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Ground Bypass Jumper
The internal ground jumper (located above the RIGHT channel load resistor, see illustration) may be used
to bypass (in the bridging position) the 100 ohm local ground isolation resistor directly to common. This
may provide more, or less, “hum” immunity, depending on your other equipment.
AGM Rechargeable Battery Operation and Charging
The Seta should always be kept powered, to maintain both a stable circuit temperature and the condition
of the AGM battery. The power consumption (no signal) when the battery is fully charged is low, less than
5 watts. If necessary, the Seta may be disconnected from the power supply for up to a few months without
adversely affecting the battery life.
Do not store the Seta at elevated temperatures
, such as in an attic or
garage.
The Seta
must
be connected to the external power supply for operation. This design insures that the
battery isn’t accidentally over-discharged, which could shorten its life. The power supply is used to
activate two normally-open relays, connecting the battery to the Seta circuitry, and the charging supply to
the battery. When a signal is detected, the second relay is deactivated, disconnecting the charging supply
from the battery (and the Seta preamplifier circuitry). The battery voltage monitoring and power
management are automatic.
The battery, when fully charged, is capable of supplying power for well over 24 hours of continuous
operation. The AGM type lead/acid battery is superior to
all
other battery types used in high-end audio
applications (see http://www.channld.com/seta.html, under the Rechargeable Battery section).
The Seta will automatically activate Charge mode under either of the following two normal conditions:
•
A signal resulting in an
output
level of less than -40 dBV isn’t detected for about 20 minutes.
•
The AGM battery has exhausted its charge.
The switching to Charge mode (or from Charge to Battery mode) will be unnoticeable, even while playing
music. A faint, mechanical click may be heard (from an internal relay) if holding an ear close to the
preamplifier.
If you want to use the Seta to burn in another component, or use it for noncritical listening, the Charge
Lock selector switch is provided to lock the Seta in Charge mode, overriding the signal level detector.
Battery Life / Battery Replacement
Typical battery life will be between 3 and 6 years; up to 20 years is possible. The battery life is deter-
mined by three factors:
(1) operating environment temperature (temperatures above 80 F should be avoided, as this will degrade
battery life)
(2) the number of deep discharges (defined as continuous operation for more than 24 hours without
activating the Charge or Manual Charge mode)
(3) battery life will be extended by keeping the Seta continuously connected to a power source (the idle
power consumption is less than 5 watts) and the battery fully charged.
The battery capacity also typically will increase slightly (by a few percent) during the first few discharge /
recharge cycles.
