Boulder 2008 User manual

Boulder 2008
Isolated Preamplifier
Owners Manual
V1.1 5/21/02
Boulder Amplifiers, Inc.
3235 Prairie Ave.
Boulder, CO 80301
www.boulderamp.com
APPENDIX RECORDING EQUALIZATION OPERATION CARTRIDGE SET UP GETTING STARTED

TABLE OF CONTENTS
GETTING STARTED
Placement of the 2008 Phono Preamplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
Connecting the Power Supply to the Main Chassis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
Connecting to the Mains Outlet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
Connecting to a Turntable. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
Phono Cables Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
Connecting to a Balanced Input Preamplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Connecting to an Unbalanced Input Preamplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
Connecting a Cartridge Demagnetizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8
CARTRIDGE SETUP
Personality Card . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Moving Coil or Moving Magnet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Gain Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Demagnetizer Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
Cartridge Loading – Resistive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
Cartridge Loading – Capacitive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
OPERATION
Powering Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Input Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
Mono. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
Equalization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
Low Cut Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
APPENDIX RECORDING EQUALIZATION OPERATION CARTRIDGE SET UP GETTING STARTED

Cartridge Demagnetization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5
Mute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
EQUALIZATION
Equalization Cards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
RIAA Reproduce Curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
FFRR Reproduce Curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
EMI Reproduce Curve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4
Columbia Reproduce Curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5
NARTB Reproduce Curve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6
USING ARECORDER
Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
APPENDIX
Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3
Notes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5
APPENDIX RECORDING EQUALIZATION OPERATION CARTRIDGE SET UP GETTING STARTED

GETTING STARTED
PLACEMENT OF THE 2008 PHONO PREAMPLIFIER
Your Boulder 2008 Preamplifier is designed to reduce interference
from external magnetic and radio fields (RF). While placement is not
critical, known magnetic fields should be avoided. Power transformers
in other pieces of nearby equipment, including the 2000 Power Supply
should be kept away by 2 feet or more.
Because the preamplifier and its power supply are heavy, a solid,
stable surface should be used. As both will generate some heat, they
should be allowed to have good air circulation around them. In partic-
ular, make certain that the fins on the rear of the supply are not
blocked.
You may want to have some access to the rear panels for cable
changes.
GETTING
STARTED
1-1

CONNECTING THE POWER
SUPPLY TO THE 2008
Your Boulder 2008 Phono Preamplifier
is supplied with a Boulder 2000 Triple
Power Supply. Each of the three supplies
is independent of the others except for the
front panel LED which confirms correct
power supply operation of all three sup-
plies.
Three cables are provided for connect-
ing the power supply to the main chassis.
Two of these cables have 4 pin connectors
and are used for connecting the left and
right audio supplies (±27V). The third one
has 5 pin connectors and is used for the digital supplies (+5V).
Care must be taken not to confuse these as any attempt to insert the
wrong connector will result in a damaged connector.
WARNING: Connect and disconnect these cables only with the
power supply turned off for at least 1 minute.
GETTING
STARTED
1-2

CONNECTING TO THE MAINS OUTLET
Your 2000 Power Supply is supplied with a mains cord suitable to
the location where it was purchased. Make certain that the “O” is
pushed on the rocker switch before connecting to your mains.
One of the features of the 2000 is its universal automatic voltage-
selecting power supply. Simply plug it into any standard outlet.
(Exact voltage and frequency compatibility is stated in the specifica-
tions section.)
GETTING
STARTED
1-3

CONNECTING TO A TURNTABLE
Balanced inputs are provided for con-
necting up to three turntables to the 2008.
To avoid hum pickup in the cabling, it is
important to follow these instructions.
Do not connect pin 1 (chassis/ground)
to either pin 2 or 3 at any point in the
cable, turntable chassis, or tonearm. Pins 2
and 3 must only connect directly to the
cartridge pins. This can be accomplished
by several wiring schemes shown on the
next page.
Do not use the Boulder ABL2 input
adapter or other “standard” RCA Phono to XLR adapter because they
connect pin 1 to pin 3. These are intended only for line level use.
Use either a connection from pin 1 to the turntable chassis or a wire
from the CHASSIS screw terminal to the turntable chassis. Using both
might form a ground loop which will create hum.
One pair of Boulder PHRCA Adapters are provided. These will
convert 2008 inputs to RCA and give acceptable performance. A sepa-
rate ground wire is provided. However, obtaining a dedicated cable
with a connector specifically for your tonearm and with 3-pin connec-
tors is preferred.
GETTING
STARTED
1-4
RIGHT
INPUT #1 LEFT INPUT #1
CHASSIS
GROUND
TERMINALS

