Owner`s manual

Warnings
1. To prevent fire or shock hazard, do not expose this
product to rain or moisture.
2. This unit operates on voltages which can cause serious
injury or death. Do not operate with covers removed.
Any necessary servicing should be carried out by your
authorized Audio Research dealer or other qualified
electronics technician.
3. Use only the plastic insulated screwdriver included with
this unit when making front panel bias adjustments.
4. The power cord on this unit is safety-tested and is
equipped with a proper grounding plug. If used normally,
it will provide a safe earth ground connection of the
chassis. Defeat of the grounding plug, or any unautho-
rized modification of the active circuitry or controls of
this unit, automatically voids warranty coverage,
5. For safe operation and protection against fire hazard,
replace fuses only with those of the same type and
rating as those supplied with this unit.
6. At 170 lbs. (77.2 Kg) net weight per chassis, the Refer-
ence 610T amplifier is too heavy for one person to lift.
To avoid injury, do not attempt to unpack, lift or move
the unit without the help of at least one other person.
7. Always mute the preamplifier when cueing a phono
cartridge stylus up or down.
Due to the immense power supply reserves, unusually
high power output, and wide bandwidth of the
Reference 610T, added emphasis must be placed on use
of your preamplifier's mute switch from a safety stand-
point. A transient signal burst or “pop” such as caused by
tonearm cueing, accidental dropping or brushing of the
phono cartridge stylus –even at a normal listening
level–could cause an instantaneous peak power demand
on the amplifier of up to 1000 watts (which the Refer-
ence 610T will try to deliver). The importance of lower-
ing the preamplifier volume level to a minimum setting
and activating the mute switch whenever cueing the
tonearm or making contact with the phono cartridge
stylus cannot be over-emphasized. Adhering to this pre-
cautionary muting procedure is equally important when
turning your system on or off, and when connecting or
disconnecting any cables in the system. Carefully follow-
ing this recommendation will minimize the chance of
causing undue stress and potential damage to your am-
plifiers and loudspeakers. (See your preamplifier Owner's
Manual for more detailed instructions on use of muting
provisions.)
Description of Controls
Front Panel Rotary Controls
There are four front panel rotary controls: Power, Power
Scale, Display/Function, and Bias.
P O W E R : This control turns the amplifier on and off, and
selects one of two operating modes. From the “Off” posi-
tion, the amplifier should be switched to “Operate.” There
will be an automatic warm-up sequence for approximately
two minutes, during which “Mute” will flash in the display
window. After this initial warm-up the amplifier is ready
for listening. The “Standby” position keeps the high voltage
regulator at half its normal operating voltage so that it is in
a warm, ready state. Tube filaments are on but the tubes
are not conducting. This reduces the time it takes the
Reference 610T to reach full sonic performance without
sacrificing output tube life, and should be used between
listening sessions. When the amplifier is switched from
“Standby” to “Operate” there will be an automatic warm-up
sequence for approximately two minutes, during which
“Mute” will flash in the display window. We recommend
that the Reference 610T be switched to “Off” when there
are protracted intervals between listening sessions.
POWER SCALE: This control selects in the display window
one of five logarhithmic, moving bar graphs to display pow-
er output: 0-10 watts, 0-30 watts, 0-100 watts, 0-300 watts
and 0-600 watts. The Power Scale function must first be
selected with the Display/Function control before selecting
a specific Power Scale mode.
D I S P L A Y / F U N C T I O N : This control selects one of three
functions: power output scale, line voltage, or output tube-
bias measurement/adjust.
BIAS: This control selects individual output tube locations
for checking output tube bias current level. When V1 and
V2 are selected, the actual bias level of these two tubes may
be adjusted by inserting the supplied flat-bladed tool into
the labeled adjustment pot and rotating until the display
reads 65mA. All other output tubes may be checked, but
not adjusted, for their individual bias levels, which should
normally fall in the range of 57–73mA. A tube which per-
sistently measures outside this range should be replaced.
DISPLAY SCREEN: The large vacuum-fluorescent display
screen on the front panel has seven levels of brightness,
including off. The illumination level of the display can only
be adjusted using the handheld remote control; this func-
tion cannot be selected via the front-panel controls. When
the display is off, the use of any control will turn the
display back on for ten seconds, then off again.
The screen displays all functions and operating modes as
they are selected: Standby/Mute in Standby mode; Power
Output bar graph as normal default in Operating Mode;
large numerals for A. C. line voltage; large numerals for bias
check; and small numerals for total hours accumulated.
Note that the “Hours” function can only be selected using
the handheld remote and will turn off after ten seconds.
Model Reference 610T
2