Introduction to LUMIN

Glossary of terms

LUMIN-Specific terms

LUMIN App: The controller for all LUMIN players. This is required for setup of LUMIN players. The App can be run on Android and Apple iOS tablets and phones.
Network Player: LUMIN players that include a DAC. These feature analogue outputs for connecting to an amplifier. Most models also feature digital outputs that will bypass the included DAC, if required.
Network Transport: LUMIN players that don't include a DAC. An external DAC will be required for playback. These players include digital audio outputs only.
Network Player Amplifier: LUMIN players that include a DAC and also amplification. These players include speaker outputs.
Playlist: This is the list of tracks that are queued for playback on a LUMIN player. They are stored on the LUMIN player (termed an on-device playlist) so are available to all controllers used in a system (phones, tablets, or computer software). This also means that different playlists can apply to different LUMIN players within the same system.

A selection of general terms

AES/EUB S/PDIF

Audio Engineering Society / European Broadcasting Union. A digital audio communication standard used on LUMIN Transports for output to a DAC with AES/EUB input.

Balanced connections

A method of connecting audio equipment using 3 (instead of 2) conductors per channel. The third conductor is grounded (to catch and remove unwanted RFI), but plays no part in passing the audio signal or providing its voltage reference. Instead, the two signal wires provide the reference voltage for each other. Effective interference rejection requires both the sending and receiving devices to have balanced output and input stages respectively. Balanced connections can be found on all LUMIN Players.

BNC S/PDIF

A type of bayonet-locking, two-terminal connector used for professional digital connections. This can be found on many of the LUMIN Player and Transport range.

Bridged Mode

This is an output configuration for audio amplifiers, a form of impedance bridging. The main reason for using this is to use two amplifiers to quadruple the power into each loudspeaker. A loudspeaker is connected between the two amplifier outputs, bridging the output terminals. This doubles the available voltage swing at the load compared with the same amplifier used without bridging. The alternative way of connecting two stereo amplifiers is Dual Mono (sometimes known as Parallel). Normally, Bridged Mode should be reserved for 8ohm loudspeakers.

Class AB Amplification

Audio power amplifiers are classified primarily by the design of the output stage. Classification is based on the amount of time the output devices operate during each cycle of signal swing. Also defined in terms of output bias current (the amount of current flowing in the output devices with no signal).
LUMIN Amp uses Class AB amplification to achieve an amplifier with more efficiency than Class A but with lower distortion than Class B. For small signals both transistors are active, acting like a Class A amplifier, but for large signal excursions, only one transistor is active for each half of the waveform, acting like a Class B amplifier. Each transistor is always operating so they respond instantly to input voltage demands.

Class D Amplification

A Class D amplifier or switching amplifier features amplifying devices (transistors, usually MOSFETs) that operate as electronic switches, and not as linear gain devices as in other amplifiers. They switch at a frequency far higher than the highest audio signal that needs to be reproduced. The low-pass filtered, average value of this waveform corresponds to the actual required audio waveform. Class D amplifiers are highly efficient (often up to 90% or higher) since the output transistors are either turned fully on or off during operation.
LUMIN M1 uses Class D amplification, which retains a digital signal path all the way to the speaker terminals.

Clock timing

The precise timing of digital audio samples is critical to the correct operation of interconnected digital audio equipment. Digital interfaces such as the AES3 and S/PDIF embody clock signals within the data stream, but these need to be accurately maintained throughout the digital chain to prevent jitter. The specification of LUMIN clock implementations vary - please see the specification of each model.

DAC

Digital to Audio Converter. Converts a digital bitstream to an analog signal. LUMIN Network Players have internal DAC stages, whereas LUMIN Network Transports require an external DAC. The specification of LUMIN internal DAC stages varies - please see the specification of each model.

DSD

Direct Stream Digital. The digital audio format used in SACD. Unlike the PCM system normally used, DSD uses a stream of single bits of information. The momentary level of the analogue wave form being represented by the bitstream is determined by the density with which the bits are 'on' and 'off'.
DSD as found on SACD is DSD64 (or DSD 2.8 MHz - 2.8 million samples per second). For DSD downloads, there are now DSD128 (5.6MHz or Double DSD), DSD256 (11.2 MHz) and DSD512 (22.5792 MHz) formats available. Different LUMIN models support different DSD maximum sample rates - please see the specification of each model.

