Hifi Preamps for your Record Player

Build the Muffsy Hifi Dual Power Supply v3

Here are the build instructions for the Muffsy Hifi Dual Power Supply v3.


A 15-18 volts AC wall adapter (do not exceed 18 volts) is needed to make this power supply work. Here is some more information about what you need to build the Muffsy Phono Preamp and Power supply.


You can also have a look at the schematics for the Muffsy products under the Modify It page.

Illustrations Explained

The picture below is a larger version of your printed circuit board. For each step, this will be used to show you which components you will be adding to the board.

PCB Overlay

This picture shows you where you are in the build process. It also shows what each component looks like, and it will contain special instructions or information.

Actual PCB with Comments

 Bill of Materials

These are the components needed to build the power supply.

Quantity  Component
 8Diodes, 1N4004 
2 Resistors, 0.25W Metal Film, 300 ohm 
 2Resistors, 0.25W Metal Film, 3300 ohm 
 2Resistors, 1W, 4.7 ohm 
 6Ceramic Capacitors, 100 nF 
 2Electrolytic Capacitors, 25V or higher, 10 uF 
 1Electrolytic Capacitor 35V or higher, 470uF 
(Grid: 5.8 mm, Diameter: 10 mm)
 4Electrolytic Capacitors, 35V or higher, 2200 uF 
(Grid: 7.5 mm, Diameter: 16 mm)
 1Voltage Regulator, LM317T 
 1Voltage Regulator, LM337T 
 1 Voltage Regulator, LM7815
 1Wall Adapter, 15-18V AC 
 1Screw Terminal, DG301, 2 Positions 
(Grid: 5 mm)
 1Screw Terminal, DG301, 3 Positions 
(Grid: 5 mm)

Step 1: Solder the Diodes

There are eight 1N4004 diodes on the board. Take your time and make sure you have them oriented correctly. The silver band on each diode matches the symbol on the printed circuit board.

Diode placement
Diodes mounted on the board - Notice the orientation

Step 2: Solder the 0.25W Resistors

Before you continue, consider if you want to change the output voltage. The Muffsy kits are made for +/-15V (which is what you get if you use the included components), but you may have other plans for the power supply. If you plan to use other operational amplifiers, check what their maximum voltage is. Some may need less voltage.

There are four of the 0.25W resistors, they can be oriented whichever way you want. It is a good idea to measure them before they are soldered in place.

Placement of 0.25W resistors
0.25W resistors soldered in place

Step 3: Solder 1W Resistors

The two 1W resistors can be mounted either way.

Placement of 1W resistors
1W resistors mounted on the board

Step 4: Solder the Ceramic Capacitors

Next you've got six ceramic capacitors to place on the board. The orientation does not matter for these, but I like to place them so that the text is outwards and visible.

Placement of the ceramic capacitors
Ceramic capacitors soldered to the PCB

Step 5: Solder the 10 uF Electrolytic Capacitors

These two capacitors must be mounted the right way around. The white band (the negative side of the capacitors) are pointed upwards on the board. See the pictures below for reference.

The 10 uF electrolytic capacitors marked on the board
The 10 uF capacitors soldered to the board, the arrow shows the white band on the caps

Step 6: Solder the Voltage Regulators

The board has three voltage regulators. One for +15V, one for -15V and a third one for +15V AUX power.


It's important to get both the placement and the orientation of the voltage regulators correct, so there's two pictures from different angles.     




Voltage regulators. Notice that the metal plates line up with the bold white lines in the component outline on the PCB.
The voltage regulators from a different angle

Step 7: Solder the 470 uF Electrolytic Capacitor

The orientation of this capacitor is important, place it as on the pictures below and solder it in place.

The 470 uF electrolytic capacitor
Notice the orientation of the capacitor

Step 8: Solder the 2200 uF Electrolytic Capacitors    

There are four large 2200 uF electrolytic capacitors on the board, for smoothing the rectified AC voltage.


Orientation is important, all the white bands are facing downwards. Double check the orientation before you solder these capacitors in place, they can be pretty hard to desolder.

2200 uF Capacitors
2200 uF electrolytic capacitors - Notice the orientation

Step 9: Solder Screw Terminals

If you are building your Muffsy Phono Preamp or MC Head amp into a B0905 enclosure, please don't solder the screw terminals just yet


The construction pages for the Phono Preamp and MC Head Amp contain info on how to mount these terminals:

If you are using a custom enclosure for your build, the screw terminals may be soldered in place now. You still  might want to consider fitting the cables before soldering the terminals to the PCB. Tinning the cable ends might also make it easier to insert them into the screw terminals.


The screw terminal with two connections  is for the 15-18V AC input, from the wall adapter. The screw terminal with three holes is for the +/- 15V DC output and ground.

Screw terminals soldered on the board

Construction Complete

Congratulations, you have built a power supply.


To complete your build, continue to the following instructions: