F5M Essentials
The "Essentials" kit includes the PCBs and the critical semiconductors for the F5m.
- 2 x F5m PCBs: Dimensions - 3.500 inch x 1.925 inch. Mounting hole spacing - 3.15 inch x 1.575 inch
- 2 x Toshiba 2SJ74
- 2 x Toshiba 2SK170
- 2 x IRFP140
- 2 x IRFP9140
DIYers have been building variants of the First Watt F5 for many years. Now, we have the first of several "minimalist" designs from Nelson Pass, the F5m; fewer parts, easier to build, and all the fantastic sound you expect from a Nelson Pass amplifier design.
With the full pictorial build guide including the power supply, this amplifier is the most approachable build for the DIYer wanting a "full-size" amplifier with a linear power supply.
Power supply requirements
A bipolar power supply of (+/- 24V) is required. The PSUs for almost all First Watt amplifiers including the F4, F5, F6, M2x, Aleph J, and Aleph Jzm are identical. The same PSU can be used for all of them.
There are three PSUs to choose from:
- Nelson's Bipolar Power Supply is the least expensive and easiest to build. It was designed to compliment the beautifully simple and inexpensive "minimalist" F5m.
- The Simple Linear Bipolar Power Supply is the choice for DIYers that prefer a higher performance power supply, but enjoy the convenience of a full kit. For builders that prefer to choose their own parts, the PCBs are also available.
- The Universal Power Supply PCBs allow the experienced DIYer to choose every part of their PSU or use what they have in their spare parts bin.
Chassis suggestions
The 3U Deluxe is an excellent choice. For builders that want more space and/or may want to build a bigger amplifier in the future, the 4U Deluxe or 5U Deluxe are great choices. We also have a back panel parts kit to make life easier, and don’t forget the Keratherm.
Key Information
- Power Amplifier Project
- Designed by Nelson Pass
- Intermediate Difficulty
- Only Essentials Kit Available
- Comprehensive Build Guide
Highlights
- Simpler design to the original F5, without compromising the qualities which made the original one of the most popular First Watt amplifiers for DIYers everywhere.
Links, Discussion & Files
A great performance from such a simple and reasonably priced project.The next chassis dual mono power supply and pair of boards built and ready to go but I need another pair of boards to try a balanced version as soon as available.
Absolutely astonishing results. Could not be more satisfied with the quality & the sound. Built dual mono.
Thanks DIYaUdio
Coming to terms With the quality of reproduction of this kit,I think I like this kit better than the version 3 F5, Which is saying a lot…… I think a lot of the builders will agree. This kit has a great tone.
Running 1000va x 4 secondaries,35v rails…each Mundorf 33,000uf
Pass has done it again. I have had the opportunity to spend time with a good variety of Pass amps. Which include both the XA.5 and the XA.8 series. This F5m has something special to it. Is it as dynamic? I would say no. But much more than it has any right to be.
Where it shines are the mids and highs. The 2nd order harmonic distortion created by the careful selection of output mosfets really give this amp a wonderful sound.
Should you build it? Well, I think for the price and it's simplicity, I would say it is a no-brainer...
The F5M is a really fun build, lots of information in the DIY forum with lots of great people to help along the way if needed. The sound is incredible!
