TEAC UD-505-X Headphone Amplifier (Black)

The UD-505 employs the latest VERITA AK4497 (developed by Asahi Kasei Microdevices) on each of the left and right channels. It is a highly-regarded high-end audio DAC, and supports DSD512 (22.5MHz) and 768kHz/32-bit PCM formats, achieving industry-leading ultra low distortion levels. OSRD (Over-sampling Ratio Doubler) technology, meanwhile, significantly reduces out-of-band noise. As a result, the UD-505 has the refinement necessary to make the most of Hi-Res formats, successfully processing information that lies outside the audible range.

A dual monaural circuit configuration is used throughout, from the power supply (including power transformers), to the D/A converters in the digital section and the Analog output stage. From the high-performance VERITA AK4497 D/A converters to the massive toroidal-core power transformers, each element is configured for single channel processing. This prevents mutual interference effects while reproducing a rich acoustic expressiveness.
In addition, the Analog audio signals of both the left and right channels are processed in full balanced mode soon after the D/A converters all the way to the output terminal, contributing to an improved S/N ratio and extended dynamic range. This allows the fantastic sense of air that Hi-Res formats possess to be processed and conveyed without any losses.

In addition to conventional SBC and AAC codecs, the UD-505 also supports LDAC™ (24/96 Hi-Res audio transmission), and Qualcomm® aptX™ HD, a codec that uses 24/48 format transmission. These allow you to playback playlists on your smartphone and tablet wirelessly.

Instead of referencing to an unstable and noisy PC clock during USB audio playback, a more accurate and on-board clock is generated by a high-precision, low phase-noise, audio-grade crystal oscillator for USB asynchronous transfer mode. The UD-505 accommodates two on-board clocks exclusively for 44.1kHz and 48kHz sampling frequencies and applies the appropriate one to incoming digital signals - those that are multiples of 44.1k or 48k - to reproduce identical sound to the original by eliminating jitter effects on the audio signal.
In addition, an external 10MHz clock input is also provided, to synchronise with an even higher-precision master clock generator, such as the TEAC CG-10M, for yet further upgraded audio playback with excellent sound quality.

Employing RDOT-NEO (Refined Digital Output Technology NEO), a fluency algorithm that renders digital audio signals smoothly, the UD-505 up-converts PCM digital signals up to 384kHz/32-bit PCM and 24.5MHz DSD. With the up-conversion function activated, you will hear an improvement in quality, even with music that you are familiar with.

When transferring large volumes of digital data for Hi-Res audio sources through USB cables using conventional isochronous transfer mode, large variations can occur in the processing loads of the sending computer and the receiving USB DAC. This can cause sound to drop out and other problems to occur. However, with our new USB transmission technology - dubbed "Bulk Pet" - a fixed amount of data is transmitted constantly, levelling out the processing burden on both devices and contributing to stable data transmission. Changing the processing burden on the computer directly affects audio quality so users can select the setting they prefer (from four transmission modes).

On the UD-505, there are two types of DSD filters and another five types of PCM digital filters, allowing you to apply the filter that best matches the file format or type of music you're listening to. The filter can be changed at the touch of a button on the remote control, allowing you to enjoy the different sonic nuances of each filter.

* When receiving signals at 352.8 kHz, 384 kHz or higher, the digital filter will be disabled during processing regardless of the above setting.

In order to suppress interference between the digital and Analog sections, the UD-505 employs an independent power supply and ground circuit, so eliminating cross-interference in the signal path where digital and Analog sections connect. A digital isolator is employed at the input section to eliminate noise originating from any connected digital sources, including noise that is generated from the computer via USB, power line and the ground path. This isolation circuit also makes a significant improvement in the signal-to-noise ratio as well as the final sound quality.

The dual monaural theme continues. Two over-sized high-capacity toroidal-core power transformers are employed in the UD-505, supplying stable, individual current sources for each of the left and right channels. This means neither channel will be affected by changes in the power consumption of the other during digital processing.

