ATI ML200 User Manual

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ML200

MICROPHONE AMPLIFIER

OPERATING AND MAINTENANCE MANUAL

© Copyright 2008, Audio Technologies Inc.

Audio Technologies Inc. ■ Toll Free 800-922-8001 ■ [e-mail] ■ www.

audio.com

GENERAL

The NANOAMP Series ML200 dual channel microphone preamplifier is an in
expensive high performance, low noise amplifier designed to cleanly boost
professional microphones to balanced line level. ML200 is ideal to drive long
lines in the presence of high hum and noise or as an auxiliary rack mounted
preamplifier to convert mixer high level inputs to microphone levels.

The ML200 provides two outputs at either line or microphone level to drive
balanced and unbalanced lines. HI and LO preamp gain levels are front panel
selectable for each channel. Peak indicators monitor preamp and output circuit
levels. Switched phantom microphone power is provided and all audio
connections are made using XLR type connectors.

The ML200 accepts microphone inputs from –76dBm to +18 dBm thru a high
impedance (20Kohms) balanced, low noise, transformerless (no ringing)
instrumentation amplifier input (A1, A2) and drives servo balanced 600 ohm
(minimum load) outputs (A4, A5) to+4 dBm balanced line level (+22 dBm
maximum). The servo-balanced outputs automatically detect single-ended (one
side grounded) loads; remove drive from the grounded output and double the
signal applied to the ungrounded output thus maintaining equal gain for both
types of loading.

An internal input gain setting DIP switch used in conjunction with the front panel
HI – LO gain selector optimized the preamplifier stage gain, noise and headroom
for the microphone outputs rated at –60, -50, or -40 dBm (HI) or –40, -30, or –10
dBm (LO). Thirty dB if input headroom is provided in the HI position allowing 10,
20, or 30 dBm additional range, if necessary. The Master Gain controls (R23,
R24) adjust the output line level. Individual internal jumper plug output
attenuators (P1, P2) provide –50 dBm microphone level outputs, if desired.

PEAK indicators for each channel monitors both the preamp stage output level
(before the MASTER level controls) and the output drive voltage. The PEAK
indicators operate at 4 to 5 dB below clipping and track varying supply voltages.
If turning down the output level with the MASTER, do not turn off the PEAK
indicator when a reduction of input stage gain with HI – LO switch is indicated.

Phantom microphone power at regulated +20.2 VDC from A6 is selected with a
front panel switch and is sufficient for most powered microphone. +48 VDC
phantom power is also available as an inexperienced plug-in option (PH48-1);
consult factory.

NANOAMPS require 22 to 3- VDC and are designed to share a common external
24 VDC “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 the WA100-2 (230

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VAC) are 400 mA supplies. The DA103 and the DMA103 both draw about 100
mA at full output. Any combination of NANOAMPS, which add up to less than
the supply rating, can be powered by a single supply.

INSTALLATION

WIRING

Audio Connectors balanced XLR type inputs are outputs are wired with pins 2 as
HI and 3 pins as LOW. Pin 1 is cable shield and ground connection.

Active balanced outputs and inputs require a reference ground connection to the
source or receiving device for proper operation. This ground can provide by the
rack frame or a studio ground bus connection if the cable shield does not carry it
through.

GROUNDING

Operation in high RF broadcast environments required special attention to
grounding and shielding. The chassis must be grounded directly to 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 and free to the DC input leads to avoid RF pickup.

POWER DISTRIBUTION

Multiple NANOAMPS 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 can
short against chassis or rack frame.

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SETUP

Before mounting your NANOAMP in a rack, remove the top cover (4 upper side
screws) and set the preamp gain DIP switches (S5, 6, c and d) to match the
nominal expected input level for the HI gain position of the panel switches. Set
the LO preamp gain with the DIP rocker switches (S5, 6, a and d) to the highest
level that does not permit input circuits PEAK indications. Hot mics will require
lower gains (20 – 30 dB) while low output mics will require higher gain settings
(40 – 60 dB). Also, select line (+4 dBm) or mic level (-50 dBm) outputs with
jumper plugs P1 or P2.

MOUNTING

NANOAMPS may be rack mounted one, two, or three across in a standard EIA
19” rack and will require only 1 ¾” of vertical space. Rack mount kit P/N20604­501mounts a single unit, P/N20604-502 mounts two units and P/N20604-503
mounts three units. Each kit provides a different size pair of rack mounting
brackets and one or two horizontal joiner plates, P/N20580-1, each with four 4-40
X 5/16” oval head screws. The joiner plates mount into tapped holes on the
bottom of two side-by-side units, using the supplied screws, while the rack mount
brackets mount under the existing 6-32 cover securing screws in the front sides
of the units.

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 a horizontal joiner kit.

OPTIONS

230 VAC OPERATION

The WA100-2 tabletop power supply accepts 230 VAC/50-60 Hz via an IEC320
male 3 pin AC input connector. User supplies a matching line cord for the local
power system.

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BATTERY OPERATION

Alkaline battery packs (BBU100-1), 24 VDC gel call rechargeable battery packs
(PPA-1) and a DC converter (DCA100-1) to operate from 12 V belt peck, NP-1 or
auto batteries.

48 VDC Phantom Power (DMA103 only)

A DC converter (PH4801) can boost the phantom power up to 48 VDC.

MAINTENANCE

There is no routine required by your NANOAMP. If you have a problem, check
the panel LED indicators to assure that the units have DC power, eliminate by
substitution input and output cables, connectors, downstream device, DC
interconnect cables and Wall Wart power supplies.

POWER SUPPLY LEVELS

The recommended loaded DC input voltage range is 22 VDC minimum to 32
VDC maximum over the full range of AC line voltage tolerances. The audio
circuits will continue to work with reduced headroom below 22 VDC but the
phantom microphone power will drop out of regulation. Momentary surges up to
36 VDC will cause some increased internal heating.

OPERATING POINTS

An Internal reference voltage equal to ½ 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.

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TECHNICAL SPECIFICATIONS

GAIN HI: 80, 70, 60 dB. LO: 60, 50, 30 dB

NOMINAL POWER -50 dBu in, +4 dBm out at 40 dB preamp

gain

PEAK LEVELS -20 dBu in, +22 dBm out to 600 ohm

balanced loads. 40 dB preamp gain

HARMONIC DISTORTION .02% max. at Peak Levels, .01% max. at

Nominal Levels, 20 Hz to 20 kHz

FREQUENCY REPONSE -.25 dB, 20 to 20,000 Hz

CROSSTALK 70 dB minimum at 10 kHz

INPUT IMPEDANCE Balanced, 20 kohms bridging

OUTPUT IMPEDANCE Balanced, 40 ohms maximum Zs

PHANTOM POWER 20.2 VDC regulated, PH48-1 48 VDC

phantom power accessories available.

DIMENSIONS in. (cm) 1.75” (4.45) H by 5.6” (14.2) W by 5.75”

(14.6) D; weight 1.25 lb, (.57 Kg) net

TECHNICAL SPECIFICATIONS Jumper programmable, 50 to 100 ohms

INPUT LEVEL 250 mVrms maximum @ 1 KHz

5 mV nominal @ 1 KHz for+4 dBm out.

OUTPUT LEVEL +18 dBm into 600 ohms, balanced or

unbalanced, 10 Vrms single ended into
high Z load.

CONNECTORS XLR, locking

POWER 24 VDC @ .1A nominal, 22 Vmin. To 30

Vmax, loop thru cylindrical connectors, 2.0
mmID, sleeve is positive.

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ACCESSORIES

All units require 24 VDC power supplies, which are ordered separately. NANOAMPS can share a
single supply-using loop thru DC cable (P/N20602-1). Do not exceed rated supply current.

WA100-1 Wall mount power supply (UL), 24 VDC @

.4 amp, 115 VAC/60 Hz.

WA100-2 Table top power supply, 24 VDC @ .4

amp, 230 VAC/50-60 Hz with IEC 320
male 3 pin AC input indicator. User
supplies matching AC line cord for local
power system.

BBU100-1 Battery Pack unit houses four 9V alkaline

batteries (batteries not included); 6 to 8
hour life.

PPA-1 (-2) Rechargeable 24 VDC gel-call battery

pack with charger for 115 VAC (230 VAC).

DCA100-1 DC to DC converter powers several units

from 12 VDC mobile and belt pack
batteries. Supplies 24 VDC @ .2 amp
operation.

20602-1 DC power cable assembly for looping the

DC power between NANOAMPS.

RACK MOUNT KITS

20604-501 Center mount for single unit.
20604-502 Side-by-side mount for two units.
20604-503 Side-by-side mount for three units.

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).

FIELD ACCESSORIES

PROK-1 Side protection plates with side mounts for

quick-change battery packs.

ARAG-1 Carry case with strap for unit plus power

packs (includes PROK-1).