A guide to building the Pass F4 amplifier

[charly chile]

Thank you ZM! I will report soon

 

[baeijsman]

Send me your shipping address and I'll send you the Harris triplet.

Package from Mr. Harris arrived!

After cooking for a couple of hours i now have 212-228mV on all 12 critters. Sub mV offset.

Thank you Pa!

 

[Alypius]

Got my BA-3 and Whammy up and running and they sound great! Still chip rolling, but the two are great with my DT-1990 and Clear MG.

As I finished stuffing my F4, the 4U chassis arrived! I gotta say, it's a much tighter fit than I was expecting. I'm thinking about splitting the PSU board so the transformer can be centered. Wiring will be...fun...XD

 

[vdi_nenna]

Place the toroid at front and power supply at rear of case near inputs and outputs.

 

[TungstenAudio]

With that chassis, a good way to mount the PSU board is vertically on the inside of the front panel.

 

[myleftear]

Did you try to place the toroid in a upright position? With te cap-bank turned 90° you‘d get a symmetrical arrangement, And you would have all in 1 chassis. Not sure about switch, led, and rectifiers though…

Here’s mine, 4u 300 mini… (toroid laying around under the capbank )

 

[6sX7]

This is a 4U mini-dissipante. I have the utmost confidence your F4 chassis stuffing will be beautiful.

 

[Einric]

The 4U aluminum with the Antek 400VA will allow the psu to be up on stilts above the transformer as well.
80mm M3 standoffs for drones work well.

 

[Alypius]

Wiring coming along! Calling it a night due to lack of usable light and beer. Transformer and power lines to be installed tomorrow or Monday. Yeah, keeping the xfmr on the right side; easier to work and it's an amp, not a jet. I don't care where its CG is!

 

[Zen Mod]

why I didn't ever think of that - having PSU wires longer to one channel and xformer closer to same one ....... just leads to greater entertainment factor!

 

[Holzarbeiter]

why I didn't ever think of that - having PSU wires longer to one channel and xformer closer to same one ....... just leads to greater entertainment factor!

...and cheap channel delay for echo effect.

 

[Alypius]

So that isn't going to work then. Great. I think I've been at this too long. Gonna put this away for awhile and go do something else.

 

[Holzarbeiter]

You should see what I've done to stuff two F6 dual mono power supplies into one 5U!

Dare to be different!!!

 

[Zen Mod]

you have myriad of pics, taken from Kosher builds

if you keep it symmetrical, no troubles

xformer all the way up to front plate , then bridges then Cap Bank centrally

equal length of power wires to channels, easy arrangement of signal wires to avoid ground loops

as I'm always saying - if in doubt - look at original FW pics - plenty of those around

6moons site, for example - almost every FW amp covered with high res content

 

[Holzarbeiter]

`Voice of Zen is sanity

 

[Zen Mod]

naah, I'm not that clever
but, with time, I'm trying to learn who is .......

 

[Holzarbeiter]

but, with time, I'm trying to learn who is .......

To Luddites it is you...

 

[Alypius]

F4 up and running. Right board biasing at 135mV/0mV, left board 270mV/0mV. Left P1 is maxed out with 4.75k resistor at R9.

 

[Dennis Hui]

Why are both sides biased at such significantly different levels? I believe the target is 0.2V across the 0.47R source resistors.

Are you saying you can't get the bias on the left board lower than 0.27V across the 0.47R resistors?

 

[Alypius]

6L6 said to shoot for .13 while cold and work your way up to .2 after an hour or so, hence the right board's setting.

Yep! I can't get the left bias any lower than .27V because P1 is at its limit.