Mpp

[Joachim Gerhard]

Ok, cool. You took 3 x Bf instead of 4. 4 will bring the gain slightly up ( plus 1.5dB a assume ), so i am happy.

[Joachim Gerhard]

C5 could be even lower when a slight subsonic filter is wanted.

[Joachim Gerhard]

If it works then one of my dreams comes true, a one stage RIAA if we do not count the buffer.

[sampler]

Originally Posted by RCruz

Hi Sampler

Can you post a file with the values you got in your sim ?

I need to find input stage output imp at 1kHz

Does your sim give the output imp with the riaa filter connected ?

Can you plot this impedance without the riaa filter connected ?

Hi Ricardo,
This is output impedance without anything connected to output, so it's about 1.3M parallel to shunting resistor 130k in Joachims schematics.

Originally Posted by Joachim Gerhard

Sampler, i use more or less the same input structure in my tube RIAA and it works.
For Ulf, i will show you the Transcendent RIAA. The input tubes in mine are aranged the same way.

But 1 tube is not the same piece of cake as 3 BF862 running near Ids with just ~20V to bias properly. I'm sure it will work, just getting to stable dc op point will be quite nontrivial. Here is a temperature sweep of whole circuit vs. output voltage, take it with a grain of salt but the picture is clear.
I think I saw a thread couple years ago were very similar concept was discussed in great detail, where is that search button...
Edit: Found it Great stuff with lot's of guru's

[Joachim Gerhard]

Sure, in the tube RIAA is use a tube cascode with 8mA idle.
On the other hand to build the input stage is not a big deal.
Maybe i find the time tomorrow.

[Joachim Gerhard]

Salas thinks that this circuit has not much to do with his Simplistic so i renamed it to Cro Magnon.

[Joachim Gerhard]

cromagnon

[RCruz]

Well, at least yu did not call it Homo neanderthalensis

[Joachim Gerhard]

That was my first thought (:
A phono stage so simple that a cavemen can build it.

[brianco]

Well....I'm in then!