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siemens V72

Member for

21 years 2 months
I recently got 2 Siemens V72 in very good condition. I'd like to get them racked and modified to include more, as well as variable, gain; maybe phantom power and a phase switch. Yes, an instrument input would be nice, too!

I know that there's a few companies in America and one in Australia that do it, but I live in Austria/Europe.
The good thing about this is that we have the correct voltage for these units, but unfortunately, I haven't been able to find anyone in my area (Austria or Germany) to modify them for me. As a result, I am wondering if any of you know someone in Europe you could recommend. I guess there is no "do-it-yourself" manual of sorts for someone who is not an electronics expert...

Thanks in advance and a happy New Year to all.



Member for

21 years 2 months

Pro Audio Guest Thu, 01/03/2002 - 13:01
Hi Martin,

yes, it's amazing. I too know of several such addresses in the U.S. and one in Australia, but not a single one in Europe. And I have been searching and researching for a couple of years now. The part of the problem is that there don't seem to be widely known specialists/experts in that field (restoration and modification of vintage pro equipment) in continental Europe. Also, apart from the V72 and V76, other V-Series modules, especially the later solid-state models, seem to be much more popular in the U.S. Thanks to some kind souls from the U.S. I now have the schematics for my V672 modules, something I was unable to obtain through my German connections.

Anyway, you could try this:

Charly Bohaimid
Professional Audio Sales&Service
Am Loferfeld 7
D-81249 Muenchen

Tel. +49/89/8637954-5
Fax. +49/89/8637954-9

They do the restauration of the vintage Neve modules, so I guess it's worth asking.

Good luck and please keep us informed of any progress.


Member for

21 years 2 months

Pro Audio Guest Fri, 01/04/2002 - 05:25
There are several places online that contain
the V72 schematics. It's rather easy to cable
(here's one)

You will also find that a phase switch
and phantom (since the input is transformer
coupled) is simply a matter of connecting a
high quality (low ripple) 48v supply through
a pair of matched (.1 %) resistors. There are
lots of schematics that show this configuration.
(here's one such)

All of this can be done at the touchel
connector on the back of the module. Lot's of
people (including me) use pad's on the front
end instead of wiring up a gain adjustment
(which involves accessing and modifying the
internal circuit of the V72).

An internal mod I have seen for gain control replaces the 400K resistor across the secondary of the input transformer with a 400K pot. Connect the sweeper of the pot to the top end of the secondary and the 400K fixed of the pot between the bottom end of the secondary and the EF804 grid.

As far as connecting the direct in, there is no simple approach that I've seen. Using a decent direct box may be the best option there.

Any good electronics tech should be able to use the above information to make it all happen.

Hope this helps...