F5 power amplifier

[TheShaman]

Nice to see you got it running!

I would move the IEC input and softstart to the middle of the back panel and the inputs somewhere above or below the respective speaker binding posts.

[jameshillj]

... and maybe a couple of holes for internal air circulation -

[valvesound]

Originally Posted by TheShaman

Nice to see you got it running!

I would move the IEC input and softstart to the middle of the back panel and the inputs somewhere above or below the respective speaker binding posts.

Yes something I'll do next time round. I do not have any interference or hum so not required but something I would do differently in future. Thanks

[studiostevus]

Guys, i recently moved overseas, and where my f5 has been built and biased on 230vac, my new home has 220v (at least according to spec, haven't measured actual yet as my stuff is still on its way on a container vessel).

Given the psu is unregulated, what can i expect when i turn the amp on?

[sangram]

^^Where I live the mains varies from 200 to about 260VAC and the frequency from 44 to 56 depending on the mood of the monkey turning the switches that day.

Never had an issue. I suspect you won't either

[valvesound]

yes studiostevus, no need to be concerned.

[tolikas]

Hi,

any ideas how to fight F5 Hum problems? I use 1 torroidal trafo (600w), is it possible for him to be the source of AC line humming? I am 100% sure that audio boards, power supplies, grounds are ok.

Would AC line filter before trafo help?

Thanks

[promitheus]

Hum is probably a problem of bad earthing or multiple earth points.
Do you have any photos of your wiring?
Input, output and power supply earth points?

[valvesound]

Look at the picture attached. The purple lines indicate the 0V star point. It is very important. connect both supply 0V points to the star point. From the star point all 0V connections run to individual channels. From the star point run wires to RCA inputs 0V (RCA's are isolated from chassis). keep wire lengths for left and right channels equal length. The only ground (earth) connection is indicated by blue. The mains earth is connected to the chassis there. On the power supply I have a 10ohm connecting chassis earth to the 0V point.

If you do exactly this, you will have a dead dead quiet F5 amplifier.

[triode_al]

Originally Posted by studiostevus

Guys, i recently moved overseas, and where my f5 has been built and biased on 230vac, my new home has 220v (at least according to spec, haven't measured actual yet as my stuff is still on its way on a container vessel).

Given the psu is unregulated, what can i expect when i turn the amp on?

Just less overhead. And by the way, the transformer will be cooler (less saturation). The bias will remain (almost) the same. But you will normally never hit the power rail, and the F5 intrinsically has soft-clipping anyway.