Sutherland Director Line Preamp User manual

OWNER’S MANUAL
Line Preamp
DiDirectotor
The

The Director’s basic circuitry and design concept are refine-
ments of years of expertise in high-end preamplifier manufac-
turing. Throughout its design, Ron Sutherland repeatedly
bench marked The Director’s performance to “cost-no-object”
options. The design was not complete until The Director could
stand proudly among such Sutherland smash hits as the Ph.D.
and AcousTech PH-1P phono preamplifiers. We are pleased to
make this contribution to your enjoyment of recorded music.
FEATURES
The Director fulfills the basic preamplifier functions of:
Input Selection, Volume Adjustment & Gain. But with The
Director, those functions are entirely unique and refined.
Let’s take a closer look:
Input Selection
Traditional input selection is based upon naming each input
on the front panel and then associating that name with back
panel labeling. But there’s a very good chance that the labeling
will not match an individual’s particular system requirements.
And memorizing that, for example, the phono is associated with
the AUX 2 label is certainly a less than elegant solution.
Some computer-based preamplifiers let the user assign
alphanumeric names to each set of input jacks. While this fixes
the misnaming problem, the alphanumeric display requires a
constant scanning update, creating a very intrusive high-fre-
quency buzz. By our standards, that is totally unacceptable.
With The Director, there’s no need to even label the inputs.
When a musical signal is detected at an input on The Director,
the selector automatically routes that signal into the preamplifi-
er. So, to listen to CD, hit the “play” button on your CD player.
To listen to LPs, just stop the CD player and start up your
turntable. As soon as the stylus touches the groove, The
Director will recognize that you want to listen to LPs.
Furthermore, the volume level will automatically set to the value
last used when listening to records. If more than one input is
active, the conflict is indicated on the four discrete input LEDs.
They will toggle between the active inputs, indicating the need
to shut down all but the desired input. Also, as soon as a signal
for any source is detected, that signal detector is disabled. If it
weren’t, the signal detector would add digital noise to the pre-
amplifier environment. Simple and noise-free – that’s The
Director.
Volume Adjustment
The most popular volume control chips on the market are
laden with features but short on musicality. Most contain
mediocre op amps and analog circuitry squeezed onto a chip
full of digital circuitry. Fine for home theater or car stereo, but
not appropriate for high-end goals. The Director uses a basic
attenuator function that consists of only j-fet switches and a
precision resistor ladder. It has proven to be sonically neutral
with low noise and has excellent channel-to-channel matching. It
is consistent with the simplified signal path philosophy that
drives all Sutherland Engineering designs.
Rather than the ordinary digital volume display with its noisy
multiplexing problems, The Director uses a 16 LED bar graph to
indicate volume level. Musicality takes precedence over margin-
ally useful digital minutia. There are a total of 128 volume set-
tings available on The Director, giving a volume control range of
78 db. Volume changes are smooth and click-free.
Gain
At the heart of any preamplifier is the gain stage. Any defi-
ciencies here will negate all the effort and expense of getting
everything else right. From the beginning of The Director, we
established top-level performance goals. It had to be open,
effortless and have a dynamic, explosive punch. Those goals
could not be met with op amp based gain stages. We developed
a gain stage using all discrete transistors. Hermetically sealed
dual j-fets are used in the input stage, followed by bipolar gain
stages and a class-A push-pull bipolar output stage. All bias cur-
rents are appropriately high to maintain a dynamic reserve.
Extensive use of a high-capacity, low-impedance power supply
reservoir contributes to the effortless, unstrained sonic signa-
ture of The Director.
Power Supply
The Power supply is the foundation that supports all the
other circuitry. If it is not right, not perfectly clean and stable,
everything depending on it will be compromised.
We acquired a great deal of experience from the design and
refinement of the Ph.D. phono preamplifier. In that design, using
alkaline batteries allowed for total AC power line isolation. The
results were spectacular and reinforced the importance of a
clean power source. Because of that success, we initially
planned on creating a battery-powered line stage. While the per-
formance of such a prototype was very good, it didn’t quite
stand up to the cost-no-object standards that we wanted The
Director to meet. We needed a higher-power-consuming circuit
topology to achieve effortlessly explosive dynamics. It was
decided to incorporate the high bias current discrete circuit and
then work on the power supply.
