP 1 Low Impedance Aluminum Electrolytic 47u 50V
C4P 1 Metalized Polyester/Polypropylene Film Capacitor 2.20n 35V
Diodes
D1P - D10P, D1H - D4H 14 UF4004
D5H 1 3A 40V Schottky 1N5820
Transistors
Q1P, Q2P 2 MPSA42
Integrated Circuits
LV+ 1 15V 1A Fixed Positive Regulator TO220
LV- 1 15V 1A Fixed Negative Regulator TO220
H- 1 1A Adjustable Negative Regulator TO220
HV+ 1 125V Adjustable Positive Regulator TO220
Miscellaneous
Heatsinks 3 1.0" Tall TO-220 Vertical
Heatsink Mounting Kit 3 TO-220
Header 1 2 x 3 Header with 0.1" pin spacing - See PS Schematic
Jumpers 2 2 Terminal with 0.1" pin spacing
Switch 1 DPDT PCB Mount Switch 0.1" pin spacing - alternative to heater jumper configuration.
T1 1 15-0-15/1A Toroidal Transformer - See Tweaks

 

Resistors

  • R1P, R2P, R4P, R7P, R8P are 1/8W 1% Metal Film type - 7mm lead spacing.
  • R3P is 3W 5% Power Resistor - 6mm diameter. Resistor mounts vertically, lead spacing is not important.
  • R5P is 1W 1% Metal Film Resistor - 10mm lead spacing (Vishay CCF60 Type).
  • R6P is 1/4W 1% Metal Film Resistor - 10mm lead spacing (Vishay CCF55 Type).

Trimpots

  • P1P is 3/8" multi turn cermet - 0.100" lead spacing inline (e.g., Bournes 3296W).

Capacitors

  • C1P, C2P, C5P are Aluminum Electrolytic - 2mm lead spacing 5mm diameter. 105C devices are recommended. 85C devices are acceptable.
  • C3P, C4P are Aluminum Electrolytic - 7.5mm lead spacing 16mm/18mm diameter.
  • C6P, C7P, C8P, C9P, C10P, C11P are Aluminum Electrolytic - 5mm lead spacing 10mm diameter.
  • C12P is Aluminum Electrolytic - 7.5mm lead spacing 16mm diameter.
  • C13, C16P, C17P are Polyester/Polypropylene Film - 5mm lead spacing 5mm width.
  • C14P, C15P are Aluminum Electrolytic - 3.5mm lead spacing 8mm diameter.

Diodes

  • All UF4004 or equivalent.

Transistors

  • Transistors are MPSA42.
  • MPSA42 are 300V transistors and are not strictly necessary for the voltages in this amp. Any 150V NPN transistor will do for this these parts such as 2N5551. Pay attention to the pinouts.

Heatsinks

  • Heatsinks are 1.0"H x 1.38"L x 0.5"W - Aavid 513002B02500G.

Integrated Circuits

  • LV+ is MC7815 or equivalent.
  • LV- is MC7915 or equivalent.
  • H- is LM337 or equivalent.
  • HV+ is TL783 or equivalent.

Transformer

Miscellaneous

 

Epsilon 12 Muting Circuit 

Part Quantity Description
Resistors
R1E, R2E 2 1/8W 1% Metal Film Resistor 33kΩ
R3E 1 1/8W 1% Metal Film Resistor 100kΩ
R4E 1 1/8W 1% Metal Film Resistor 2kΩ
R5E 1 1/8W 1% Metal Film Resistor 470kΩ
Transistors
Q1E, Q2E 2 BC550C
Q3E 1 MPSA14 Darlington
Capacitors
C1E 1 Metalized Polyester/Polypropylene Film Capacitor 1u 63V
C2E 1 Non Polar Aluminum Electrolytic 100u 25V or 100u 16V
C3E 1 Aluminum Electrolytic 100u 25V or 100u 16V
C4E, C5E 2 Metalized Polyester/Polypropylene Film Capacitor 10n 63V
Diodes
D1E, D2E, D3E 3 Small Signal Diode - 1N4148
Integrated Circuits
ICE 1 TL081 Opamp
LV+E 1 12V 100mA Fixed Positive Regulator
LV-E 1 12V 100mA Fixed Negative Regulator
Relay
K1E 1 12V Relay - Omron G6A-234P-ST15-US-DC12

 

Resistors

  • All resistors are 1/8W 1% Metal Film type - 7mm lead spacing.

Capacitors

  • C1E is Polyester/Polypropylene Film - 5mm lead spacing 5mm width.
  • C2E is Non Polar Aluminum Electrolytic - 3.5mm lead spacing 8mm diameter.
  • C3E is Aluminum Electrolytic - 2.5mm lead spacing 6mm diameter or 3.5mm lead spacing 8mm diameter.
  • C4E, C5E are Polyester/Polypropylene Film - 5mm lead spacing 2.5mm width.

Diodes

  • All 1N4148 or equivalent.

Transistors

Integrated Circuits

  • VR+E and VR-E are 78L12 and 79L12 respectively.

Relay

 

Full Excel BoM

This Excel spreadsheet has the parts lists and part numbers for the 7000b version of the SOHA II SSE Hybrid PCB. Most of the parts have Mouser part numbers. 

 Excel BoM
SOHA II SSE 7007b Excel BoM