Description – ATI Audio HDA100 User Manual

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Description

The HDA100 is a rugged, battery or AC powered headphone amplifier that will
provide excellent performance driving a wide range of typical stereo headphones.
It will drive the usual 32 to 600 ohm high efficiency stereo headphones to teeth
rattling levels around 120dB SPL with a combination of high output voltage swing
(16Vp-p) for high impedance phones and a protected high current capability
(.2Ap-p) for low impedance phones. It will do the above at distortion levels below
.10% and response flat to .25db both measured over the full frequency range of
20Hz to 20kHz.

HDA100 will bridge (40Kohms) both balanced and unbalanced input lines with
individual left and right XLR input jacks. Connect balanced inputs HI to XLR pin
2, or TRS-TIP and LO to XLR pin3 or TRS-RING, Shields go to XLR pin 1 or
TRS-TIP and with the cable shield to XLR pin 1 or TRS-SHLD. Be careful to
observe HI-LO input polarity to avoid monaural or center stage cancellation
effects. The unused TRS or XLR connector pair may be used to loop through the
input signal to additional HDA100s. The wiring to the rear panel TRS connectors
is not the same as the wiring for the stereo headphone jack/plug on the front
panel.

The HDA100 is shipped setup for +4dBu nominal input level (+24dBu peak). An
internal jumper plug P1 may be moved for additional input gain to accommodate
RCA jack levels at –10dBu (.25V) nominal (+12dBu peak). To change P1,
remove the top cover by removing the four upper Phillips head screws (two on
each side). P1 is located on the PC board directly behind the volume control and
has two positions; for –10dBu inputs move the plug to the front, for +4dBu inputs
move the plug toward the rear. Ensure that no internal wiring is caught or
pinched, replace the cover and screws.

The HDA100 will provide a comfortable listening level of 1mW at around 12
o’clock on the volume control for most headsets. The amplifier is capable of
driving many headsets to dangerous levels over 120dB SPL. If you can hear
distortion, it’s TOO LOUD! Levels near 120dB SPL can easily cause
PERMANENT HEARING DAMAGE.

The HDA100 is powered by 24VDC from an external power module such as the
WA100-1. The DC power connector is center pin negative, sleeve position with a
2.1 mm center pin and a 5.5mm outer sleeve. Two HDA100 can share one
WA100-1 with accessory DC loop-thru cable 20602-1.