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SolStice
TM
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APPeNDiXeS to SolStice iNStRUctioNS
A) imPeDANce coNSiDeRAtioNS with AcoUStic iNStRUmeNt PickUPS
Piezo pickups are particularly sensitive to the “input impedance” of the
first stage of electronics into which they are plugged. The effect is the
audio equivalent to trying to balance a 200-pound gorilla on a seesaw with
a 40-pound child...without moving the fulcrum point. if the input imped-
ance is too low, as it is with most guitar amps or Pa boards, the resulting
mismatch will rob your pickup of output and low end warmth, just about the
last things you want when amplifying an acoustic instrument! impedance
matching is basically a balancing act with a slight twist: it is best to send a
lower impedance output (for instance a pickup) to a preamp with an input
impedance many times greater.
also, pickups do not do a great job of driving a signal down a cable, and
this is why most high quality piezo pickups have on-board preamps to con-
dition the signal for its trip to the amp or console. if you do use a “passive”
piezo system in your instrument, keep cable length to a minimum. You will
know whether your guitar pickup system is active or passive by whether it
needs battery power or not. some magnetic pickups and nearly all piezo
pickups work best when there is a preamp/buffer stage right in the guitar.
Pickups do not make great “line drivers” and you can suffer significant sig-
nal loss and degradation with long runs of cable. We have designed your
solstice preamp to work with either style of pickups, but if you are going
to go passive, use the shortest, lowest capacitance cable you can get to
preserve maximum signal.
B) eQ, USe AND miSUSe
one of the keys to getting great sound is to use just as much eQ as you
need and no more than necessary. a good rule of thumb is that if a signal
source needs a lot of eQ to sound decent, it’s probably a bad source. in the
best recording studios in the world, the engineers will first choose the best
microphone(s) for the instrument and work carefully with mic placement to
get the sound they are after. only then will they apply eQ to shade the basic
sound they are getting from the straight sound of the mic. overzealous
use of eQ can cause more problems than it solves by altering the phase
relationships among sounds and by just adding too much noise and a pro-
cessed quality to the end result. if you think your pickup needs a lot of eQ
to sound right, perhaps what you really need is a better or more appropri-
ate pickup.
it is helpful to understand just what problems you are trying to solve using
eQ. is it the guitar sound itself? is it the sound of the Pa? is it a room
specific problem? it is also important not to be duplicating or counteracting
what might be going on elsewhere in your system with other eQ devices.
You may not even realize how much eQ your instrument signal is going
through when you plug into a Pa, there may be some in your instrument,
there’s the eQ on solstice or an amplifier, then the eQ on the channel(s) of
the mains Pa console and perhaps a separate monitors console, there may
be auxiliary outboard eQ patched into the console, and then there is usually
some eQ dedicated to the speakers and/or room taming. You may just be
dealing with as many as five or six different equalizers in your signal chain
when one or two may just do the trick.
one of the best ways to dial in your sound for amplified acoustic instru-
ments is to work with headphones to dial in your pickup blend (if using dual
sources), eQ, and effects. Take solstice’s output into a headphone amp or
through a console and use high quality headphones to monitor your sound.
This way you will know that you are using your gear to get just the right
instrument sound free of anomalies with loudspeaker response or room
resonances. Then when you play out live, you can deliver your concept of
correct tone to a sound engineer with the instructions to do nothing or as
little as possible to that sound. he or she should already have their dedicat-
ed Pa and room eQ set correctly, and then the only further possible need of
eQ might be for feedback control in cases where you are trying to achieve
loud monitor levels on stage with acoustically lively instruments.
some musicians go so far as to carry their own vocal mics with them along
with acoustic instrument preamplification and even stage monitors so
they have as close to the same sound on stage every night no matter what
might be happening in the house with the main Pa. solstice and d-Tar’s
other fine acoustic amplification gear makes this easy. You can carry your
own personal sound with you, feed that to the Pa, and have several less
things to worry about.
c) A Few NoteS Re. PhASe, SoUND, AND FeeDBAck ReDUctioN
acoustically, a sound wave is physically made up of alternating low and
high pressures acting on your eardrums. Phase is the relationship, in time,
between the “the peaks and valleys” of two sound sources (or signals).
if the soundboard or loudspeaker creating a guitar signal first moves out-
ward, the first thing that hits your ear is a positive pressure, which pushes
your eardrum inward. if the soundboard or speaker cone first moves in, it
creates a negative pressure on your ear, pulling the eardrum out.
Guitar tops, pickups, preamps, amplifiers, and speakers all affect this phase
relationship, and things really get complicated when you combine these
elements and then start pushing sound levels up further and further. certain
phase relationships among all these elements can lead to uncontrollable
feedback at even moderate volume levels.
having the ability to switch the phase relationship between your guitar
signal and the speakers can make all the difference between being in feed-
back hell or sonic heaven. This can be worth 4 to 10 dB more level when
you need it.
FX Blend
Control
Hi-Z Input
Single ended
10M - 0 to 24dB
Gain trim
Balanced Input
1k - 40dB
20dB Pad
Hi-Z Input
Single ended
10M - 0 to 24dB
Gain trim
Balanced Input
1k - 40dB
20dB Pad
Level
Indicator
Summing Amp
12dB fixed gain
B/M/T Gyrators
EQ Summing
non-inverting
Level
Indicator
Summing Amp
12dB fixed gain
B/M/T Gyrators
EQ Summing
non-inverting
Phase
Inverter
Phase
Inverter
Channel 1 Balanced Out
Channel 1
Insertion
Tip - Send
Ring - Return
Channel 2
Insertion
Channel 2 Balanced Out
Back Panel
Master FX Loop
Return
Amp
Buffer Amp
front
panel
Mute
Switch
Summing
Amp
6dB
Master
Volume
Output Buffer
non-inverting
Blended Signal
Output
Turner Out
Balanced Line
Blended Output
Ground
Lift
Functional Block Diagram - DTAR Solstice
