The D-15000 OTL/OCL Signature is a world-class, reference level DAC. It offers unbelievably realistic, holographic sound-staging combined with incredible resolution, clarity, micro-dynamics, and drive. Instrument and vocal tones and timbres are breathtakingly lifelike, and the placement of instruments and bodies in three dimensions startling, life-size, and addictive.

The D-15000 OTL/OCL Signature has no voice of its own, none. It is silent, except for the music emanating from the blackest of backgrounds. As a result, the D-15000 OTL/OCL Signature DAC is very sensitive to the quality of recordings, upstream components, cables, and first and second gain stage output vacuum tubes. D-15000 OTL/OCL is intentionally engineered with no oversampling, conversions, or filtering yet processes a broad range of information in native format.

Finally, the stunningly realistic sonic quality is matched by the D-15000 OTL/OCL Signature’s industrial design, the classical elegance, flexibility, and ergonomic functionality of its casework and connection options.

The D-15000 OTL/OCL Signature is truly a masterpiece and is Allnic Audio’s top DAC.

D-15,000 OTL/OCL "Signature" DAC

$26,400.00

Quantity

To design and build the D-15000 OTL/OCL Signature DAC’s digital processing section, Allnic partnered with highly regarded Korean custom digital audio development consulting firm ABSTECH. ABSTECH’s design brief was to meet or exceed Allnic’s demanding sound quality and user option requirements, focusing on:

• an extremely high level of resolution

• outstandingly low noise and distortion

• maximized compatibility with Allnic’s analog output stage

• eschewing add-on features such as upsampling

• a broad range of connection types

To achieve these goals, ABSTECH created a conversion board based on the dual mono ES9039PRO - 32-bit HyperStream® IV architecture DAC technology.

The ABSTECH DAC solution has the following features:

USB input: PCM up to 32-bit/384kHz, DSD Native up to DSD512, and DSD over PCM (DoP) up to DSD256

Drivers: Devices using Mac OSX 10.6+ or Linux (with UAC2 compliant kernel) do not require an additional driver to allow full use of the D-15000 OTL/OCL’s USB sample rate capabilities. For Windows based devices, the KS, Wasapi, and WDM drivers for Win7, Win8, Win10/11 (32-64bit), and the Combo384 ASIO Windows driver are available for download online.

S/PDIF inputs: PCM up to 24-bit/192kHz

I 2 S over HDMI: PCM up to 32-bit/768kHz, DSD Native up to DSD1024, and DSD over PCM (DoP) up to DSD256. The I2 S over HDMI connection is compliant with PS Audio’s connector format.

Internal, high-quality OCXO clock: Provides stability in the +/-5 ppb (parts per billion) range. Input connection for external clock: The D-15000 OTL/OCL DAC has a 10MHz reference external clock input using a PLL that guarantees an RMS period jitter of no more than 5ps. While the D-15000 OTL/OCL Signature DAC uses a high-quality OCXO internal clock, data under-run or over-run and, therefore, distortion can occur when a source’s word clock and the DAC’s internal clock are not synchronized absolutely. With the D-15000 OTL/OCL DAC’s clock input PLL, when a high-quality external clock is connected, potential errors caused by data underrun or over-run can basically be eliminated.

The ABSTECH digital processing solution meets ALLNIC’s demanding requirements, mating exceptionally well with Allnic’s unique, unmatched in purity, vacuum tube analog output stage. The result is the new flagship Allnic D-15000 OTL/OCL Signature DAC, a state-of-the-art marriage of digital and vacuum tube audio technologies.
Allnic’s unique OTL/OCL analog output stage is the defining characteristic of the D-15000 OTL/OCL Signature DAC’s sound quality. It is an outstanding, innovative technical achievement that eliminates two primary sources of deviation from the signal a vacuum tube output stage amplifies.