PHONO CABLES
CARTRIDGE 2008 PHONO INPUT
TURNTABLE CHASSIS
3-POS INPUT
2-POS INPUT
1-POS INPUT
CHASSIS
CARTRIDGE 2008 PHONO INPUT
TURNTABLE CHASSIS
3-POS INPUT
2-POS INPUT
1-POS INPUT
CHASSIS
CARTRIDGE 2008 PHONO INPUT
TURNTABLE CHASSIS
3-POS INPUT
2-POS INPUT
1-POS INPUT
CHASSIS
N.C.
GETTING
STARTED
1-5

CONNECTING TO A BALANCED
INPUT PREAMPLIFIER
For maximum sonic advantage, con-
nect your 2008 Preamplifier’s balanced
outputs to balanced inputs such as provid-
ed on the Boulder 2010 Preamplifier. With
the 2008’s low output impedance, dis-
tances of more than 50 meters between
Phono Preamplifier and Line Preamplifier
are practical. Connect each preamplifier
input to the connectors labeled “OUT-
PUT.”
GETTING
STARTED
1-6
RIGHT
OUTPUTS LEFT OUTPUTS

CONNECTING TO AN UNBALANCED INPUT
PREAMPLIFIER
Aspecial cable is required to make this connection. This cable con-
nects pin 1 to the shield and pin 2 to the center pin. It leaves the out-
put pin 3 unconnected.
Connecting the unused output pin (usually pin 3) to ground will
cause excessive ground currents and degrade performance. Use an
ohmmeter or continuity checker to determine how a cable is wired.
GETTING
STARTED
1-7
UNBALANCED OUTPUT CABLE
3-NEG OUTPUT
2-POS OUTPUT
1-GROUND
LINE
PREAMP
INPUT

CONNECTING A CARTRIDGE
DEMAGNETIZER
The Boulder 2008 Phono Preamplifier
has RCA jacks for connecting your car-
tridge demagnetizer. Connect each chan-
nel of the demagnetizer to the left and
right jacks labeled DEMAG.
For further instructions, see page 2-2
and 3-5, or consult your Boulder dealer.
GETTING
STARTED
1-8
RIGHT
DEMAGNETIZER
JACK
LEFT
DEMAGNETIZER
JACK

CARTRIDGE SET UP
PERSONALITY CARD
Each 2008 input has two slots for personality cards, one for left, and
one for right channels. The cards serve two functions– switches to set
the electronics for the type of cartridge used at that input, and places to
solder the custom load termination resistor and capacitor.
The 2008 is shipped with all 6 cards installed in the rear panel and 4
additional spare cards.
The cards installed for inputs 1 and 2 are set to HI GAIN and MC,
and have a load resistor installed to set the input impedance to 100Ω.
These are the most commonly used settings for a MC cartridge.
The cards installed for input 3 are set to HI GAIN and MM, and
have no additional load resistor thus leaving the input impedance at
47KΩ. These are the most common settings for a MM cartridge.
WARNING: Press the POWER pushbutton until the POWER indi-
cator is off before removing or inserting the personality card. Failure to
do so might result in very loud clicks.
To remove, pull the card firmly. To insert, push the card until it
completely seats into the connector and the face is flush to the panel.
CARTRIDGE
SET UP
2-1

MOVING COIL OR MOVING MAGNET SELECTION
Set the bottom switch to either Moving Coil (MC) or Moving
Magnet (MM) depending on your type of cartridge.
In the MC position, the maximum input resistance is 1000Ω without
additional components installed on the card. Two of the cards are
shipped with a resistor to bring the impedance down to 100Ω, which is
recommended for MC. Also in the MC position, an additional low
noise, 20 dB gain stage is inserted at the input.
In the MM position, the maximum input resistance is 47K Ω with-
out additional components installed on the card. This is the impedance
recommended for MM.
GAIN SELECTION
The middle switch marked LO GAIN, HI GAIN adjusts the output
stage gain by 10 dB. This switch is used to more closely match your
preferred volume setting on your line preamplifier.
When using modern very low output cartridges, it is recommended
to try setting this switch to HI GAIN.
If in doubt about a setting, try the HI GAIN position first. If you
find that you are having to reduce the volume on your line preamplifi-
er more than usual, then you might try the LO GAIN position to ensure
you are not overloading the input of your line preamplifier.
CARTRIDGE
SET UP
2-2

