Alpha Nirvana 39w 8ohm Class A Amp

Anand,

Here's another part that should work:

https://www.newark.com/molex/39-28-1043/connector-header-4pos-2row-4-2mm/dp/38C9738

Still available at Newark, but out of stock at Mouser and Digikey it seems...

Do,

I am not sure if the X and JPS64 made provision for directly connecting the MOSFET to the board - can you check please?

P.S. Found a higher priced item that is available at both Digikey and Mouser: Check for Molex part # 39-29-0043
 
Last edited:
Do,

I considered direct solder option as well but since it was going in my NPXP I wanted something quick. I might reconsider it if the Alpha Nirvana sonics are so good that it becomes a permanent build. I think X’s original idea was to design something flexible, quick but reliable (ie not oscillate).

Zman,

Thanks for the Molex option. I had seen that before but didn’t know if it would mate with the male Wurth connectors I have. It should, given that it is 4 pin, etc…just more expensive.

Thank you both!

Best,
Anand.
 
Last edited:
Founder of XSA-Labs
Joined 2012
Paid Member
Wurth and Molex Minifit 4 pin are interchangeable. When properly crimped, they are a very reliable and easy to disconnect/reconnect option.

This is what a good crimp looks like (the wire is wrapped evenly and tightly with the metal pinch band, the wire part is tightly crimped with a cold weld.
766390d1562259773-slb-smooth-butter-active-rect-crc-cap-mx-class-power-supply-gb-6eee70b6-6005-4595-bc5d-2ab3fe7ebb67-jpeg
 
Last edited:
Member
Joined 2004
Paid Member
Hi X,
I appreciate a good example of a properly crimped Molex connector. However, the problem for occasional users like myself is that there are too many types of these connectors and housings to know what to use, UNLESS the parts are explicitly indicated by designers/PCB makers.

I have carefully watched and read this thread in order to build Hugh’s Alpha Nirvana design, but after all this I’m still not sure that I have the right connectors and housings, as well as the right crimp tools to make it happen.
 
Francois G,

If crimping makes you uncomfortable, you can hack readymade cables; something like this:

https://www.amazon.com/OOMIAK-Power-Supply-Female-Extension/dp/B07R3YG2B4

- Keep the male header that is required and cut off the other end.

- Identify the 3 pins that correspond to the ones for the MOSFETs on the amp PCB, and cut off (or clearly mark) the wire that is not required.

- There are 2 colors of wires - black and yellow - if you want a 3rd color, wrap heat-shrink tubing of a different color around one of the wires.

- Connect the Source, Gate, and Drain of MOSFETs to the correct individual wires and triple check.

I used a premade cable harness like this for my FH9HVX amplifier build. The wires were not as high quality as the ones X and Vunce have used, but the amplifier works fine.
 
Founder of XSA-Labs
Joined 2012
Paid Member
Hi WW,
Glad you are getting the hang of crimped connectors. That’s why in automotive applications, solder is not allowed on connectors. It turns a flexible wire into a stiff solid wire due to the solder wicking into the wire.

If you must solder a wire to a PCB, use a pin crimp tube to isolate the wire from the solder joint and this provides strain relief.

Like this:
949826d1620456692-diy-sony-vfet-builders-thread-vfet-amp-build-grounding-02-jpg
 
Last edited: