F-5 boards

[Helpdesk]

This thread is for discussions about the F5 clone boards. For more information on this product, please see the product page below.

• Product Page
• Build Guide
• 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: How to build the F5
• 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: F5 For Low Z Loads ?
• Review: 6moons.com - industry features: Swansong for an ugly duckling

[labjr]

The F5 schematic in the store shows P3 on the F5 board. However, I don't see P3 on the board. Is it now included or are there plans to add P3 to the board? Also there are some small changes to the F5 circuit as seen in the F5 Turbo manual. Are those changes on the boards yet?

[JojoD818]

Hi,

P3 is for fine tuning the input section for minimum distortion. However, it entails the use of elaborate spectrum and distortion analyzers which may not be available to the common builder (I for one don't have one).

It was included in the schematic to keep it updated with the most recent schematic from Nelson, and also in the BOM for the sake of completeness. However, if you are to use P3, it should be "hard-wired" or soldered "point to point" on our boards.

In our official F5 prototype, P3 was set aside and was not used. I believe the small changes, especially the parts values, are already included in our board and BOM.

[labjr]

The changes in the bias ciruitry are not changed in the schematic that's in the store. I assume they are not on the board either?

P3 could have been added to the board. The builder could choose to install it or not. Adding it in as a Kludge makes the board look messy.

[bear]

look at the flip side of the board, and a higher res imageon the website would be nice too...

[labjr]

Also the input resistors are configured differently in the F5 Turbo manual. Any idea why?

[bear]

I like the fat foil traces...

[JojoD818]

Originally Posted by labjr

The changes in the bias ciruitry are not changed in the schematic that's in the store. I assume they are not on the board either?

P3 could have been added to the board. The builder could choose to install it or not. Adding it in as a Kludge makes the board look messy.

What changes in the bias circuitry are you referring to? Could you please elaborate on that? The two schematics were drawn differently but still have the same bias circuitry the last time I checked except for the position of the thermistors which should not be an issue at all.

Regarding P3, iirc the boards have long been here before P3 came about. However, if the equipment needed to adjust it is available to you, then it is very easy to adopt the board to accept P3 without it looking messy or as you say, a kludge.

[Jason]

Originally Posted by bear

look at the flip side of the board, and a higher res imageon the website would be nice too...

Your wish is our command! Hi resolution, color enhanced version uploaded to the F5 page.

[bear]

better, less white border, more board... still not that easy to see the details... fwiw. I could use higher res on this screen. Not everyone is at 1480 wide, some are still 1024 I am sure.

_-_-