Mercury Mastering D/A Converter

120 Volt Technology

SPL's 120 Volt technology aims to push analog signal processing limits by combining high-grade components and optimized circuit design. This technology, utilizing the highest operating voltage for audio applications, has been used in SPL's Mastering series products for years. It is based on internally developed op-amps by SPL's co-founder Wolfgang Neumann, with advanced generations featured in the Hermes Mastering Router. The supply voltage is crucial for a processor's dynamic response, analogous to cylinder capacity in an engine. The text states, "You can't replace cylinder capacity with anything else, except more cylinder capacity."

DLP120

The DLP120 is another technological specialty of the Mercury. The output signal of a DAC-IC requires filtering by a low-pass filter, often done digitally on-chip. The analog signal processing stage typically operates at a lower voltage (e.g., 5V), limiting dynamic range and signal-to-noise ratio. The Mercury employs the DLP120, which stands for "Dual Low Pass." It uses two separate analog filters operating in 120V technology. Depending on the digital signal type (PCM or DSD), the analog signal passes through the respective filter, unfolding into a large dynamic range. The complete processing stage operates at a voltage of +-60V.

120 Volt Technology - Diagrams

These diagrams illustrate the advantages of 120-volt technology compared to circuits with lower operating voltages. A higher operating level directly correlates with a higher maximum level a circuit can handle, positively impacting dynamic range, distortion limit, and signal-to-noise ratio, resulting in a more natural sound.

Diagram: Operational Voltages
A bar chart compares operational voltages. For the '+/- 15 Volt' setting, the operational voltage is 36V. For the '+/- 18 Volt' setting, it's 30V. For the '+/- 60 Volt' setting, the operational voltage is 120V.

Diagram: Maximum Levels
A bar chart compares maximum output levels in dBu for different configurations: OPA 134@30V shows 21.5 dBu, OPA 134@36V shows 22.5 dBu, and SPL-OP@120V shows 33.2 dBu.

Diagram: Dynamic Range
A bar chart compares dynamic range in dBu: OPA 134@30V shows 124.2 dBu, OPA 134@36V shows 129.1 dBu, and SPL-OP@120V shows 141.4 dBu.

Diagram: THD&N
A bar chart compares Total Harmonic Distortion plus Noise (THD&N) in dBu for different configurations: TL 071@30V shows -111.7 dBu, OPA 134@36V shows -114.2 dBu, and SPL-OP@120V shows -106 dBu.

The document notes that dB scales are exponential. A 3 dB increase doubles acoustic power, +6 dB doubles sound pressure level, and +10 dB doubles perceived loudness. The 120-volt technology offers performance approximately 10 dB higher in maximum level and dynamic range compared to common components. THD measurements of SPL op-amps show an improvement over OPA134 at 36V, corresponding to over 50% improvement in sound pressure level. The common operating level for audio equipment is 30 volts.

Voltage Selection

Before connecting the Mercury Mastering D/A Converter to the mains, ensure the voltage selection matches your local power grid (230 or 115 volts). An opening inside the power connector, next to the on/off switch, displays the selected voltage. To change it: Open the power connector lid with a small screwdriver. Use the screwdriver to lever the red fuse holder upwards. Remove the fuse holder and replace the fuse with one matching your local power grid specifications (values are on the unit's rear or page 16). Turn the fuse holder 180 degrees and reinsert it. Closing the lid should reveal the correct voltage. A video guide on changing mains voltage is available on the product website (https://mercury.spl.audio).

First Steps

Before powering on, connect the included 3-pin power cord to the 3-pin IEC socket. The transformer, power cord, and IEC socket comply with VDE, UL, and CSA regulations. Avoid installing the unit near equipment emitting magnetic fields or heat, and protect it from heat, moisture, dust, and vibrations. Ensure the unit is powered off before connecting or disconnecting cables. Use the rear panel On/Off switch; an illuminated red LED on the front panel indicates operating status. The rear placement of the switch minimizes emissions. No specific sequence is required for connecting/disconnecting devices, but for audio chains, power amplifiers should be powered on last and off first. The unit can be powered via a circuit breaker, provided the total load does not exceed its rating.

XLR Inputs and Outputs

Switchcraft/Neutrik XLR connectors are used for optimal connectivity. The XLR connectors are balanced and have three conductors: Pin 2 corresponds to the (+) or hot signal. For unbalanced connections, correct polarity must be observed.

Diagram: XLR Pinout
A diagram illustrates XLR connector pinout for input and output, both balanced and unbalanced. For balanced connections, Pin 1 is GND, Pin 2 is 'hot' (+), and Pin 3 is 'cold' (-).

Ground Lift Switch to Avoid Ground Loops

A "GND LIFT" switch on the rear panel helps avoid ground loops, which occur when connected gear in the same network have different potentials. The GND LIFT switch disconnects the equipment ground from the service ground. The function is activated (equipment ground disconnected) when the switch is depressed.