We determined that the conventional approach of using a
voltage regulator for isolation from the AC power line would not
meet our design goals. Its output was still too close to the
noise on the AC power line. We instead chose to use an active
constant-current regulator followed by multiple layers of passive
pi RC filters. The constant-current regulator gave very high
impedance isolation from the AC power line. In this case, high
impedance is very desirable as it represents the electrical “dis-
tance” from the AC power line. However, the active preamplifier
circuit requires a low-impedance power source. A low impedance
gives the circuit direct and quick access to power. The original
high impedance current source is transitioned to a low imped-
ance voltage source using a shunt voltage regulator. This combi-
nation of an active, high impedance current source, passive pi
RC filtering, followed by a low impedance shunt voltage regula-
tor gave us the electrical (and sonic) equivalent of battery
power.
DiDirectotor
The

Remote Control
The upper row of two buttons controls the volume. The left
button reduces the volume. The right button increases the vol-
ume. The volume LED bar on The Director will move left or right
to indicate a response to the remote control signal.
The lower row of two buttons controls muting. The left but-
ton mutes the audio. When the mute signal is received, the vol-
ume LED bar on The Director will quickly move all the way to
the left. A flashing volume LED indicator will then indicate the
stored volume level. The right button restores the volume level.
The volume level will quickly ramp up to restore the previous
listening level.
Optimizing Gain On Each Input
Although there are standard recommended voltage levels for
line-level sources, not all manufacturers comply with those
standards. In particular, some products have a VERY elevated
output voltage level. They hope their product will be perceived
as “more powerful” or just “bigger.” In reality, the only thing
that can be done with a large input signal is to attenuate it
until it is brought in line with standards. To accommodate the
wide range of input levels that might be encountered, each of
the four line-level inputs of The Director can be individually con-
figured.
The Director is shipped with all four inputs configured for
standard input voltage levels. When configured DIRECT, the
maximum input voltage before clipping is 3 volts rms.
When sourced from components with a higher line-out volt-
age, the inputs associated with that source should be config-
ured ATTN. When configured ATTN, the maximum input voltage
before clipping is 18 volts rms.
Configuration is easily set by moving the red, gold-plated
shunt connectors located near each pair of input jacks to the
appropriate setting. On the circuit board are silk-screened leg-
ends showing the configuration settings.
Unity Gain
The Director is well suited for inclusion in multichannel sys-
tems. In such systems, The Director would control the front
two channels of audio. Two-channel music sources go to the
line-level inputs of The Director. A multichannel controller would
handle multichannel sources. Its two front channel line outputs
would then go to one of The Director’s line level inputs. That
input would then be assigned a unity gain. When listening to a
multichannel source, The Director will automatically sense the
signal coming from the multichannel controller and then pass
that signal straight through with unity gain.
Assigning Unity Gain
Send a signal to The Director from the multichannel con-
troller. When it is detected, The Director will indicate the selec-
tion of that input by lighting the amber LED associated with
that input.
Program that input as unity gain by pressing the volume-up
button on the remote control and, while still holding the vol-
ume-up button, turn the volume knob clockwise.
When an input has been assigned as having unity gain, the
volume controls on the remote and the volume knob on the
unit will have no effect. If volume control commands are sent,
the unity gain input LED will blink.
Restoring Variable Gain
Send a signal to The Director on the input to be restored.
When it is detected, The Director will indicate the selection of
that input by lighting up the amber LED associated with that
input.
Program that input as variable gain by pressing the volume-
down button on the remote control and, while still holding the
volume-down button, turn the volume knob counter-clockwise.
Display Brightness
The brightness of The Director's display is user-adjustable.
The control is on the bottom of The Director, at the center of
the front of the unit. There is a space between the front panel
and main chassis frame where you'll find a small thumb-wheel
knob mounted on the front panel circuit board. Turn the knob
to adjust the brightness of your display. Do not be forceful with
the knob.
Note: All voltages on this board are very low, so there is no
risk of shock. An input must be selected for the brightness
control to be sensed, i.e. a yellow light must be on.
