Pro-Ject Audio Phono Box DS3 B True Balanced, Dual Mono & Fully Discrete Audiophile Phono Stage



The Phono Box DS3 B model offers some of the high-end features of the Phono Box RS2 at an affordable price and trusted Pro-Ject quality. One of those is our new True Balanced Connection.


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The new DS3 phono stage
The Phono Box DS3 B has a steel chassis that is covered by screwed aluminium panels. This construction
brings very good rigidity and splendid isolation against interferences. Phono Box DS3 B is available in silver or
black. Magnetic wooden side panels are sold separately.

„B“ stands for balanced
The Phono Box DS3 B employs a true fully balanced gain stage design. Connect your turntable either with the 5-pin
mini XLR cable or standard XLR cables & profit of the balanced signal path. Symmetrical, or also called balanced,
transmissions consist of a hot and a cold (also called + and -) signal. Both signal chains effectively carry the same musical information.
A truly balanced gain stage can now extract the final musical information out of the +/- signals and subtract, and remove,
all noise that could potentially be added along the transmission. As there are two separate signal chains, we also needed two individual amplifier sections.

Discrete Circuitry
The Phono Box DS3 B uses fully discrete audio circuitry. A discrete circuit is composed of electronic components
which are disparate, individual devices, also called discrete components. Countless hours of listening tests
and years of experience have shown us that even the very best Op-Amps do not tend to be so neutral, natural, dynamic or vivid.
Standard phono pre-amplifiers with integrated circuits have a few tens or hundreds of components, but discrete designs
will employ hundreds or thousands of components by comparison.

Passive EQ
After treating the balanced symmetrically they are added back together and processed by the fully passive and discrete
RIAA equalisation stage. By keeping the gain stage fully symmetrical we can optimize the signal-to-noise ratios,
giving the EQ section the best source to work its magic on. Fully split passive equalization allows for better
impedance matching and lower deviation from the ideal RIAA curve. For the balanced XLR outputs, a discrete balancing stage
generates a symmetrical signal, so you benefit from balanced signal transmissions again. The single-ended RCA outputs run their own fully discrete output stage, served directly by the RIAA EQ.

Cartridge loading options
You can connect two turntables at the same time & easily set everything on the front plate. Each input setting is stored in the memory.
Large ranges from 40dB up to 65dB are possible. A fully balanced design makes all the difference here, handling
amplification levels this high. You can perfectly match it with a wide variety of cartridges and perfectly integrate
it into the rest of your Hifi system, matching the volume levels accurately to other sources like CD players or streaming devices.
Load impedance can be set continuously via a potentiometer, a system invented by Pro-Ject Audio Systems.
It allows you to seamlessly adjust the impedance during playback and immediately assess the impact of different loading options. This is necessary to find just
the right load impedance for your cartridge. No other manufacturers implement this feature in this extreme way!

External power supply
The Phono Box DS3 B is powered by an external adapter. It is important to keep all the parts that can radiate
electromagnetic fields out of the amplifier range. This is the reason why we are using an outboard power supply.
Due to legal requirements, this power supply must be a switch mode type with guaranteed stand-by mode power consumption 0,1W.
An outboard power supply with linear construction is even better, because it can offer much cleaner power.
When you want to manufacture such clean and really high-end power supplies, you have to use a transformer
with a very low core saturation and preferably with shielding between primary and secondary windings.

Power Box DS2 Sources – linear power supply upgrade
Low core saturation decreases radiation of the outer electromagnetic field which can be inducted into sensitive circuitry.
Shielding between windings works as a very efficient filter that effectively suppresses interference from mains.
When it is combined with a DC-blocker which avoids the saturation of a core by DC current, the resulting filtration is even better.
The mechanical vibration of the transformer is also reduced. It is critical that the transformer in use is also vacuum impregnated.
Obviously, such a transformer becomes larger than one would expect. Also, much more expensive. That is why such a power supply requires
a cabinet the size of the Phono Box DS3 B itself. The location of the power supply shouldn’t be close to Phono Box DS3 B.
Additionally, the Phono Box DS3 B shouldn’t be exposed to big transformers in power amplifiers or other appliances which can cause
electromagnetic interference either. Strong electromagnetic fields from big transformers in very close proximity can even penetrate
the heavy metal/aluminium chassis of the Phono Box DS3 B. Even a chassis like this has its limits! The best arrangement is to keep
the Phono Box DS3 B as far away as possible from those harmful electromagnetic fields.


Input impedance: Stepless 10 – 1000 ohms or fix 47kOhms
Input capacitance: 50, 150, 300, 400pF
Gain (+ 6dB using XLR Out): 40, 45, 50, 55, 60, 65 dB
SNR MM (40dB): 104dBV, 111dBV – ‚A‘ weighted
SNR MC (60dB): 85dBV, 91dBV – ‚A‘ weighted
THD at 1 kHz: <0,001% MM, < 0,004% MC
THD (20Hz-20kHz): <0,005% MM, < 0,01% MC
RIAA-equalization accuracy: < 0,25dB / 20Hz – 20kHz
Subsonic filter: at 20Hz with 18dB/octave
Input: 1x 5-pin mini XLR / 1x pair XLR / 1x pair RCA phono
Line-level output: 1x pair RCA, 1x pair XLR
Wiring XLR sockets: 1 ground, 2 “hot” and 3 “cold”
Trigger In/Out: 12V on/off detector
Outboard power supply: 18V/500mA DC
Power consumption: 18V/max.290mA DC, <0.5 W standby
Dimensions: 206 x 72 x 194 (205 with sockets) mm
Weight: 1480g without power supply

Additional information


Black, Silver


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