Rear Panel Overview

The rear panel features the following connections and controls:

• 1 USB: USB 2.0 Type B port for PCM and DSD audio.
• 2 Optical 1 and Optical 2 (TOSLINK): Two optical inputs supporting two-channel signals up to 192kHz (PCM), 16-24 bits. Uses IEC 60958 Type II standard.
• 3 Coaxial 1 and Coaxial 2 (S/P-DIF): Two coaxial inputs for two-channel PCM audio up to 192kHz, 16-24 bits. Uses IEC 60958 Type II standard.
• 4 AES 1: AES/EBU input for two-channel PCM audio up to 192kHz, 16-24 bits (IEC 60958 Type I). Uses an XLR female jack.
• 5 AES 2 [DW L and DW R]: Two XLR female jacks. Supports regular AES signals and Dual Wire (DW) mode for doubled sampling rates by using both jacks for left and right channels. DW mode is activated automatically when a mono channel is detected.
• 6 Word Clock: Input for synchronization to an external word clock via a 75 Ohm BNC connection.
• 7 FIX OUT: Analog balanced stereo output (XLR, male) calibratable to common reference levels.
• 8 VAR OUT: Analog symmetric stereo output with a variably adjustable level, allowing use as a monitor controller.
• 9 Ground-Lift: Switch to avoid ground loops (details on page 7).
• 10 Voltage: Mains voltage selector (details on page 6).

Front Panel Controls

The front panel features illuminated push buttons for input selection and status indication:

• 1 USB: Selects the USB input. Illuminated when active.
• 2 AES 1: Selects the AES 1 input. Illuminated when active.
• 3 AES 2: Selects the AES 2 input. Illuminated when active.
• 4 Coax 1: Selects the Coax 1 input. Illuminated when active.
• 5 Coax 2: Selects the Coax 2 input. Illuminated when active.
• 6 Opt 1: Selects the Opt 1 input. Illuminated when active.
• 7 Opt 2: Selects the Opt 2 input. Illuminated when active.
• 8 Mute: Engages mute for FIX OUT and VAR OUT signals. Illuminated red when active.

Rear Panel Controls and Display

The rear panel also houses controls and a display:

• 9 Sync: This button manages synchronization status and selection. It illuminates blue when a source (other than USB) is synchronized. It's used to select synchronization sources (Word, Source, AES 1, AES 2, Coax 1, Coax 2, Opt 1, Opt 2) and reference levels. USB cannot be synchronized to another source. If a source is not wired or lacks a valid sync signal, the sync button LED flashes, and the sample rate display remains blank. The Mercury supports sampling rates from 44.1kHz to 768kHz (PCM) and DSD to DSD4/DSD256. Pressing Sync for two seconds enters reference level selection mode. The default reference level is calibrated to 0dBfs = 18dbu.
• 10 Display: Shows the sync source, sample rate of the selected source, and the selected reference level.
• 11 Output: An analog potentiometer (ALPS RK27 "Big Blue") controls the level of the VAR OUT output, serving as a volume control.

Connections

Use only the described connections. Other connections can lead to health risks and equipment damage.

Water and Humidity

Do not use this device near water (e.g., in bathrooms, damp cellars, near swimming pools) as this poses an extreme risk of fatal electrical shocks.

Insertion of Objects or Fluids

Be careful not to insert objects into chassis openings, which could lead to contact with dangerous voltage or short circuits. Never allow fluids to be spilled or sprayed on the device, as this can cause dangerous electrical shocks or fire.

Ventilation

Vent openings are for preventing overheating; never cover or block them.

Power Supply

Power the unit exclusively with the specified voltage rating. Contact your dealer or electric provider if unsure. Disconnect from the electric grid when not in use for extended periods. Ensure the mains plug is easily accessible.

Opening the Unit

Do not open the device housing unless you are a certified SPL technician or engineer. Opening the device poses a risk of damage or dangerous electrical shock, even after disconnection.

Cord Protection

Arrange power and audio signal cords to prevent them from being stepped on, crimped, or damaged. Avoid overloading power connections to wall sockets, extension cords, or signal inputs. Always follow manufacturer warnings to prevent fire hazards and dangerous shocks.

Lightning

Before thunderstorms or severe weather, disconnect the device from wall power. Do not do this during a storm to avoid lightning strikes. Similarly, disconnect power connections for other interconnected devices, antennas, and phone/network cables before severe weather to prevent lightning damage.

Controls and Switches

Operate controls and switches only as described in the manual. Incorrect adjustments can lead to damage and repair costs. Avoid excessive or extreme changes.

Repairs

Unplug the unit from all power and signal connections and contact a qualified technician if repairs are needed, or if moisture, foreign objects, or damage (e.g., from dropping) are suspected. This also applies if the unit is not functioning normally. For power supply/cord damage, turn off the main circuit breaker before unplugging.

Replacement/Substitute Parts

Ensure service technicians use original replacement parts or those with identical specifications. Incorrect parts can cause fire, shock, or further damage. A thorough safety check by a technician is recommended after repairs.

Cleaning

Do not use solvents, as they can damage the chassis finish. Use a clean, dry cloth (optionally with acid-free cleaning oil). Disconnect the device from the power source before cleaning.

Notes on Environmental Protection

At the end of its operating life, this product must not be disposed of with regular household waste but must be returned to a collection point for the recycling of electrical and electronic equipment. The wheelie bin symbol on the product, user's manual, and packaging indicates this. Materials can be reused according to their markings. Recycling contributes to environmental protection. Consult your local administrative office for responsible waste disposal points. WEEE Registration: 973 349 88.

Declaration of CE Conformity

The construction of this unit is in compliance with the standards and regulations of the European Community.