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  • 2500


This pair of F-5 Clone circuit boards use the same circuit as the Nelson Pass / Firstwatt F-5 model.  This is V3.0 of the boards, and it should be assembled using the F5v3 Build Guide.

Circuit Description

The F5 is a Push-Pull, Class-A power amplifier. It is unique in that it has no capacitors in the amplifier circuit. The F5 is a voltage source amplifier, requiring nothing out of the ordinary from your preamp or speakers.

The F5 is probably the most popular amplifier being built on DIYaudio these days. It is simple to make, sounds fantastic, and has similar gain to many commercial amps.

Populate these boards with your components, then add your own power supply, chassis and heat sinks to complete the amplifier. The mounting hole spacing is the same as all other diyAudio Version 2 UMS boards.

Output power

25WPC into 8ohm

Power supply requirements

A Bipolar power supply of (+/- 24V) is required. This will require an 18V+18V (or 36V Center Tapped) transformer from 300-500VA, and PSU capacitance of 30,000uF per rail or more. The PSU for the F4, F5, and Aleph J are all essentially identical. See the F5 build guide for details.

Chassis suggestions

The 4U Deluxe Amplifier Chassis makes a great home for this amplifier, and has pre-tapped holes that match the circuit board and transistor mounting positions.  The diyAudio "Universal Mounting Specification" (UMS) is a common mounting pattern between the amplifier PCB and the heatsinks. If you utilize the UMS on your heatsinks or use one of the pre-drilled chassis from diyAudio, you will be able to quickly and easily mount different amplifier boards in the same chassis. For example, a 4U 'Jack of all Chassis' with a 400VA, 18V+18V transformer and PSU board, will give you a power supply and chassis where you could try the F4, F5, F5C, Aleph J, and other Pass/Firstwatt amps in the future merely by swapping the amp PCB. The investment in Chassis and PSU needs only be made once.

Please see the F5 thread in the store support forum for any questions you might have and a definitive list of relevant links and resources.

Change history


  • Initial release


  • Updated to suit UMS


  • Change to F5 schematics from F5 Turbo article
  • Minor diagram change in NTC and limiter sections
  • P3 added to adjust N/P variations to reduce distortion
  • Relabelling of resistors to match schematics

Layout changes

  • JFETs moved further away from current traces
  • Hole for OUT moved to other edge of board to make it prettier and increase symmetry
  • Middle mounting holes removed


Additional Information

V3 information (the current board is V3)


V2 information to be used for reference only


Dimensions 170mm x 50mm
Mounting holes UMS Heatsink Compatible
Number of boards included 2
Layers 2
Board Revision 3.0


Customer Reviews

Based on 20 reviews

Really top grade PCBs, the Mosfet seems far enough for heat spreading well , I love it.


boards are of exelente quality, nice and thick.


Professional service. Product looks good.

F5 boards

Fast shipping , excellent quality , thank You very much !

F5 PCB's

Fantastic quality of PCB as well as amp. I've had no problems whatsoever to put it together and I honestly can say it just sounds sublime.
Very, very happy - thank you very much :-)

F5 PCb's

Great quality, short delivery time. Very happy with these PCB's.

F5 boards & components

Dear DIY-Audio,

I am in the process of collecting all the parts to build the F5 power amp that I have seen such good reviews. I ordered these parts from you to start the process though the project will take me through the winter months. The order was easy to place, requests for additional tracking information were dealt with in good time, the components were delivered in good order, thank you. Additionally I have registered with the DIY forum and I am getting plenty of advice on build standards. I am very pleased to have found you
Best regards


F5 V3 boards

Quick delivery even overseas! PCBs are premium quality, really well made! Happy to start my F5 project with such a smooth transaction. Still some way to go till completed amp but it started well.
Greetings from Latvia

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