Amplifier 擴音機 / TEAC / UD-503

Dual-monaural USB DAC that supports 11.2MHz DSD with built-in fully-balanced/parallel-unbalanced headphone amplifier


DAC with dual-monaural structure is even more advanced
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High-performance VERITA AK4490 DACs support 11.2MHz DSD and 384kHz/32-bit PCM
For DAC chips, which are the keys to digital audio, we have used VERITA AK4490 DACs, which are made by Asahi Kasei Microdevices Corporation and have an established reputation for use in high-end audio equipment.* The VELVET SOUND architecture provides the fine expressive capability suitable for the playback of high-resolution audio sources that reproduce sound waves outside the human audible range. Furthermore, a newly developed low distortion technology enables performance of S/(N+D) = 112 dB. This is the best level in the industry for a 120dB class DAC.

Not only is native playback with direct processing of 11.2MHz DSD signals possible, support is provided for an even greater variety of high-resolution audio sources, including 384kHz/32-bit PCM digital input. We have realized expression of the fine smooth detail and outstanding sense of sound placement that characterize high-resolution audio sources.
*The AK4490 is a product in the Audio4pro™ family brand developed by Asahi Kasei Microdevices Corporation for professional audio equipment and high-end digital audio applications.
Dual-monaural structure supports fully-balanced transmission and realizes further advancement
Behind the expressiveness of the UD-503, which exceeds the level expected of its class, is an indulgent dual-monaural circuit structure that encompasses every aspect from the power and D/A sections to the analog output stage.

Starting with the toroidal core power transformers, which feature the ability to supply stable current, and the high-performance VERITA AK4490 DACs, the dual-monaural structure has a complete mono circuit for each channel. This prevents the signals from interfering with each other as much as possible. Interference is suppressed between the left and right channels, which is particularly important for headphone listening, so this unit can also be used as a high-performance headphone amplifier.

Furthermore, by processing the output signals of each channel completely with a differential from immediately after D/A conversion to the final output stage, common mode noise is removed and the sense of air that high-resolution audio has is not lost in transmission during balanced output.
In addition to 44.1kHz and 48kHz internal clocks, 10MHz external clock input is also supported./dt>
When connected by USB, rather than synchronizing with a computer clock that is unstable and noisy, the UD-503 supports asynchronous USB transfer mode, allowing it to control PCM and DSD signals by synchronizing with its own clock generated by its built-in high-precision crystal oscillator. Two dedicated internal clocks running at 44.1kHz and 48kHz are built in. By applying clock from an audio grade high-precision crystal oscillator, which features low phase noise, to input signals which that sampling frequency are whole number multiples, the effect of jitter on audio quality can be largely suppressed and the audio source can be reproduced faithfully.

In addition, with support for 10MHz external master clock input, synchronization with master clock signals of even higher precision is possible. By synchronizing with clock that has an even higher precision, you can enjoy changes in tone quality and improved audio quality that can be felt physically.
DSD Up-conversion function using a custom chip
Using an FPGA (programmable IC) of our own design that utilizes a fluency algorithm to smoothly augment digital audio signals, in addition to the 2x, 4x and 8x upconversion of PCM digital signals, DSD up conversion is also supported. Using this, you can easily experience the dense sense of air that DSD files have even when listening to CDs from your collection.
You can up-convert 44.1kHz/16-bit audio files ripped from CDs up to 11.2MHz DSD format files, which have about 256 times the amount of data as the original CD files. 48kHz PCM audio files can be played back in 12.2MHz DSD format.


Digital Audio Input
Connector RCA jack x 1
1/8" (3.5mm) Mini jack x 1 (compatible with Optical Input)
Input Level 0.5 Vp-p
Input Impedance 75 ohms
Supported Format DSD, PCM
DSD 2.8MHz (176.4kHz/24bit DoP transfer)
PCM 32k / 44.1k / 48k / 88.2k / 96k / 176.4k /192kHz, 16 / 24bit
Connector TOS link x 1
1/8" Mini Optical jack x 1 (compatible with Coaxial Input)
Input Level –24.0 to –14/5dBm peak
Supported Format DSD, PCM
DSD 2.8MHz (176.4kHz/24bit DoP transfer)
PCM 32k / 44.1k / 48k / 88.2k / 96k / 176.4k /192kHz, 16 / 24bit
Connector USB B type x 1
Supported Format DSD, PCM
DSD 2.8M / 5.6M / 11.2MHz
PCM 32k / 44.1k / 48k / 88.2k / 96k / 176.4k /192k / 352.8k / 384kHz, 16 / 24 / 32bit
Analog Audio Input
Connector RCA jack x 1 pair
Input Impedance 51k ohms
Sensitivity 130mV
Analog Audio Output
Balanced XLR 3-32 x 1 pair
Unbalanced RCA jack x 1 pair
Output Impedance
Balanced 188 ohms
Unbalanced 150 ohms
Max Output Level
Fixed (0dB) 2.0Vrms (XLR/RCA)
Fixed (+6dB) 4.0Vrms (XLR/RCA)
Variable 12.0Vrms (XLR), 6Vrms (RCA)
Frequency Response 5Hz to 80kHz (+1dB/–3dB)
Signal-to-Noise Ratio
Balanced 112dB (A-weighted, 1kHz)
Unbalanced 110dB (A-weighted, 1kHz)
Total Harmonic Distortion 0.0015% (1kHz, LHF: 20Hz to 20kHz)
Headphone Output
Connectors 1/4" (6.3mm) Stereo jack x 2
Format Balanced, Active Ground, Unbalanced
Balanced Tip: HOT, Ring: COLD, Shield: GND
Active Ground Tip: HOT, Ring: COLD, Shield: GND
Unbalanced Tip: L, Ring: R, Shield: GND
Max Output Power
Balanced 700mW + 700mW (32ohms loaded, THD 1%)
Unbalanced 500mW + 500mW (32ohms x 1 loaded, THD 1%)
350mW + 350mW (32ohms x 2 loaded, THD 1%)
Supported Headphone Impedance 16 to 600 ohms
Audio Settings
Up-conversion x8, x4, x2, Off
DSD Cut-off Frequency 50kHz, 150kHz
PCM Digital Filter FIR Sharp, FIR Slow, Short-delay Sharp, Short-delay Slow
Line Output RCA, XLR (Pin2: HOT), XLR (Pin3:HOT)
Line Output Level Fixed (0dB), Fixed (+6dB), Variable, Off
Supported OS
Windows Windows 10 (32/64-bit), Windows 8.1 (32/64-bit),
Windows 8 (32/64-bit), Windows 7 (32/64-bit)
Macintosh Yosemite (OS X10.10), Mavericks (OS X10.9),
Mountain Lion (OS X10.8), Lion (OS X10.7)
Operation Power
US/Canada AC 120V, 60Hz
UK/Europe AC 230V, 50Hz
Power Consumption 16 Watts (0.4 Watts at Standby Mode)
Overall Dimensions
(including protrusions) 11.4" (W) x 3.2" (H) x 9.8" (D)
290 (W) x 81.2 (H) x 248.7 (D) mm
Weight 9.3 lbs. / 4.2 kg
Accessories Remote control (RC-1319), AAA Batteries x 2, RCA-Mini Plug Cable, Power Cord, Cushion for Foot x 3, Owner's Manual (including Warranty card)