Input impedance for Zen Variations

[DrewP]

Sadly, about a year ago I let the smoke out of the mosfets of the Zen revisited I was building. The heatsinks and pi filtered power supply have been sitting in my garage waiting for me to get back the courage to fill the loungeroom with silicon stink once more.

In the new cct of the Zen variations (figure 6) with the Aleph current source, waht will the input impedance actually seen by a preamp be and what voltage will I need to feed in to get full output?

I'll be running my amp on the original 34 volt rail

Many thanks in anticipation

Drew

 

[Nelson Pass]

The Gate of the Mosfet is held at virtual ground for
AC signal, so the input impedance is that of the input
resistor, which is quite low.

Part 4 of the Zen Variations will get this up to 47K,
so say tuned.

 

[DrewP]

Many thanks

Thought that might be the case. ~500R is a pretty scary input load
OK, I'll be patient and just concentrate on getting my new backhorns built till episode 4 arrives.

Arrgghh! So many projects to do!

Drew

 

[paulb]

Re: Many thanks

Arrgghh! So many projects to do!

...and so little time...

 

[Nelson Pass]

For those of you holding your breath, the addition of the
newer input circuit is very easy to tack onto an existing
Zen, so go ahead and don't wait for it.

 

[till]

Be shure, i built variation 1, variation 2, and awaiting nervously to build variation 3 and following... checking everyday two times if it is posted.

The variation 2 is already now the best sounding amplifier i ever owned, because i´d never the money to buy a really good one, and was always not willing to buy a normal consumer product.

Ok, i´ll use the time until var 3 comes out to build a simple preamp.

Thank you Mr. Pass for publishing this detailed guide that enables even me to build a great sounding device.