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dirkwright 5th July 2012 01:26 PM

Anyone build Zen I/V?
I found this article by Mr. Pass:

I did a search on this forum and didn't find anything about it here. I've been flopping around with my own I/V stage design and was wondering about this one.

Ken Newton 5th July 2012 01:35 PM

dirkwright 5th July 2012 01:39 PM

OK, thanks.

jazz 5th July 2012 03:28 PM

I did and still use it:)

AudioSan 13th July 2012 09:10 PM

so how is it? i was thinking of this with a TP COD DAC.

oliverniekamp 13th July 2012 10:36 PM

I did it too and like it more than the output stage of the pass D/A converter, i used before.
I suggest to use a second order filter:)

dirkwright 14th July 2012 01:27 AM

The circuit is very sensitive to DC offset in my simulations of this circuit, so I don't think it's a good idea to use it with a DAC that has an offset. Putting a current source on the input to offset the DC current output of the DAC works in simulation, but I think in reality it would be unstable and lead to unpredictable results.

I'm thinking now that a good transformer is the best interface for a DAC with balanced current source outputs and a DC offset in spite of the increased distortion from the transformer.

EUVL 17th July 2012 07:18 PM

Simulation is of course virtual reality only. :)


dirkwright 17th July 2012 07:25 PM


Originally Posted by EUVL (
Simulation is of course virtual reality only. :)


How close to reality were your simulations of your circuits? I suppose the accuracy of the simulation depends a lot on the quality of the models.

I do not have an AP, nor do I intend to buy one, so there is no way for me to verify any of the circuits I may build. I can only do basic measurements on anything I build. I have built one of my own design (unrelated to the Zen circuit) so far and it measures the same as I simulated.

EUVL 17th July 2012 07:31 PM

The reality is that two people have built the SEN IV Version 18 for ES9018.
And they have DC offsets below 3mV at start up, dropping to <0.5mV at steady state.
They did not use any servo.

Don't take my word. Ask them.

But we are discussing at the wrong place here.
This place, and thread, should be for Nelson's ZEN IV :

So we should all go back to Nelson's circuit.


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