Where evolution becomes revolution
The DPA-1 Distribution Preamp is an entirely new
class of pro audio equipment. It represents the melding
of technologies and capabilities found in Coolohm's
past products, brought together in a unique blend of useful
features in an ergonomic package.
• A pristine all-tube mike preamp
• The ultimate D.I. box
• A super-cool amp switcher and gain boost
• Perfect mike preamp with hard-core line driving and
splitting capabilities
There is simply nothing else like Coolohm's DPA-1.
Its all-tube signal path uses proprietary technology,
like our road-proven Gain Cell, where active signal boosting
is available in precise decibel increments. The 21-detent
output level allows repeatable settings through the massive
output buffer driving two 600-ohm XLR jacks. Each output
has its own 20dB pad and ground lift. This "pristine path"
is so clean you'll think it's solid state! But it can
add warmth and compression whenever you need it.
The line and microphone inputs each have their own transformer
for optimum signal handling. The instrument input is buffered
by a transparent jfet-current-mirror for extremely low
noise and high input impedance. This allows proper interface
even with a raw piezoelectric pickup. The output of this
input buffer is directly accessed through the 'tuner'
output jack.
The TRS outputs provide a range of textures from very
clean to classic analog grind. There is definitely a vintage
vibe here! Bass and treble frequencies can be tailored
individually, with two presets for each. The level controls
and presets can be selected via a remote foot-switch for
on-the-fly gain and EQ change. Each transformer-isolated
output has its own 20dB pad and ground lift.
There are two primary operating modes: "distribution"
or "split".
Distribution Mode: Signals are selected from
either the mic-input, the line input or the instrument
input and boosted through the gain-cell. The signal is
fed to both the main level control and the AMP
LEVEL controls. The main level sets the output
via the XLR jacks - the pristine path with incredible
line driving capabilities. The AMP
LEVEL controls how hot the TRS output will
be.
Guitar and bass players can use the AMP-1/AMP-2
remote selection footswitch to boost the signal going
to their effects or on-stage amplifier. They can even
select which amp is receiving a signal in multiple-amplifier
set-ups.
Split Mode: The pristine path accepts only line
or microphone inputs. The signal is processed through
the pristine path only and outputs via the XLR jacks.
The instrument input is live but is only available via
the vintage path, outputting via the TRS jacks.
Split Mode allows two signals to be processed independently.
Use it to warm up a stereo signal prior to digital processing
or recording, or on playback from the digital realm..
Use the mic input for superb vocal capture while the vintage
path handles guitar: perfect for the one-man band with
an ear for tone!
Silky-smooth Performance
Modern switching and interface circuitry is seamlessly
incorporated with the audio path. Input selection, gain
setting, pad, lift and operating mode selection is quiet
and effortless. Long-life switch elements are used well
below their limits, further enhancing reliability.
Muting is accessed through both the front panel and remote
switching, with all outputs muted except the tuner. The
front panel switch over-rides the footswitch. Automatic
muting occurs during power-up and power-down.
Sequential switch selections, such as the low-frequency
filter turn-over, are maintained between sessions, even
when the main power supply is turned 'off'. As long as
the supply is plugged into the mains, the extremely low-power
"memory" supply will allow the last switch setting to
be "remembered".
Expandable System
Each DPA-1 is built in a half-width 2U rack chassis
- called a "half-rack" in the industry. The outboard power
supply is built into an identical chassis, so both pieces
can sit side by side on a rack shelf. But there's more...
Each power supply can support three DPA chassis! So you
can expand your system easily and cost-effectively.
Future Coolohm half-rack units will include a dual-mic
preamp and a dual-EQ.
Sound Reliability
Coolohm Audio builds to the highest standards.
Signal transformers are very wide-bandwidth and low-distortion.
Metal-film and flame-proof resistors are used throughout.
Solen and Wima plastic caps are used in the audio path
and for local filtering within the DPA chassis. High-temperature
low-leakage long-life electrolytics are used within the
power supply. Custom toroidal power transformers have
three levels of shielding, while providing world-wide
mains compatibility. Inrush current limiting and extensive
protection assures long life and low EMI radiation or
line intrusion. PCB construction assures consistency from
unit to unit, utilizing heavier copper traces than the
industry standard.
Tube access is via the rear panel. Tubes can be changed
with the unit still in the rack. All four 12A_7 tubes
are widely available at low cost, and any type within
this family can be used in any position of the DPA tube
card. However, optimal performance is attained with the
prescribed tube configuration. DC heater current is limited
to improve tube life and all supply voltages are heavily
filtered and decoupled.
Coolohm's DPA. A new standard in flexibility
and performance.