DATA S H E ET
General Description
The Rane RA 27 Realtime Analyzer is a single rack space
unit providing 27 bands of realtime frequency/amplitude
information in a 3-LED vertical band format. Broadband
signals applied to either the Microphone or Line inputs of the
RA 27 are divided into 1/3 octave increments by ANSI Class
II filters. The outputs of these are applied to LEDs on the
front panel to visually indicate the amplitude of each band. In
operation, the RA 27 is used to visually judge the character of
the Pink Noise signal received by the measurement
microphone. The operator may now adjust a 1/3 octave
equalizer for optimum response of a sound system based on
the readings presented by the LED display.
Front panel controls include an input Level sensitivity
adjustment, calibrated in dB SPL, a Window switch which
calibrates the sensitivity of the metering system, and a Pink
Noise on/off switch. The MIC 1 is a flat-response microphone
supplied with each RA 27 connects to the front panel Mic
Input jack only. These factory tested microphones are flat to
within 1 dB from 20 Hz to 16 kHz. An Aux Mic Input is
provided on the rear panel, allowing the user to use a
microphone of another type.
RA 27
REALTIME ANALYZER
To provide a reference for proper use of the RA 27, a
pseudo-random digital Pink Noise generator is included in the
unit. The output of the Pink Noise generator is flat within 1
dB from 16 Hz to 20 kHz and has a crest factor of 4.
The rear panel of the RA 27 includes a Pink Noise Output
jack, Aux Mic Input (XLR), a Line Input (¼" unbalanced),
and a recessed Pink Noise Level adjustment.
The included Rane MIC 1 condenser microphone is a
professional quality back-electret condenser microphone with
an omnidirectional pickup pattern. Its power is provided from
the RA 27, but may be powered via batteries for other uses
(see RaneNote 104, “Microphones and the RA 27”).
The MIC 1 comes complete with an extra long 40 ft
(12.2m) cord to facilitate distant placing of the microphone
from the analyzer. Included with the RA 27 is a zippered,
weather-resistant carrying/storage bag for added convenience
and protection of the mic. The MIC 1 has a non-reflective
black wrinkle powder-coat finish that is extremely durable
and scratch resistant.
When ordering the MIC 1 separately, please contact the
Parts Department and specify part number 11151.
Features
• 27 ANSI Class II Filter Bands
• 3-color LED display per band
• Digital Pink Noise generator
• Flat-response Microphone with 40-foot cable
• 3 dB/1 dB Window switch
Rane MIC 1 (included)
• Aux Microphone Input
• Line Input
• Analyzer Sensitivity control
• Pink Noise Level control
• Meets CE requirements
Data Sheet-1
RA 27
REALTIME ANALYZER
Parameter Specification Limit Units Conditions/Comments
Analyzer: Range ±1 or ±3 0.3 dB Switch select able “green” window
..........Level 70 to 120 5 dB Microphone loudness SPL
..........Frequency Response 40 Hz-16 kHz 0.5 dB
..........Attack Time Constant Peak Instantaneous
Frequency Accuracy 5 %
Analyzer Filters ANSI Class II
Pink Noise: Type Pseudo-random Digital Crest factor: 4
Level Off to +4 1 dBu
Response 16 Hz-20 kHz 1 dB
Aux Mic Input: Type Active Balanced/Unbalanced
..........Connector 3-Pin XLR type
..........Impedance 100k 1% ohms
..........Max Gain 98 3 dB
..........Min Level 15 5 uV
Line Input: Type Active Unbalanced
..........Connector ¼" TRS
..........Impedance 100k 5% ohms
..........Max Gain 38 3 dB
..........Min Level 15 5 mV
Microphone: Type Back-Electret Condenser 6 mm capsule
..........Frequency Response 20 to 16,000 1 dB +2 dB at 20 kHz
..........Polar Pattern Omnidirectional
..........Impedance 1.8k 5% ohms With 2.2k ohms load
..........Sensitivity -64 3 dBV re 0 dB=1V/µbar, 1 kHz
(0.63 mV @ 74 dB SPL) 1 µbar = 74 dB SPL
..........Maximum SPL 140 dB 1 kHz
..........Signal-To-Noise Ratio 58 (re 94 dB SPL) Min dB 1 kHz, A-weighted
..........Phasing Non-inverting Positive pressure on diaphragm
equals positive output voltage
..........Power: Voltage Range 1.5 to 10 VDC Absolute min & max ratings
...............Rated Voltage 2.0 10% VDC
...............Sensitivity Loss -3 dB @ 1.5 VDC
...............Current Demand 0.5 Max mA At 2.0 VDC
..........Cable Attached; 40 ft (12.2 m) Long 1 cond. shielded; ¼" TS phone
..........Case 6" x 9" (15.2 cm x 22.9 cm) Zippered heavy black vinyl
..........Storage Temperature -20 to 60 oC -4 to 140 oF
..........Operating Temperature -18 to 50 oC 0 to 122 oF
..........Relative Humidity 0 to 95 % Operating or storage
Line Voltage: Domestic 95-130 VAC, 50/60 Hz
..........Export 190-250 VAC, 50 Hz
Unit: Agency Listing
..........120 VAC Model COLA (City of Los Angeles)
..........230 VAC Model CE-EMC certified EN55013 & EN55020 EMC Directive 89/336/EEC
CE-Safety certified EN60065 LV directive 73/23/EEC
..........Size 1.75"H x 19"W x 8.5"D (1U) (4.4 cm x 48.3 cm x 21.6 cm)
..........Weight 8 lb (3.6 kg)
Shipping: Size 4.25" x 20.3" x 13.75" (11 cm x 52 cm x 35 cm)
..........Weight 11 lb (5.0 kg)
Note: 0 dBu=0.775 Vrms
Data Sheet-2
Block Diagram
RA 27
REALTIME ANALYZER
Application Information
All professional sound systems suffer the mercy of driver
responses, room resonances, phase interactions, crossover
adjustments and other factors which destroy the sound
quality. Unfortunately the human ear, though very sensitive,
is neither calibrated nor consistent, and is generally unable to
determine exactly where and by how much a system’s
response is lacking. Recognizing this fact, experienced sound
technicians invariably employ some type of realtime analyzer
to identify system deficiencies, then quickly and accurately
correct them. However, the high cost and complexity of
traditional analyzer designs reserved their use to an elite few,
leaving the majority of sound system users to a hit-and-miss
equalizer guessing game.
