connector) had blue or white insulation (depending on its gender), and was intended for connections between audio power amplifiers and loudspeakers. These are manufactured by Amphenol (formerly by Alcatel Components and ITT Cannon Australia). Obsolete patterns Many other types of connectors using the XLR type shell exist, with various pin configurations. One is the now obsolete three-pin power pattern connector manufactured by ITT Cannon. The power Cannon (also called the XLR-LNE connector) had shrouded pins and red insulation; it was intended as a mains power plug, alternative to the IEC 60320 series of connectors, but was only used on a few pieces of equipment. Two-pin (XLR2) A two-pin variant was used as the DC power input socket on Yamaha's 1970s CP-series 'Electric Grand' pianos (CP-60, CP-70 and CP-80). Technical usage information This section contains more technical information relating the most common applications of XLR connectors. Three-pin in audio use EIA Standard RS-297-A describes the use of the three-pin XLR - known as XLR3 - for balanced audio signal level applications: Prior to the introduction of this standard, the wiring of pins 2 and 3 varied. The pin 2 "hot" and pin 3 "cold" convention was typically used by European and Japanese equipment manufacturers, but American companies used pin 3 "hot" and pin 2 "cold". This caused problems when interconnecting equipment with unbalanced connections. The pin 3 "hot" convention is now obsolete but is still found on vintage equipment. Pin 1 has always been ground and/or shield if the cable is shielded, and many connectors connect it internally to the connector shell or case. Although covered in industry technical standards, there is still some disagreement on the best way to handle the use of pin 1 for grounding (earthing). The main controversy is whether the shell of the connector should be connected to pin 1 or the shield, or left floating. AES standards mentioned above recommend that shells of cable-mounted connectors should never be connected to pin 1 or the shield, because inadvertent contact of the shell with another grounded surface while in use can create unwanted current paths for fault current, potentially causing hum and other noise. On the other hand, equipment containing active circuitry should always have pin 1 connected to the conductive enclosure of the equipment as close as possible to the point where the signal enters the enclosure. The argument centers on the radio frequency shielding provided