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© Semiconductor Components Industries, LLC, 2005
November, 2005 -- Rev. 0
1 Publication Order Number:
AND8177/D
AND8177/D
Audio Circuits Using the
NE5532/4
Audio Circuits Using the NE5532/34
The following will explain some of ON Semiconductors
low noise op amps and show their use in some audio
applications.
Description
The 5532 is a dual high--performance low noise
operational amplifier. Compared to most of the standard
operational amplifiers, such as the 1458, it shows better
noise performance, improved output drive capability and
considerably higher small--signal and power bandwidths.
This makes the device especially suitable for application
in high quality and professional audio equipment,
instrumentation and control circuits, and telephone channel
amplifiers. The op amp is internally--compensated for gains
equal to one. If very low noise is of prime importance, it is
recommended that the 5532A version be u sed which has
guaranteed noise voltage specifications.
APPLICATIONS
ON Semiconductors 5532 High--Performance Op Amp is
an ideal amplifier for use in high quality and professional
audio equipment which requires low noise and low
distortion.
The circuit (Figure 1) included in this application note has
been assembled on a PC board, and tested with actual audio
input devices (Tuner and Turntable). It consists of a
Recording Industry Association of America (RIAA)
preamp, input buffer, 5--band equalizer, and mixer.
Although the circuit design isnot new, its performance using
the 5532 has been improved.
The RIAA preamp section is a standard compensation
configuration with low frequency boost provided by the
Magnetic cartridge and the RC network in the op amp
feedback loop. Cartridge loading is accomplished via R1.
47 kΩ was chosen as a typical value, and may differ from
cartridge to cartridge.
The Equalizer section consists of an input buffer, 5 active
variable band pass/notch (depending on R9’s setting) filters,
and an output summing amplifier. The input buffer is a
standard unity gain design providing impedance matching
between the preamplifier and the equalizer section. Because
the 5532 is internally--compensated, no external
compensation is required. The 5--band active filter section is
actually five individual active filters with the same feedback
design for all five. The main difference in all five stages is
the values of C5 and C6, which are responsible for setting the
center frequency of each stage. Linear pots are
recommended for R9. To simplify use of this circuit, a
component value table is provided, which lists center
frequencies and their associated capacitor values. Notice
that C5 equals 10 × C6 and the value of R8 and R10 are
related to R9 by a factor of 10 as well. The values listed in
the table are common and easily found standard values.
RIAA
C1
R1
3
2
1
RIAA Out
+
--
1/2 5532
C2
R2 R3
C3
Equ In
R5
5
6
+
--
1/2 5532
+
--
1/2 5532
R5
7R7
R9
C6
C5
R8
R9
2
3
1
R10
+
C7
R11
6
5
7
+
--
1/2 5532
REPEAT ABOVE CIRCUIT
FOR DESIRE NO. OF
STAGES.
FLAT
EQUALIZE
TO VOL./
BAL AMP
R12
R4
C4
R7
Figure 1. RIAA -- Equalizer Schematic
APPLICATION NOTE
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