Clear-Com Partyline
When the Clear-Com Partyline System was constructed in the late 1960's, it was to serve the live performance markets. This was mostly for concerts which were, at that time, growing in prominence and worked on by the founders of Clear-Com. The Clear-Com Partyline System was constructed to be as practical in deployment as possible and therefore built around standard 3-pin XLR cabling. This system allowed everyone on the line to communicate in the loudest of environments in a simple to deploy system.
Over time, customers took notice and adapted the system to other applications and markets and started to require more granular way of communication with more channels or switchboard outputs. Clear-Com systems evolved where multiple channels could be deployed in a single system, each one contained in a single 3-pin XLR cable or combined - optionally along with separate Program Audio - on a 6-pin Switchcraft Style XLR connection wired to a multicore with each signal contained in a shielded pair.
TW Partyline
TW Partyline Systems gained popularity in the late 1970's in the broadcast industry which had a requirement for multiple channels of intercom, IFB and Program Audio. Just like the Clear-Com systems, the TW method uses unbalanced audio, which is bridged by an audio input and output, yet puts two channels of intercom audio into a single 3-pin XLR for a very convenient distribution - especially in OB applications. The convenience came with some calculated trade-offs, like crosstalk between channels as cable lengths started increasing due to the shared ground between the two signals, lack of shielding between them and a capacitance effect in addition to noise from carrying power on the audio circuit(s), some of which could be offset with better cables and grounds. Additionally, TW systems required a different signaling systems compared to the Clear-Com for things like Call Signals and Remote Mic Kill, which utilized tone control in the TW system.
Clear-Com and TW
Clear-Com added TW capabilities in the early 1980's at the request of broadcast customers. TW was added to an existing Clear-Com system using an adapter originally called the TW-12 (very much unrelated to the current day TW-12C) and was later updated to TWC-10, TWC-701 and the current TWC-703, which is the first one to convert Call Signals between Clear-Com and TW.
Along with the TW adapter, Clear-Com introduced the CP-300 beltpack, which has evolved to the existing RS-703. This method was devised to provide customers that needed TW distribution with the best of both worlds where the bulk of the system was wired with the higher quality audio of the Clear-Com Partyline, with TW being used where quick deployment of 2 channels was needed on 3-pin infrastructures. Since then, Clear-Com has added TW capabilities to various devices, including all digital systems, such as HelixNet, FreeSpeak II, LQ Series, and FreeSpeak Edge, which all allow native integration of TW with both channels and signaling.
Current Clear-Com TW Capable Products
User Stations: RS-703 Beltpack, AB-120 Commentator Console
Adapters: TW-12C CC-TW System Bridge, TWC-703 CC-TW Line Adapter, TW-47 Radio Interface, EF-701M 4-Wire Interface
Main & Base Stations: LQ 2-Wire Interfaces, HelixNet HLI-2W2 Module, FSII-BASE-II Base Station
Legacy Clear-Com TW Capable Products
User Stations: CP-300 Beltpack, RS-502TW Beltpack, RS-603 Beltpack, EB-TW Adapter Module, PIC-4000/4704 IFB System, TR-62, AB-100 Commentator Console
Adapters: TW-12B CC-TW System Bridge, TW-12, TWC-10, TWC-701 CC-TW Line Adapter, TWC-704 CC-TW Adapters