So why do ribbon mics sound so different? These obvious sonic differences
result from variations in the few simple mic components; the ribbon, the
magnetics, the transformer, and the interfacing design of these elements. The
craft and design to combine these three components is most important, as with
any transducer… little things can make BIG differences! Let’s look at each of
these four areas in detail, and discuss how we created VELO-8 to be the best
ribbon mic possible.
1. The Ribbon element:
RCAmics had ribbons ranging in size from 2” long
by 1/4” wide, down to about a quarter of that size. The thickness of the
aluminum ribbon could vary from as thin as 2 microns to as thick as 8 microns.
As most of the old ones have been rebuilt (usually with thinnest material
available), few can be found with their original RCA-produced elements intact,
and have usually been rebuilt many times using whatever thin aluminum they
could find. Also, the thin aluminum was hard to come by when RCA got out
of the ribbon mic business in the late ‘50s. One common trick of the old studio
techs was to use the aluminum peeled off a gum wrapper, which is about 3
microns. Hand tensioning of the ribbon, or stretching it across the magnetic
field, was critical and rarely measured in any meaningful way… the old guys
just had a feel for it (or not!). Of course, the way the ribbon is crimped (or not
crimped) also contributes to the end audio result as well. This is why so few
vintage RCA mics today, even of the same models and era, sound exactly alike.
But some common truths are found; the larger the ribbon element the more
output level it generated (i.e., the RCA 44), and the thinness contributed to
more (or less) detail as well as more (or less) reliability. For example, a thicker
ribbon meant more durablity but gave less detail.
We like the old classic velocity mics VERY much, but didn’t want to just
“reissue” an Elvis impersonator mic, as many have done. However, we did take
a page from RCA velocity mics of the ‘50s, and a few tricks from Bang &
Olufsen (B&O) ribbon mics of the ‘60s, and made ours a unique offering
which stresses the advantages of the ribbon mic, but also addresses the
shortcomings. For example, our ribbon element is big and thin; VELO-8’s
aluminum ribbon is over 2 inches long, 1/10” wide, and is just 2.5 micron thick
(human hair is about 10 microns, so it’s a quarter of the thickness of a strand
of hair!). The ribbon element itself is also uniquely shaped; it is very precisely
“dual formatted” to have two shapes, and both contribute to detail and
reliability. VELO-8’s ribbon has both a curved area (in center) and a crimped
suspension area at either end of the ribbon to help it hold its precise tensioning.
This allows for maximum signal output and good long term stability. It is also
precisely tensioned by a special proprietary GT computer controlled system;
we call this “ribbon tuning”, so they all sound exactly the same (a must for
GROOVE TUBES
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