|Warranty length||2 Years|
Inputs: RCA 3.5mm jack, 1 Opt
Impedance/Level: 0.5 Vp-p, 75Ω
Optical: TOSlink, 1/8" jack, 1 Coax
Input Level: –24 to –14/5dBm peak
Supported Format: DSD, PCM
DSD: 2.8MHz (176.4kHz/24bit)
PCM: 32k /192kHz, 16/24bit
USB: B Type x 1 (DSD/PCM)
USB DSD: 2.8/ 5.6/11.2MHz
USB PCM: 32/384kHz, 16/24/32bit
Analog Audio Input: RCA jack
Impedance/Sens: 51KΩ, 130mV
Balanced Out: XLR 3-32 x1 pair
Unbalanced Out: RCA jack x1 pair
Balanced Out Impedence: 188Ω
Unbalanced Out Impedence: 150Ω
Fixed (0dB) Level: 2.0Vrms (XLR/RCA)
Fixed (+6dB) Level: 4.0Vrms (XLR/RCA)
Variable: 12.0Vrms (XLR), 6Vrms (RCA)
Freq Response: 5Hz-80kHz (+1dB/–3dB)
Balanced SNR: 112dB (A-weighted, 1kHz)
Unbalanced SNR: 110dB (A-weighted, 1kHz)
THD: 0.0015% (1kHz, LHF: 20Hz to 20kHz)
Connectors: 1/4" Stereo jack x 2
Format: Bal, Active Ground, Unbalanced
Balanced Polarity: HOT, COLD, GND
Active Ground: HOT, Ring: COLD, Shield: GND
Unbalanced: Tip: L, Ring: R, Shield: GND
Bal Max Out: 700mW + 700mW
Unbal Max Out: 500+500mW, 350+ 350mW
Up-conversion: x8, x4, x2, Off
DSD Cut-off Frequency: 50kHz, 150kHz
PCM: FIR Sharp/Slow, Short-delay Sharp/Slow
Line Out: RCA, XLR (Pin2/3: HOT)
Line Out Lev: >Fixed (0dB), Variable, Off
UK/Eur Power: AC 230V, 50Hz
Power Consumption: 16W (0.4w Standby)
Dimensions (WHD): 290 x 81.2 x 248.7 mm
Weight: 9.3 lbs/4.2 kg
The NT-503DAB supports high-res audio over USB and high-res streaming over network. WAV/FLAC files can be played from a PC or NAS drive while the radio supports DAB/DAB+ (built-in) along with Spotify, Deezer, TuneIn radio portal and aptX Bluetooth. TEAC’s HCLD circuit delivers high performance for single-ended headphones up to 600Ω.
VERITA AK4490 DAC
For DAC chips, which are the keys to digital audio, we have used VERITAAK4490 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 realised expression of the fine smooth detail and outstanding sense of sound placement that characterise high-resolution audio sources.
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 analogue 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 synchronising 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 synchronising 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, synchronisation with master clock signals of even higher precision is possible. By synchronising with clock that has an even higher precision, you can enjoy changes in tone quality and improved audio quality that can be felt physically.
Using an FPGA (programmable IC) of our own design that utilises 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.
4 PCM filters + 2 DSD filters
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.
Between the digital and analogue 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 analogue 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.
Toroidal core power transformers
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 design and enables the stable supply of current to each channel without being influenced by the changes in current consumption due to processing of the other channel's signal. Even thought it is small, we have incorporated approaches that are used in much larger high-end audio devices. Analogue output circuits that have been further improved.
In order to transfer music signals to output devices without losing their great dynamic range, we have included TEAC-HCLD (High Current Line Driver) circuits. These increase the current transfer capability that is crucial for analogue output circuits. We have applied the expertise that we have gained in the design of audiophile equipment, and for each channel side included two buffer circuits with high current transfer capabilities. By using differential drive for balanced output and parallel drive for unbalanced output, we have increased current transfer capabilities, allowing the transfer of music signals without losing their dynamism.
TEAC-QVCS high-Precision Volume Control
The UD-503 can also be used as a preamp. One pair of XLR balanced outputs and one pair of RCA unbalanced outputs and included and can be set to either an adjustable or a fixed volume level, allowing a simple system to be put together in combination with a power amplifier or active speakers. We have even considered connection of record players such as the TEAC TN-300 turntable, cassette decks and other analogue sources with line outputs by also including one pair of analogue RCA inputs.
For the preamp circuit, we have utilised the TEAC-QVCS (Quad Volume Control System), which is a circuit with a fully balanced design that uses balanced processing of the audio signal at every stage from immediately after conversion from digital to analogue until it reaches the volume amplifier.
