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Pro-Ject Phono Box DS3 B Balanced MM/MC Phono Preamp

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  • $ 799

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The Phono Box DS3 B comes in a steel and aluminum chassis providing very high rigidity and splendid isolation from interference. Phono Box DS3 B is available in silver or black. Magnetic wooden side panels are sold separately.

‘B’ for Balanced

In addition to settings for MM (Moving Magnet) cartridges, the Phono Box DS3 B allows you to upgrade to True Balanced operation with a MC (Moving Coil) cartridge on most Pro-Ject turntables. Balanced transmissions consist of a hot and a cold (also called + and -) signal. Both signal chains effectively carry the same musical information. A true balanced gain stage can now extract the final musical information out of the +/- signals and subtract the hum and noise picked up during the transmission. This is the same concept used with every microphone in every professional recording studio worldwide.

Discrete Circuitry

The Phono Box DS3 B uses fully discrete audio circuitry 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 as neutral, natural, dynamic nor vivid as we’d prefer. This discrete circuitry is designed in a full dual mono configuration for optimal channel separation and clarity.

Passive EQ

After treating the balanced signals they are added back together and processed by the fully passive and discrete RIAA equalization stage. By keeping the gain stage fully symmetrical we can optimize the signal to noise ratio, 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, one balanced, one single ended. Switching between the two and all other settings are conveniently available on the front panel. Input settings for each input are stored individually and recalled automatically.

A large gain range from 40dB up to 65dB is possible. You can match it with a wide variety of cartridges and seamlessly integrate it into the rest of your hifi system, matching the volume levels accurately to other sources like CD players or streaming devices. The loading options for MM and MC are designed for compatibility with a wide array of cartridges. Ultra low values like 50pF or 10 ohms allow you to account for special situations, for example less-than-ideal higher capacitance cables. The Phono Box DS3 B has always got you covered!

  • Input impedance: Stepless 10–1000 ohms or fixed 47k ohms
  • Input capacitance: 50, 150, 300, 400pF
  • Gain (+6dB using XLR out): 40, 45, 50, 55, 60, 65dB
  • SNR MM (40dB): 104dBV, 111dBV (‘A’ weighted)
  • SNR MC (60dB): 85dBV, 91dBV (‘A’ weighted)
  • THD (1kHz): <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
  • Inputs: 1x 5-pin mini XLR / 1x pair XLR / 1x pair RCA
  • Line-level output: 1x pair RCA / 1x pair XLR
  • Wiring XLR sockets: 1 ground, 2 ‘hot’, 3 ‘cold’
  • Trigger in/out: 12V on/off detector
  • Outboard power supply: 18V/500mA DC
  • Power consumption: 18V/max.290mA DC, <0.5W standby
  • Dimensions: 206 x 72 x 194mm (205mm with sockets)
  • Weight: 1480g without power supply

WARNING: California Residents - Proposition 65. This product can expose you to chemicals known to the State of California to cause cancer and birth defects or other reproductive harm. For more information, go to



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