Pro-Ject Tube Box DS2 Vacuum Tube Phono Preamplifier Instruction Manual

: June 6, 2024
: Pro-Ject

Table of Contents

Safety instructions
Potential incorrect use and fault conditions
Service
Warranty
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INSTRUCTIONS FOR USE
Pro-Ject Tube Box DS2

Dear music lover,
Thank you for purchasing this tube phono preamplifier from Pro-Ject Audio Systems.
In order to achieve maximum performance and reliability, you should study these instructions for use carefully.
Warning of a hazard for the user, the unit, or possible misuse
Important notice

Safety instructions

AC outlet voltages vary from country to country. Before connecting to the mains, make sure that the voltage in your area meets the voltage requirements printed on the power supply.
The power supply is used to connect/disconnect the unit from the mains. Make sure that the power supply is easily accessible at all times. Never handle the device, the power supply while your hands are wet or damp. Avoid letting liquids enter the device or the power supply. Never place any item containing liquid, such as a flower vase on or near the device. Never spill any liquid on the device or the power supply. Never place any naked flame sources, such as lighted candles on or near the device.
The product shall not be used in damp or wet locations, next to a bathtub, sink, swimming pool, or any other similar conditions.

Connectors

Make all connections whilst the phono amplifier is disconnected from the power supply.
Do not connect the phono amplifiers output to a phono input (sometimes labeled gram, disc, or RIAA) on the amplifier.
Never use any other power supply than the one supplied with the unit.
Connecting one or two record players
IN1 and IN2 allow the connection of two turntables or one turntable with 2 tonearms. By switching between IN1 and IN2 the individual settings are retrieved. Connect left and right channels of the tonearm signal lead to the sockets marked IN1 or IN2 of the phono amplifier. The earthing wire may be connected to the screw terminal if you encounter hum problems when using the record player.
Connection to the amplifier
Connect the output sockets marked OUT1 or OUT2 of the phono amplifier to one or two-line inputs (such as AUX, CD, Tuner, Tape, or Video) on your amplifier.

Mains power connection
Connect the low voltage plug from the power supply to the Power 18V DC socket of the phono amplifier before connecting the power supply to the mains.
Remote power on – triggers
The phono amplifier can be switched on & off via a special connection from other Pro-Ject products equipped with trigger connections via the 2,5mm socket marked Trigger Input.
The remote power-on signal can be relayed to further units via the Trigger Output socket. Cables are offered as accessories on request (polarity).

Controls

To switch on from standby or to standby
The switch on the left-hand side of the front panel turns the unit on or back into standby. The blue LED above the standby switch shows that the unit is switched on. Tube Box DS2 can be used immediately.

Settings
Use the buttons and the rotary control at the front to control the unit. Any change of settings will be automatically stored for the chosen input when input is changed or the unit is switched into standby mode.
Input and Output
Tube Box DS2 has two separate inputs IN1, IN2 and outputs OUT1, OUT2. The button Input selects between inputs and the button Output switches between outputs.

Subsonic
Turn on and off the subsonic filter. Any change will be automatically stored for the chosen input when input is changed or the unit is switched into standby mode.

Adapt to the connected phono cartridge
The rotary control and the 3 control buttons on the right side of the front panel are used to set gain, input impedance, input capacitance. You will find all details about the construction principles and technical data in the manual of the phono cartridge. The gain to be selected depends on the output voltage of the pickup and also on the characteristics of downstream devices. If in doubt, consult your dealer for advice.