Control signals transmitted from the volume knob simultaneously adjust the variable gain amp type volume controls for a total of four independent circuits—positive and negative for both of the left and right channels. Using this system, the unnecessary manipulation of audio signals is eliminated, and the left/right and positive/negative independence of the audio signals is preserved, achieving clear sound quality with outstanding channel separation. (This does not apply when using unbalanced analogue input.)
This volume control system realises 256 steps of volume adjustment in 0.5dB increments over the complete range from −95 dB to +24 dB. Precise volume adjustment has been made possible using a remote control, which is difficult using motorised analogue volume. In addition, optimal volume levels can be achieved for headphone listening, which requires precise volume adjustment, using headphones with various levels of efficiency.
Headphone amp with discrete construction
The connection of balanced drive headphones is enabled by also using for headphone output TEAC HCLD circuits that are for line output and are composed of 4 output transistors each for both left and right channels. Furthermore, even during single end use, drive that is much stronger than an ordinary single end headphone amplifier is possible by making these transistors operate in parallel. In this unique circuit design, due to the AB class amplifier that greatly expands the A class operating range, A class operation is used for most of the range used in ordinary headphone listening. The potentials of various types of headphones can be brought out, starting with 600Ω high-impedance headphones.
On the front of the unit, two 3-pole TRS (standard stereo) jacks are provided as headphone outputs. These can be switched between three types of drive operation. In addition to connecting balanced drive headphones, you can also use unbalanced drive to connect two pairs of ordinary headphones, as well as use active ground* drive, which can further decrease noise during silences and enhance the expressiveness of delicate sounds.
Hi-Res Audio Playback from PC via USB Cable
With a single USB Cable, Hi-Res Audio data including 11.2MHz DSD and 32-bit/384kHz PCM can be played back without complex settings. TEAC offers a free music app, "TEAC HR Audio Player,” for Windows and Macintosh systems. It allows listeners to create, save, and recall their own playlists, or simply just drag-and-drop music files to the playlist window.
High-res Audio Streaming
The NT-503 is a versatile network player that offers network audio capability with DLNA 1.5. Hi-Res Audio formats such as 5.6MHz DSD and 24-bit/192kHz WAV/FLAC can be played back from a PC or NAS (Network Attached Server.) Playback can be controlled with a free app for iOS or Android, “TEAC HR Remote”. Gapless playback is also supported when playing back files of the same sampling frequency, even if the file format varies between WAV, FLAC, AAC, Apple Lossless, WMA, OGG Vorbis, and MP3. The NT-503 supports Bluetooth wireless connection using advanced codec technologies like aptX, AAC, and SBC for the best audio performance possible. Enjoy high-quality music streaming from your smartphone or tablet.
Front USB port
The NT-503's USB port on front panel supports 5.6MHz DSD and 192kHz PCM stored on a USB Flash Memory, as well as conventional MP3 and WMA files. The free app "TEAC HR Remote" for iOS/Android turns your smartphone and tablet into a touch-screen remote controller to browse and select music files on the USB Flash Memory. Gapless playback is also supported when playing back the same sampling frequency files between, WAV, FLAC, AAC, Apple Lossless, WMA, OGG Vorbis, and MP3.
The free apps "TEAC HR Remote" for iOS and "TEAC AVR Remote" for Android allows the NT-503 to subscribe on-line music services like Pandora*, Sirius/XM*, Spotify*, Deezer*, and Slacker*. In addition, access the Internet radio portal that provides over 100,000 radio stations and 4 million podcasts all over the world for free. Since the NT-503 directly receives those streaming signal from Internet, – not via your smartphone or tablet – your ringtone will not interrupt the music.
Fine Details of DSD
The NT-503's high-quality analogue output circuit, based around its dual-monaural design and the “TEAC-HCLD” circuit, creates the ideal pre-amplifier unit. The NT-503 delivers both balanced and unbalanced audio signals, either at "Fixed (±0dB)", "Fixed (+6dB)" (optimised for DSD sources), or "Variable" to connect to a power amplifier. In addition to these settings, the "Off" setting disables audio signals to the rear connectors, concentrating its performance on the headphone output.
Like the UD-503, the NT-503 also employs a high-performance headphone amplifier that delivers 500mW+500mW of output power. The “TEAC-HCLD” circuits, based around four output transistors in parallel drive mode, drive conventional single-ended headphones powerfully and precisely. In addition, a uniquely-designed class-AB amplifier with extended class-A operation range allows the NT-503 to process most part of amplification process in class-A mode, and maximises potential of wide range of headphones, including 600 ohms high-impedance ones.