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Wow, you copped a hiding on this one ...

so I kinda feel guilty adding to it but I'd like to share a couple of experiences along the lines of what you describe. Years ago I modded some ARC Ref 600 PP amps. One of the first things I did was to add a choke to a simple SS bridge / big C, HT PS. The gain in smoothness was not insignificant. I went on to add a Mosfet regulator to stabilise the HT voltage (for other reasons) and to be honest, it didn't make a great sonic difference.

Down the track I built some 845s and thought I'd try a simple Mosfet Regulator again. I built one exactly as you've described and for the heck of it I wanted to see the difference the regulator made with and without a choke. The choke always helped, though by a smaller margin with the regulator in circuit.

One big warning ... actually a couple if you try this. First, make sure that you ramp the voltage up slowly or you'll wonder why those expensive Mosfets keep blowing up … no matter how much current they'll handle. How do I know this? Well I almost went deaf and blind in the process! BTW, bipolars aren’t any better. Second, you have to take the Mosfet’s input capacitance into account and drive it with a low impedance or you'll lose the highs. Alternatively, (but not ideal) you can bypass the Mosfet with a small C. You'll get back the highs but you'll forego the benefit of HF regulation.

Rgds,
Naz

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