New Zen I/V proposed from Nelson Pass

In case anyone missed it : http://www.diyaudio.com/forums/diyaudio-com-articles/172983-zen-i-v-converter.html

This is significant in that the D1 stage has been highly regarded as one of the best DAC analog stage to use for over 15 years.  There have been a lot of complex ideas floating around in the DIY community the past decade but none I have found sound as good as the D1.

For Nelson to endorse this it is definately worth a look.   I may try this out on my 1862 DAC.

R1, R2, C1 and C2 are simply passive filters.

If you think your 30V supplies are noise free then you can modify or delete the filters. C3 and C4 capacitively couple the output so that we don't have DC arguments. R5 is simply a resistive load, which you can modify or delete if you like. C5 is the high frequency filter, which you can also modify or delete. There is no feedback. The Jfets were selected for matched Idss at 10mA, and present a DC offset voltage at the Source about 1 mV, which is plenty low. If you have unmatched Jfets, then I suggest you use a low impedance resistive voltage divider to offset the DC Gate voltage by the required amount. By low impedance, I suggest that the resistor to ground be on the order of 10 ohms or so.

Note that at 10 mA bias, the Fets will end up with about 15 volts Drain-Source. With other Idss bias figures you may adjust the values of R3 and R4 up or down to get this figure. If you want more gain (and I bet some of you do) then you can increase R3 and R4 to 2.2 Kohm each for twice as much, but you then need to add about 10 more volts to each supply rail to arrive at the +/-15 Volt Drain voltages on the Jfets. The input impedance is the inverse of the transconductance of the two Jfets in parallel, which at 30 mS each comes out to around 15 ohms. The output impedance is roughly the values of R3 and R4 in parallel, and for the example shown that is around 500 ohms.

I've tried most of whats been up at diyhifi and diyaudio,  none I find as good as a simple D1.   I agree the coupling cap is an issue,  but this new zen should easily be servoed by monitoring the output with an opamp outputing to the gates I believe.  

I've tried most of whats been up at diyhifi and diyaudio,  none I find as good as a simple D1.   I agree the coupling cap is an issue,  but this new zen should easily be servoed by monitoring the output with an opamp outputing to the gates I believe.  

But I think Nelson Pass designs are normally top notch.  Are you implying this gift isn't worth building 'cause of a couple capacitors in lieu of complexity?