ATI Technologies L200 Operating instructions

Audio Technologies Inc. | 154 Cooper Road #902 | West Berlin, NJ 08091 | Voice 856-719-9900 | Fax [phone] | www. audio.com
© Copyright 1997-2005, Audio Technologies Incorporated - Printed in USA
L200
LINE/SUM/MIKE AMPLIFIER
OPERATING AND MAINTENANCE MANUAL

Audio Technologies Inc. | 154 Cooper Road #902 | West Berlin, NJ 08091 | Voice 856-719-9900 | Fax [phone] | www. audio.com
DESCRIPTION
Your L200 Dual Line/Buffer Amplifier is an inexpensive, high performance
amplifier, which is ideal as a gain block, attenuator, impedance converter,
summing amplifier and signal splitter.
The inputs provide balanced 40Kohm bridging impedance for line levels up to
+24dBm. The high input impedance allows the L200 input to also bridge -10dBu
(hi-fi, RCA plug) lines without loading.
Front panel, screwdriver adjust, full range gain controls provide 26dB gain at full
clockwise rotation, unity gain at twelve o’clock and a smooth audio taper to full
off.
The output drivers are servo controlled, ground-sensing circuits, which will supply
over +22dBm to 600 ohm balanced loads and +20dBu to high impedance,
unbalanced loads. The L200 uses rugged XLR type input and output connectors.
Loop-through DC connectors allow several NANOAMPS to share a single
external 24VDC power supply. Battery packs and DC-DC converters for portable
use are also available.
Up to three NANOAMPS will mount side-by-side in only one rack unit using the
available rack mounting kits. Your L200 may also be neatly stacked or mounted
side by- side on your desk with the available angled desk mounting kits.
CIRCUIT DESCRIPTION
INPUT STAGES
The balanced input stages of the L200 Line Amplifier utilize a FET input LF347
quad opamp in a clean, quiet inverting instrumentation amplifier configuration.
Input levels up to +24dBm will be handled without clipping, excess levels cause
only clean clipping without hang-up or phase reversal. Equal -6dB gains from
both HI and LO inputs allow unbalanced sources to be easily accommodated.
Bridging impedance is a high 40Kohms with good CMR.
GAIN STAGES
A low noise NE5532 provides 26dB maximum gain. Inexpensive linear controls
are used in a unique circuit configuration to provide a logarithmic gain control
characteristic in a variable gain stage with optimum noise performance. Output
noise at unity gain is low enough to allow performance to exceed 16-bit digital
dynamic range even at -10dBu nominal output.

Audio Technologies Inc. | 154 Cooper Road #902 | West Berlin, NJ 08091 | Voice 856-719-9900 | Fax [phone] | www. audio.com
LINE OUTPUT
Balanced output stages of the L200 utilize a unique active balanced output driver
IC, the Analog Devices SSM2142, that senses whether the connected load is
balanced and floating or is unbalanced due to either side being grounded. A
balanced output load will be driven with equal and antiphase levels on the HI and
LO output lines. An unbalanced (one side grounded) load will cause the driver IC
to shut off the signal output to the grounded side of the load and double the
output level applied to the other side, thus maintaining equal output to either type
of load. The output stage provides 6dB gain and will drive loads of 600 ohms and
higher. Nominal output is +4dBm with clipping at +22dBm (10Vrms) into 600 ohm
balanced loads for 18dB nominal headroom. Maximum output is reduced to
+20dBu (7.8Vrms) when driving an unbalanced load since the full output swing of
only one driver is available. This still provides a very comfortable 30dB of
headroom above the typical -10dBu nominal unbalanced signal.
POWER SUPPLY
The L200 requires 22 to 30VDC and are designed to share a common external
24VDC "Wall Wart" type power supply. A pair of loop-thru DC connectors on the
rear of each module permit several units to be daisy-chained with P/N20602-1
DC power cables to a single power supply. The WA100-1 and WA100-2
(230VAC) are 400mA supplies. The L200 draws 70mA. Any combination of
which add up to less than the supply rating can be powered by a single supply.
INSTALLATION
UNPACKING
Inspect the equipment. If there is any visible damage to the unit or to the box it
came in, contact the factory but do not return anything to ATI without prior
authorization and shipping instructions. It may be necessary to have the shipping
company inspect the unit and the box at your location. Count the pieces! Don't
throw out the boxes and packing material until you are sure you have everything
that is coming to you. They need either their own separately ordered WA100
power supply or a DC cable, P/N20602-1 to share the supply of another.
Rack and desk mounting hardware may be packed in with the unit even though
ordered separately. Wall mount power supplies must be ordered separately but
may either be included with the unit or shipped in their own box.

