1.2.4. Separate Substation AC chassis
This is a key element contributing to the performance of the Overdrive SE. A
separate Substation enables more densely packed energy storage for each
voltage, more optimized layout and creates space between the magnetics in the
supplies and the Overdrive Chassis to eliminate coupling.
2. Thermal Considerations –
extremely important
Both the Substation AC and Overdrive SE chassis run at elevated temperature. The
Overdrive and Substation chassis should always be placed side-by-side, never stacked.
Avoid placing them on a warm shelf or on top of another warm component. The primary thing
to be careful for is that the tops of the chassis not be too hot to touch. If you cannot keep
your hand on either one, the location or environment is too hot and accelerated wear-out or
failure may occur. It is best to run the Overdrive in Low-Gain mode if possible to minimize
heating. The ambient room temperature should not exceed 75 degrees Fahrenheit or 24
degrees Celsius. Alternately, you can run in High-Gain mode and adjust the volume down.
3. Break-in
All electronics needs a period of break-in. New capacitors and dielectric insulators must
stabilize with voltage and current applied. The Overdrive SE is broken-in by Empirical Audio
for approximately 5 days before shipping. An additional 25 days of 24/7 break-in is required
for full break-in, with all inputs driven. Each input breaks-in independently, so all should be
driven with a signal. Outputs do not have to be connected in order to break-in.
4. Volume settings
4.1. Volume Control
The volume control mode can be selected by using the right-most recessed toggle
switch on the front panel. Up position selects volume control. The switch selects
between volume or line-out on power-up only, not on-the-fly. To make a change, you
must power off the Substation and back on using the front-panel power switch. As with
all systems, at initial power-on, the volume should be rotated to its lowest setting before
playing music.
4.2. Optimum Remote Control
Remote volume control capability can be achieved quite easily by using a combination of
the manual volume control, a digital volume control (such as iTunes, Amarra or Pure
Music volume) and the USB interface. If one adjusts the volume to a comfortable
listening level with the manual control with the software digital control at max, then only
small reductions of the digital control from maximum are necessary to adjust the track-
to-track amplitude variation. Up to –9dB of reduction is possible without degradation in
sound quality with a high-quality digital volume. This is even better than having yet
another remote control. Most of us already have too many of those. It allows you to use
an iPod Touch or iPad for everything: song selection, muting and volume control,
without any loss of resolution. This is the best possible scenario.
4.3. Gain Switch
A two-position gain switch is recessed into the front-panel. It is the left-most of the two
switches. The upper position is low-gain, which is typically used for volume control
direct to amps. The lower-position is high-gain, typically used with volume driving amps
directly to low-efficiency speakers, or line-level to a preamp. This can be switched at
any time, but will only take effect after powering down the Substation and back up again
using the front-panel power switch. For driving most amplifiers directly with 1V
sensitivity for full power, the switch should be in the “L” position. If you have low-
sensitivity speakers, you may need the “H” setting.