DEMAGNETIZER SELECTION
ADEMAG connector for your cartridge demagnetizer is provided
on the rear panel. If you want to allow demagnetization of the car-
tridge connected to a particular input, set the top switch to DEMAG
OK. Otherwise, set it to NO DEMAG.
Only the inputs which have the switch set to DEMAG OK will be
connected to the DEMAG connector when the DEMAG indicator is red.
WARNING: Do not demagnetize a MM cartridge.
CARTRIDGE
SET UP
2-3

CARTRIDGE LOADING – RESISTIVE
For MC cartridges, the maximum resistive load is 1,000 Ohms. This
is the value when there is no resistor added to the Personality Card.
This value may be lowered by adding a resistor (as shown) at R1
whose value is calculated by the following:
R1 = 1/(1/RDESIRED – .001)
Some typical values are:
Desired R (Ω)R1 (Ω)
50 52.3
100 110
200 249
500 1,000
For MM cartridges, the maximum resistive load is 47,000 Ohms.
This is the value when there is no resistor added to the Personality
Card. This value may be lowered by adding a resistor (as shown) at R1
whose value is calculated by the following:
R1 = 1/(1/RDESIRED – .0000213)
Some typical values are:
Desired R (Ω) R1 (Ω)
1,000 1,020
5,000 5,620
10,000 12,700
20,000 34,800
CARTRIDGE
SET UP
2-4
R1

CARTRIDGE LOADING – CAPACITIVE
The 2008 Phono Preamplifier inputs have only “parasitic” capaci-
tance of less than 50 pF directly across the cartridge inputs. If desired,
additional capacitance can be added on the personality card at C1. The
capacitor chosen should be 50 pF less than the desired value.
Solder holes are provided for two different size capacitors. There
are two pairs of holes as shown, two at left and two at right. Each pair
is connected together. The capacitor need be soldered to only one of the
left and one of the right holes.
All solder holes have grommets to reinforce the PC board when
parts are installed and removed. Do not remove these grommets.
BOULDER SUGGESTS: While there are some cartridge manufac-
turers who recommend using capacitive loading, we suggest that you
do not do so. Adding more capacitance only lowers the resonant fre-
quency of the capacitor and the cartridge winding inductance, particu-
larly with MM cartridges. The resonance peak is still just as high and
destructive to the sound.
Instead, try a lower resistor value; the lower the value, the “heav-
ier” the load and the lower the resonance peak (not frequency) thus
giving better dampening to the cartridge.
With low level MC cartridges, there is virtually no effect of capaci-
tive loading because the cartridge output impedance is inherently very
low.
2-5
CONNECT CAPACITOR
FROM ONE LEFT HOLE
TO ONE RIGHT HOLE

OPERATION
POWERING UP
With all your connections made, you are ready to listen to your
Boulder 2008 Phono Preamplifier.
Push on the upper portion of the rocker switch on the rear panel of
the 2000 Triple Power Supply. The indicator on the supply will first
turn red, then amber.
The indicator will be amber during normal operation. If for any
reason, any of the power supplies’ voltages are low, the indicator will
change to red.
Press the POWER pushbutton on the front of the 2008. The POWER
indicator will be amber. The MUTE indicator will be red and the out-
put will be muted for the first 3 seconds.
The front panel POWER pushbutton can be used for everyday turn
on and off. This pushbutton mutes the outputs, turns off the audio
electronics, and puts the 2008 in a standby mode.
If you are going to turn off the 2000 power supply, it is highly rec-
ommended to turn off the 2008 by pressing the POWER pushbutton
first causing the POWER indicator to be off.
OPERATION
3-1

INPUT SELECTION
The Boulder 2008 Phono Preamplifier provides inputs for 3 car-
tridges. These can be from one or more turntables. Only one of these
inputs can be used at a time.
Select an input by pressing one of the pushbuttons labeled ONE
through THREE. The 2008 will immediately mute the outputs and the
MUTE indicator will be red for 3 seconds. After that time, the output
will be unmuted and the MUTE indicator will be off.
Anytime a different input is selected, the 2008 will similarly mute
for 3 seconds.
It is not recommended to select an input that has no cartridge con-
nected. Make connections to an input first and then select the input. If
it is necessary to have all inputs disconnected, then mute the preampli-
fier temporarily.
MONO
To enhance monaural recordings, it is often desired to mix the left
and right channels together to form a true monaural signal. In the 2008
it is possible to do this at the output of both channels by turning on
MONO mode.
Pressing the MONO pushbutton will place the 2008 into monaural
mode and the MONO indicator will be red.
To return to normal stereo operation, again press the MONO push-
button. The MONO indicator will be off.
OPERATION
3-2