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Test tone files for download or playing

Checking the AFILS frequency response using 3 fixed tones at 1kHz, 100Hz and 5kHz

Ideally, this test should be done AFTER the loop system is set up satisfactorily using representative speech through the system microphone(s). This procedure is used instead of the procedure in the standard user instructions when a variable frequency tone generator is not available and a 3 frequency fixed tone test is used.

1. Switch the induction loop equipment on.

2. Set the drive control on the loop amplifier to ?, follow the manufacturer's instructions or leave it set where it is if the controls have been previously set correctly.

3. Set the TONE (filter) switch to the FLAT position.

4. Move the RANGE switch to the HI position.

5. Hold the meter upright with the top at the position a hearing aid is likely to be used.

6. Observe the LED bargraph.

7. Using a sinusoidal tone generator or an audio CD/MP3 player etc., apply a 1kHz tone (CD track 1) to one of the amplifier or mixer inputs and adjust the input volume and/or gain control(s) (NOT the drive control) so that the -6dB and -3dB LED's on the bargraph are both lit equally.

8. Maintain all volume and gain controls at these settings and reduce the frequency of the test source to 100Hz or play track 2 of the audio CD/MP3 player etc. Either the 6dB LED or -9dB LED or both should show. If the LED lit is lower than 9dB then the low frequency response of the system is inadequate to meet the requirements of BS7594. In this case check any bass or low frequency tone control settings on the loop amplifier.

9. Now increase the frequency of the test source to 5kHz or play track 3 of the audio CD/MP3 player etc. Either the -6dB LED or -9dB LED or both should show. If the LED lit is lower than 9dB then the high frequency response of the system is inadequate to meet the requirements of BS7594. In this case check any treble or high frequency tone control settings on the loop amplifier. Depending on the type of induction loop system, this may also be due to metal loss or an incorrectly wired loop cable.

Connevans Limited
Bridge House
1 Nutfield Road
Merstham, Surrey, RH1 3EB
United Kingdom
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