Ok! So just for fun I have built myself a F2 amp. Sounds nice on Fostex Sigmas! 
Spec:
19VDC PSU.
300VA 2x15Vac toroid.
6x22000uF capacitors.
No CCS, but with resistor 5ohm 200w.
Bias = 2A
Output power.....= about 1w...
But I have one issue I hope somebody can help me with -> ripple voltage from PSU-> irritating noise in speakers.
I have no resistors between capacitors in the PSU. Probably should but how big resistors?
oks
Spec:
19VDC PSU.
300VA 2x15Vac toroid.
6x22000uF capacitors.
No CCS, but with resistor 5ohm 200w.
Bias = 2A
Output power.....= about 1w...
But I have one issue I hope somebody can help me with -> ripple voltage from PSU-> irritating noise in speakers.
I have no resistors between capacitors in the PSU. Probably should but how big resistors?
oks
Fantastic! Thanks a lot! Will give it a try as soon as i get the time!
Suppose -out will still be -out?
Will output resistance be changed?
Fantastic! Thanks a lot! Will give it a try as soon as i get the time!
Suppose -out will still be -out?
Will output resistance be changed?
Output impedance will be the same. From an AC point of view gnd and v+ are shortened through psu capacitors.
I guess -out will now become +out, but don't take my word for it.
As for resistors in the powersupply, I use 0.47 Omhs x2 in parallel in my F6. No problem with hum. No problems at all, in fact
Where in Norway are you located?
cheers,
Dyrevennen.
Thanks again, Zen!
Hello dyrevennen!
-out will stay -out when thinking AC. Don`t think DC!
My F2 has no CCS, I think thats one of the reasons I get them hum in the first place.
Thinking F6 sounds nice!?
I am located the most far west in the sognefjord, where the seagulls start speaking english...
Best
oks
Hello dyrevennen!
-out will stay -out when thinking AC. Don`t think DC!
My F2 has no CCS, I think thats one of the reasons I get them hum in the first place.
Thinking F6 sounds nice!?
I am located the most far west in the sognefjord, where the seagulls start speaking english...
Best
oks
My F2J has no Ccs and the hum si very low. I have to put my ear against my high efficiency speakers to hear it.
For sure a R in the PSU will help lower the ripple (mine is built as per Nelson s recommendation... Just increased the C values a bit)
Try to put away the toroids from the rest of the circuit. It worked for me (actually I could lower the hum furthermore if I had a separate PSU... But finding the right toroid orientation helped 99%)
For sure a R in the PSU will help lower the ripple (mine is built as per Nelson s recommendation... Just increased the C values a bit)
Try to put away the toroids from the rest of the circuit. It worked for me (actually I could lower the hum furthermore if I had a separate PSU... But finding the right toroid orientation helped 99%)
Ok! The R1-R8 in the PSU is 1ohm 3w resistors for the F2?
The other First Watts have 0,47 ohm.
Thinking Zen`s solution to connect speaker + to V+ will cancel all hum (have not tested yet, on vacation)
My toroid is not so close to the circuit. The brand of the toroid is Noratel, made in Norway.
Where can JFET for F2J be bought? Cost?
The other First Watts have 0,47 ohm.
Thinking Zen`s solution to connect speaker + to V+ will cancel all hum (have not tested yet, on vacation)
My toroid is not so close to the circuit. The brand of the toroid is Noratel, made in Norway.
Where can JFET for F2J be bought? Cost?
Getting DC on output after connecting speaker connectors between out and V+, about 18,5v.
Tried removing R13, 14 and 15. Still 11VDC on output. Tried with cheap speaker connected and it moves out and stays out. Any good ideas?
Thinking maybe it`s not so good idea to connect speaker between out and V+....??
Looking at Nelsons De-Lite article and he is connecting speaker between out and ground, using 1ohm resistor in PSU to take care of some of the hum. Not seen before speakers connected between V+ and out?
http://www.firstwatt.com/pdf/art_delite.pdf
Looking at Nelsons De-Lite article and he is connecting speaker between out and ground, using 1ohm resistor in PSU to take care of some of the hum. Not seen before speakers connected between V+ and out?
http://www.firstwatt.com/pdf/art_delite.pdf
I think there must be something wrong with your output capacitor. Is it a polarized cap? If so, you should probably turn it around if you want to connect one side to +v (through the speaker).
Thanks Zen! I`m far from expert, but saw it finally!
Have now turned polarity on output cap, removed R14 and 15 and only R13 parallel with speaker. Removed bleeder resistor over PSU (2,2K) and moved light diode with 10k parallel with big R (5ohm 200w). Now no DC on output when turn on! Sound test tomorrow, late Sunday in Norway....
I`m far from expert, but saw it finally! Have now turned polarity on output cap, removed R14 and 15 and only R13 parallel with speaker. Removed bleeder resistor over PSU (2,2K) and moved light diode with 10k parallel with big R (5ohm 200w). Now no DC on output when turn on!
Sound test tomorrow, late Sunday in Norway....
Thanks again Zen and dyrevennen for helping! Now my F2 plays nicely! Almost no hum at all, must put my ear almost in through the speaker to hear noise.
Im using it on Fostex FE108 Sigma in MJ King OBs with B4 as active crossover. Xover at 400Hz I can't get it to run out off power. Thinking 1w is enough!
My F2 probably having a ton off distortion, but who cares!
Almost no hum at all, must put my ear almost in through the speaker to hear noise.Im using it on Fostex FE108 Sigma in MJ King OBs with B4 as active crossover. Xover at 400Hz I can't get it to run out off power. Thinking 1w is enough!
My F2 probably having a ton off distortion, but who cares!
