diyAudio F5 Build Guide

[Jason]

This thread is for discussions about the diyAudio F5 Build Guide we have created for the First Watt F5 Amplifier by Nelson Pass. For more information on the boards available from the diyAudio Store, please see the information below.

Please note: The V2 and V3 boards have different parts placements.

• New V3 build guide here: Firstwatt F5 amplifier v3 - diyAudio Guides
• Old V2 build guide here: diyAudio F5 Build Guide
• Product Page
• Store support area thread for discussion the boards themselves specifically
• Schematic
• Bill of Materials
• Dimensions

Threads on diyAudio that relate to this product (If we have missed one, please post it in this thread and we will add it to the list):

• Build Thread: F5 power amplifier
• Build Thread: http://www.diyaudio.com/forums/pass-...-build-f5.html
• Build Thread: An illustrated guide to building an F5
• Build Thread: Initial setting of F5 bias--help, please!
• Listening Impressions: F5 Listening Impressions & Discussion
• Modifications: F5 Amps - Building a Quartet of Amps in search of the Ultimate F5
• Modifications: F5 with 2SK2013/2SJ313
• Modifications: http://www.diyaudio.com/forums/pass-...w-z-loads.html
• Review: 6moons.com - industry features: Swansong for an ugly duckling

[ljufa]

Thanks, very useful, added to bookmarks

[thor61]

Very nice guide ! Have some question's though. Why was the purple transformer drain wire not used ? Why are the psu caps only 10,000uf @ 25v ? Could one use a Antek 300Va as opposed to a 400Va ? And last were CL-60's used on the primary of the transformer as shown in the schematic, if so how ? Thank's

[JojoD818]

Originally Posted by thor61

Very nice guide ! Have some question's though. Why was the purple transformer drain wire not used ? Why are the psu caps only 10,000uf @ 25v ? Could one use a Antek 300Va as opposed to a 400Va ? And last were CL-60's used on the primary of the transformer as shown in the schematic, if so how ? Thank's

Not all transformer have this feature and so for brevity, the purple wire was not used.

Those caps were already there at the time of publishing. The psu schematic calls for 15,000uf/25V, please follow that.

I believe a 300VA can be used also.

Yes the CL-60s were used, please see Page 35. The CL-60s were soldered directly to the leads of the transformer and insulated accordingly. It is however for a mains of 240VAC, please see Page 5 for 120V mains operation.

[JZatopa]

What about a guide for matching semiconductors? I know you can find out how with a search online but adding a "why to/how to" to this post would help people out.

[JojoD818]

Originally Posted by DJNUBZ

What about a guide for matching semiconductors? I know you can find out how with a search online but adding a "why to/how to" to this post would help people out.

I actually made a matching jig that can be used with an external power supply and a DMM to match the fets used in our prototypes but that should be for another thread. Thank you, maybe in the next revision.

[JohnGeneva]

Great guide JopJo, so useful. I am slightly under sized in caps, I have 10000 on hand, will this make a big difference? or should I try to add more caps after the power supply board.

thanks, John

[JojoD818]

The prototype used 10,000uf caps because that's what we already have in hand at the time. So far we noticed no noise in the amp and been using it as it is for quite some time now.

I'm glad you found the build guide useful.

Cheers

[sjhomey]

I am rebuilding my F5, completed a couple of years ago, before this excellent build guide was around. I made some mistakes and am in the process of repopulating new boards. I have a couple pairs of Toshiba 2SK1530/2SJ201 mosfets and am wondering if I can use them without straying to far from this BOM. I would prefer to stay with the tried and true, but would like to use them if it could be easily done. I see some discussion in the original F5 thread regarding their use, but I don't know that a "best" setup was ever agreed on.
Thank you.

[6L6]

If I recall correctly, the Toshiba needed only a bit more resistance across the bias pots to bias properly...

Ask jackinnj or blues. (send either a PM) They should know off the top of their head.