ATI Technologies SUM100 User manual

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
SUM100
LINE/SUM/LINE 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
The SUM100 Summing Amplifier is an inexpensive, high performance amplifier
that is designed as a line level stereo to mono summing amplifier. It is also useful
as a gain block, and as an impedance converter and summing for IHF (RCA
type) signals.
The inputs provide balanced 40Kohm bridging impedance for line levels up to
+24dBm. The high input impedance allows the SUM100 inputs 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 driver is a servo controlled, ground-sensing circuit, which will
supply over +22dBm to 600 ohm balanced loads and +20dBu to high impedance,
unbalanced loads. The SUM100 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 amplifiers will mount side-by-side in only one rack unit using the
available rack mounting kits. NANOAMPS 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 SUM100 Line Amplifier utilize a FET input
LF347 quad op-amp 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. Linear
panel adjust trimpots for both left and right signals are designed to be operated at
their 12 o’clock position for maximum resolution.
SUMMING AMPLIFIER
Left and right signals are combined in an active summing network (A1B) which
yields unity gain for each individual signal, three dB gain (RMS summation) for
program audio signals and six dB gain for correlated inputs.

Audio Technologies Inc. | 154 Cooper Road #902 | West Berlin, NJ 08091 | Voice 856-719-9900 | Fax [phone] | www. audio.com
GAIN STAGE
A low noise NE5532 section (A1A) provides 26dB maximum gain. A linear control
is used in a unique circuit configuration to provide a wide range logarithmic
MASTER 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. Unity overall
gain is achieved at approximately 12 o’clock pot position.
LINE OUTPUT
The balanced output stage of the SUM100 utilizes 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 SUM100 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 permits 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 SUM100 draws 70mA. Any
combination of amplifiers, 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

Audio Technologies Inc. | 154 Cooper Road #902 | West Berlin, NJ 08091 | Voice 856-719-9900 | Fax [phone] | www. audio.com
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. The amplifiers need either their own separately ordered
WA100 power supply or a DC cable, P/N20602-1 to share the supply of another
amplifier.
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.
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

Audio Technologies Inc. | 154 Cooper Road #902 | West Berlin, NJ 08091 | Voice 856-719-9900 | Fax [phone] | www. audio.com
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.
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. 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

Audio Technologies Inc. | 154 Cooper Road #902 | West Berlin, NJ 08091 | Voice 856-719-9900 | Fax [phone] | www. audio.com
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
ADDITIONAL GAIN
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.

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
Dimensions: 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.
Nanoamps 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).
Four-to-six-hour life
DC100-1: DC to DC converter powers several units from 12VDC mobile and belt pack
batteries. Supplies 24VDC @ .2amp maximum
20602-1: DC power cable assembly for looping the DC power between NanoAmps
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)
20617-505 Horizontal joiners for 2 units (side by side)
21075-501: Rack mount system mounts three units in one rack