Gain dB
Gain for the outputs can be set between 40dB, 45dB, 50dB, 60dB and 65dB in steps of 5dB or 10dB. Any the change will be automatically stored for the chosen input when input is changed or the unit is switched into standby mode.
Input impedance, variable – low-output MC cartridges
The button Loading Ω must be set to Variable. Use the rotary controller to set input impedance to the desired value (10Ω-1000Ω)

Input capacitance is irrelevant for low-output MC cartridges
Input impedance, 47k – high-output MC and MM cartridges
The button Loading Ω must be set to 47k.
Input capacitance, variable – high-output MC and MM cartridges
The rotary control must be set to 10 Ω. Press Loading Ω until the LED marked by 47k lights up. The device has a basic capacity of 47pF, and the Load pF button can be used to increase the terminating capacity by 100pF, 220pF or 320pF depending on the LED display, making the values 47pF, 147pF, 267pF or 367pF available
To find out which type your cartridge is, please consult the literature accompanying your cartridge.
The literature for cartridges should also specify the correct input impedance (low-output MC cartridges) and the correct input capacitance (high-output MC and MM cartridges), into which the cartridge is designed to work. If in doubt please consult your dealer.

Examples of typical settings

Ortofon 2M Red
(MM)| Rotary control| 10Ω
---|---|---
Loading Ω| 47kOhm
Gain| 40dB
Loading pF| 100pF
(plus basic capacitance 47pF adds up to total of 147pF)
Ortofon MC3 Turbo
(High-Output MC)| Rotary control| 10Ω
Loading Ω| 47kOhm
Gain| 45dB
Loading pF| 320pF
(plus basic capacitance 47pF adds up to a total of 367pF)
Ortofon MC Cadenza Black
(Low-Output MC)| Rotary control| 20Ω
Loading Ω| variable
Gain| 60dB
Loading pF| capacitance for Low-Output MCs is not relevant

The values given by the manufacturer for capacitance settings for MM, MI, and high-output MCpickups are guideline values. Since the right setting is also dependent on the capacitance of the tonearm cable used and the inner wiring of the tonearm, experimentation with settings can be carried out. The recommended terminating resistance for Low-Output MC cartridges is also a guideline. The gain should be set to the highest value, which makes distortion-free playback still possible. You cannot destroy anything when experimenting with the different settings. What you like best is right!

Technical specifications Pro-Ject Tube Box DS2

Tubes:
Input impedance :
Input capacitance :
Gain:
Output voltage typically:
Noise floor:
THD:
RIAA-equalisation curve accuracy:
Input:
Line-level output:
Outboard power supply:
Power consumption:
Dimension W x D x H (D with sockets)
Trigger output/input:
Weight (without power supply):| 2 x ECC83 (12AX 7A)
variable 10-1000 ohms/ 47.000 ohms (47kΩ)
47pF, 147pF, 267pF, 367pF
40, 45, 50, 60 and 65 dB (switchable)
500 mV/1kHz at 5mV/1kHz (at 40dB)
88 dB (A weighted, at 40dB gain)
<0,04 %
20 Hz – 20 kHz / +0,2dB / -0,2dB
2 pairs RCA/phono sockets
2 pairs RCA/phono sockets
18 V/1000 mA DC
490mA DC, <0,5W in standby
206mm x 227 (239)mm x 91mm aluminium
240mm x 227 (239)mm x 93mm wood
12V (2,5mm jack)
1500g aluminium
1960g wood
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Potential incorrect use and fault conditions

No signal on one or both channels:
No connection between player and phono amplifier or amplifier. This could be due to a faulty plug, broken wire or solder joint, or simply a loose plug/socket connection.
Strong hum: No earth connection from cartridge or arm, or arm cable to phono amplifier, or earth loop.
Output too quiet or too loud, or distorted: Input gain incorrectly set – input overloading or insufficiently amplified.

Service

Should you encounter a problem that you are not able to alleviate or identify, please contact your dealer for further advice. Only if the problem cannot be resolved there, the unit should be sent to the responsible distributor in your country.

Warranty

The manufacturer accepts no responsibility for damage caused by not adhering to these instructions for use. Modification or changes to any part of the product by unauthorized persons release the manufacturer from any liability over and above the lawful rights of the customer.

Copyright, trademarks
Pro-Ject Audio Systems is a registered Trademark of H. Lichtenegger. This guide was produced by:
Pro-Ject Audio Systems Copyright ©2017. All rights reserved.

The information was correct at the time of going to press. The manufacturer reserves the right to make changes to the technical specification without prior notice as deemed necessary to uphold the ongoing process of technical development.