X-SOZ... just a dream for now

[Giacomo Pagani]

Hi all folks.
First of all a brief intro: this is the first time I write, but I have read a lot on this forum... really the best for diy enthusiasts. I'm a 17-years-old Italian boy, so please forgive me for my English if it's not good.

Well, let's start from the beginning: I have been feeling a sort of admiration for Nelson's jewels since I saw them on the web. Then I found this forum and learned that I could build them... I started studying the Aleph 4 and I wrote several e-mails to Nelson asking him some information. He had been very kind, and I was decided to build that Aleph.
But something made me change my plans: I listened to RD Laura horn loudspeakers, loved and bought them. So the 100 watts of the Aleph became too much for my needfulness.

I just need an amp with NO-feedback, class A single ended operation and an output impedance of about 4 ohms (at best).
In this days I put the eye on the Son Of Zen. I am able to build it, no doubts of any sort (maybe some would come during the work, as it always happens ).
However, I was almost decided when I saw that "X". I could avoid all troubles and go with the classic SOZ... but in this way I would cut a lot of fun.
So I want to and obtain the best I can.

I have tried to read the whole thread about SOZ, but it's quite BIG and I scanned the posts quickly. I hope that my questions won't be stupid or already-answered, in such case I apologize.
My troubles are the following:
- I have found a lot of schemes, but what is the definitive one? For example, I read that some things in some schemes take the project far from the principle of the Zen concept (the two gain stages, if I remember right). What's the best of those works?
The last I have seen is the Henrik's one, but I don't know...
- If I'll do it, I think I'll go for a 50 watt version. What about the components? The original Pass' SOZ page explains clearly all about the devices for the 50 watt version... but what about the new devices in the X?
- the last one: is the X-SOZ still NO-feedback?

I know this is a very long post.... sorry but I'm not able to write without explaining ALL the story.

Thank you all for your attention, and thanks again to Nelson for the great patience he had with me and for allowing people to build his beautiful electronics.

Cheers
Giacomo

P.S.: my DIY works consist in the "Insulto", a SET amplifier from TNT-Audio (transformed in SE penthodes, 4 watts instead of 2) and some cables. Not a big experience at all, but I have been studying electrotechnics for only 1 year and a half until now.

[Giacomo Pagani]

Ooooops:

Originally posted by Giacomo Pagani

I have tried to read the whole thread about SOZ, but it's quite

I meant the X-SOZ thread. Not the SOZ one.

Sorry
Giacomo

[stefanobilliani]

Hallo Giacomo.

I start answer your last question: no the X is a feedback arrangement .

That's all for now .

[stefanobilliani]

... and Welcome on board!

[Giacomo Pagani]

Thank you Stefano.

So why does Audioguida report "no feedback" for the X amps?
I read that on X-1000, X-600 and X-350.

Giacomo

[stefanobilliani]

Really don't know...

[stefanobilliani]

...but I know that X employs very small amounts of feedback
compared to some multiple stage feedback amplification arrangements .

SuSy reduces distorsion by a factor of 1/100 without the same amount of feedback!

Also: x feedback do very little to each half of the circuit(single ended) but balanced...

[akira]

As far as I know I would say that the last schematic should be the one from Hendrik page 17 of the long thread about XSOZ.

But WOOOW, 50W XSOZ, that will be a big one.

Post some pics when you complete your project. I ll probably also try to build one but 10W will be enough for me.

And yes, X does need some feedback. Check the schematic page 17. The feedback is resistor 212 and 213.

Ciao

[Nelson Pass]

Originally posted by Giacomo Pagani
So why does Audioguida report "no feedback" for the X amps?
I read that on X-1000, X-600 and X-350.

By that they mean that the output stage is not enclosed
in the "X" loop on those models. People get confused
easily on this issue.

[Henrik]

Giacomo

- If I'll do it, I think I'll go for a 50 watt version. What about the components? The original Pass' SOZ page explains clearly all about the devices for the 50 watt version... but what about the new devices in the X?

The XSOZ is scaleable just as the SOZ.
The powerrating is just the same as for the SOZ.
50W SOZ/ZSOZ is quite extreme!
If You want to try my version of the XSOZ, be shure to use some preamp capeable of driving a 120 Ohm single ended load.