Technical Description

Combining a high performance CD player, FM tuner, state-of-the-art digital amplification and lustrous Primare design, Primare’s ultra-compact CDI10 introduces great sound, simple convenience and a beautifully understated Scandinavian style to the compact system market.

By sharing the same CD transport as the award winning CD31, the CDI10's CD replay is of an exceptionally high standard. An advanced 24-bit/196kHz conversion is employed to provide extraordinary fidelity with a compact disc source.

Amplification is through a high performance Class-D (switch mode) design capable of delivering 75 watts into an 8 ohm load. To ensure the purest sound quality, all audio signals are balanced to remove noise before the amplification stage.

Inputs and outputs

The CDI 10 has three sets of RCA inputs as well as recording and preamplifier outputs. In addition to these, a 3.5mm combined headphone output and line input mini jack socket is found at the front of the CDI10. Using this front input, an iPod®, MP3 or minidisk player can be connected and control of volume is moved to the CDI10. This same jack is also able to convert into an audio output so to drive a pair of headphones.

Furthermore, the CDI10 incorporates an A/D-converter, which ensures that a digital SPDIF-output will be available regardless of the selected input source, making high quality digital recordings possible on, for example, a minidisk or other digital audio recording device.

The user interface

To satisfy Primare’s signature desire for operational simplicity, full remote operation is supported by the major function controls conveniently mounted on the top panel, together with an interactive graphical display.

The top cover overlaps the back panel allowing for placement near a wall with all cabling covered by the unit.

CD

The CD-transport is the high performance DSL710 from DVS, a drive mechanism Primare has used with excellent results in more costly units.

The electrical circuit consists of a PCM1738 D/A-converter, which performs conversion for the CD-player. The current-to-voltage conversion stage consists of Burr-Brown OPA2134 high performance op amplifiers and is finished in a single-ended output stage. Here you’ll find a single MOSFET transistor together with an active current source instead of the use of passive resistors.

Volume control is performed by a carefully isolated PGA2311 from Burr-Brown together with a DC-servo circuit instead of the use of capacitors in the signal path. Before reaching the class-D amplifier, the signal is converted to balanced. This is done to cancel out noise and distortion that may have arisen during transmission, leaving only the pure audio signal to reach the power stage.
  
Tuner

No entertainment system is complete without the availability of a variety of FM radio broadcasts. Primare’s advanced tuner circuitry ensures low noise with exceptional signal capture extracting the best audio fidelity possible from the FM band. 40 FM presets provides ample programming options for organizing your favorite radio stations.
  
Amplification

Developed, manufactured and sold by Primare in cooperation with a Swedish partner from the power supply industry, the self-modulating class-D amplifiers used by the CDI10 are of a proprietary design and are not ICE power modules! Their performance can be compared to some of the best of class-AB amplifiers.

The technology used in these modules is extremely simple and still displays world-class audio performance in the entire audio band. This extraordinary amplifier performance is achieved by carefully choosing component parts and a very thorough printed circuit board layout.

The amplifier is self-modulating which means that the switching is controlled by the delay in the loop. The amplifier starts increasing the output voltage as soon as it is a little too low and starts decreasing the output voltage as soon as it is a little too high. The inertia in this process causes the amplifier to oscillate in a controlled manner at about 550kHz. You could say that the amplifier controls and corrects the output voltage 550,000 times per second with zero error tolerance during each control cycle. The self-oscillating modulator is so linear in itself that it does not need additional feedback paths and this gives a very robust amplifier with low cost and extremely good audio performance. The distortion is not only very low, it is also nearly frequency independent giving a very homogenous sound. The very low noise floor of about 70uVrms allows for every micro-detail to be displayed in the sound stage without deterioration.

The input signal is received by a differential stage built around a high precision op amp from Analog Devices. This eliminates potential ground loops and improves crosstalk between channels. The signal is forwarded to the modulator which is controlled by a second op amp, this one also a precision type from Analog Devices. All self-oscillating amplifiers drop their switching frequency as the output signal approaches clipping and this may cause unpleasant high frequency distortion. In order to avoid this, a special “one point clipping circuit” has been developed which is completely transparent.

The output stage is controlled by a driver developed by International Rectifier. This driver is totally dedicated to Class-D amplifiers and has patented solutions for pulse by pulse current limiting and dead time settings. A close relationship with International Rectifier has made it possible for the driver’s behavior to be optimized for the topology that is being used. The selection of the power devices in the output stage is crucial in order to reach the best audio performance. The devices used in these modules are the best available for building Class-D amplifiers.