F5 power amplifier

[WithTarragon]

I would also be interested in a board.

I recall there was mention that at some point in time PASS DIY would be offering F5 boards for sale. Perhaps that has fallen by the wayside?

[merlin2069er]

Does anyone know which issue NP does a write up in AudioXpress on the F5?

[udailey]

I just shot you an email. But nevermind it. Here is a link to all you need to build it.
http://www.firstwatt.com/downloads/F5-om_sm-080527.pdf
Uriah

[increek22]

here is yet another layout. 137mm x 51mm (5 x 2 inches)

[rdk845]

please help a newbie... I have made one up with p to p using the Juma's lay out. I have reduced the P1 and P2 value to minimum ( they are 1-5 ohm now) as stated in the Nelson's article and used variac to slowly move up the AC. The fuse blows up before rail voltage reaches 2V.. If I disconnect +- 24 and ground from main board, rail voltage reaches 26V no problem... It appears to me that if P1 and P1 is minimum value all the voltage is applied across JFET. Is this O.K.? What am i doing wrong? I'm using psu board from peter daniel and it seems psu is o.k...

Thanks!

[bluemartini]

The raw parts are fairly easy to find in the USA. He supplies 10K for for R21-22. I thought I read somewhere that those were changed to 22K ?

You did its back at post 1948, so you would have to replace the 10K provided.

[cviller]

Originally posted by umut1001



we can make single sided pcb ourselves..a double sided board will be better for group buy if Nelson permits....and we need fairchild output transistors..i am agree for group buy

Haha. Are you guys serious? The number of layers is quite irrelevant - you can make the most absolute horrible layout using double layer if you want to. I have used a single layer because no more is needed for this application (when I do phono stages and digital circuits I usually make a ground plane as well). If I had to get the boards manufactured, I might throw in another layer to reduce board size, but then the old farts in here might have troubles stuffing the boards.

Originally posted by rdk845
please help a newbie... I have made one up with p to p using the Juma's lay out. I have reduced the P1 and P2 value to minimum ( they are 1-5 ohm now) as stated in the Nelson's article and used variac to slowly move up the AC. The fuse blows up before rail voltage reaches 2V.. If I disconnect +- 24 and ground from main board, rail voltage reaches 26V no problem... It appears to me that if P1 and P1 is minimum value all the voltage is applied across JFET. Is this O.K.? What am i doing wrong? I'm using psu board from peter daniel and it seems psu is o.k...

Thanks!

Sounds like you have a short or have connected your power fets wrongly (if connected wrong, they are just power diodes). Try monitoring the voltage across the source power resistors (r11 and r12) when you turn up the voltage slowly. Otherwise post some detailed pictures and people in here might be able to help you.

[steenoe]

Originally posted by cviller


Haha. Are you guys serious? If I had to get the boards manufactured, I might throw in another layer to reduce board size, but then the old farts in here might have troubles stuffing the boards.

LOL

[thermos]

The PCBs I would like would be PassDIY F5 PCB's.
That would be cool.

[jackinnj]

Originally posted by bluemartini
The raw parts are fairly easy to find in the USA. He supplies 10K for for R21-22. I thought I read somewhere that those were changed to 22K ?

You did its back at post 1948, so you would have to replace the 10K provided.

I am now including 22k1 in the parts kit for the F5.