Manley TNT MICROPHONE PREAMPLIFIER - Manual (Page 9)

At very low impedance settings with dynamic and
ribbon mics another effect can come into play.
Damping is a term normally associated with speakers
that refers to the fact that a dynamic speaker comes to
rest faster and is better controlled when connected to
a very low impedance amp. (It was one of the biggest
selling-point features when early solid-state amps with
tons of negative feedback first came out.) Damping
often has a dramatic effect on a speaker’s frequency
response and is one reason why some speakers work
better with solid state and some better with tube amps
(they were designed to, or what they were designed
with). A similar effect often happens with dynamic
mics and the bottom tightens up at low impedances.
Whether this is desirable tends to depend on whether
you are aiming for a tight and probably ‘truer-to-the-
source’ sound or the sound of the mic that you and the
world is more familiar with and might be viewed as
more authentic or traditional. You might even use the
tight 300 Ohm settings for tubby instruments and the
2K setting for drier sources and mics.
To complicate matters further, it depends on the mic.
Modern FET condenser direct coupled (transformerless)
mics are mostly immune to whatever setting impedance
you select, (though you might isolate some of those
cable and preamp circuit effects described above) so
expect generally very subtle or negligible differences.
At worst, with loud sources and lowest impedances
you might introduce early clipping with the occasional
FET condenser mic. Tube condenser mics are fairly
immune, but the impedance may affect the frequency
response of the transformer. And with ribbon mics, one
concern might be getting enough highs to start with,
so you might want to especially watch out for losing
highs while you focus on the tighter bottom with low
impedances. But the good news is that ribbon mics
tend to be famously forgiving when boosting the highs
with a good EQ so it may be easy to “get the cake and
eat it” this time.
And for those who just don’t want to be bogged down
by any technical issues and complications: you are in
luck again – just turn the knob and pick the setting
that sounds best for the track. In fact, this is the best
advice for those that love all the technical explanations
too, and when you get down to the session, the most
important thing is to listen and choose based on the
heart and the tapping foot rather than the intellect and
some words in a manual or web-site. Remember the
music, remember to listen. The old adage remains
valid “If it sounds good, it is good”.
We touched on using the impedance switch by ear
and how the low impedance settings may be tighter
in the lows, the medium impedance settings might
be the ticket for the advantages of blended preamp
whose settings represent typical mic pre impedances,
and how the highest impedance may be useful for
squeezing the last drop of highs (but not necessarily
the most accurate highs).
One way (not the only way) to approach the
IMPEDANCE switch is to begin at the middle or “600”
setting. Listen to what you get. If the sound strikes
you as OK but already a bit bright then try the lower
impedance settings. If your first impression is that this
instrument/mic sounds good but a little dark, then try
the higher settings. Quite likely, your first impression
is that it won’t sound exactly OK or good enough, so
the best advice is that you should really be out in the
studio adjusting the mic position and you are not at
a point where the subtle effects of adjusting preamp
impedance will help enough. Maybe you started off on
the wrong foot, or wrong mic in this case. You might try
approaching mics the same way as the IMPEDANCE
switch. If the instrument is hard sounding, try a softer
sounding mic, and vice versa. When you have a bright,
stinging instrument, maybe you don’t want to use the
brightest mic in the brightest position and coupled to
a bright preamp in its brightest setting, followed with
EQ in maximum “air” settings. The real trick to getting
“air” is letting that track and the others “breathe”, give
it some room to move, rather than add some electronic
artifacts. It doesn’t take Einstein to suggest sounds or
tones in a song are “relative” (and so is volume).
A proven approach is first to listen to the instrument
in the studio, walk around, get a handle on where it
sounds best and how the tone changes around the
instrument. We do that because instrumental projection
isn’t necessarily obvious and because it gives you a
starting point and the information needed to tweak mic
positions. Then one might choose a microphone or 3,
maybe based on complementary characteristics. We
might also suggest experimenting with mic positions
by ear rather than by the eyes, or ego. One might say
the first task of an engineer is recreating the sound
that the musician is hearing and intended. The second
task might be understanding the musician intended
it to sound better than what he got in the room and
that maybe something larger than life (as opposed
to squashed and smaller) might be what the sound
becomes in the mix. Some of you laugh and say “Not
my clients, not my mixes!” One can hope.
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