Activeforever Bellman and Symfon Maxi Personal Amplifier - Manual (Page 3)

Features

Digital signal processing

Omni-directional electret condenser microphone
 Telecoil pickup for inductive loops

10 channel dynamic range compressor

10 channel dynamic noise suppression
 Adaptive feed-back manager

Intuitive user interface
 LED lightbar for excellent readability
 9 step volume control (5 dB/step)
 5 step tone control
 Mic and T-mode indicator
 Low battery warning indicator

Auxiliary stereo signal input (2.5 mm telejack)
 Headphones stereo output (3.5 mm telejack)
 Push-To-Listen mode (Int. mic and Aux in mixed)

Soft-mute when switching between signal sources
 Requires no individual fitting

Powered by two AA-size alkaline batteries
Advanced settings
Balance control
Compensates for example for hearing loss in
one ear. 5 dB / step.
Basic attenuation
Limits the maximum output level Useful for
e.g. a child. 3 dB / step.
Tone control blocking
Makes it easier for some end users to handle
the personal amplifier.
Tone control preset
Select preset tone.
Used together with Tone control blocking.
Disable T-coil
Makes it easier for some end users to handle
the personal amplifier.
Noise cancellation
Noise cancellation operates in frequency-domain
and uses ten channels to continuously analyse and
attenuate stationary noise. The noise cancellation
dynamically adjusts the gain for each frequency
band to give an optimal dynamic range, thus sup-
pressing noise without affecting speech or other in-
teresting information. Noise is suppressed with 5 dB
without sacrificing resolution or introducing sound
artefacts, which increases the listening comfort.
Dynamic range compression
The dynamic range compressor operates in the
frequency-domain and is implemented as 10
channels, logarithmically. Each channel has indi-
vidual attack/decay, expansion, compression and
saturation distance parameters, which have been
trimmed to reduce microphone noise, emphasise
speech or other interesting information and still
offer a natural sound.
Feedback manager
The adaptive feedback manager is especially
designed for use in sound environments where the
listening conditions changes. It is is automatically
activated when the internal microphone is selected
and will quickly adapt, for example, if a user moves
or the position of the headphones are changed
relative the internal microphone. It continuously
analyses the input signal to detect feedback and
eliminates it by changing the phase and amplitude
of the output signal. This normally occurs even be-
fore the user experiences a buildup of feedback.
Battery level supervision
The supervision of the battery voltage level is conti-
nuously operating in the background, making a mea-
surement every 10th second. The result is presented
on the Low Battery indicator. The battery supervision
indicates a Battery Low condition when the esti-
mated remaining battery time is around 10 hours.
In-depth technical information
Technical specifications

Dimensions: 140 x 45 x 27 mm (L x W x T)

Weight: 133 g (including batteries)
 Battery type: Two AA-size alkaline batteries

Battery life: Up to 150 h

Ext. mic./Aux in connector: 2.5 mm stereo telejack
 Headphones connector: 3.5 mm stereo telejack

Volume control: 9 steps (5 dB/step)

Tone control: 5 pre-set steps, push-buttons
 Power switch: On/off toggle button

Mic and T-mode: Separate mode select buttons
 Ext. mic / Aux in accessories
Automatically selects Aux in or external
microphone when plugged in

R/L-channel balance setting
0-20 dB programmable attenuation
(in steps of 5 dB)
 Maximum volume setting
21 dB programmable attenuation
(in steps of 3 dB)
 Dynamic compressor
 10 channels
 Dynamic gain range: 0-35 dB
 Compression: 3:1 Expansion: 1:1.5
 Attack time: 25 ms
 Release time: 250 ms
 Dynamic noise reduction
10 channels Adaptive frequency domain
noise reduction

Feedback cancellation
Adaptive time domain feedback cancellation
 Digital signal processing
 19.948 kHz sampling frequency
 16-bit resolution in stereo
Acoustic specifications

Full-on gain with BE9122 headphones
51.07 dB @ 1.6 kHz(60 dB input signal)
 Ref. test gain with BE9122 headphones
29.21 dB (SPL70)

Full-on gain with BE9125 stetoclips
56.57 dB @ 1.6 kHz(60 dB input signal)

Ref. test gain with BE9125 stetoclips
38.9 dB (SPL70)
Electrical specifications

Output power: 125 mW/channel (@ 16 Ohm load)
 Impedance, headphones: 8 - 72 Ohm
 Distortion: 0.557 % THD (electrical)

SNR: 82 dB
 Frequency range
 40 Hz – 10 kHz
 Tone, high: [email protected] kHz, -6dB@250Hz
 Tone, mid: flat
 Tone, low: [email protected] kHz, No bass boost

Aux in sensitivity (max input lvl.): +6 dBV
Subject to change without prior notice.
130
120
110
100
90
80
dB SPL
100 1k 10k 20k
Hz
Input signal
70 dB SPL 80 dB SPL 90 dB SPL
10
70
60
Output using BE9122 headphones
130
120
110
100
90
80
dB SPL
100 1k 10k 20k
Hz
Input signal
70 dB SPL 80 dB SPL 90 dB SPL
10
70
60