TEAC UD-503 Product information

Supplementary New Product Information (SNPI)

UD-503 USB DAC/Headphone Amplifier

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

■ Main functions

 Two built-in AK4490 DACs made by Asahi Kasei Microdevices support resolutions up to 11.2MHz DSD and

384kHz/32-bit PCM

 Dual-monaural structure thoroughly separates independent left and right circuits from the power supply to the

output stage

 Built-in preamp circuits are ideal for setting up systems with power amps and active speakers

 Analog RCA input pair enables use with analog sources

 In addition to fully-balanced operation, the headphone amplifier supports parallel-unbalanced and active

ground headphone operation

 Our original TEAC-HCLD output buffer circuit, which is a current-enhancing output buffer circuit, conveys the

dynamism of music

 Capable of upconversion up to 12.2MHz DSD and 384kHz PCM

 TEAC-QVCS high-precision volume control with a four-circuit structure allows 256 setting steps

 In addition to high-precision internal clocks, 10MHz external clock input is also supported

 Full-metal body with three independent pinpoint feet realizes high vibration suppression and stability

Brand TEAC

Series Reference

Model UD-503-B UD-503-S

UPC Code

EAN Code

Main Unit Dimensions/NW

W x H x D

Package Dimensions/GW

W x H x D

Qty. per Master Carton 1

043774 031481 043774 031474

4907034 219445 4907034 219438

290x81.5x248.7/4.2(mm/kg) 290x81.5x248.7/4.2(mm/kg)

440x190x340/5.35 (mm/kg) 290x81.5x248.7/4.2(mm/kg)

Supplementary New Product Information (SNPI)

Overview

The UD-503 is a dual-monaural USB DAC and fully-balanced headphone amplifier in a compact body with a footprint the
size of a piece of paper. It represents the distillation of TEAC audio design expertise developed for over 60 years with
audiophile design concepts.
The same dual-monaural structure, which is an audiophile design concept, as in the UD-501 is used. In addition, two
AK4490 DAC chips which are the newest models made by Asahi Kasei Microdevices Corporation, enable native playback
of the most advanced 11.2MHz DSD and 384kHz/32-bit PCM formats. Furthermore, analog output circuits could be called
the cornerstone for audio quality, so we have now included four TEAC-HCLD circuits, which are current-enhancing output
buffer amps. Operation is fully-balanced when using balanced XLR output and parallel-unbalanced when using
unbalanced RCA output. We have realized a DAC section with expressiveness that exceeds the expectations of its class.
The headphone amp, which shares the amp section with the line amp, has a discrete structure. Two TRS phone jacks are
available on the front panel, and they offer powerful driving force when used as a fully-balanced or parallel-unbalanced
headphone amplifier. In addition, the TEAC-QVCS high-precision volume control that provides 256 setting steps and the
remote control enable use as a high-quality preamp.
The UD-503 is the next generation of USB DAC/headphone amplifier that is leading desktop audio to the next level.

DAC with dual-monaural structure is even more advanced

■ 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

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

Supplementary New Product Information (SNPI)

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 upconvert 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.

■ Four types of PCM digital filter and two types of DSD filter

In addition to four types of PCM digital filters and an OFF mode, the unit has two types of DSD digital filters, so you can
choose the best filter for the input file format and type of music. You can enjoy the subtle sound nuances of different
filters without needing to connect different USB DACs.

PCM filters

· FIR SHARP: An FIR filter with a steep roll-off sharply cuts signals outside the audio band.

· FIR SLOW: An FIR filter with a slow roll-off gently cuts signals outside the audio band.

· SDLY SHARP: A short delay filter with a steep roll-off sharply cuts signals outside the audio band.

· SDLY SLOW: A short delay filter with a slow roll-off gently cuts signals outside the audio band.
DSD filters:
CUTOFF 50kHz and CUTOFF 150kHz

NOTE: When receiving signals at 352.8 kHz or 384 kHz, the digital filter will be disabled during playback regardless of this setting.

■ Isolation circuit that completely separates the grounding of the digital and analog sections

Between the digital and analog sections,
the circuit design uses a digital isolator to
completely isolate both the power supply and the ground. So, all noise coming from digital input sources, starting with
noise from the computer via USB, is prevented from entering the analog section by way of the power line or the
ground. An isolation circuit offers significant benefit particularly when playing high-resolution audio sources with high
sampling rates. The UD-503 is the first product in our Reference Series to include one.

■ Independent high-capacity toroidal core power transformers for left and

right channels

Both left and right channels each have one dedicated high-capacity toroidal core power
transformer that supplies stable current. This is also a continuation of the dual-monaural