Dual Mono

This is an output configuration for audio amplifiers. It allows two stereo amplifiers to be connected to two loudspeakers without raising the output voltage. This configuration is normally used for 4 ohm and 6 ohm loudspeakers.

Earth / Ground

Ground is defined as the point of zero voltage in a circuit or system, the reference point from which all other voltages are measured. In electrical power systems, ground connections are used for safety purposes, to keep equipment chassis and controls at zero voltage and to provide a safe path for errant currents.
LUMIN Players all feature a ground wire in the electrical power cabling. Some LUMIN models and LUMIN Power Supplies also include a separate Earth/Ground connector. These can be used to connect the unit to an earthing terminal if no mains earth is available or for joining the earths of other components in your system to improve noise reduction.

Firmware

Firmware is the operating system of our hardware. All LUMIN players feature a Programme of Continuous Development, which means the Firmware is upgradable for further features and enhancements. If your LUMIN is connected to the internet, these upgrades can take place automatically. Otherwise, firmware upgrades can be performed using a USB disk.

Gain

The amount by which a circuit amplifies a signal, normally denoted in decibels (dB).

Library

This refers to your source of music. This can be in the Cloud (i.e. Spotify, TIDAL or Qobuz); on a local music server such as NAS, LUMIN L1, or computer; or on a USB-attached disk.

Music Server

This refers to software serving your your music library. This can be a NAS, LUMIN L1, or computer; or when a USB disk containing music is attached to LUMIN it will start an in-built Media Server.

Optical S/PDIF (TOSlink)

A method of communicating digital audio between components using light carried on optical fibre. See TOSLink. The data format accords with the S/PDIF specification.

Output Impedance

The source impedance that an amplifier presents to a loudspeaker. The lower the source impedance, the greater difficulty a loudspeaker will have in feeding back EMF to the driving amplifier, and the greater the level of control the amplifier will be able to exert over the loudspeaker.

PCM

Pulse Code Modulation. A means of digital encoding. In a PCM stream, the amplitude of the analog signal is sampled regularly at uniform intervals, and each sample is quantized to the nearest value within a range of digital steps. The resolution of the signal is described by two figures:
Sample rate: The number of times per second that samples are taken.
Bit depth: The number of possible digital values that can be used to represent each sample.
So, a common figure (found on CDs) of 16-bit/44.1 kHz means that samples of 65,536 (2¹⁶) distinct values are taken 44,100 times a second.

RCA (Phono)

The most common method of analogue stereo connection. This connector is also used for electrical (as opposed to optical) digital audio connection. RCA analogue outputs can be found on all LUMIN Network Players (often labelled 'Unbalanced Out'), while RCA digital can be found on all LUMIN Network Transports.

Signal-to-noise Ratio (SN)

The range or distance between the noise floor (the noise level of the equipment itself) and the music signal, expressed in decibels (dB).

UPnP AV (OpenHome)

Universal Plug and Play with Audio Video extensions. An open set of computer network protocols created by the UPnP Forum. UPnP is based on internet-based communication standards.
For a typical LUMIN system, UPnP includes specification for the following components:

Media Server: In a LUMIN system, this is the place where music is stored - either a computer, NAS or LUMIN L1. When a USB disk containing music is attached to LUMIN, it will start an inbuilt Media Server.
Media Renderer: This is your LUMIN player.
Rendering Control: This allows hardware settings such as output port, resampling, display brightness, sleep timer, etc by the LUMIN App running on iOS or Android.
Remote User Interface: This is music browsing and playback control by either the LUMIN App running on iOS or Android, or another compatible OpenHome controller such as Linn Kazoo.

Note that LUMIN uses OpenHome which is an open standard built on top of UPnP AV. OpenHome differs from UPnP in that it gives much more control of playback to the Renderer. This enables reliable gapless playback, on-device playlists, and Multi-Room, and LUMIN can continue playback even if communication with the Control Point is interrupted.
LUMIN is still compatible with UPnP Music Servers, but browsing features are enhanced when using OpenHome compatible servers such as MinimServer.

USB

Universal Serial Bus. A bidirectional port. The function of LUMIN USB ports varies. Most can be used for attaching USB disks and firmware upgrades but some also allow Digital Audio Output - please see the specification of each model.

XLR

A robust (often latching) type of connector used for Balanced Analogue and Digital Audio. All LUMIN Network Players feature XLR Balanced Audio Output, and all LUMIN Network Transports feature XLR Digital Output.