My amp has been running for 5 full months now with daily use of 5 or 6 hours. It is truly impressive that the bias does not drift at all for both channels. And not a single unintended pop or other noise coming out ever. The only glitches were the 1.6A fuse (on 220V line) blew twice at switch on during this period. Now replaced with a 2A fuse. With such great sound coming from such simple circuit, the designer is really a master.
Have you got a thermistor in the primary side of the transformer? If not, it may help with the fuse blowing. See Post in thread 'F5m kit' https://www.diyaudio.com/community/threads/f5m-kit.408290/post-7620032.
The power supply boards are Nelson's Bipolar Power Supply. One board and one transformer per channel. The CL-60 & AC Cap PCBs are installed. One per channel. Now looking back, I should have replaced the 4700uF caps that came with the kit with 10000uF. Maybe after I finish the F5T I am working on.
After looking at this a little closer, I am intrigued by your use of those black little towers to attach cables to. That means that I have to come up with something cool like these.
You can download the 3D print files here for the wire management towers. I posted the 3D printed stuff I've designed and found useful for diyaudio under the parts threads.
Search "3D Print" posts by me.
Search "3D Print" posts by me.
Congratulations on you successful build.
You chassis looks pretty sleek - what are the dimensions of the heat sinks?
Hi
The heatsinks I'm not sure of right this second...but it's the 2025 deluxe 2U/400mm...forgot a pic with switch engaged and light on...daylight of course but the lighted switch is pretty subtle...and for what little I've let it run so far it's DEAD silent...no hum ,no hiss, no buzz, no noticeable on or off thump
Thanks for the help , pointers, and the kind comments everyone.
Cheers
Jody
The heatsinks I'm not sure of right this second...but it's the 2025 deluxe 2U/400mm...forgot a pic with switch engaged and light on...daylight of course but the lighted switch is pretty subtle...and for what little I've let it run so far it's DEAD silent...no hum ,no hiss, no buzz, no noticeable on or off thump
Thanks for the help , pointers, and the kind comments everyone.
Cheers
Jody
Attachments
What Nelson did here for the DIY community is unbelievable. So simple a design with one resistor in the signal path, but... the measurements are crazy good. That very slight reduction in gain above 10kHz or so is just perfect, the distortion vs. frequency dependency is almost flat (!! unbelievable !!), and an increase in distortion vs power output even against 4 ohm loads is stunning - minimal, linear. This amp will keep its special character up to its full power regardless of the load connected to it OR the frequency. Then, he gives the compact design for both PCBs as well, preventing wiring/grounding errors.
@birdbox a note of appreciation to Dan aka BB. Sticker applied to the business end. Your instructions were crucial to success, one of the more fiddly tasks but totally worth the outcome 
Looks really good on that brushed steel plate! Nice work.
I have 3 more in that silver color and one in black if anyone wants one (continental US only please due to shipping).
I have 3 more in that silver color and one in black if anyone wants one (continental US only please due to shipping).