F5 pcb group buy...

[Peter Daniel]

OUT means positive output, negative is common ground on main filter caps, see more info here: F5 pcb group buy...

[mymindinside]

What is the pin spacing (pitch) of the 1/4W and the 3W resistor locations on the board.

cheers,
mymindinside,

[Peter Daniel]

The spacing is 200mil on small resistors and 700mil on large ones. The latter have also option for TO-220 package (which is 200mil)

[Peter Daniel]

I just received F5 amp boards and will start shipping today.

[Eric]

Peter,

I realize I'm a little late to this party (seems to be the story of my life lately)... Any chance that I can get a pair of your F5 amp boards and a PSU? I'm interested in building one stereo F5 chassis.

Thanks,
Eric

[Peter Daniel]

The party has just started. I have enough boards to last me for a good part of a next year

[regiregi22]

Have you made PSU boards too??

BTW, here's my F5 with Peter Daniel's boards. Great quality and design, nice boards!

I haven't finally used the thermistor nor the current limiting protection. I have used Caddocks MK132 as the board is intended to, and mills resistors. No input capacitor, DC coupled. These are two mono channels each with its own PSU and trafo. Here I used 250VA each and up to 88.000uF per channel in a CRC configuration.

At the moment I have it biased at 1A per mosfet (not 1.3A as Nelson proposes). Is there any difference if I take it lower? What would be the minimum advisable? In very rare occasions I pull more than 1W per channel, and heatsinks seems to be a bit on the small side.

[AndrewT]

Originally Posted by regiregi22

In very rare occasions I pull more than 1W per channel,

I should hope not.
A 27W amplifier should be ticking along producing an average power of less than 1/4W to leave ~ +20dB of overhead for the transient peaks and thus avoid the worst of the clipping that is inevitable when trying to reproduce good music.

The F5 is a ClassA amplifier upto it's ClassA current limit.
It then moves into ClassAB for any current transients that exceed that ClassA limit. It does this seemlessly.

As an experiment, put the F5 out in the snow, bias it up to 1.3A and listen to the speakers in the comfort of your listening room.
Then bring the F5 back into the warmth and bias it to 700mA. Listen again. Does it sound the same or different?

[ma_coule]

Congrats regi, very impressive work!

One suggestion & one question...
Please, add. wide washer under the mfet screw, even better nice little heatsink...
Were did you find that power-in connectors?

Peter, sorry for OT!

& for fun!

[regiregi22]

I have read that higher bias sounds better (Nelson sez it), while other says that hotter sounds better than colder. I don't agree with that last one, if we move inside acceptable limits.

We don't have snow around here so the experiment will be difficult to perform. Should I bet higher current in colder conditions achieve better sound, due to transient peaks staying in ClassA?

Regards,
Regi