As the A-135-4C envelope follower was designed about one year after the
A-138p the first pcb version of the A-138p does not have an internal
connector for the A-135-4C. Only the second version of the A-138p
(manufactured from about June 2017) is equipped with the additional
connector JP1 (labelled "TO ENVELOPE FOLLOWER OPTION"). The pc boards are
marked "A-138p PERFORMANCE MIXER VERSION 2". The dot near to JP1 denotes the
red wire of the ribbon cable which is used to establish the connection to
A-135-4C. You have to look at the pc board to find out which version you
own. It has nothing to do with vintage or standard, just with the pc board
because both (vintage and standard) are have been manufactured in the old
and new version. It depends upon the period of storage of the dealer in
question which they have for sale.

Best wishes
Dieter Doepfer

> wooh! i have an A-138p Vintage Edition!
> can all vintage editions accept A-135-4C
> or i should research before ordering the later
> got confused with this one