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This set of circuit boards is used to make the F-5 Turbo power amplifier from the mind of DIY hero and audio genius, Nelson Pass.

One set of PCBs will make a stereo F-5T v2, or a single monoblock F-5T v3.  This is the third revision of the boards, which has nothing to do with using them to make a V2 or V3 F-5T!

Please read the F-5 Turbo Article written by Mr. Pass to familiarize yourself with the different versions.

Illustrated build guide

An Illustrated build guide showing all sorts of useful information on how to build your F5Turbo can be found here - Illustrated Build Guide

Circuit Description

The F-5 Turbo is a Push-Pull, Class-A power amplifier. Esentally a scaled-up F5, with more output devices and a higher voltage power supply. The F-5 Turbo is a voltage source amplifier, requiring nothing out of the ordinary from your preamp or speakers.

The F-5 Turbo is the biggest offering in the Nelson Pass/Firstwatt DIY series of amplifiers. The v3 will handily drive 100Watts into 8ohm, and much more into 4ohm. This circuit also has the ability to scale up to truly amazing power levels.

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 compatible with the diyAudio Universal Mounting Specification mounting pattern found in the Deluxe Chassis.

Output Power

  • F-5T v2 - 50 Watts per channel into 8ohm
  • F-5T v3 - 100 Watts into 8ohm. (The v3 should be built as monoblocks.)

Power supply requirements

A stereo F-5T v2 requires a bipolar power supply of (+/- 32V). This will require an 24V+24V (or 48V Center Tapped) transformer from 600-800VA, and PSU capacitance of 80,000uF per rail or more. The DIYaudio Universal PSU v3 was made with the requirments of this very amp when it was designed.

The F-5T v3 will require two of the above PSU. (One for each monoblock)

The amplifier has the ability to use a higher voltage PSU for more power, but you must 'cascode' the driver stage of the amp to protect the input Jfets. (And have even more heatsink.) See the article for more details.

Chassis suggestions

This is a high-wattage Class-A amplifier. It has lots of excess heat that needs to be dealt with. The 5U Chassis is of suitable size and disipation for a Stereo v2 or a mono v3.

The 5U 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. The new revision driver board will fit on the heatsinks, between the output boards.

Helpful Links

Other Notes

  • The F-5 Turbo, an F-5 on steroids, with outputs up to 100w per channel
  • With these PCBs you can make a 2 channel amp, or a massive monoblock depending on the output desired, PSU voltage, and the heatsinking available! Either way it should be used with the 5U x 400 chassis. You could also make a smaller monoblock using the 4U x 300 chassis, and only 2 of the output boards.
  • For questions about the PCB itself and myriad links to the original article, discussion threads and build threads, please see the F-5T boards support thread
  • This is not a beginners project
  • These boards are the newest revision, having a new layout of the Front-End board featuring many new solder pads, and rationalized labeling and numbering across all the PCBs. The layout has been only slightly modified, but it is different from the v2 PCB.
Mounting holes UMS Heatsink Compatible
Number of boards included 6
Layers 2
Board Revision 3.0

Customer Reviews

Based on 21 reviews
David P.
F5 Turbo

I live in the UK, the boards JFETS and MOSFETS arrived within two weeks. The F5 Turbo is my most challenging yet surprisingly straight forward build to date. I used a 5U Galaxy enclosure and 2 X 625 VA Transformers 24-0-24v bolted vertically to the front panel it’s not pretty but functional. Thus the two large bolts in the front panel. Thanks to 6L6’s build guide the build was straightforward. I opted for the V3 build without the extra transistor. Care has to be taken with the components as the MOSFETS and diodes are identical. The biasing is a slow process but was eventually biased to 350 mV. The guide has excellent instructions. It sounds superb and slightly more dynamic than the normally aspirated F5 which also sounds superb. Thank you Nelson, 6L6 and all the team at DIY Audio.

Steve W.
I eventually built it!!!

Bought the boards from DiyStore in April 2018 and it was going to be next months project..... I eventually got to it about month ago and build it without any problems. Using a 30v Antek 800VA transformer to give me 41V DC and currently have it biased at 0.330v and monitoring the heatsink temperature which seems to be fine and sitting at roughly 50deg Celsius. After a couple of hours of playing it with the Noir pre-amp the sound settled and it sounding absolutely stunning now… a project well worth it and highly recommended!!!

I’m planning to pair this with the electrostats I’m building, but that’s for next month.

Glen C.

Excellent quality boards. Fast delivery.

Sebastian S.
High qality pcb

All great.Thx

F5-T PCBs again 🙂

Second time purchase together with MOSFETs. And quickly delivered as usual half the earth around to little Norway 🙂.

Nizam K.

Received this pcb together with the F6 pcb and JFETs. The delivery is fast. The quality and design is excellent. The packing is very good. I have not built this amplifier yet. Thanks.

Luca D.
f5 turbo pcb

the pcb have arrived! they are of excellent quality, the shipping in italy was very fast! i can't wait to start building my f5 turbo!! thanks to all the staff!!!

Peter S.

High quality , fast delivery ,Thanks !

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