Gotham Cable

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Gotham audio cable has never been well known like Mogami or Canare but over the years many audio professionals have insisted on Gotham for demanding applications and high end installs. I have always felt that it was superior to those brands and I’m very pleased that Roadworthy Cables is using Gotham cable. The design, with its finely stranded copper wire, double Reussen shielding,and supple jacketing assures superb flexibility, easy and fast handling, low memory and reliable, long life.

What is double Reussen shielding?

The best way to shield balanced audio cables against RF interference, hum pickup, and crosstalk is by surrounding the audio conductors with two separate spiral shields wound in opposite directions so that the layers strands are at 90 degree angles to one another. Winding the shields in opposite directions reduces inductive effects on long cable runs and improves cable flexibility. Most of Gotham’s “GAC” cables feature double Reussen shielding with hair thin copper strands.

Below, you’ll see more history on Gotham cable, along with a summary of cable types that are made, and links to our web store.

Gotham GAC Double Shielded Analog Cables — The best known and most popular types. Most feature double Reussen shielding, though some utilize a foil shield and drain wire. This group includes 2 and 3 conductor microphone cables, small diameter installation cables, special low noise and halogen free types, Star-Quad, Active Loudspeaker, Tube Microphone, 2-Pair Round and Flat types, and Multicore Cable. Other important cables in this group are GAC-7 Tube Microphone Cable,, with 7 conductors and double Reussen shield, and GAC-2111, with an ultra-strong cut resistant jacket (a remake of EMT-2111 mic cable).

GAC-3 triple conductor microphone cable ( See sidebar) - GAC-3 is Gotham’s signature 3-conductor microphone cable, a studio standard for decades. Double 96-conductor shields, with 115db RF rejection. Available in black, traditional gray, and thick jacket versions. We also have a limited supply of new old stock Gotham GAC-3 with a soft brown jacket. (See sidebar)

Cutaway view of a Roadworthy Cable
Jacket: 1 PVC, Ø 6.3mm
Shield No. 1: 2 90x Bare LCOF copper wires (0.10 mm) 100% coverage
Shield No. 2: 3 98x Bare LCOF copper wires (0.10 mm) 100% coverage opposite wound
Layer: 4 PVC, semiconductive black

Isolation: 5 Cellular PE, Ø 2.50mm
Layer:
 6 PVC, semiconuctive black 0,75mmØ

Conductor: 7 Stranded bare LCOF copper wires 7 x 0.20mm (0.22mm²)

Why 3 Conductor Cable for an Audio Signal?

    Some Gotham cables utilize 3 conductors, plus a double Reussen shield. Most veteran engineers and studio techs have encountered EMT or Gotham 3 conductor mic cable. Here are the benefits of this unique mic cable construction:
  • Grounding/shielding: With the third conductor connected to ground, together with the two shields, RF-rejection is increased to 115dB (20dB better than standard) at 25 kHz. This was confirmed in the November 1994 AES paper by Mr Neil A. Muncy “Noise Susceptibility in Analog + Digital Signal Processing Systems.” Gotham GAC-3 was named the best performing microphone cable available.
  • Round Construction: 3-conductor constructions are round constructions, and since the cable has the freedom to move in all directions, especially on the strain relief of a connector, the cable will survive more movement cycles.
  • Phantom Power: The 3rd conductor can be wired as a drain wire for a reliable connection of phantom power to the microphone without affecting the shield.
  • Each of the three conductors consists of 96 (!!) strands of 0.05mm copper wires being the finest stranding for audio cables available. This provides improved flexibility, better signal transport and longer lifetime (moving cycles). (Heavy duty version with 5.8mm ø also available)
  • For more information: Noise Susceptibility in Analog and Digital Signal Processing Systems by Neil Muncy, presented at 97th AES Convention San Francisco November 1994 Revised April 13, 1995 Journal of the Audio Engineering Society Vol 43 #6 June 1995 p.435-453
Gotham AG

Based in Switzerland, Gotham AG manufactures a premium line of cables designed for minimal noise and maximal fidelity. Though initially only available in Europe, Gotham cables have been available on the U.S. market since the mid-1970s. Gotham has grown in popularity among U.S. engineers and now ship standard with Neumann microphones — which may give a hint to their quality.

