Pickup Combinations - A Primer
Since we've been in the business of putting together preamp
systems for acoustic instruments longer than anyone else, we've
come across most of the configurations that players would like
to use with their instruments. The bottom line is that nearly
everyone wants something different, and needs a different approach
to achieving it. For that reason, we've tried to incorporate
as many features as you're likely to need both now and in the
future. Since most players find that one pickup can't do the
entire job, the SPS-1 is designed specifically for blending a
pickup with something else, be it another pickup, an internal
mic, or an external mic. What combination you choose depends
a lot on your playing style - flatpicking or fingerpicking, playing
solo instrumental music, accompanying vocals, or playing with
other instruments at high sound pressure levels. Even whether
you play in small clubs or with a concert sound system. The choices
you make also depend on whether you're playing live or in the
studio. Here are a few of the most popular combinations, and
why people use them.
Two External Mics
The faint of heart need not apply! If you're a purist, and
you're playing solo guitar in a studio environment, this is the
combination you're most likely to use. However, it requires a
pair of high quality condenser mics, and a great sounding room.
Since the SPS-1 has two studio-quality mic preamps, parametric
EQ and stereo output, it's the ideal preamp for going directly
to DAT or digital multitrack. Perfect for recording you solo
record yourself. No one would think of using this combination
live, however, and expect to be heard. Unless, of course, you're
doing a classical concert in a great European hall.
Pickup + External Mic
This is probably the ideal combination for solo acoustic performance,
when you're looking for a good representation of the sound of
your instrument but want some control over how 'woody' your guitar
will sound. In most cases the pickup will be some sort of string-sensitive
device, either a saddle or under the saddle piezo (that's pee-ay-zo
folks, not pee-zo or pie-zo) transducer or a magnetic soundhole
pickup. Some work better than others, some are easier to install,
and some are just awful! The idea here is to use the pickup to
provide the direct 'in-your-face' sound of the vibrating string,
and combine it with the ambient sound of the wood vibration the
external mic gives you. By varying the blend between the direct
and ambient sound, you can get a very reasonable representation
of your instrument. You can use more pickup in a very lively
room, and more mic in a dead room.
By using a single pickup or two pickup Preamp Module in one
channel of the SPS-1, and an external mic in the other, you can
have complete control over this blend on stage. Many players
find that piezo transducers flatter light fingerstyle playing,
but are harsh when the strings are hit hard. The best magnetic
pickups, on the other hand, don't fold up when played hard, but
are too 'round' sounding for players who prefer that 'brash'
piezo sound. The choice is up to you. Check out what your favorite
player is using, and see if it works for you. In addition, most
studio recording of acoustic instruments also relies on using
these two sound sources. During mixdown you can establish the
blend of pickup and mic that gets the guitar to cut through the
mix. The downside is that you have to have to stay glued to one
position for the mic to be effective. This doesn't work for everyone.
And, you can't use this setup with high stage levels or in a
band situation, since both feedback - and more important - leakage
of other instruments into the mic, will present major problems.
Mic selection and placement will often help solve some of these
problems, but not in all cases, or even in all rooms.
Pickup + Internal Mic
This is currently a hot combination, since it gives you the
benefits of an external mic, and you can move around. There is
a price to be paid, however, since a mic inside a guitar will
never sound as good as a mic out in front of your guitar.
It may come pretty close, and in many cases it works very well,
but it's still a compromise. After all, it's is a mic in a box.
All that said, it works quite well in many applications, particularly
for solo players or groups where the stage levels are low. The
problems encountered with external mics, namely feedback and
leakage, are also problems here. Feedback problems can usually
be cured by keeping the mic out of the stage monitors, which
the SPS-1's monitor output allows you to do. Leakage, however
is another matter. The mic is in a resonant box with a hole in
it, which acts as a 'magnet' for low frequency sound, particularly
drums and bass. You can roll off all the low end on the mic,
but isn't that what you wanted the mic for in the first place?
A word about soundhole covers: You may think that by blocking
the sound hole, you're blocking external sounds from reaching
the internal mic. This is true, but you're also preventing air
from moving inside the instrument. If the air doesn't move, neither
does the diaphragm of the mic. Consequently, the output of the
mic drops dramatically, and sounds pretty dreadful. Venting the
cover by putting a few holes in it sometimes works, but often
the results are less than satisfactory. Sometimes you see a gauze
pad over a soundhole, which lets the guitar 'breathe'. It only
attenuates high frequency leakage though, not kick drum and bass.
Mic placement is another matter. The two most popular positions
are at the 2:00 or 5:00 position (neck is 12:00, bridge is 6:00),
tucked inside the soundhole about 1-2", 1" below the
top, and aimed out at the strings. At certain positions inside
the instrument there are 'nodes' where the low end boominess
is less severe. Hunt around until you find a position that sounds
best without EQ. Some mics are less boomy to start with, particularly
hypercardioid capsules. Sometimes, pointing the capsule up directly
at the top, as close to the top as possible without touching
(sort of a PZM configuration), works well with large-body instruments.
A little time searching for the best position will pay off in
the long run.
To sum up: internal mics work well when stage levels are low,
the mic is kept out of the monitors, and you've invested some
time in hunting for a sweet spot inside the guitar.
If you're playing in a band, and it's loud, you can rule out
any type of mic. In this case, there are a couple of options.
You can get a 'woodier' sound by blending a string-sensitive
pickup with a contact piezo transducer mounted to the top. Although
the contact pickup can feed back, the feedback occurs at the
cavity resonance of the instrument, which can easily be notched
out with parametric EQ on the SPS-1. The advantage, of course
is that leakage is no longer a problem. You won't get the sound
of the pick or your fingers hitting the strings, but at high
sound levels this isn't a great sacrifice. You will get some
body noise, though - the sound of your shirt sleeve scraping
against the top, or your perspiring forearm peeling off the top.
Another alternative is to blend two string-sensitive pickups.
A common combination is a saddle piezo pickup blended with a
magnetic soundhole pickup. Here, you're getting two different
tonal colors which you can blend to your liking. The piezo transducer
is great for that brash, 'in your face' sound, and a biting attack.
The magnetic pickup is ideal for getting harmonics out of your
instrument (especially for tapping), and does very nice things
for slide playing. It definitely opens a lot of possibilities.