Altec 588b brochure

Page 1

SPECIFICATIONS

Type:

Input: (Ref: 0 dBv =
0.775 vrms)
Type:
Input Impedance:
Source Impedance:
Maximum Level:

Output: (Ref: 0 dBm =
0.775 vrms across 600
ohms)

Type:

Internal Source
Impedance:

Load Impedance:
Gain:

Maximum Output:

Distortion:
Frequency Response:
Noise (A-weighted):

Shielding:

Operating Temperature
Range:

Power Requirements:
Connector:
Dimensions:

Weight:

Plug-in solid-state preamplifier with transformer-
isolated input.

Balanced, Transformer

200 ohms

1501250 ohms

- 19 dBv (Vcc = 20 VDC, Gain = 33.5 dB,

FIN = 1000 Hz)

Single-ended

<10 ohms

>600 ohms

Variable, user adjustable 33.5 dB maximum,
20 dB minimum wIth a resistor wired between
pins 2 and 6 of the octal socket

+14 dBm (V c = 20 VDC, RL 2 600 ohms,
le = 30 to 0,000 Hz.)

<1 °/o TH D, 30 to ZUJJUU Hz.

30 to 20,000 Hz, :1 dB

< -90 dBm for an equivalent input noise. EIN, of
< - 124 dBm

Mu-metal case provides 90 dB of effective
shielding for the input transformer

Up to 55°C (131 F)
From +12 VDC at 13 mA to +20 VDC at 20 mA
Octal plug

16/16 (3.33 cm) diameter x 1-13/16 (4.60 cm)
seated height

1.5 ounces

_ ALTEC

P.O. BOX 26105, OKLAHOMA CITY, OK 73126-0105, U.S.A.

ALT
LANSING'

15883
MICROPHONE PREAMPLIFIER

OPERATING
INSTRUCTIONS

DESCRIPTION

The ALTE015883 Microphone Preamplifier
is a sealed, plug»|n solid-state module with
a transformer-Isolated input and improved
noise characteristics. The built-in trans-
former provides the preamplifier with a
balanced and isolated input for protection
from RF and other stray fields normally
induced on low-level microphone lines.

APPLICATION

The 15883 preamplifier may be used with
power supply voltages ranging from +12V
dc to +20V do. The 15883 draws a maxi-
mum of 13 mA do from a 12V supply and 20
mA dc from a 20V supply. The 15883 is used
with an input from a microphone. Wiring to
the intended mounting socket for the 15888
should be in accordance with Figure 1.

Interchangeability

The gain and subsequent overload charac-
teristics of the ALTEC 15883 Microphone
Preamplifier may be externally controlled
by an external resistor. The range of gain
obtainable and the resultant overload char-
acteristics are shown in Figures 2 and 3.
The difference between these figures is the
operating voltage, which has an effect on
the overload characteristics. Figure 2 is for
a supply voltage of 15V and Figure 3 is for a
supply voltage of 20V. To use the graphs for
determlnation of the external resistance
value, either the desired gain may be
selected from the left side of the graph, or
the overload point (in dam) may be selected
from the right side of the graph. A hori
zontal line is drawn from the selected point
to the intersection with the curve. A vertical
line from this intersection to the base of the
graph gives the resistance value for opera-
tion at the selected conditions.

Specifications and components sub/ear 10 change without
notice Oman perrarmnnce wt! 15,, maintained or Improved.

4202042511
REVISION O4
LITHO IN U.S.At 786-2.5M

Page 2

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with 15V dc Supply Voltage

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Figure 1. 15883 Pln Connections and Peformance Data

The following example is typical. Assume
an Input overload level of --6 dam on the
right side of the graph and draw a horizontal
line to the intersection of the curve. A line
from this point to the base line shows a
resistance value of 18K ohms is required.
For this value a gain of 20.5 dB is obtained
from the 15883.

The external resistor Is connected between
pins 2 and 6 of the octal mountlng socket.
The resistor may be mounted directly on the
socket. If it Is desired to include a switch on
the control panel, it is recommended the
resistor be placed on the switch and then

connected from the switch to the socket by
either a twisted pair or a shielded pair.

INSTALLATION

Each preamplifier should be carefully
inserted in Its mounting socket to prevent
possible damage to the locating key or con-
nector pins of the plug and/or socket.

ll the unit receiving the 15888 Is connected
to a power amplifier, be certain the power Is
shut off the power amplifier before insert-
ing the 15885.

IK
GAIN com-m kssrsuutt w OMMS

It
you r

I max

Overload and Gain versus Gain Control Resistance

with 20V dc Supply Voltage

MAINTENANCE

The 15885 preamplifier is a sealed unit and
should be repaired only by an ALTEC Quali-
fied Service Representative. For factory
service, return the unit to:

ALTEC Customer Service/Repair

10500 W. Reno

Oklahoma City, OK 73128

For additional Information or technical
assistance, call (405) 324-5311, or Telex
160369 ALTEC OKC.