Cables - SDI 12G Q &A Considerations When Configuring and Selecting Cables for Microphone Systems With the growing demand of recent years for both greater physical comfort and savings in energy consumption, systems incorporating digital control based on the latest advances in electronics are coming into wider use for air conditioning and lighting systems. As all these systems come on line, we cannot help but be reminded of the fact that the wiring used for these digital control systems generates pulse - based electromagnetic noise of the kind that affects the very delicate signals used in microphone lines. Microphone cables are designed to carry a range of signals that span the spectrum from 1/100 of a volt (10 mV) to 1/1,000,000 (1 µV). One small error in wiring procedure or cable selection and the entire microphone system turns into an antenna collecting the surrounding noise. The following section uses a question and answer format to cover a list of the essential points for configuring microphone systems. Under what sort of conditions should a two - conductor microphone cable be used? The two - conductor microphone cable is suited to environments where noise is not such a great factor and the audio signals are in the comparatively high - 20 dB to 0 dB level range. In such cases, the two - conductor cable offers the advantages of smaller diameter and lower cost. Of course if microphone level, rather than line level, is the criterion being used, star quad cable should be used instead. Under what conditions should star quad microphone cable be used? This type is used for environments with a higher noise factor and where audio signals are in the low - 50 dB or less range. This type of cable performs well under noise conditions that exceed the capacity of the two conductor shielded cable, effectively shielding out over ninety percent more noise. (See Figs. 1, 2) However, should this type be routed alongside a power cable of any significant capacity it should probably be encased in metal conduit just to be safe. Fig. 1 Noise induced in two - conductor shielded cable (MVVS) Isn’t star quad cable expensive? The cost for this type of cable has fallen significantly in recent years. Several decades ago, cost was so prohibitive a factor that only large musical auditoriums and broadcasting facilities could afford them. Canare succeeded in developing a low - cost star quad cable using aluminum foil in 1981. In addition to traditional professional facilities, this type gained wide use in such non - traditional areas as wedding halls and school lecture rooms. Fig. 2 Noise induced in star quad cable (Canare L - 4E5AT) 1. Flush along power cables for 20 m distance 2. Power cable connected to lighting fixture dimmed to 50% capacity with load of 1 kW. 3. The noise induced in the audio cable was boosted by 50 dB in the head amplifier and viewed on a spectrum analyzer. Star quad cable with aluminum foil shield

When avoiding use of metal conduit, how far away should microphone cable be from power cables? When foregoing the use of protective metal conduit, use the graph shown in Fig. 3 as a general guide for distancing cables. Note that ignoring basic guidelines for positioning cables can easily result in noise induction problems which are very difficult to deal with later. Encasing microphone cables in metal conduits is highly recommended for applications that utilize the delicate signal range. 1. Cables are the star quad type. 2. Power cables are in the circular cab tire configuration. 3) Aluminum...

Cables Star Quad Cables The Star Quad Story Canare Star Quad obtains its name from the 4 - conductor style construction that minimizes the “loop area” between twists of the conductors. This “double balanced” pairing, reduces susceptibility to electromagnetically induced noise. The improvement in noise rejection is so noticeable, that even SCR dimmer noise (stage lighting consoles), is reduced to less than 1/10 the level found in other 2 - conductor microphone cables. Canare Star Quad is designed for use with microphones but is also excellent for all line - level signals (e.g. mixer to power amps)....

Star Quad Cables Website Effectively reduce noise levels to 1/10 that of general - purpose, 2 - conductor shielded cables. ■ Aluminum Foil Shield Composition Type Electrical characteristics Cross sec. area (AWG) and cond. comp. Twist pitch Jacket color : GRY Insulation : Cross - linked PE Dielectric strength : 500V AC/min. AL foil + double braid Fiber - Optic Systems Technical Trend Sales units Star Quad Microphone Cables (Single) *Capacitance between conductors **Capacitance between conductor and shield. • Designed for fixed installations • Aluminum foil shielding provides 100% coverage • DuPont...

L - 4E3 - **P Star Quad Cables Website Multichannel Star Quad Microphone Cables ■ Aluminum Foil Shield Unit composition Type Insulation : Cross - linked PE (blue - blue, white - white) Jacket, inner Jacket : PVC Electrical characteristics Shield DCR Cross sec. area (AWG) and cond. comp. Twist pitch Dielectric strength : 500V AC/min. *Capacitance between conductors **Capacitance between conductor and shield. (dB) L - 4E3 - **AT, L - 4E4 - **AT • The multichannel microphone cable is the cable of choice for music auditorium and studio facilities where noise prevention and audio quality are the prime...

Two - Conductor Shielded Cables Website ■ Aluminum Foil Shield Composition Nom. O.D. Electrical characteristics Cross sec. area (AWG) and cond. comp. Twist pitch Technical Trend Sales units Two - Conductor Shielded Cables (Single) Jacket colors : GRY BLK SEPIA Dielectric strength : 500V AC/min. L - 2B2AL, L - 2E5AL • Cables for connecting devices with which wrapping tools can be used. • Drain wire included. Fig. 1 Pull Load and Stretch Ratio for Cable L - 2B2AT, L - 2E5AT • Ideal for internal rack wiring. • Drain wire included. • The L - 2E5AT contains the Tetoron cable filler reinforcement material....