At the heart of Analog section are TEAC-HCLD (High Current Line Driver) buffer amp circuits, designed to enhance current supply. Each channel employs two identical buffer amps that process differential drive for balanced output, and parallel drive for unbalanced output. By increasing the current supply to the buffer amp section, the Analog audio signal is passed to the next step without any loss of dynamism.

processing performance, a wide range of Analog/digital inputs, and fixed/variable level XLR (balanced) and RCA (unbalanced) outputs. These allow you to build a fully-fledged hi-fi system around the UD-505 with a stereo amplifier/pair of monaural power amplifiers and floorstanding speakers, or a simplified system based on a pair of active speakers
The TEAC-QVCS (Quad Volume Control System) is a precise volume control design incorporated in the pre-amp section. This circuit employs four sets of variable gain-amps controlling volume for left, right, positive and negative (L+, L-, R+, R-). Each variable gain-amp is located on a simplified signal path which helps eliminate interference noise by creating a shorter signal path.
In addition, the TEAC-QVCS provides precise volume control in 0.5dB steps in "dB" display mode, or 100 steps in "step" display mode.

The UD-505's headphone amplifier circuit provides balanced-drive by using the TEAC-HCLD circuit, - comprised of four output transistors for each left and right channel - for headphone output. Furthermore, by driving these transistors in parallel when a single-ended headphone is connected, the UD-505 delivers stronger driving power than most ordinary single-ended headphone amps provide. When listening to conventional headphones, it also operates in Class-A (by expanding the Class-A range of operation), despite using a Class-A/B amplifier. With challenging 600Ω high-impedance headphones for example, the UD-505 allows you to bring out the potential of these type of headphones.

The active-ground is a new driving mode that employs the principles of balanced connection. It forcefully drives the ground, by lowering the ground level to 0V, providing an ideal ground condition (rather than just connecting to the conventional ground) This means it also suppresses hum noise from the power supply and enhances the purity of silent pauses by lowering the noise floor. Subtle detail, such as the breathing of artists and the textures of sounds, will feel even more convincing.

In addition to the dual conventional 1/4" TRS jacks for balanced connection, the UD-505 employs a newly designed single headphone jack for balanced drive. The Pentaconn jack is a new 4.4mm 5-pole jack that has been developed by NIPPON DICS Co., Ltd, and complies the RC-8141C JEITA Standard, providing a single-jack solution for balanced headphones. More Pentaconn jack-equipped headphones and cables are expected in the near future.

Just as with the successful Reference 503 series, the UD-505 employs aluminum-alloy panels - including iconic side guard-bars - and a robust metal chassis with a compact A4-size footprint* that completely matches with the 500 series and the new CG-10M master clock generator. The full metal construction isn't just beautiful, it's also functional. It's highly effective at isolating the internal circuits from electromagnetic noise.

The UD-505 is equipped with both balanced and unbalanced Analog audio outputs. A pair of XLR connectors and another pair of RCA connectors - each gold-plated - are symmetrically laid out, hinting at the dual monaural arrangement inside, and allowing a wide range of possible audio configurations. A wide-spaced pitch layout for the RCA outputs accommodates professional grade plugs with large-diameter shells. The UD-505 has a total of 5 digital inputs: USB audio, coaxial, optical on the rear panel, and a combination jack on the front panel (for coaxial and optical, supporting PCM 24/192 and DSD64 in DoP format).
A pair of RCA Analog audio input connectors allow the UD-505 to function as a pre-amplifier equipped with a high quality and precision volume control (TEAC-QVCS).

The UD-505 employs TEAC's patented "Pin-Point" feet. These ingeniously comprises two separated metal sections in a in an integrated housing. One is has a spiked top and is attached to the bottom of the chassis, the other is a basin-shaped base that hangs down from the spiked section with a flange-shaped cup to simply installation.
Three "Pin-Point" foot are used for support, two at the front and one at the rear, for excellent stability, even on an uneven floor.
As a result, the three "Pin-Point" feet help improve the accuracy of clock oscillation by minimising vibrations and resonance. This, in turn, reduces mid and low frequency muddiness, improves the soundstage and enhances fine sound detail.

A high contrast full-dot OLED (organic EL display) with 4-step dimmer is employed, for excellent visibility. Even better, a highly legible, large font size allows you to easily verify the volume level, input source and other information, even when sat at a distance.

The next-generation Hi-Res formats, DSD512 (22.5MHz) and PCM 768kHz/32-bit are supported via the TEAC HR Audio Player software for Windows and Mac. This software guarantees the best available playback quality with any combinations of audio format and computer configurations via a single USB cable. All the user has to do is choose the UD-505 from the pull-down menu showing target output devices.The TEAC HR Audio Player is available from TEAC's web site, and is completely free to use.