Review
update
The SansAmp
Acoustic DI has been replaced by the SansAmp Para Driver DI. Tech
21 say that this is based on their RPM rackmount unit, which in
turn was developed from the SansAmp Acoustic DI. There are two
obvious additions or changes to the design, a footswitch, that
toggles between the active EQ and transparent active DI modes
and a drive control that adjusts the overall amount of gain and
overdrive (similar to when the output stage of a valve amp is
being pushed). Unfortunately the addition of the footswitch has
meant the loss of the alternate 'input to XLR' and as a result
the effects loop configuration, using the 'output' jack as an
output to the effects, using the 'input to XLR' as the loop input
and taking the final signal out from the XLR, is no longer possible.
The Blend control is now a smaller control next to the Mid shift
control, allowing the other controls to shift along one step to
make room for the Drive control on the end. The slide switch that
performed the footswitch function on the Acoustic DI, now on the
Para Driver DI switches a -20dB pad in and out for the XLR output.
The SansAmp Acoustic
DI reviewed
The controls
In 'active' mode the
SansAmp Acoustic DI has a three section equaliser with treble,
mid and bass controls all providing both boost and cut from the
centre flat position. The mid control is augmented by a mid shift
control to sweep the mid boost or cut between 170Hz and 3.5KHz.
In cut mode this is useful for taming acoustic feedback. The treble
and bass control range is plus or minus 12dB, while the mid peaks
or notches by plus or minus 16dB. With such an effective EQ it
would be useful to have some panel markings to indicate the approximate
flat position, although the 'active' switch can be used to bypass
the EQ for comparison. Next to the EQ controls is a 'Blend' control
that blends in an amount of 'valve warmth'. Turn this fully anticlockwise
and the valve emulation is turned off. The final control is the
level control that controls the amount of signal sent to the outputs.
With the level at maximum the SansAmp does provide a certain amount
of gain. Setting level to the middle of its rotation appears to
be the unity gain position.
The switches
A pad switch provides
for use with high sensitivity mixer microphone channels by switching
in a -20dB gain reduction on the XLR output only. The centre ground
connection can be lifted and as a result the phantom power turned
off, with the 'phantom & ground connect' switch. Turning off
the 'active' switch bypasses the EQ, the Tube/Microphone emulation
circuitry and the Level control and turns the SansAmp Acoustic
DI into 'transparent' DI box. The active LED goes out with the
switch in this position and you might expect the SansAmp to be
switched off, but even in bypass mode the SansAmp Acoustic DI
still requires some power. The only way to turn it off is to remove
any jacks plugged in to the inputs.
Power supply options
Power for the SansAmp
Acoustic DI is either from the usual 9 Volt battery, easily accessed
through clip-on hatch in the base, from an outboard supply plugged
in to the co-axial external power socket, or, very usefully, from
a phantom power feed via the XLR output connector when the DI
is plugged in to a mixing desk with an XLR lead. Battery power
is activated in the usual way by pushing a jack plug into either
input socket
Inputs and outputs
The SansAmp Acoustic
DI is designed with passive piezo pickups in mind. Passive piezo's
require very high input impedances otherwise they lose bass. The
'input' is ideal for passive piezos at 4.7 Megohm while the 'input
to XLR' is a little lower at 1M impedance, which is ideal for
passive magnetic pickups. The signal from the 'input' jack routes
via the tone controls and feeds both outputs while the 'input
to XLR' routes directly to the XLR output connector. An external
effect insert path is available through connecting the effects
input to the SansAmps 1/4 inch output jack, connecting the effects
output to the 'XLR input' jack and taking the final output signal
from the XLR connector.
In Use
In use the SansAmp
Acoustic DI is very quiet (unlike an amazing number of other pedals
and DI devices) and the active EQ provides plenty of tonal adjustment.
It even works very well for recording clean electric guitar -
plug in an archtop guitar, add a little valve warmth with the
blend control and you're rewarded with a gorgeous jazz tone. The
phantom powering is a very handy feature, since you never have
to worry about flat batteries and in any case with a power consumption
of only 7mA maximum, the battery life is pretty long. The only
criticism we have is that for such a feature rich product the
user manual is a little vague on certain points. For example it's
easy to assume that the SansAmp Acoustic DI is in totally passive
mode and not draining the battery, when the 'active' switch is
in bypass and the 'active' LED isn't illuminated.
Conclusion
If you're looking for
a simple 'plug-n-go' DI then the SansAmp isn't it, this is one
of those pieces of kit where you really do need to read the manual
and learn all of its features, to get the best out of it. For
something simpler the new SansAmp XDI, designed for DI guitar
recording on a PC based digital recording rig, is worth considering
and we are hoping to review this new unit soon. However if you're
looking for a really quiet active DI with powerful tone controls
and great sound on acoustic or clean electric guitar then the
SansAmp Acoustic DI really nails it.
Copyright 2003 Terry
Relph-Knight |
|
Tech21
and the solid-state, analogue 'valve sound'
Tech21 has built a
reputation for making great sounding guitar pre-amplifiers and
amplifiers using solid-state components to create analogue emulation
of the valve sound. Tech21's proprietary valve emulation was originally
developed to reproduce, often quite aggressive, overdriven valve
distortion sounds. In the SansAmp Acoustic DI it's employed in
a modified form to add a more subtle warmth and fatness, similar
to a high quality tube microphone.
We recorded the track
'Harbour Nights' from Hugh's soon
to be released jazz CD 'Synchromatic' using a Gretsch C400 archtop
guitar with a Dan Armstrong pick-up plugged into a SansAmp Acoustic
DI feeding the line input of an M-Audio Audiophile USB audio I/O
box. |
