A vital part of creating a loop system complying with the IEC standard is an insightful and pro-active planning resource. Univox employees have the right skills to help any customer to obtain the right solution for every venue. You don’t have to know what to ask – we will ask the right questions for you to find the best solution for your need.

We don’t make the planning process and the choice of amplifier more complicated than it is. We know our products will cope with almost any circumstances and we don’t believe in “offering” the customer an unnecessary and expensive “support package” for a simple loop planning. Instead you will always receive prompt, accurate and free support to all questions you might have regarding our loop amplifiers and other systems.

We and our network of trained Univox distributors all over the world are here to help you through your projects. We are here for you – don’t hesitate to contact us!

Initial planning

Select an amplifier (amplifiers) based on

Start by finding out the conditions for achieving a good result:

  • Size of the room and coverage area – one or several amplifiers
  • Overspill to other areas – SLS or PLS amplifier, Hollow Core slab
  • Placement of the amplifier
  • Placement of the cable – in the roof or in the floor.
  • Cable – standard or copper foil
  • Heavy metallic influence

See our online planning tool, Univox Loop Designer.

Please note!

Univox amplifiers coverage area are specified to generate the peaks (0 dB and 400 mA/m) specified by the standard. They cannot be compared with amplifiers specified for only 100 mA/m (16 times lower power!)

The distance between the cables should be less than 10 m in a perimeter loop. If not, plan for more sections or figure 8.

Cable 2 x 2.5 mm² is the most flexible cable. Using a twin-cable makes it possible to choose between one/two or parallel turn loop configuration and is suitable for most installations. There are no specific demands of isolation of the cables, ordinary speaker cables are excellent. You can also use a flat copper foil cable for venues where it is difficult to install an ordinary cable. Begin with a two-turn loop (especially if the area is significantly smaller than the amplifiers maximum coverage area.)

The amplifier’s maximum coverage area is measured in a free field situation. In reality (with metallic objects, like reinforced concrete) the coverage can be reduced by approximately 20-50%. Choose an amplifier with at least 20% to compensate for metal loss due. Read more about SLS or PLS.

On site planning

Measure the background noise with a FSM 2.0 field strength meter, a professional stand-alone measuring instrument for installers, sound engineers and technical staff.

The background noise should be lower than -47dB relative 400m/A/m, but up to -32dB can be acceptable. (The certificate of conformity included in the FSM 2.0 and with all Univox amplifiers provides you with an easy step-by-step instruction how to perform the background measurement and other measurements to fulfil the IEC standard 60118-4.)

Start with a two turn loop. This is important especially when you will cover an area that is considerably smaller than the stated maximum coverage area of the amplifier.

Installation of SLS system with copper foil cable

Click here to watch our YouTube film sequence showing an example how to install an SLS system with copper foil cable.


  • Avoid placing the loop cable close and/or parallel to metal constructions, like reinforcement grid.
  • The cable must NOT be placed above or close to an inner ceiling made of metal grid.
  • If the floor is heavily reinforced, place the cable on the wall, 3-5 dm from the floor level, to increase the field strength.
  • If the loop is larger than 200 m², the distance between the listening area (standard listening area is 1.2 m above floor level) and loop, must be more than 1.2 m.
  • Wheelchair spaces should be included in the loop.
  • The cable should not be covered by metal, neither solid nor grid.
  • Plan the location for the amplifier/amplifiers.
  • Connection wire should be twinned or paired and have the same diameter as the main cable.
  • The loop cable cannot be placed parallel or near microphone or mixer cables. Crossing is allowed. Nor should it be placed nearby technical equipment, e.g. mixers, projectors.
  • Follow the installation guide of the amplifier. Pay extra attention to how to set the input sensitivity level with the AGC-system.
  • It is preferred to use balanced inputs with low impedance.
  • Pay special attention to low level inputs.
  • Do NOT use dynamic microphones, as this results in an increased risk for magnetic self-oscillation.
  • Certify installation – see Comply with standard.
  • Inform and instruct staff of the function and position of the loop system and how to use the testing instrument, e.g. Univox Listener. Keep certification and all manuals available.
  • Put up signs clearly showing the hearing aid users that a loop system is installed, for example at the entrance to the looped room/s.

Certify installation

It’s important to plan and design the loop carefully and check the system when the installation is completed. To ensure the loop installation meets the requirements of field strength, consistency and frequency response, it must comply with the international standard IEC 60118-4.

To comply with the standard, please see Certify installation