If you live in USA, Antek 400VA 18+18v secondary is good enough for stereo F5. Going with 500VA won't hurt either.
Bias
Need a little help trouble shooting. My F5 has been working perfectly. This week I swapped out the PS to increase the capacitance. Now I am having issues being able to bias one channel. PS voltages are at 23V. With the 2K2 resistors at R5 and R6 I can get to about 70mV with zero dc offset; with 4K4 resistors I can get to about 90mV; with 6K8 resistors I can get to about 150mV. I have also swamped 3 different pairs of Mosfets which had no impact. Before I keep increasing the values for R5 and R6 is there something else I should be checking? It seems odd that I would need to increase R5 and R6 resistance (it seems like I would need to go over 10K) when the 2K2 resistors were working fine just a couple days ago.
Need a little help trouble shooting. My F5 has been working perfectly. This week I swapped out the PS to increase the capacitance. Now I am having issues being able to bias one channel. PS voltages are at 23V. With the 2K2 resistors at R5 and R6 I can get to about 70mV with zero dc offset; with 4K4 resistors I can get to about 90mV; with 6K8 resistors I can get to about 150mV. I have also swamped 3 different pairs of Mosfets which had no impact. Before I keep increasing the values for R5 and R6 is there something else I should be checking? It seems odd that I would need to increase R5 and R6 resistance (it seems like I would need to go over 10K) when the 2K2 resistors were working fine just a couple days ago.
That's very weird.
What voltages do you see across the 10 ohm resistors R3 and R4? Do you have
the 200 ohm P3 pot installed?
What voltages do you see across the 10 ohm resistors R3 and R4? Do you have
the 200 ohm P3 pot installed?
Hello Dennis,
P3 is not installed. I see 57mV and 59mV across R3 and R4. I removed the board, reflowed all the solder joints, etc., but that just made things worse. Now max bias is about 20mV with zero offset.
Hi, guys. Unfortunatly, F5 PCB is out of stock in DIYaudioStore. Does anyone have gerbers for the F5 PCB? Can you share it with me?
Great! I would like to buy parts for a second F5 but when I try to purchase from the store, and it wants me to prove I'm not a robot, the wheel just keeps spinning and never lets me in. Is there a problem with the site? Actually also going to buy a Wayne Crossover kit too.
Nevermind! I left Firefox and went to Chrome, started over and it all worked. Order placed. When I get all of this built, I'm going to use the crossover and the two F5 amps to power a pair of 2-way speakers. Experiment between the sound of line level crossover + biamp and traditional passive crossovers in the speakers. A curiosity satisfying project that will keep me occupied for a bit.
Another working F5
Last night I finished my F5 build.
Nothing unusual, just a text book build, using everything I learnt from reading the diyaudio forums.
Thank you to the experts, who kindly share their insight.
An even bigger thank you to those who shared mistakes and disasters. Reading about them helped me check my work very very carefully.
My tips:
Remember which end of the soldering end gets hot.
Position the big 0.47 ohm resistors so that you can attach your multimeter hooks, I have them standing off the board a little.
Make very sure that the vairable resistors are dialled down to the minimum.
I measured the 2.21K resistors that are in parallel.
Memorize which way you need to turn the pots.
It could be either way, depending on how you position your pot on the board.
And finally Mr Pass sir, thanks for the design and the posts!
Last night I finished my F5 build.
Nothing unusual, just a text book build, using everything I learnt from reading the diyaudio forums.
Thank you to the experts, who kindly share their insight.
An even bigger thank you to those who shared mistakes and disasters. Reading about them helped me check my work very very carefully.
My tips:
Remember which end of the soldering end gets hot.
Position the big 0.47 ohm resistors so that you can attach your multimeter hooks, I have them standing off the board a little.
Make very sure that the vairable resistors are dialled down to the minimum.
I measured the 2.21K resistors that are in parallel.
Memorize which way you need to turn the pots.
It could be either way, depending on how you position your pot on the board.
And finally Mr Pass sir, thanks for the design and the posts!
The Forum is great. Congrats on your success. I know I still love my F5 and it drew me into an F5 Turbo build, which I love even more.