USING YOUR DIRECTOR
Machined Aluminum Front Panel
Aircraft grade 6061 aluminum
Precision grained and clear anodized
Ball bearing mount of control knob
Custom machined control knob
Silky-smooth feel “forever”
Extremely robust
Steel cover and case
Heavy 12 gauge (1/8” thick)
Extreme magnetic and electrostatic shielding
Durable powder coated epoxy finish
Gold plated, Teflon dielectric RCA connectors
Musically truthful
Reliable, robust
Vishay/Dale resistors
1% tolerance
Industrial grade
Color-banded version of Military RN55
Environmentally sealed with conformal, protective epoxy
Controlled temperature coefficient
Low voltage coefficient
Excellent high-frequency characteristics
Low noise
Fire cleaned, high purity ceramic core
Laser trimmed nickel chrome alloy element
Wima capacitors
Polypropylene dielectric for lowest dielectric absorption
Rugged, reliable potted construction
Established reliability
Made in West Germany
Socket ICs
Each pin of an IC is grabbed by 4 gold-plated
beryllium-copper fingers
Each contact is loaded into a precision-machined shell
High contact force
Easy replacement of ICs without risk of board damage
Circuit board
Environmentally stable FR4 fiberglass substrate
Ground plane pours on both sides of board establish a stable
ground reference, as well as electrostatic shielding
Torroidal power transformer
Low radiated magnetic field
Encapsulated in epoxy for rugged environmental protection
Dual primary for 120/240 volt operation
QUALITY OF CONSTRUCTION

1500 S. Ninth, P.O. Box 1905, Salina, Kansas 67402
785.825.8609 • Fax [phone] • www.acousticsounds.com
Sutherland Engineering products, like those of AcousTech Electronics,
are designed by Ron Sutherland for exclusive distribution through Acoustic Sounds, Inc.
SPECIFICATIONS and OPTIONS
INPUTS
4 high level inputs
VOLUME STEPS
31 steps of 1 dB in the range of –27.3 dB to –57.3 dB
96 steps of 0.5 dB in the range of +20.7 dB to –27.3
dB
UNITY GAIN OPTION
Any one or more of the inputs can be assigned unity gain
pass thru for home theater use.
MAXIMUM INPUT VOLTAGE
Each input of the Director can be configured as DIRECT
or ATTENUATED.
When configured DIRECT, the maximum input voltage
is 3 V rms.
When configured ATTN, the maximum input voltage
is 18 V rms.
MAXIMUM DISTORTION
Less than 0.01% total harmonic distortion plus noise
‘A’ weighted, output level 2.5 volts rms, 1 kHz
MAXIMUM GAIN
DIRECT +20.7 dB
ATTN +3.8 dB
INPUT IMPEDANCE
When configured DIRECT 42,000 ohms
When configured ATTN 29,000 ohms
OUTPUT IMPEDANCE 270 ohms
MAXIMUM OUTPUT VOLTAGE 8 Volts rms
POWER CONSUMPTION 10 Watts
FUSE TYPE 1⁄8amp, slo-blo
DIMENSIONS 17” wide X 4.25” high X
15” deep
NET WEIGHT 24 lbs. (11 kg)
SHIPPING WEIGHT 29 lbs. (14 kg)
The Director is retailing for $3,000. Yet, we know that it com-
petes sonically with cost-no-object designs. So, how is this pos-
sible?
In many of the expensive high-end preamplifiers you will see
extravagantly machined cases that contribute nothing to sound
quality. The Director is encased in a very robust, epoxy-powder
coated 12-gauge steel case and a machined aluminum panel.
The machined knob turns in a large steel ball bearing. This is
all first-class material, but with The Director you’re not paying
for extra (and unnecessary) jewelry.
Without solid engineering, even the most expensive compo-
nents will not make a great sounding preamplifier. The Director
is based upon a solid technical foundation. It is a no-non-
sense, focused design, and it is not based on tweaking exotic
and problematic components.
The power cord supplied with The Director is a “cheapie.” It is
plenty adequate, but some users may want to upgrade the
power cord. We decided to keep the cost of high-end power
cords out of The Director’s retail price and instead let the cus-
tomer make that decision.
The Director’s remote control is not the kind of machined case
remote control you would find with much more expensive pre-
amplifiers. On the other hand, it is compact, attractive, light-
weight and simple to use.
Construction has been simplified. It was decided to make an
extra investment in the up-front engineering expenses to simpli-
fy the construction of each production unit. This investment
helps keep the cost to assemble each unit reasonable. When
you look inside the case of The Director you will immediately
see the neat, tidy layout. There is an elegant functionality to
each design decision.
The Director is a streamlined design. It is not laden with extra
features. Everything about it is focused on sound quality. And
now it’s yours to enjoy.
A BIT MORE ABOUT YOUR DIRECTOR