Bo Edin AB

1) Connect a signal source to both systems, preferably a sine wave
2) Connect both MASTER and SLAVE loops to both amplifiers
3) Set the output level to minimum for the SLAVE systems
4) Adjust the level for both MASTER systems to approx. -3dB
5) Listen to the sound of the loop with a loop listener (Univox Listener or Univox FSM) while shifting the phase (wires) on one of them until a correct sound is heard. One position will sound distorted whereas the other will sound clean.
6) Repeat step 3-5 in the procedure above for the SLAVE systems as well
7) After you’ve completed the above procedure, adjust/certify the systems according to the IEC 60118-4 standard

This is possible if you use Univox SLS amplifiers. Read more about Univox SLS and Hollow core slab

Try to use a more powerful amplifier to compensate for the thin cable.

It is a big area to cover and it is almost impossible to receive a smooth field strength with a standard amplifier. We recommend to use Univox SLS amplifier system to for a good sound quality. By using SLS it is possible to use different program material in different parts of the arena. Read more about Univox SLS.

Try first to isolate the two systems.

Is the PA and Loop Amplifier working separately without any problem?

If the Loop Amplifier self-oscillate (the input LED is emitting), reduce the output loop current or remove the loop wires. If the problem stops the cause could be

1) the loop wire could be short-circuit to safety ground somewhere
2) the loop amplifier does not work

If self-oscillation only occurred when the systems are connected together try to reduce the output loop current to minimum. If the self-oscillation disappears it is most likely that there is a feedback problem between sensitive inputs and loop wire in the system. For example, there are sensitive dynamic microphones close the loop wire. Inputs and outputs (loop-wire) shall not be placed close to each other to avoid feedback. For more information visit on site planning.

The specification of the coverage area is calculated for a free-field (no metallic objects) with a square-loop (hardest figuration) at 1.2m height. In many installations there are metallic objects that influence the field strength. The field is therefore attenuated especially in the high frequency region. Therefore loop sides wider than 10 metres should be avoided.

Example: In a room with reinforced concrete/metal works the power demand is increased by 20 to 50%, sometimes even more. A stated 170m² maximum coverage area of an amplifier will only cover approximately 130m² in a normal reinforced concrete room.

If you use a Univox SLS, Univox Super Loop System, it is easier to estimate the coverage area.

Inform the user(s) that the loop current must be individually adjusted in each location.

We recommend a SLS system to avoid overspill and to reach a smoother magnetic field with a better frequency response. If you use a standard loop amplifier there is a risk to get acoustic feedback if you use electric guitars or other instruments in the auditorium. Read more about Univox SLS.

Yes, if you use the Univox SLS system above the seating area. Please contact us for more detailed information.

Univox SLS system makes it possible to install loops close to each other without overspill. Read more about Univox SLS.

We have measured the level with different cables; 0.5, 1.0, 1.5, 3.0mm² and you do not hear the difference. But to get MAXIMUM coverage area, the cable shall not be too thin.

The difference between 1.0 and 3.0mm² is 2dB. The difference between 0.5 and 1.0mm² is 1dB.

Yes, you can use the output RCA connector to feed another amplifier.

Always start with a 2-turn loop. If you do not reach an acceptable field strength level, try with a 1-turn loop.

To achieve a good result the cable has to be placed in the middle of the tiles, not close to the metallic frame. You should not place the cable at a height above 3m.

Always start with a 2-turn loop. If you do not reach an acceptable field strength level, try with a 1-turn loop. In small premises like this, the 2-turn loop will probably give the best result.

We recommend to solder the cable for best result. It is also possible to splice with standard cable as long as the area is the same as the area of the copper foil cable. For termination and slicing to a standard cable, you can also use Ebeco crimping tool.

It is possible to place the loop cable outside the church walls. Please contact us for more detailed information.

Try to use a more powerful amplifier to compensate for the thin cable.

Yes, that is possible, but it is important to measure the loop installation before adding putty.

Normally it works well, but it is important to make a test with measurement before putting the floor on top. Please contact us for more detailed information.

Yes, that is possible, but the reinforcement of the concrete can have a negative influence on the final result. Therefore it is important to measure the loop installation before casting.

That depends on the size of the loop. A room 15x15m the loop can be placed in the ceiling at 4m height with a good result. If you have a smaller room, for example 7x7m, the loop should not be placed higher than 2.4m to receive a good result.

You can place the cable plinth or in the ceiling.

The installation has to be tested and measured to confirm that it fulfils the IEC 60118-4 standard. Read more here.

Yes, use the “0dB Out” outlet.

With the supplied cable reel of 35 meters it covers 75 m². If you add the extension cable, it doubles the area to 150 m².

Yes, there are 2 microphone inputs on the CLS-1 amplifier.

Old products:

If you are using DLS-50 there is one special mic.input that has a controllable gain. Please use that for the main microphone and for the second microphone (we normally recommend only one to keep the acoustic noise down) other combined mic and line input. All the inputs have phantom voltage to the microphones.

Using DLS-70, there are two mic. Inputs with just the AGC-regulation function normally well but cannot be fine tuned for exact sensitivity and background acoustic noise.

If you are using our loop pad just install it and connect speaker to the headphone socket. Active speaker works best. If not active and the speaker level is too low use the cushion or the loop output (the loop and cushion connecter are paralleled). An active speaker is easiest to use, but any normal speaker that could easily be built-in is useful.

We recommend Univox CLS-1 with our loop pad, i.e. the CTC systems. If you use other loop pad the overspill could be more than 1m.

Yes the EJ-700 series of receivers have diversity.

You can us up to 4 microphones at the frequency 863-865 MHz. If you need to use more microphones, there are receivers on other frequencies available.

Please contact us for further information.

Check if the green LED on the transmitter and the yellow LED on the receiver lights up when the sound disappears. If so, it probably is wrong with the microphone.

The main issues with long cables are subdued treble and risk of induced interference from surrounding systems (loudspeaker cables, winding wires, data cables, etc.).

The maximum length can’t be specified in general, but the signal cable must always be balanced if the length is more than about 2m.

The maximum length is calculated by several combined parameters, e.g. how well shielded and balanced is the cable, how well balanced is the mixer, the level of the mixer (at least 0dBV = 0.775V, preferably + 4dBV) and also the output impedance of the mixer.

Signal cable placement is very important. It should never be near and parallel to the other long lines such as loop wire, speaker cable, computer networks, etc. A rule of thumb is at least 3dm from adjacent lines. Intersecting lines doesn’t interfere.

When ordinary general installation rules for audio and tele-technical installations are followed, then the length can amount to over 100m. In principle there is no upper limit.

Note that it is relatively rare that professional line level (signal between the mixer and the external devices) are causing the problems. Usually it’s the microphones low signal level that can interfere with other systems.