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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 32 reviews
Koichi S.
Modified the F5 board to F7

Very good board.
I modified the F5 board to F7.

1-Cut 3 places (orange line).
2-Add 2 resistors back face.
3-Cross drain pin & sorce pin of power mos-fets.

Cody T.

Absolutely love these boards! Very nice quality board, and the layout is superb. DIY Audio never disappoints!

Luis P.

excellent quality thank you for stocking these boards ,can't wait to start my build *

Graeme D.
F5 pcb and kit

Usual amazing quality of DIYAudiostore products. All faultless and as specified. And of course great service from the Store answering queries. Thanks.


Excellent very helpful staff when I stuff up order

Andrew B.
Good Kit at a good price

As the title

Leo v.D.
very nice board

easy to build, will try the sound a couple of days from now

Roy P.
F5 V3

This is a well made and well designed board that made building and adjusting the amp very easy. It is also well documented with a parts lists for the board, a schematic diagram, an illustrated build guide, many supporting threads and a Nelsen Pass article showing how everything works. It is best used with the store power supply board, which is also a well documented project. The only flaw IMO is the lack of a quick connect option for power and speaker connections. It makes disassembly much easier in case of problems. My choice would be the faston connectors which are available on the PSB board and the soft start/speaker protection board.

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