Introduction
The MLD7 Induction loop driver has been designed as a high quality dual channel amplifier for use
with multiple loop or Phased Array loop designs.
An Array System provides a solution where a simple loop around the room perimeter will not work.
Arrays are the standard solution for buildings with metal structure or reinforcements, or for covering
large areas. Arrays can also dramatically decrease the ‘spill’ of the magnetic signal outside of the
room, allowing induction loops to be installed in adjacent rooms, and providing an improved level
of confidentiality. Arrays can also be used to change the way two loops interfere with each other,
providing ways of solving even the most complex installation problems.
Depending on a number of factors regarding the installation of the loop and the set-up of the
amplifier the MLD7 can provide compliance with IEC60118-4 for perimeter loop areas of up to 2 x
700m
2
or phased array systems upto 840m
2
.
Ease of installation and use have been major factors in the design, combined with optimised
performance, and the freedom from R.F.I. generation.
The MLD7s two output channels can be configured with or without 90° of phase shift between
the two, allowing the use of array systems or two separate loops with the same signal therefore
doubling the area coverage.
The MLD7 has two balanced inputs. These can be configured for microphone or line inputs with
individually selectable phantom and gain boost.
For more complex installations, you may need ancillary equipment such as microphone pre-
amplifier(s), adaptor(s) for use with 100V line, or signal processing units. See Accessories or
contact Ampetronic for advice.
QUICK START
For those who have a good appreciation of loop systems, the following is a very quick guide to
setting up the amplifier: All you need is an ac power source, a signal source and a Phased Array
loop pair. See ‘Designing Induction Loops’ handbook (supplied) or contact Ampetronic for advice.
Installation
a. Turn all controls fully anti-clockwise.
b. Connect loop cables.
c. Connect signal input(s).
d. Connect power. See points 6 and 7 in SAFETY section.
e. If rack mounted remove all rubber feet from units. DO NOT re-fit the feet fixing screws as this
may cause damage and invalidate the warranty
Operation
1. Switch ON – check ‘ear symbol’ flashes during self test and illuminates continuously when
checks are complete.
2. Apply input signal and increase the input control until two green COMPRESSION LEDs are
illuminated on the peaks of the signal.
3. Select phase shift required 0 or 90°.
4. Adjust the CURRENT controls until the CURRENT LEDs illuminate to achieve the desired
peak currents.
5. Repeat step 2 for any other inputs used.
6. Listen to the magnetic field produced inside the loop area using a receiving device (e.g.
Ampetronic ILR3), or examine the performance in more detail with a field strength meter.
7. Adjust MLC control to achieve a flat frequency response.
Ampetronic MLD7 Installation Handbook
Page 2
