French term (edited): Mesure du d�passement des t�tes vid�o double.......

I am 100% sure of the 'video head protrusion' bit --- you can put in or leave out the 'the' as you wish, since the style seems a little abbreviated anyway.

The only bit about which I have the slightest doubt is the 'double' --- and only really more context would make it clear.

Basically, (except for certain very special instances, not applicable here) video heads ALWAYS consist of a pair of diametrically-opposed heads; so there is normally no need whatsoever to specify 'double' --- this could just be an example of the French over-stating the obvious (unless it is meant for a lay readership, where they might be seeking to emphasize the point).

HOWEVER, having said that, there are certain special purposes for which different types of head are used. Many domestic VHS recorders are referred to as '4-head', as they have an extra pair of heads for slow-motion, pause and other special functions. But I see no reason why these heads should be specified for this simple kind of test purposes.

On the other hand, if this were a professional Betacam or similar recorder, they do, literally, have 'twin heads'.

My only feeling is to let the 'double drop, UNLESS you have extra information to explain why it is there. They MIGHT just be meaning 'measure the protrusion of BOTH video heads' --- this SHOULD always be done as a matter of course! The reason for measuring the protrusion, by the way, is to see how much the (beneficial) abrasive effects of the cleaning tape have (undesirably) worn down the heads, thus considerably shortening their life!

If you need to keep the 'double' in, then it probably should be 'twin' in English, though 'dual' and 'double' would be other, slightly less likely, possibilities. You might just say 'the pair of video heads', thus side-stepping the problem! But it makes the sentence structure clumsy to fit the 'protrusion' in...

--------------------------------------------------
Note added at 14 hrs 21 mins (2004-11-16 08:42:16 GMT)
--------------------------------------------------

As David so rightly says, keeping the \'twin\' in is probably the best option. My only real reservation is that makes the wording a bit more awkward, to have to say \'protrusion of the twin video heads\' instead of \'video head protrusion\' --- but the alternative \'twin video head protrusion\' sounds quite unnatural to me.

--------------------------------------------------
Note added at 14 hrs 29 mins (2004-11-16 08:49:43 GMT)
--------------------------------------------------

Paul\'s thoughtful answer above deserves more than a bald \'Disagree\'

Residual \'video head protusion\' after use of abrasive cleaning cassette is a standard measurement.
There is no such thing as video head clearance as far as the tape is concerned; the heads protrude exactly so that they can penetrate the tape to ensure intimate contact with the magnetic coating. \'Video head penetration\' is indeed the other term that could have been used; except that you can actually measure \'protrusion\', whilst \'penetration\' can only be implied.
IMO, \'clearance\' cannot really be interpreted as the same thing as \'protrusion\' here; and the heads\' position at rest is the same a their position in opeation, except that they are whizzing around -- but always in the same cylindrical plane.

Sorry Paul, I hate ever to be so dogmatic on KudoZ, but I really AM sure of my ground here! When you\'ve cleaned as many of the darned little blighters as I have... :-)