Art ARTcessories DUAL RP User manual

ARTcessories
Service Manual

IMPORTANT SAFETY INSTRUCTION – READ FIRST
This symbol, whenever it appears alerts you to the presence of uninsulated dangerous voltage inside the
enclosure-voltage that may be sufficient to constitute a risk of shock.
This symbol, whenever it appears, alerts you to important operating and maintenance instructions in the
accompanying literature. Please read the manual.
Read Instructions: Retain safety and operating instructions for future reference. Heed all warnings printed here and on
the equipment. Follow the operating instructions printed in this user manual.
Do not open: There are no user serviceable parts inside. Refer any service work to qualified technical personnel only.
Environment: Protect from excessive dirt, dust, heat, and vibration when operating and storing. Avoid tobacco ash, drink
spillage and smoke, especially that associated with smoke machines.
Handling: Protect the controls from damage during transit. Use adequate padding if you need to ship the unit. To avoid
injury to yourself or damage to the equipment, take care when lifting, moving or carrying the unit.
Servicing: Refer servicing to qualified technical personnel.
Installation: Install the unit in accordance with the instructions printed in the user manual.

1
INTRODUCTION
Thank you for purchasing Applied Research and Technology’s DUAL RP. The Dual RP is the ideal solution to
increasing the performance of your ribbon and Dynamic microphones. This remotely powered preamp brings out all
of the nuances of your mic before running into your recording interface or Mixer through long cable runs. With the
Dual RP you can tailor the loading on the mic through the variable impedance controls.
The balanced output drives long cable runs with ease allowing you to place the preamp as close as possible to the
mic before picking up any noise.
The Dual RP is packaged in a rugged extrusion with rubber feet for long, reliable operation.
Get the very best out of your mics with the Dual RP!
FEATURES
• Two very low noise mic preamps
• Variable Impedance controls
• Low Cut filter single pole, 150Hz
• Adds at least 20dB of gain to your mic
• Runs off a Phantom power supply
• Able to drive long balanced cables
• Heavy duty extruded chassis
• Designed and developed in the USA

2
INSTALLATION and OPERATION
Connect the outputs of the Dual RP to a Phantom powered source such as a mixer or preamplifier.
Connect the Dual RP inputs to your Ribbon or dynamic mics.
Make sure you start with the gain pots set to their minimum settings. Once connected engage the Phantom power
and adjust the gain on the Dual RP for the desired level. The phantom power will not pass through to the inputs thus avoiding
any potential damage to any dynamic or ribbon mics. As an added feature you have the ability to remove any unwanted
wind noise or rumble by enabling the Low Cut filter per input.

3
APPLICATIONS
Perfect for: getting the most out of your ribbon and dynamic mic!
The Dual RP may be used in a wide variety of applications and environments. Self-contained in an extruded
enclosure, the remote mic Preamp is designed for continuous professional use. Because the unit is compact and
lightweight, mounting location is not critical.
LOW CUT FILTER control
The Low Cut Filter is a single tuned High Pass Filter. The input signal can be filtered to remove low frequency
information. The roll off frequency is set at 100Hz. Since it is single tuned, it preserves some low frequency content
so its use is less obtrusive. It is especially useful in close mic’d applications cutting out pops and wind noise.
Variable Impedance Function
Using this variable impedance function allows the user to adjust the input impedance seen by the microphone, in
turn getting a better tonal response from your microphone used.
Dynamic Mic
Dynamic (coil) microphones are sensitive to loading. If these mics are not coupled correctly, the result maybe a
loss in frequency response and could result in added distortion.
As an example a common mic like the SM57 prefers a 600 Ohm load. When the load is varied above or below the
600 Ohms, then the mid range resonance could sound harsh and distorted. The low-end response will also sound
more controlled with a 600 Ohm load. There are many dynamic mics that may have similar issues but not be as
sensitive to loading as the SM57.
Ribbon Mic
Ribbon type (transformer coupled) microphones are sensitive to the input impedance of the preamps or mixers
used to achieve the optimum frequency response. A Ribbon mic would like to see an input impedance several times
larger than its output impedance. Ribbon mics, being transformer coupled, have increased impedance at high and
low frequencies. On the low end the mic is power bound, as you load it there becomes a low frequency cut off at
higher levels, so it may sound distorted. At the high end, the output impedance of the transformer increases
(independent of level), so the greater the load the less high end.
As an example, a typical ribbon mic with a characteristic impedance of 300 Ohms may have an inherent 600 Ohm
impedance at 20kHz and a 2k impedance at its low frequency resonance (about 50Hz). If you set the input
impedance to 10k Ohms your result would be a 0.25dB drop at 20kHz. This would also drop the low frequency
resonance by 1.3dB. Compare this to a typical mixer input (3k input impedance) where you would get a 0.75dB
drop at 20kHz and 3.6dB at resonance.
So increasing the input impedance seen by the mic using the impedance pots on the Dual RP will result in an
optimum performance from the ribbon mic used. If the preamp or mixer input impedance is too low then you will
start to limit the frequency response of the ribbon mic. When this occurs, the low-end of the microphone’s sound
quality will be limited and the transient response will sound flat degrading the overall performance of the
microphone. So by adjusting the impedance pot on the Dual RP, you can achieve a clean full frequency response
from your microphones using the Dual RP.
The beauty of the DRP and the RP-1 may be the ability to operate at higher impedance or
control the impedance vs. the mixer
1
you are currently using.
1
A Phantom power capable input has around 13K maximum impedance simply due to the 6.8k Phantom power pull-up
resistors.