The term "Adapter" is used to describe a specialized connector with different types of connector on each end. An adapter can be used to either make connections between two pieces of equipment that both have either balanced or unbalanced connections; or to connect balanced equipment to unbalanced equipment.
There are two basic types of adapters:
- Adapters that have connectors for balanced connection on both ends or adapters that have connectors for unbalanced connections on both ends. These will be referred to as "Balanced or Unbalanced adapters."
- Adapters which have a connector for balanced connections on one end and unbalanced connections on the other end. These will be referred to as "Balanced to Unbalanced adapter cables."
Balanced or Unbalanced Adapters
The connectors must have three conductors to provide connection for the non-inverted and inverted signals plus the shield. The two most common type of connector used for balanced analog audio interconnection are the 3-pin XLR and 1/4" T.R.S. "phone" plug. The name "phone" refers to the original use of this type of connector in early telephone "switchboards."
"Unbalanced" adapters have two conductors to provide connection for the signal conductor and shield. The two most common type of connector used for unbalanced analog audio interconnects are the "RCA" or "phono" plug and the 1/4" T.S. phone plug.
Balanced to Unbalanced Adapters
In order to make connections between balanced and unbalanced equipment, a special type of adapter is required that either:
- Connects two of the three conductors in the balanced connector together.
- Leaves one of the three conductors in the balanced connection not connected to anything.
The most common type is (1) and virtually all “off-the-shelf” adapters are constructed in this manner. Typically, the Shield and “inverting” conductors of the balanced connector are connected together and this is connected to the Shield (signal return) conductor of the unbalanced connector. For example, in an XLR to RCA socket adapter; Pin 1 and Pin 3 of the XLR are connected together and to the outer contact of the RCA socket. Pin 2 of the XLR is connected to the center contact of the RCA socket.
Please note that it is important to properly configure all Lavry analog balanced outputs before making unbalanced connections to avoid increased distortion of the audio signal. The outputs are protected against short-circuits; so it is very unlikely that any damage would result if an output is improperly connected; unless operated in this manner for an extended period of time.
All Lavry AES/XLR digital audio inputs and outputs are transformer coupled; so it is OK to use this type of adapter with coaxial 75 Ohm “S-PDIF” cables when making connections to RCA S-PDIF inputs and outputs; as long as cable length is within recommendations for coaxial S-PDIF applications. Lavry recommends using adapters which have an insulator between the RCA socket and the housing of the XLR for best results. Neutrik® brand NA2FPMF and NA2MPMF are examples of this type of adapter. Here is an example of a female XLR to RCA socket adapter similar to those included with the LavryBlack DA11: