ATI Audio DP100 User Manual

Page 2

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DESCRIPTION

Channels LL and RR of both the DP100 and the MM100 convert unbalanced IHF inputs
via RCA phono jacks J1 and J2 into transformer balanced 600 ohm XLR outputs at J3
and J4. The RCA inputs are RF bypassed and diode protected from excessive level.
Panel gain controls R9 and R10 allow a reference +4dBm output to be set for inputs
ranging from less than .1V to over 1.0V and will allow many playback devices having
front panel output level controls to be simply preset to their maximum. The input stages
A1-3 and A1-4 provide a stage gain adjustable from +8 to -24dB. Output stages A2-1
and A2-2 provide 14dB additional gain and the total isolation, faraday shielding, superior
balance, improved RF immunity and ease of application of a true transformer coupled
balanced output. A unique feedback technique totally avoids the transformers
characteristic limitations of high distortion, poor response and hum pickup. Typical
output distortion measurements made at both peak (+22dBm) and nominal (+4dBm)
levels barely exceed generator residuals at .004% from 20Hz to 20,000Hz. Hum pickup
from the power supply is non-existent and flat response is greatly extended. The output
is protected from short circuits but will drive over a half mile of shielded cable with less
than 1dB of signal rolloff at 20,000sHz.

The MM100 bi-directional interface additionally incorporates a pair of differential
amplifier channels, A1-1 and A1-2 (L and R) which bridge balanced (or unbalanced)
XLR input, 600-ohm lines at J5 and J6 and convert their signals to IHF level (.25 Volt, -
10dBu) at phono jack outputs J7 and J8. Heavy common mode bypassing of the inputs
gives excellent RF protection and internal CMR trimmers R35 and R36 allow 80dB hum
nulls to be set and maintained. Output level controls R39 and R40 accommodate 0 to
+8dBm nominal inputs or allow presetting of connected IHF recorder input controls. The
IHF outputs may be paralleled for mono.

Your ATI interface operates from an internal, double filtered bipolar 16VDC supply,
which uses a couple of unique regulating devices called zener diodes. In contrast to
fancy IC regulators, zener diodes will live through most power line transients and
simultaneously protect your expensive circuitry. The supply is designed for minimum
susceptibility to power line conducted RF with bypassed ferrite beads, RC primary side
bypassing and a non-concentric wound, semi-toroidal power transformer.

APPLICATION

Consumer audio equipment can offer unique features, good performance and attractive
pricing making it very desirable for professional use. Unfortunately, RF pick-up,
crosstalk, high frequency roll off, hum loops and distortion are often the results of direct
connection of low level unbalanced IHF outputs into the 600 ohm systems used in studio
or broadcast environments.

This manual is related to the following products:

MM100