Ok, thank's !
On the picture under, you have 8949.
It would be seem to be manufactured at the end of 80 years.
The Swiss Alembic retailer sold this preamp like a demo model ... very oldtimer demo !!
But it was not expensive, just 480 USD !!
I changed the tube and it has a nice sound with my Yamaha P5000 S amp.

Just for fun, I took a closer look.

Thank's Mr Sherlock ;o)

As far as the price goes, these used to sell for about that price in the US back when this one was made and sold.  They're more like $800 these days, so I think everyone involved got a pretty good deal on this one.
 
I suspect that demo preamp was sitting around a long time so you may want to look in the FAQ section for information about cleaning the jacks.  Not a bad idea to give them a little cleaning before they start to make noise.
 
-Bob

Thank's. I will call the Alembic distributor to know the truth !
I called him now ... he promised me that this preamp never left his warehouse !
;o)
Maybe the truth, maybe his truth ?
Smile...;o)

Finally I bought Helectro Harmonix and Groove Tube 12AX7, I will try these differents sounds.