Realizing this, Rane set out to literally redefine the design
and application of the realtime analyzer, developing a
complete, innovative analyzer system which is simple, quick,
extremely accurate and incredibly cost-effective. The concept
for the RA 27 was to take the fear, cost and complexity out of
realtime analyzers. By designing a simplified analyzer in a
single rack space unit, Rane created an extremely useful piece
of sound reinforcement gear. One where a small venue can be
equalized within minutes with accurate visual guidance.
Instead of the traditionally complex and costly LED
matrix array, the RA 27 uses an ingenious color-coded
display which instantly gives you all the practical information
needed from an analyzer. For each frequency band there is a
column of three LEDs: red, green and yellow from top down.
If the red LED is lit, response is too high; if the yellow LED
is lit, response is too low. In either case you simply adjust the
corresponding slider on your graphic equalizer until the green
LED lights. When all the green LEDs are lit, your system is
aligned to 1 dB or 3 dB accuracy—your choice. Just that
simple. And when you finish the pink noise test, unplug the
Microphone from the front panel jack and the display will
automatically monitor the program through the Auxiliary Line
level Input section. Now you can keep an eye on problem
feedback frequencies during the performance and make quick,
effective adjustments.
The RA 27 comes complete with built-in Pink Noise
generator and a flat response condenser microphone with 40
foot cable and case. The Auxiliary Mic Input on the RA 27
allows system alignment to the response of your microphone,
yielding more favorable results in choral, orchestral or other
similar situations where the same microphone model is used
to provide all program input.
The RA 27 will enable accurate system performance time
after time, in every location, with incredible ease and speed.
In just a few short minutes you obtain minimum feedback and
clean, uncolored sound. From here, further EQ can easily and
effectively be accomplished by ear. Once the RA 27 gives
you the consistent flat reference point, you may fatten the
bass, sweeten the highs or make any further adjustments to
suit the particular type of music, audience and location. With
so much sound quality to gain at such little cost, no professional sound system is complete without the RA 27.
Data Sheet-3
RA 27
REALTIME ANALYZER
Rear Panel
Architectural Specifications
The realtime analyzer shall provide three LEDs for each
of 27 bands located on standard ISO center frequencies, and
be contained in a rack mount chassis requiring one (1) rack
space. A red LED shall indicate signal level in excess of the
selected range; a green LED shall indicate signal levels within
the selected range; and a yellow LED shall indicate signal
levels less than the selected range.
A switchable 1 dB or 3 dB range shall be provided, as
well as an input level control with a range of 70-120 dB SPL.
The unit shall come complete with an electret condenser
microphone with a 40-foot cord packed in a carrying case.
A digital pseudo-random number generator based pink
noise source shall be built-in.
A line level auxiliary input shall be included and be of
active unbalanced design terminated with ¼" TRS (tip-ringsleeve) connector. An auxiliary microphone input shall be
provided with a three pin connector and balanced amplifier
input stage.
The unit shall be capable of operation by means of its own
built-in power supply connected to 120 VAC (240 VAC
where applicable) and meet CE requirements. The unit shall
be entirely constructed from cold-rolled steel.
The unit shall be a Rane Corporation Model RA 27.
MIC 1 Details
The MIC 1 is a back-electret condenser microphone. The
“back-electret” is an improved version of the standard electret
condenser design where the polarization charge voltage, or
electret bias, is applied to the rear backplate. This provides
increased mechanical strength, improved resistance to
environmental effects, and better sensitivity and stability of
the charge. Since the electret is permanently charged (we
think 30 years qualifies as permanent) it does not need the
high voltage powering common to standard condenser
designs—a major benefit. This benefit is reduced, however,
by the electret requiring an impedance converter (built-in
JFET) which does need low voltage powering. So, as always,
you just can’t quite win.
Details of the simple power supply appear in the Electrical
Diagram below. As shown, the recommended standard
operating voltage is +2 VDC supplied through a 2.2k ohm
resistor. Usually the 2 volts is zener regulated to a higher
voltage and resistively divided down. Regulation and tolerances are not critical; however, the supply should be as noise
free as possible. While 2 volts is recommended, the MIC 1
runs equally well up to 10 volts. When using higher voltages
be sure to observe the absolute maximum voltage limit of 10
volts. See RaneNote 104 “Microphones and the RA 27” for
more details and battery power options for the MIC 1.
Available Accessories
• SC 1.7 Security Cover (to cover the lights?!?)
• MIC 1 (order part # 11151)
MIC 1 Electrical Diagram
©Rane Corporation 10802 47th Ave. W., Mukilteo WA 98275-5098 TEL (425)355-6000 FAX (425)347-7757 WEB http://www.rane.com
Data Sheet-4
All features & specifications subject to change without notice. DOC 103123 PN 01742
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