Two major categories of noise affect all audio cables: electrical interference and micro-phonics. Unbalanced signal core audio cables are much more sensitive to electrical interference than balanced cables which, because of their twisted pair configuration, have the ability to mutually cancel EMI. Microphonic noise is caused by a static charge generated when the conductor is rubbed against its insulation. This occurs to some degree whenever the cable is moved. The microphonic effect is evident by a clicking noise in the system, usually occurring when the cable is handled or moved. Gotham GAC-1 unbalanced cable has been engineered to minimize these affects. With this ultra Pro version we have gone one step forward by adding yet another lawyer of conductive plastic between the conductor (7) itself and the isolation of the Conductor. Making a sandwich kind of conductive material between the 2 copper shielded and the conductor itself.

Technical Datas:

Conductor resistance:
< 85 Ohm/km Shielding resistance: < 11.30 Ohm/km Capacitance cond/cond
< 70 nF/km Test voltage: 1000 Veff (2 minutes) Temperature range:
flexi-installed: -5° to +50° C
fix-installed: -30° to +70° C
Cutaway view of a Roadworthy Cable
Jacket 1 PVC, ø 0.21 in
Viscose fiber coat 2 Counter wrapped to the shield
Shield No. 1 3 Bare copper wires (38 AWG), 100% coverage
Shield No. 2 4 Bare copper wires (38 AWG), 100% coverage
Layer PVC 5 conductive
Insulation 6 PE, ø 0.05 in
Conductor 7 Stranded bare copper wires, 48x41 AWG (24 AWG)
Conductor resistance < 30.5 Ohm /1000 ft
Shielding resistance < 8.5 Ohm /1000 ft
Capacitance < 44.5 nF /1000 ft
Test voltage 1000 V eff. (2 minutes)
Temperature range (flex) –5° to +50° C

GAC-3

Why three conductors for an audio signal? Here are some answers: Grounding/shielding: With the third conductor put to ground, together with the two shields, we have increased RF-rejection to 115dB (20dB better than standard) at 25 kHz. This fact has also been conformed at the AES-paper held by Mr Neil A. Muncy (“Noise Susceptibility in Analog + Digital Signal Processing Systems”) in November 1994. The GAC-3 was named the best performing microphone cable available. Round Construction: 3-conductor constructions are round constructions, and since the cable has the freedom to move in all directions, especially on the strain relief of a connector, the cable will survive more movement cycles. Phantom Power: The 3rd conductor can be wired as a drain wire for a reliable connection of phantom power to the microphone without affecting the shield. Each of the three conductors consists of 96 (!!) strands of 0.05mm copper wires being the finest stranding for audio cables available which gives you improved flexibility, better signal transport and longer lifetime (moving cycles). (Heavy duty version with 5.8mm Ø also available). 1 Jacket PVC, ø 0.19 in (10701 - 10716) PVC, ø 0.23 in (10801 - 10803) 2 Shield No. 1 Bare copper wires (38 AWG), 100% coverage 3 Shield No. 2 Bare copper wires (38 AWG), 100% coverage 4 Viscose fiber coat Counter wrapped to the twisted triple 5 Insulation (cond.) PVC, ø 0.05 in, white, brwon and green, twisted triple 6 Conductor Stranded bare copper wires, 96x44 AWG (24 AWG)
Conductor resistance < 24.4 Ohm /1000 ft
Shielding resistance < 6.1 Ohm /1000 ft
Capacitance cond /cond < 45.7 nF /1000 ft
Capacitance cond /shield < 73.2 nF /1000 ft
Characteristic impedance at 10 kHz 150 Ohm
Test voltage cond /cond 500 V eff.
Test voltage cond /shield 2000 V eff.
Operating voltage low voltage
Temperature range (flex) – 5° to +50° C
Temperature range (fix) –30° to +70° C