Build This MoFo!

Stanislav · 2021-01-15 11:00 pm

You can always use a CapMx with a MosFet, between the SMPS and the PCB.
That will eat 4V and you'll end up with 21VDC. Also will provide a slow start to the amp and make it very quiet. Perfect.

3kes · 2021-02-14 4:04 pm

Here my fugly build. I use this built methode to temporary test the amp. First thing after this build is the BA-3, my normally used preamp isn’t powerful enough. Also had some issues with different volume levels per channel, psupp is exactly the same, voltage over L1 also. Not found the exact problem yet. Can it be a different Ids?

Vunce · 2021-02-14 5:56 pm

3kes,
Nice implementation of the MoFo with active cooling and PWM control

You will be able to crank up the bias current, those cpu cooler can handle it. Your chokes will be the limiting factor.

3kes · 2021-02-14 7:08 pm

Learned from the best!

Those heatsinks don't even get warm (with the Noctua's running at minimum speed). And, as you mentioned before, the fans aren't hearable at all.

3kes · 2021-02-14 8:05 pm

And I found the volume issue. One positive speakerclamp was shortend to minus. Lucky for me I had no smoke.

Vunce · 2021-02-14 11:30 pm

Good catch! Luckily there wasn’t any damage. With the right preamp, the MoFo Rocks!!
Enjoy your newborn!!

:cheers:

audiodesignguide3 · 2021-02-17 5:50 pm

Some pcb of my Mofo are available and also the files to produce it.

thimios · 2021-02-17 5:59 pm

Please can you remind the post where the gerbers is?

Dennis Hui · 2021-02-17 6:08 pm

Post #2907

https://www.diyaudio.com/forums/pass-labs/313649-build-mofo-291.html#post6467933

vdi_nenna · 2021-03-06 3:55 pm

Cautionary Tale and a Bit of Luck

The other day I inserted the MoFo monoblocks into the system. Always enjoy hearing them, but from early on there would be some static from the "left" amp. Eventually it would go away. Thought it might be a leaky cap or a cold solder joint. I didnt know exactly how cold.

Decided this morning was the time to get to the bottom of the issue. Disconnected all leads, unscrewed the mosfet, unscrewed board from the standoffs.
Pulled the board out, but the mosfet was stuck to the heatsink! The board pads were clean.
I did not solder the mosfet to the board! :headbash:

So it ran this way for a couple of years...

...I'm a lucky MoFo!!!

Soundhappy · 2021-03-06 3:59 pm

vdi_nenna said:
The other day I inserted the MoFo monoblocks into the system. Always enjoy hearing them, but from early on there would be some static from the "left" amp. Eventually it would go away. Thought it might be a leaky cap or a cold solder joint. I didnt know exactly how cold.

Decided this morning was the time to get to the bottom of the issue. Disconnected all leads, unscrewed the mosfet, unscrewed board from the standoffs.
Pulled the board out, but the mosfet was stuck to the heatsink! The board pads were clean.
I did not solder the mosfet to the board!

So it ran this way for a couple of years...

...I'm a lucky MoFo!!!

Incredible DIY miracle story haha :cheerful:

Congratulations!

e_fortier · 2021-03-06 4:05 pm

Indeed, very lucky..good story. Is it the same for both channels ?

Is the static noise gone ?

BR
Eric

vdi_nenna · 2021-03-06 4:12 pm

Other channel is fine. Mosfet soldered.
No static from repaired channel.

Vunce · 2021-03-06 4:31 pm

Omg!
You must go out and play your Lotto numbers, luck is on your side at the moment!!

Dennis Hui · 2021-03-06 4:34 pm

Congrats! That's a lucky and funny mofo story.

Eric · 2021-03-06 4:51 pm

Wow! And it WORKED !!! That's some fine assembly technique, Vince! I can hear the commercial on TV now: "Our assembly standards are so high, we don't NEED solder!"

twitchie · 2021-03-06 5:03 pm

that is a funny one indeed!

Glad you finally solved that mystery before any magic smoke escaped :djinn:

zman01 · 2021-03-06 5:08 pm

vdi_nenna,

Quite an experience!

Good that the root cause has been identified and corrective measures taken.

Enjoy the MoFo!

nicoch58 · 2021-03-06 5:27 pm

good job

Zen Mod · 2021-03-06 5:45 pm

vdi_nenna said:
The other day I inserted the MoFo monoblocks into the system. Always enjoy hearing them, but from early on there would be some static from the "left" amp. Eventually it would go away. Thought it might be a leaky cap or a cold solder joint. I didnt know exactly how cold.

Decided this morning was the time to get to the bottom of the issue. Disconnected all leads, unscrewed the mosfet, unscrewed board from the standoffs.
Pulled the board out, but the mosfet was stuck to the heatsink! The board pads were clean.
I did not solder the mosfet to the board!

So it ran this way for a couple of years...

...I'm a lucky MoFo!!!

what a Bstrd!!!

Omission - ZM worthy!!

:clown:

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