Topic: DIY Nelson Pass F5 Turbo

[Abad Santos 7]

Hi All,

This is my first DIY Solid State Amp build and it happens to be in experimental mode.  I decided to study first how the amplifier behaves. 
Its strong points and weaknesses....

I have used 2 different PCB for Right and Left Channel....with identical result (at least to my ears :lol:  :lol:  :lol: )
Im running at 1.6Amp per Channel....and yes it is generating lots of heat that can be used as a winter heater.

The picture of the whole AMP.


I thought my heat sink will be sufficient enough for this build and I was wrong... During summer I have no choice
but to lower the bias to 1Amp per channel since the heat sink temperature is rising beyond 55oC.  But now its winter
And I could adjust the bias at 1.6Amp...with least with 25oC rise above ambient...

[Abad Santos 7]

The Power Supply:

I use dual mono set-up for best possible result.

I decided for CRC filtering method with 12,000uf X 16 per channel which has 20mv amount of ripple loaded.
Transformer is at 400VA each.  At 1Amp bias, there are very silent.  However at 1.6Amp bias, I can feel already
some mechanical vibration....wont rise the bias as of the moment...



Need to control also the inrush current and a soft start circuit is a must...



I will plug amp the Amp directly to the wall outlet, thus I decided to put a dedicated power filter...

[Abad Santos 7]

The Amp Circuit:

The left Channel is a short profile PCB.  Its seems this is better for the heat distribution per FETs...
I can put easily it in the center of the heatsink which good control of the heat.  Ground design is also
good.



The right Channel is a long profile PCB.  For Pogie factor this is better as compared with the short profile.
Control of heat is very hard to center on the heat sink.  Due to design, I have to remove the diode to prevent
thermal run away for the amp since the diode location is very close to the Fets.

[Abad Santos 7]

HOW DOES IT SOUNDS:

I dont know but I fall in love with CLASS A.  I will not worry for a little increase of Meralco Bill compare to the SQ you can
hear with CLASS A. 

WHERE DO I GO FROM HERE:

I decided for the full 100W CLASS A for my 2014 project with full understanding of the CLASS A circuit of F5 Turbo.
Still gathering parts for this amp to be house for my new music room in future.

Cheers.

[romymartinez]

Wow! congrats!

[Abad Santos 7]

Wow! congrats!

Thanks Sir...

[JojoD818]

that sure looks awesome! congrats!

[romymartinez]

For a long time I've been asking a friend to build an F5 for me. But he can't find the time to do it.

Again nice amp and congrats!

[RXV]

Wow very nice amp

[ATJr.]

For a long time I've been asking a friend to build an F5 for me. But he can't find the time to do it.

Again nice amp and congrats!

if you buy kits, you can do it yourself...many here will walk you thru the build....

[brainf]

Nice work Loi! Very neat too.   Mine's a mess. You know, one of those "experimental builds" which never got round to being "finalized" because it just works, and works so well. 

Wifey accidentally left it ON the whole day recently, was horrified when a I got home from work and saw it still on 14 hours later.  Took a likin' and still kept on tickin'   - testament to a good circuit design and key components (Custom Traffo from our very own Edrel Sison).

Happy holidays everyone!

[tony]

Leslie, can you post pictures of your amp with Edrel's traffo?