Introduction to connectors (in the recording studio) by Ric Ording

connectors

In the recording studio, the sheer variety of interconnection technologies can be overwhealming. There are so many different types of leads and sockets, and often a device will have several interconnection options. Not only do you have to figuer out how the connections work, but which is best. Even experienced sound engineers may not know the theory aspects of all the interconnects they use. But sometimes it's not necessary to know all the details.

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Here are the primary interconnection leads ...

Common name Signal type Connector Cable type Typical uses / comments
XLR / Mic cable Mono balanced analogue microphone level audio (low amplitude), with phantom power. XLR (canon). 3 cores. For analogue signals, X=external/earth, L=Live/hot, R=Return/cold). To connect an analogue microphone to a mic pre-amp or mixer. To connect a DI box (guitar?) to a mixer.
Mono balanced analogue line level audio (high amplitude). XLR (canon). 3 cores. For analogue signals, X=external/earth, L=Live/hot, R=Return/cold). To connect a professional tape recorder to a mixing desk. To connect a professional effect unit or dynamic processor to a mixing desk. To connect professional 2 tracks (tape, DAT, CD players etc).To connect a professional SMPTE device to a tape recorder.
XLR / AES digital AES3 digital (mono/stereo unbalanced, up to 24-bit/96KHz). Originally known as AES/EBU. Identical data to AES-id. 7volts. XLR (canon). 3 cores.

110 Ω twisted pair cable used
To connect 2 professional devices with a balanced digital signal (AES/EBU).
       
AES42 digital microphone signal. XLR (canon). 3 cores. To connect an digital microphone to a digital mic pre-amp or mixer.
D-sub 25 / AES59-2012 AES59 8 channel bi-directional digital audio. D-sub 25 to D-sub 25 or to 8 XLRs (breakout cable). Up to 25 but typically 16 or 24 (4 x 3 cores digital cable in, 4 x 3 cores digital cable out). Essentially the AES ratified version of the Tascam D-sub 25 pin-out arrangement for balanced digital audio. Carries 8 channels bi-directionally (in and out simultaneously) in 4 pairs (1-2, 3-4, 5-6, 7-8). Can also be used for analogue.

Employed originally by Yamaha and Tascam for interconnection between their digital recorders (eg DA88) and mixing desks (eg O2R). 2 pin-out schemes are popular (Yamaha unbalanced) and Tascam (balanced). The Tascam pin-out has been adopted as AES59-2012 standard by the AES. A typical cable may connect a mixer or network interface equipped with a D-sub connector to multiple AES
Balanced jack to jack Mono balanced analogue line level. 1/4" stereo jack. 2 cores and shield (live, return, earth). To connect a semi-pro tape recorder to a mixing desk. To connect a semi-pro effect unit or dynamic processor to a mixing desk. To connect semi-pro 2 tracks (tape, DAT, CD players etc)To connect a SMPTE device to a recording device.
Headphone Stereo unbalanced analogue headphone level. 1/4" or mini stereo jack. 2 cores and shield (left, right, earth). To connect headphones.
Jack to jack Mono unbalanced analogue line level. 1/4" mono jack. 1 cores and shield (live, return/earth). To connect a keyboard, sound module, sampler, drum machine etc to an audio interface or mixing desk. To connect a guitar or bass to an amplifier or DI box.
To connect a consumer tape recorder to a mixing desk. To connect a consumer effect unit or dynamic processor to a mixing desk. To connect consumer 2 tracks (iPod, MiniDisk, DAT, CD players etc)To connect a SMPTE device to a recording device.
Guitar lead Mono unbalanced analogue pickup level (mic). 1/4" mono jack. 1 cores and shield (live, return/earth). To connect guitars with electric pickups to amps of DI boxes. Cable not too dissimilar to tat used for a jack to jack lead.
Head speaker lead Guitar / bass head to cab speaker level 1/4" mono jack. Speaker cable, heavier gauge core and no shield. The output from a guitar amp is at a much higher level that that of a guitar, requiring a different type of cable.
Analogue phono lead Mono unbalanced analogue line level. Phono plug 2 cores (live, return/earth). To connect domestic consumer audio devices ((iPod, MiniDisk, CD players etc).
Digital phono/SPDIF lead SPDIF digital (mono/stereo up to 24-bit 48KHz). 0.7volts. Phono plug (known as coaxial RCA when used for S/PDIF) 2 cores (live, return/earth).

