BROWN SP-2B User manual

SP-2B Stereo Preamplifier
Owner’s Manual!
1

Introduction:
Thanks for purchasing the SP-2B Stereo Preamplifier, this preamplifier designed and
built using the best components available, and will give you several years of reliability and
performance. The SP-2B, is a full function preamplifier, with both MM phono stage ,and
line stage section. The phono stage features two dual triode 6SL7 valves, using active RIAA
equalization, coupled to a MOSFET source follower for lower output impedance and
greater drive to the line stage. The line stage itself features a dual triode 6SN7 valve which is
known for it’s linearity and tonal qualities. The power supplies of the SP-2B are the heart
of the preamp itself, a heavily filtered, and well regulated power supply, able to deliver
ample current to the critical stages of this unit.
Specifications:
Inputs: MM Phono, CD,TV, Tuner,Media/Aux(unbalanced RCA)
Outputs: Two RCA unbalanced
Frequency Response: Line Stage 5 ~ 100,000Hz. (+/-0.2dB). Phono Stage
20 ~ 20,000Hz. (+/-0.4dB)
Input Impedance: 100,000 ohms
Output Impedance: 350 ohms
S/N Ratio: Greater than 90dB
Tube Compliment: 2- 6SL7’s. 2-6SN7’s. Power supply tubes can vary from
unit to unit, depending on customers choice, and availability.
Power Consumption: ~30 Watts
Dimensions: 4.25”X 18”X 10”
Weight: 17lbs
2

Unpacking Procedure:
1.Remove Top Cover
2.Remove packaging from around tubes make sure tubes are properly seated
during installation, they should have a faint glow during power on.
3. Remove protective cushioning from around signal tubes.
Power Up Procedure:
1. Connect all components to appropriate inputs.
2. Connect to Power Amplifier(s) and AC Cord.
3. Make sure mute switch is in the “Operate” position.
4. power up sources first, then preamp and lastly the power amplifiers.
5. There should be a delay of about 30 seconds before outputs are engaged, the
mute LED will flash for 30 seconds, you will hear a slight clicking noise, and
the LED will remain on.
6. when powering down, engage the mute switch back to the “mute”
position. Switch power amplifiers down first,Then the preamp, and lastly the
sources.
Fuse Replacement:
Replace fuse with 750mA (250V) Slow-Blo Time Delay. Size is 5mm X 20mm
cartridge.
Caution: Allow for adequate ventilation, as the preamp tubes produce quite a
bit of heat.
3

4
Setting up MC head amp
Only required set up on the MC board are
The load settings for your particular cartridge,
the Moving Coil head-amp is only required for
low output moving coil cartridges >2.5mV,
make sure that both switches at the back of the
unit, the input switch and board switch are in
the MC position
Pictured above are the red colored load switches
Found inside on the MC board, 4 different load
settings are included from top to bottom are:
1000,100, 50 and 20 ohms, if you need a custom
load, simply call or email with request
Pushing the switch to the right will engage the
load for that switch, ALWAYS power down
preamplifier before changing load setting.

Adjusting Gain
The line stage incorporates gain adjustments pots, that can be adjusted to
suit proper output level for both channels. Pictured below is the line stage
with the location of the trim pots, a small insulated screwdriver can be used to
make necessary adjustments.
Turning clockwise will increase the gain, turning counter-clockwise will
decrease the gain.
5