All
Headphones amplifiers — AuraSonics 4AMP
Description, images, technical data and specifications
AuraSonics 4AMP
Image source — © AuraSonics
The AuraSonics 4AMP is a four-channel headphone amplifier in a compact metal case, built so that up to four pairs of headphones can listen to one programme while each listener sets their own level. It followed the 4SUM mixing amplifier in the AuraSonics range of professional audio gear, and the brand lists it for joint music making, rehearsal rooms, recording and broadcast studios, language labs and listening classes. The box includes the amplifier, an external power supply and a manual in Russian.
Key specs that matter
Each of the four outputs delivers up to 270 mW into 33 ohm, and the output impedance is also 33 ohm. The makers state that this is enough to drive all headphone types, including high-impedance models. Maximum gain exceeds 86 dB, the inputs accept up to +22 dBu and present 10 kOhm, frequency response runs from 20 Hz to 20 kHz, and harmonic distortion is listed at 0.001%. The main inputs are two balanced 6.3 mm jacks for left and right, which can also run as a single unbalanced stereo input. Power comes from a 12 V adapter rated at 2 A. The case measures 105 x 118 x 50 mm and weighs 0.55 kg.
Engineering and use context
Balanced main inputs let the amplifier sit a long way from the mixing desk or interface without the signal degrading over the cable run, which matters in rehearsal spaces and classrooms where the headphone station is placed next to the performers. Switching the main input to unbalanced mode allows the 4AMP to be fed from the stereo headphone output of another device, and a stereo jack cable for this purpose is part of the connection scheme. Besides the shared bus, every channel has its own unbalanced stereo Direct In, so an individual musician can receive a separate mix on one output while the others hear the main feed. A MONO switch on each channel folds the stereo signal to both ears, handy when a mono source feeds the bus. A global mute button silences all four outputs together. When more than four listeners are needed, two 4AMP units can be linked in series to double the number of headphone outputs.
Pairing
The balanced inputs suit the line or monitor outputs of a mixing console or an audio interface, while the Direct In jacks accept a stereo signal from any source with a headphone-level output. The circuitry is specified with a rise time of 33 ns and a response time of 10 microseconds, and the high gain reserve leaves room for low-level sources. The per-channel volume controls let each listener trim the level to suit their own headphones.
Alternatives
The 4AMP is the single headphone amplifier in the current AuraSonics catalogue, and no second model of this type is offered.
Key specs that matter
Each of the four outputs delivers up to 270 mW into 33 ohm, and the output impedance is also 33 ohm. The makers state that this is enough to drive all headphone types, including high-impedance models. Maximum gain exceeds 86 dB, the inputs accept up to +22 dBu and present 10 kOhm, frequency response runs from 20 Hz to 20 kHz, and harmonic distortion is listed at 0.001%. The main inputs are two balanced 6.3 mm jacks for left and right, which can also run as a single unbalanced stereo input. Power comes from a 12 V adapter rated at 2 A. The case measures 105 x 118 x 50 mm and weighs 0.55 kg.
Engineering and use context
Balanced main inputs let the amplifier sit a long way from the mixing desk or interface without the signal degrading over the cable run, which matters in rehearsal spaces and classrooms where the headphone station is placed next to the performers. Switching the main input to unbalanced mode allows the 4AMP to be fed from the stereo headphone output of another device, and a stereo jack cable for this purpose is part of the connection scheme. Besides the shared bus, every channel has its own unbalanced stereo Direct In, so an individual musician can receive a separate mix on one output while the others hear the main feed. A MONO switch on each channel folds the stereo signal to both ears, handy when a mono source feeds the bus. A global mute button silences all four outputs together. When more than four listeners are needed, two 4AMP units can be linked in series to double the number of headphone outputs.
Pairing
The balanced inputs suit the line or monitor outputs of a mixing console or an audio interface, while the Direct In jacks accept a stereo signal from any source with a headphone-level output. The circuitry is specified with a rise time of 33 ns and a response time of 10 microseconds, and the high gain reserve leaves room for low-level sources. The per-channel volume controls let each listener trim the level to suit their own headphones.
Alternatives
The 4AMP is the single headphone amplifier in the current AuraSonics catalogue, and no second model of this type is offered.
Specifications
Model name
4AMP
Maximum Power, 32 Ohms (mW RMS per channel)
4 x 270
Maximum Power, 50 Ohms (mW RMS per channel)
N/A
Maximum Power, 300 Ohms (mW RMS per channel)
N/A
Maximum Power, 600 Ohms (mW RMS per channel)
N/A
Frequency response low +/- 3dB (Hz)
20
Frequency response high +/- 3dB (Hz)
20 000
Gain (dBu)
N/A
THD (% at 1V RMS, 300 ohms)
0.001
Signal to Noise Ratio (dB)
N/A
IMD (%, CCIR, 300 Ohms)
N/A
Crosstalk (dB, 20Hz-20KHz, 300 Ohms)
N/A
Output Impedance (Ohms)
N/A
Dimensions (mm)
105 x 118 x 50
Weight (kg)
0.55
Official link