Pass f6 toroidal transformer

Once the amp is correctly biased, the heat sinks will be quite warm, but not hot. You should be able to leave your hands on them indefinitely. The process for setting the bias will take an hour or more. This gives the amp enough time to reach its thermal equilibrium. Once the bias and offset have been set, the amp will not need further adjustment. The following instructions are from the F6 Illustrated Build Guide.


P2 is marked BIAS on both PCB. Adjust this pot as necessary to set bias. Please note that as the pots and source resistors have the 1000uF capacitor in-between, the adjustments will happen in slow-motion and take a while to stabilize. Make small adjustments and wait as necessary. Patience is a virtue.


With DC voltmeter across the 0.47 source resistor, start by setting a bias reading of .5V (500mV) This will give a current of 1.05A, (.5V / 0.47ohm = 1.05A) which with a 24V rail gives about 25W of heat. Then zero your DC offset. Once you are satisfied that everything is stable and happy, you may increase the bias if you choose.

Remember the 3 rules of maximum bias… stop when you reach any of these -

Heatsink of 55C and/or Transistor pin 2 65C
Total bias , both channels, (in watts) of no more than 1/2 the power transformer’s VA
1/2 the maximum dissipation (in watts) of the output device. In the case of the IRFP240, it’s a 150W device, so no more than 75W. (Which is really, really hot…)
 
hi folks, trying to figure out exactly which power supply transformer I need for the F6 kit and where to buy it as it doesn't look to be available on the DIY store? I see people referencing a toroidal unit with varying specs -

Any advice on exactly which Should try to find and order is appreciated- shielded too?

Any specific parts houses that folks like for things like this ?

thank you !
 
Trying to find out the exact toroidal power supply transformer I should get for the F6 kit and where to get it from, it looks like it's not avail on the DIY store?

Also, I need to get the power supply board from the DIY store regardless of where I get the power supply transformer right?

Does anyone know the specs for the PSU and is there a preferred parts house for sourcing it?

thank you (newbie)
 
Trying to find out the exact toroidal power supply transformer I should get for the F6 kit and where to get it from, it looks like it's not avail on the DIY store?

Also, I need to get the power supply board from the DIY store regardless of where I get the power supply transformer right?

Does anyone know the specs for the PSU and is there a preferred parts house for sourcing it?

thank you (newbie)

I just finished building an F6 last summer and compiled a BOM for the chassis + power supply with prices and links here.

I do not have one for the F6 boards themselves.
 
thank you, just ordered it per your note !

FWIW, if you're building in the 4u chassis, it's kind of a tight fit. I flipped the IEC inlet upside-down to clean up the wiring a bit and mounted the PSU on the faceplate and used bridge rectifiers (less soldering involved with these) to make it easier to work with.
 

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It's the GBPC3502 ON Semi Bridge Rectifiers referenced in the parts spreadsheet I linked in my previous post in this thread.

I'm using it with a focusrite scarlett solo for a dac/pre combo and it sounds surprisingly clean and liquid. Certainly better than the Denon AVR I was using as dac/pre before, what a piece of trash. I did noise measurements with roomeq wizard and the focusrite's noise is much flatter and better-shaped.

The speakers I'm using are old 6 ohm vienna acoustics mozarts. The F6 made them sound better than anything else had before, and it wasn't even close. Swapping the Denon for the focusrite blew my mind. My next upgrade is to build the whammy pre and pair it with something like the schiit bifrost. I have doubts that I will be able to hear further improvements on the focusrite, but I like the idea of having separates and of having an excuse to continue to tinker and build. I'd like to start with a single-ended whammy and try out various op-amps, then add another and convert to a completely balanced/differential signal path by adding another F6 and turning my current one into a balanced monoblock. I may build a dedicated, passive, switching volume controller to sit between DAC and pre, so I can build it high-quality (expensive) and make it reusable. For that I'll probably use Amb.org's lcduino.

Then again, it's all sitting in my garage because I don't have room in the house for such a setup. So I think it's hilarious that my garage has better sound than I've ever had in the house, and I might put off all of this building until I find a bigger house that I can carve out a dedicated listening room in. Then again, I live in Texas. I don't really need the heat indoors in the summer, driving up my AC bill.
 
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