The F6 Revisited

What's on Deck..

I have PCBs already waiting for some parts to arrive from Mouser. This is the version of the F6 that I originally built to make the most of higher voltage rails & higher bias current supported by the FQH44N10 Mosfets. The Diamond buffer is a minor variation of the Austin input stage that Mark J. designed for the M2x. It became my favorite and remains in semi-permanent installation in my M2x. The Toshiba TTC004B and TTA004B bipolars are able to withstand higher voltage and power dissipation than the ZTX parts used originally. This version of the F6 should be able to run up to 28 or 30V rails depending on heat sinking capacity. Think 400mm deep chassis.

I have a tube of Fairchild NOS FQH44N10 parts waiting for this one. Will also try a set of the IRFP048 to see how they sound in comparison. These boards are going to be swapped into my original F6 chassis to give them a workout.


  • First Watt F6 Diamond.pdf
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Would the gate capacitance prevent secondary saturation...?? I don't know... but, it might be worth checking...
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My plans are to build and test the new F6 Diamond PCBs over the weekend; parts are scheduled to arrive this afternoon. There is a lot more going on with this design, and I want to make sure everything is Ok before releasing it.
As with the previous boards, these are just for the Jensen JT-123-FLPCH.
Here is a list of parts that are specific to this build, plus some recommended resistors and trimpots.


  • F6 Mouser sheet.pdf
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Just a quick question TA, on the Jfet board the pots P1 and P2 have inline pins, and on the parts list for the diamond buffer version you show in post #48 you have pots P1 and P2 with staggered pins (the X version pin layout) - is this correct, as I am just getting a Mouser order ready.