Audio Technologies Inc. | 154 Cooper Road #902 | West Berlin, NJ 08091 | Voice 856-719-9900 | Fax [phone] | www. audio.com
MOUNTING
Single desk mounting kits consist of a pair of angled base plates that mount
under the lower front and rear cover screws of a single unit, to raise and to tilt it
for easy use. In addition, one or more sets of vertical stacking plates, mounting to
the upper front and rear cover screws of the bottom unit, allow multiple units to
be stacked. Several units can be desk mounted side-by-side and even stacked
side-by-side using horizontal joiner kits together with mounting base and stacker
kits. P/N20617-501 is the angled base kit. P/N20617-502 is the base plus one
stacker kit (two high). P/N20617-503 is the base plus two stackers (three high).
P/N20617-504 is the stacker kit by itself and P/N20604-504 is a horizontal joiner
kit. Rack mount system 21075-501 mounts three units in one rack
WIRING
AUDIO CONNECTIONS
Balanced XLR type inputs and outputs are wired per figure 1 with pins 2 as HI
and pins 3 as LOW. Pin 1 is the cable shield and ground connection. Pin 1 is
grounded as shipped but may be floated to interrupt a hum producing ground
loop by opening the unit and clipping out the GND LIFT jumpers. Unbalanced
lines use pin 2 as HI and ground pins 3 and 1. Active balanced outputs and
inputs require a reference ground connection to the source or receiving device
for proper operation. This ground can be provided by the rack frame or a studio
buss connection if it is not carried through by the output cable shield.
GROUNDING
Operation in high RF broadcast environments requires special attention to
grounding and shielding. The chassis must be grounded directly to a good, low
impedance studio ground system. Input and output connections must be properly
shielded and free of ground loops. It may even be necessary to add shielding to
the DC input leads to avoid RF pickup.
POWER DISTRIBUTION
Multiple amplifiers sharing a single wall-wart power supply should be looped
through each other using the DC interconnect cables P/N20602-1. Hum and
noise performance of the units can be degraded by poor DC ground connections
between units sharing a common supply, use of the recommended rack and desk
mounting kits will assure a good ground connection between units by firmly
strapping their chassis together. CAUTION! The outer shell of the DC
interconnect cables is positive relative to the chassis. Do not allow a DC cable
plugged into a powered unit to hang loose where it might short against the
chassis or rack frame.

Audio Technologies Inc. | 154 Cooper Road #902 | West Berlin, NJ 08091 | Voice 856-719-9900 | Fax [phone] | www. audio.com
OPTIONS
230VAC
The WA100-2 tabletop power supply accepts 230VAC/50-60Hz via an IEC320
male 3 pin AC input connector. User supplies a matching line cord for the local
power system.
Battery Operation
Alkaline battery packs (BBU100-1) and 24VDC converters for operation from 12V
belt pack or automotive batteries (DC100-1) power modules are available.
MAINTENANCE
There is no routine maintenance required by your amplifier. If you have a
problem, check panel LED indicators to assure that the units have DC power,
eliminate by substitution input and output cables, connectors, downstream
devices, DC interconnect cables and Wall Wart power supplies.
POWER SUPPLY LEVELS
The recommended loaded DC input voltage range is 22VDC minimum to 32VDC
maximum over the full range of AC line voltage tolerances. The audio circuits
continue to work with reduced headroom below 22VDC. Momentary surges up to
36VDC will cause some increased internal heating, but above 36VDC may cause
IC failure.
OPERATING POINTS
An internal reference voltage equal to 1/2 the supply voltage is generated. All
audio stage IC inputs and outputs should show a DC level equal to this voltage
when measured with a high impedance meter. Audio inputs and outputs are
capacitor coupled and ground referenced.
MODIFICATIONS
If more gain is required for a particular application increase the values of R25
(left) and R34 (right). 20K ohms adds 6dB, 30K ohms adds 10dB, 62K adds
16dB, 100K adds 20dB. A corresponding decrease in the input clipping level will
result. SUMMING AMPLIFIER if you wish to sum the inputs, remove the cover
and find the jumper plug J4. Move J4 from the parked position so that it jumps
both terminal pins. Either input signal will now appear at both outputs at a level
as set by the individual input gain control. The summing network causes 6dB of
loss however the two inputs sum to +3dB (+6dB for in phase sine waves).

Audio Technologies Inc. | 154 Cooper Road #902 | West Berlin, NJ 08091 | Voice 856-719-9900 | Fax [phone] | www. audio.com
PERFORMANCE SPECIFICATIONS
GAIN: 28dB maximum, 0dB at 12 o’clock pot position
NOMINAL LEVELS: +4dBu in, +4dBm out to 600 ohm balanced load
PEAK LEVELS: +24dBu in, +22 dBm out to 600 ohm balanced load
NOISE 20kHz B.W.: -90dBm maximum output
HARMONIC DIST.: .02% Max at Peak Level
20Hz to 20 kHz .005% max at Nominal Level
FREQUENCY RESP.: +.25dB, 20 to 20,000Hz
CROSSTALK: 70dB minimum at 10kHz
INPUT IMPEDANCE: Balanced, 40kohm bridging
OUTPUT IMPEDANCE: Balanced, 40 ohms maximum Zs
DIMMENSIONS: 1.5"H by 5.5"W by 5.75"D; Weight: 1.5 Lb. Net
CONNECTORS: XLR (balanced input/outputs)
POWER: 24VDC @ .07A, connector sleeve is positive.
POWER SUPPLIES: All units require 24VDC power supply, which is
ordered separately. Amplifiers can share a single
supply-using loop thru DC cable (P/N 20602-1). Do
not exceed rated supply current
WA100-1: Wall mount power supply (UL), 24VDC @ .4 amp,
115 VAC/60 Hz
WA100-2: Tabletop power supply, 24VDC @ .4 amp, 230
VAC/50-60 Hz with IEC 320 male 3 pin AC input
connector. User supplies matching AC line cord for
local power system
BBU100-1: Battery Pack unit houses four 9V alkaline batteries
(batteries not included). 4 to 6 hour life
DC100-1: DC to DC converter powers several units from
12VDC mobile and belt pack batteries. Supplies
24VDC @ .2amp maximum

Audio Technologies Inc. | 154 Cooper Road #902 | West Berlin, NJ 08091 | Voice 856-719-9900 | Fax [phone] | www. audio.com
20602-1: DC power cable assembly for looping the DC
power between
DESK MOUNT KITS: 20617-501 Angled Desk Mount Base
20617-502 Angled Desk Mount Base and One
Stacker (2 units high)
20617-503 Angled Desk Mount Base and Two
Stackers (3 units high)
20617-504 Stacker (2 units high)
20604-504 Horizontal Joiner (2 units side-by-side)
RACK MOUNT KITS: 21075-501 Rack mount system