In common circuits, output capacitors or output transformers are required to separate the AC music signal from the DC operating potential. If this is not done, the latter will destroy the power amplifier, 2 the loudspeakers, or both. However, these two coupling devices also introduce their own influences on the transmission of the musical signal, adding their own character (colouration), increasing distortion, and consuming small signals, all as predicted by physical efficiency theory. In addition, they also limit signal dynamics. For these reasons, the elimination of output transformers and capacitors has been considered the best solution for the design of the most accurate amplifiers. Removal of these two coupling devices from the signal path achieves the best results possible:

• No colouration of the musical signal

• Extremely detailed expression, natural harmonics and subtle musical decay • The lowest possible distortion

• The widest musical dynamics and frequency range

In the D-15000, there is no coupling device between the DAC and the preamplifier; that is, the final gain/output tubes are directly connected to the preamplifier. Thus, the benefits listed above are fully present in the Allnic D-15000 OTL/OCL.

Some circuit experts might be concerned about DC potential in the music signal in an OTL/OCL design. However, the chance of this problem occurring can be essentially and reliably 100% mitigated. To do this, Allnic uses a “floating power supply circuit”, a design that deals with the issue by not creating any DC potential in the first place, or such a small potential that it is harmless.

The D-15000’s OTL/OCL circuit is basically SEPP, “Single-Ended, Push-Pull”, so a “cancellation circuit” is required to adjust the balance of signal between the upper and lower power output tubes’ input grids. Allnic uses an extremely sophisticated “Active Balanced Positive and Negative Feedback Circuit”, in which the ECF80 triode-pentode frequency converter tube perfectly controls the circuit’s operation with extremely low distortion and incredible speed.
Inputs:

• One I2 S over HDMI (compliant with PS Audio’s connector format) • One USB (Type B)

• One AES/EBU digital (XLR)

• One coaxial digital (RCA)

• One optical (“Toslink”) digital

• One BNC type external clock

Sample Rates:

USB:

• PCM up to 32-bit/384kHz

• DSD Native up to DSD512 and DSD over PCM (DoP) up to DSD256

S/PDIF inputs (AES/EBU, COAX and OPT [Toslink]):

• PCM up to 24-bit/192kHz

I 2 S:

• PCM up to 32-bit/768kHz

• DSD Native up to DSD1024 and DSD over PCM (DoP) up to DSD256

Outputs:

• One (1) pair unbalanced (RCA)

• One (1) pair balanced (XLR)

Output Frequency Range:

• 20Hz - 20KHz flat

Output RMS Voltage:

• 1.75 volts

Output Impedance:

• 50 Ω (Constant)

Total Harmonic Distortion (THD):

• Less than 0.1%

Signal to Noise (S/N) Ratio:

• - 86db (CCIR, 1KHz)

Power Consumption:

• 70W at 230 V / 110/120 V / 50 / 60 Hz

Tubes:

• Two (2) x ECF80 (Equivalent to E80CF, 6BL8)

• Two (2) x 12AU7 (Equivalent to ECC82, E82CC, 5814, 6189, CV4003)

• Four (4) x 6C19P (Equivalent to 6S19P, 6C19Pi, 6C19-n)

Fuse:

• AC 5A, 250V, 5x20mm Slow-Blow for 110/120 volt regions AC 3A, 250V, 5x20mm Slow-Blow for 230/240 volt regions

SPECIFICATION CHANGE: Notwithstanding what may be printed above any D-15000 OTL/OCL DAC’s IEC inlet, the correct rating for the mains fuse is 5A 250V 5x20mm SlowBlow for 110/120V regions and 3A 250V 5x20mm Slow-Blow for 230/240V regions.

Dimensions:

• 430mm (16.93 inches) x 320mm (12.5 inches) x 170mm (6.7 inches) (W x D x H)

Weight:

• 13.06 Kg (28 lbs.) unpacked; 17 Kg (37.4 lbs.) in original packing

D-15,000 OTL/OCL "Signature" DAC

ABSTECH Custom Digital Processing

ALLNIC’S OTL/OCL ANALOG OUTPUT SIGNAL PATH

Technical Specifications

Professional Reviews

Manual