75 Ω cable used
To digitally interconnect domestic consumer and semi-pro audio devices.
Record deck lead Stereo unbalanced analogue phono level. 2 x phono plugs and earth lead. 5 cores (left-live, return/earth, right-live, return/earth, separate earth). To connect a record deck to a phono pre-amplifier (or DJ mixer)
Speaker / monitor Mono unbalanced speaker level typically 30A) Un-terminated, Speakon or banana plug. 2 cores. To connect a power amplifier to a loudspeaker / monitor.
MIDI lead MIDI / computer level (very low amplitude). 5 pin DIN 3 cores including shield MIDI device interconnection. To transmit MIDI performance and system messages (eg between a synthesiser and a sound module)
USB MIDI and digital audio / computer level (very low amplitude). USB. 4 cores. To connect a controller keyboard (MIDI) to computer. To connect semi-pro audio/MIDI interfaces to a DAW. To connect semi-pro FX and processor units to DAWs. etc
Firewire MIDI and digital audio / computer level (very low amplitude). FireWire. 6 cores. To connect an audio/MIDI interface to a computer. DSP racks/farms to computers. Digital mixers to computers. etc
Optical SPDIF/TOS SPDIF/TOS digital (mono/stereo optical/digital, up to 24-bit 48KHz). Toslink. Fiber-optic Mono or stereo consumer and semi-pro interconnection, for example between a CD player and a DAT recorder, or an effects processor and a digital mixer (send/return).ADAT 8 channel digital interconnection, typically from a device such as a voice channel or mixer to an audio interface.
Optical ADAT/TOS ADAT digital (8-channels of 24-bit 48KHz optical/digital). Toslink. Fiber-optic To connect semi-pro/pro devices such as digital mixing desks and DAWs.
BNC AES3-id digital (mono/stereo, up to 24-bit/96KHz).). Data is identical to AES3. BNC. 2 cores. Stereo professional interconnection such as the digital out from a mic pre-amp to a digital mixing desk.
MADI - Multi-channel Audio Digital Interface (up to 56 channels of 24-bit 96KHz digital audio) BNC. 2 cores. Professional digital multitrack to large format digital mixing desk.
MADI-X Multi-channel Audio Digital Interface (up to 64 channels of 24-bit 96KHz digital audio) BNC. 2 cores. Live sound / broadcast /recording applications.
Ethernet Ethersound (Digigrams’s format) RJ-45 (Cat5) ethernet. 8 cores. To connect nodes in a distributed audio processing system (eg several Macs can acts as processing nodes for a Logic system).
Audinate / Dante (audio over IP) Cat5, Cat6 Cat5, Cat6 Increasingly popular Gigabit audio over IP network protocol. Adopted by multiple manufactures including Yamaha and Focusrite.
SuperMAC (48 digital audio channels) RJ-45 (Cat5) ethernet. 8 cores. Sony invented audio networking system.
HyperMAC (384 digital audio channels) RJ-45 (Cat5) ethernet. 8 cores. Sony invented audio networking system.

 

Cost implications

As you can see, there are many types of connecting lead used for these different types of signal. Some signals can be sent down several different types of lead. It is worth remembering that equipment manufacturers will often choose a lead/connector type based on cost rather than robustness. Also some leads do not need to be strong. Phono leads which are often used to connect hi-fi are cheap and cheerful but are usually connected once and then left alone. Guitar leads will be plugged and unplugged many times and must therefore be reasonably strong.

Further reading

Unbalanced and balanced audio signals and connectors

Mono and stereo connections