Manual-4
600
Ω
USER INFORMATION
The AVA 22d’s Inputs are specified for a n4 dB
u
input, which is a voltage referenced level of 1.228 volts rms.
(0 dB
u
= 0.7746 Volts). At this
voltage
level, the AVA 22d provides 16 dB of headroom. Users who wish to operate the AVA 22d in
600 Ω systems must provide their own 600 Ω input resistor across the input terminals. This enables the AVA 22d to accept a +4 dB
m
input and allows delivery of +4 dB
m
to a 600 Ω load. Confusion among 600 Ω users of the AVA 22d may occur if one assumes the
input and output impedances of the AVA 22d are 600 Ω – they are not. Therefore, when evaluating the AVA 22D do not assume that
+4 dB
m
4 dB
u
unless you have ensured that all input and output impedances in your test setup are 600 Ω.
Advantages of Hi-Z in/Lo-Z out systems:
(from
Audio System Design and Installation,
by Phillip Giddings, Howard W. Sams, 1990, pp. 129-130.)
1. Less distortion in output due to smaller output current needs.
2. Lower noise pickup by interconnecting lines due to lower source impedance.
3. Greater lengths of cable may be driven for a given high frequency roll-off.
4. Many pieces of equipment can be driven from one output without the use of distribution amplifiers and with no concern for
matching or level changes.
5. Better reliability resulting from less heat generation due to less power drawn from the output stage.
6. Because of the AVA 22d’s 200 Ω output impedance, the addition of a 600 Ω load termination drops the delivered voltage by about
2.5 dB.
7. Greater signal voltage swing as 6 dB of signal is not lost in the (600 Ω) source impedance.
8. Smaller currents reduce inductive coupling and crosstalk between cables.
AVA 22d CONNECTION
When connecting the AVA 22d to other components in
your system for the first time,
leave the power supply for last
. This
gives you a chance to make mistakes and correct them before
any damage is done to your fragile speakers, headphones, ears,
or brains. The AVA 22d passes audio while it is unpowered by
virtue of its fail safe bypass relays (when the AVA 22d functions
as a wire). Turn the system volume down before plugging in the
AVA 22d’s power.
INPUTS
The AVA 22d’s Inputs are electronically balanced. Use only
balanced wiring. Pin 2 is “hot” per AES standards.
OUTPUTS
The AVA 22d’s Outputs are balanced line drivers. Pin 2 is
“hot” per AES standards.
REMOTE RECALL TERMINALS
Each channel of the AVA 22d has two nonvolatile Memories,
“A” and “B”. Connecting a switch between the GND and MEM
terminals permits remote stereo recalling of the Memories. Only
a change in the switch position is sensed. When the switch
closes, both channels’ Memory B’s are recalled. When the switch
opens, both Memory A’s are recalled. See the Operating Instruc-
tions for more details or an option.
