Audio Induction Loop Systems that are much more complex than the simple "wire-around-wall" installations can and are being designed and installed.
These systems vary from very large area requirements such as cathedrals, sports halls, etc. to irregular-shaped areas such as theaters with balconies, to loop systems requiring low-spillover for confidentiality or proximity to other induction loops such as lecture halls or multi-screen cinemas. Recent developments also allow loop condition monitoring and remote signaling, meeting the requirements important for systems such as Voice Alarms.
For these special situations, we supply a range of equipment that enable these special requirements to be met with essentially "standard" units.
For the majority of these situations, these units are set up in the factory for a particular location, and this is part of our design support work. In most situations, any design charges are included in the list price of the equipment.
We must be contacted when specifying / ordering ILC5 or CTU11 / CTU12 units as they are always adjusted for a particular site.
ILC5 Combining Unit
Where large Audio Induction Loops are needed, the simplest solution is often a perimeter loop, often at significant height, driven with a high current. With the long cable length of such an installation, the voltage drop is significant, especially due to the inductive component of the loop. Therefore, the total power needed to drive such a loop can be very high. The AMPETRONIC ILC5 combining unit is designed to hold up to 5 ratio transformers, to sum the output of multiple Loop Amplifiers so that a very large loop can be driven with a master-slave configuration. This allows the output power of multiple ILD9 Loop Drivers to be efficiently summed into a single loop, optimizing the transfer of power by a suitable transformation of voltage and current. This can be obtained from 5 off ILD9 with combiner. This permits loops covering up to 4000 m² / 43,000 ft². Many other transformation options can be used with this equipment. Detailed computer design of the loop is essential using these configurations.
The ILC5 is built into a standard 2U high rackmount case and is supplied with rackmount hardware.CTU11 / CTU12 Current Ratio Unit
When installing loops in irregular areas, it is sometimes necessary to operate some areas at different current to obtain correct field strength. Instead of using several amplifiers, a passive Current Ratio Unit permits one amplifier to satisfy these different conditions. The CTU11 / CTU12 are designed to take the output from a Loop Amplifier and generally provide two separate outputs with different current level. One output is the same as the Loop Amplifier output current, while the second output is scaled to drive a second loop which may be part of a cancellation layout, or other requirement. Sometimes, it can also be used where the current / voltage ration needs scaling to match a specialized loop requirement. The requirements can only be decided during detailed computer design of the Loop System.
The CTU11 / CTU12 are built into a standard 1/4 width rackmount cases. They can be wall mounted using WMS1U wall mount kit.SP5 Signal Processor (or SP5a)
This signal processor is used to fulfill two different requirements.
The standard format for Low-Spill Induction Loop Systems use two loop arrays, which are overlaid in the same area, are are driven by two loop amplifiers operating with a 90 degree phase difference between the signals into the amplifiers. Achieving this phase difference over the audio band while maintaining correct frequency response is a very specialized process which is embedded in this processor unit.
This same phase shift requirement may also exist when driving balconies in public spaces which overhang a seating area. To minimize the effects between the two loops, a phase shift between the signals is extremely valuable. It is also very valuable when running two separate loops covering the same area for Voice Alarm, as the sum of the signals is only 3dB higher than using a single amplifier. Hence, failure of one amplifier has less effect than using signals which are in phase, and therefor cause a 6dB change in level.The second use of this processor is as a separate Metal-Loss corrector for use with Loop Drivers which do not have the facility as standard. For this purpose the unit is available without the phase shifter, and is specified as SP5a. This metal causes a frequency-dependent loss of magnetic field. The actual loss can be up to 3dB per octave, with a lower corner frequency between 0.1Hz and 100 Hz. This loss equals 15dB change from 150Hz to 5kHz. There is no simple solution, but the metal loss correction permits the frequency response to be leveled, being fully adjustable from 0 to 3dB per octave. The actual loss at higher frequencies still necessitates a powerful amplifier to obtain adequate field strength, but a suitable equipment installation can minimize the effect of the metal in the structure. Site measurements are always necessary to quantify the loss problem. Please contact us for additional information and support.
The SP5 /SP5a is built into a standard 1/6 rack width unit and must only be used with AMPETRONIC constant current driving amplifiers.
Loop Condition Monitoring
Recent developments in safety standards require systems which offer full loop condition monitoring. This entails the continuous testing of the loop cable for correct impedance, absence of faulty connections, checking of amplifier operation and remote signaling to satisfy the Voice Alarm standards. AMPETRONIC can now satisfy there requirements with a new Loop Condition Monitor for the ILD9 amplifier. The system will also operate where multiple units are used with combiners.
Please contact us for further details.
PS3 Power Supply
While all the preamplifiers and signal processors listed elsewhere can be connected to, and powered from the AMPETRONIC Loop Amplifiers, there are many instances where they are used independently. The PS3 power supply is designed to operate this equipment, supplying the correct regulated voltages ( ±15V DC) so that the various units will operate correctly. It is connected to the regular AC power, 230 V or 115 V as specified by client.
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