From InAVate magazine Peer Review:
Induction loop systems have to fulfil the demands of International Standard IEC60118-4 after installation – the reference to which every induction loop installation should be tested. Additionally, during the planning and the mounting of the loops and associated devices, a lot of challenges are evident. One of the main problems is reinforced concrete with a high grade of core iron within the structure of the area the loop is being installed into. This may cause frequency dependent losses of up to 10dB and more.
Standard perimeter loops cannot solve these problems and there is, therefore, a need for special designs to cope with such high losses.
Most ‘normal’ loop amplifiers on the market are not capable of delivering satisfactory results under such circumstances. Generally, loops configured as phased arrays have a long cable run and consequently not only have a higher ohmic resistance, but also a significant inductive component.
In critical installations, values up to some millihenry (mH) are possible. Thus the amplifier must not only be capable of delivering the necessary high currents, but must also be in a position to deliver adequate output voltage to successfully drive the high frequencies. This is the point where most amplifiers on the market start to struggle.
Ampetronic has a longstanding reputation as a manufacturer of high quality amplifiers for induction loop systems. From my personal point of view, Ampetronic is the only producer of truly constant current amplifiers. All other brands only produce what I call ‘castrated’ voltage amplifiers with associated bad performance, so I was very curious about the new ILD1000G. Ampetronic promised a lot in technical terms: real 13A peak and 50V output voltage at full current are bold claims.
The unit comes in a standard 19”-1U size, with all important controls and indicators on the front panel. The controls are hidden in the front panel and can only be adjusted by the use of a screwdriver. This is a good safety measure as it should not be necessary to change anything after the commissioning of the system.
The ILD1000G offers three inputs: Input 1 (Mic, XLR, with switchable phantom power and sensitivity), Input 2 (XLR, Mic/Line switchable) and Input 3 (TRS-Jack, Line). In my opinion the three inputs are a nice extra, but not really necessary as this type of unit is only used in large professional systems where the signal comes from a professional mixer, matrix or other piece of equipment. I believe that this amplifier will seldom be used as a stand-alone system.
On the back, you will also find the insert socket for use with phase shifters (Ampetronic SP5), or to cascade more units for large and complex systems. The loop is connected via a Speakon connector, which ensures safe and reliable function.
The power stage of the amplifier is designed as a Class-G amplifier, which results in low power consumption and high efficiency.
It was very exciting to test the ILD1000G both in the lab and in the field. From the very beginning, the ILD1000G fulfils all expectations and more. It is a really great unit and, to my knowledge, is the best amplifier on the market.
For the full news story please click here, InAVate magazine Page 64
