MPP

[Joachim Gerhard]

Here is an idea to lower the impedance in the feedback network. I know it looks weird and LEDs have unlinear capacitance. I wonder if a bias spreader could be used there too.

 

[Joachim Gerhard]

There is another way to make a direct coupled input. It is fully differential and does not have the noise disadvantage of a long tail pair. The RIAA could then follow with a differential Opamp as I did in my Phonostage article in Linear Audio.

 

[Joachim Gerhard]

Maybe I turned around the phase, anyway. Did I ? I always get confused with differential circuits.

 

[as_audio]

This is not differential, but it is stereo ..
Perhaps you can couple both parts in a way to get there.

 

[Joachim Gerhard]

I do not agree on this. The cartridge is put between the inputs.

 

[as_audio]

Then again it is a differential pair.

 

[Joachim Gerhard]

No, the gain is double.

 

[Joachim Gerhard]

And there is only the noise of the Ube. Trust me, with the right transistor and fitting idle it is super low noise. A long tail pair with the same amount of transistors and the same idle can not compete in terms of low noise.

 

[as_audio]

In a diff pair gain is also + 6 dB if you use both outputs, like here.

 

[as_audio]

In order to avoid confusion :

The attached image shows a differential amp or differential pair
(if driven differentially as indicated), corresponding to post 11202.

A long tailed pair is a particular example of another differential amp.
With equal bias etc both have the same gain and the same noise.

 

[Joachim Gerhard]

If you use both outputs, yes.

 

[Joachim Gerhard]

I meant the Version where
one is the input and the other Transistor is used for Feedback

 

[as_audio]

In that case you can use both outputs also.

 

[Joachim Gerhard]

Yes, like a folded cascode to both sides.

 

[Joachim Gerhard]

That is only the stupid input stage. There is so much more to it that it does not fit a screen.

 

[Joachim Gerhard]

I know, complex does not sound good. The late Manny Bayer said : you can do complexity but then better make no mistake.

 

[sq225917]

Whatever happened with the Zion?

 

[sq225917]

Joachim, you might want to edit out those first three unseen internet window titles, lol.

 

[Joachim Gerhard]

Well, it is symmetrical.
The top looks the same the other way around.
Anyway, you find what we published in the Zion thread.
When we started that thread we wanted to make a ready made stage that you can buy.
It got so incredibly complex in the end that we gave up on that idea.

 

[Joachim Gerhard]

sq, you are too fast for this world.