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6L6 17th February 2013 11:03 PM

Building an F5 Turbo v2 (in-Progress)
Building the F5 Turbo v2

This is the "in-progress" thread for the official build guide of the F5Turbo. This is not the final guide.

I am building a V2, with 2 outputs per side, source diodes, and no cascode. DIYaudio store PCB are being used and it will all go into a 5U 400mm "BIG Amp Chassis"

The Firstwatt F5 Turbo article from Nelson Pass, in case you haven't seen it -

Anyway, on to the build. :)
The Chassis in the shipping box and the PCB.
While we are at it, here is a good photo of the Front-end board
And here are the output boards. The component numbering on all these boards don't quite match up with the schematic, that will need to be clarified in the guide. In the time being, a bit of logic and inspection will let you figure it out.
A large transformer. :)

Building the PSU -
Components - PCB, Caps, resistors, thermal shutoff, inrush limiter, line cap, ground loop breaker, rectifier diodes. Not shown are rail LEDs, bleeder resistors.
Why 2 PCB? to hold the (16) 10,000uf 50v capacitors. :)
We will only need one Bridge PCB, and the rest can be cut off the boards.
The PSU will be built on the 'DIY friendly' baseplate, shown here with some of the chassis hardware.
The first PCB will hold only caps and the filter resistors. But there is only room for eight, and the board holds fourteenů
So a bit of stacking is required.
The other board will have the LEDs and bleeders. Please note that the resistor pads must be jumpered.
Testing the LEDs with a bench PSU
The 2 PCB now stuffed. The left will have the input from the rectifier, the right will be the output to the amp.
The other side of the PCBs
Looking down at the first PCB
Looking at the second. Again, please note the jumpers where there are the resistors.

a.wayne 17th February 2013 11:13 PM

Wait , what ..!

Another baby , Whats with all the dinky toy 2 pr output builds :rolleyes:

outputs aren't that expensive , c'mon guys , Do a 4 pr, its a turbo for bleeezus sakes , why not make some power !!!


6L6 17th February 2013 11:16 PM

Why? Three reasons -- Heatsink, heatsink and heatsink.
A 2pr stereo is about all the 5U can handle. :)

oneplustwo 17th February 2013 11:19 PM

Yay! Another 6L6 build log! Looking forward to seeing the progress. I'm still very happy with my F5... and afraid of building a turbo for fear of not wanting the original anymore! Besides, I don't think I need the extra power or electricity bill increases. I have the Aleph Xs for that. :P

a.wayne 17th February 2013 11:20 PM


Originally Posted by 6L6 (
Why? Three reasons -- Heatsink, heatsink and heatsink.
A 2pr stereo is about all the 5U can handle. :)

Only if you increase the amt of class-a bias ....

buzzforb 17th February 2013 11:25 PM

looks great, as usual.
I am interested to see how that bottom takes the weight of the toroid. I have a suspician you might have some give.

my V3 is at home on sinks. Just didt get the PSU's finished.

PKI 18th February 2013 12:08 AM

I will make some photos how I reinforced the bottom cover.

buzzforb 18th February 2013 12:10 AM


Zen Mod 18th February 2013 12:13 AM


Originally Posted by buzzforb (
I am interested to see how that bottom takes the weight of the toroid. ......

just fine - if screwed properly to side brackets

6L6 - be sure , later , to (edit) include link in first post in thread - directly to powering up/biasing procedure ..... which you are going to write , in detail

good for us greenhorns ...... and handy , for later


buzzforb 18th February 2013 12:23 AM

Pots definitely need turning down if you have high Idss Jfets. If not, and amp is powered up, the fets are biased too high with pots set as they are from the vendor.

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