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CORDA ARIA headamp with analog and USB inputs
USER MANUAL
Dear music-lover,
The CORDA ARIA is a small-power amplifier, specially designed to drive headphones. It offers a sound quality and driving capabilities far beyond that of an ordinary headphone socket found on a CD-player or amplifier and thus allows you to exploit the full sonic potential of your phones.
In addition to its analog inputs the amplifier also has a built-in digital-to-analog converter (DAC) and can be directly connected to an USB-port of your computer. Sound is improved as the qualities of this DAC as well of the analog section clearly surpass those on the soundcards found on most computers.
Due to the close contact to your ears, headphones provide an extreme channel separation whilst listening to stereo recordings. Unlike loudspeakers, none of the sonic information in the left channel is acoustically transferred to the right ear and vice versa. Although this adds to the extreme high level of detail that can be achieved with headphones, it subconsciously also introduces mental stress. The natural correlation of stereo sound interpreted by the brain is lost.
The CORDA ARIA not only offers normal stereo reproduction of your music, but it also has a facility to add some of the left channel information to that of the right channel and vice versa. Thus mental stress is reduced and music can be enjoyed with more ease.
To obtain the best possible results with your new headphone-amplifier, we ask you to read these instructions carefully. The CORDA ARIA was developed by music-lovers for music-lovers and we hope that it will serve you well for a long time.
Jan Meier
Power
The CORDA ARIA has a built-in powersupply and can be connected to mains by a standard IEC powercord. The voltage range used, 100 .. (115) .. 120 Volts or 200 .. (230) .. 240 Volts, can be selected by the voltage selector switch found on the rear side of the amp. By default this selector is set to 230 Volts.
!!! Always check the position of the voltage selector before connecting to mains !!!
On the rear side of the amp, as part of the power terminal, a small compartment can be found that contains a standard size T 100 mA fuse. If the amp is connected to a mains voltage > 200 Volts with the voltage selector set to 115V this fuse will blow and protect the amp. It can be easily replaced but please always use a fuse of the same value.
If the headphone plug is not properly inserted in the headphone socket on the front site this may result in a short-circuit of the output. This is not a faulty design of the amp but an inherent property of this interconnect system. Depending on the input signal and the volume settings this short circuit may also result in the fuse to blow. Before replacing the fuse always check the position of the headphone plug.
Connections
At the rear side of the CORDA ARIA a pair of analog inputs allows you to connect an audio source that has a typical output voltage above 0.1 Volts (CD-player, tuner, minidisc-player, ...).
If you use several sources that are all connected to a central amplifier, then you might prefer to connect the CORDA ARIA to the tape-out of this amplifier. Although the source now can be selected by the Rec-switch, sound quality is not affected by the tone controls and the volume control of this central amp.
If you like to listen to music on your computer system, then you might choose to connect the CORDA ARIA to one of the USB-ports. An appropriate A-to-B USB-cable comes with the amplifier. When connected the blue LED on the right front side of the amp will be lit, even if the power of the headamp is turned off. With the power turned on the computer will automatically recognize the amplifier as an USB-audio device and configure it as its default. You may have to close and restart any running media application for them to recognize the device change. Apple users may have to go to the computer control panel and actively select the amplifier as their new sound device.
Activation of the device
After connection to mains the amp can be switched ON/OFF by the switch on the left frontside. If turned ON the blue LED above the switch will be lit.
Although power consumption is low we recommend to turn the amp off while not in use.
Source selection
With the switch on the right front side of the amp in its lower position one will be listening to the input signals at the analog inputs.
With the switch in its upper position the incoming USB-signals will be heard.
Volume control
The volume of the CORDA ARIA is controlled by the dial on the front panel of the amp and is increased by clock-wise rotation.
!!! In USB mode set the software volume control on your computer to full volume. !!!
This has to be done both in your media-application as well as in the soundcard device settings in your operating system. With non-maximal volume the digital resolution of the signal will be lowered and sound quality will be reduced.
The driving capabilities of the CORDA ARIA by far exceed that of a regular CD-player. This not only guarantees less distortion, but also has the danger of severe hearing damage.
While listening to headphones we lack several feedback mechanisms on volume level that are present when we listen to loudspeakers. Much less distortion, no feeling of the lower frequencies by our body and no psychological restraints not to annoy our fellow-men easily seduces us to listen at volume levels that are detrimental to our hearing.
Hearing damage from regular exposure to high sound levels progresses slowly but is irreversible and can result in permanent hearing loss.
!!!! Please choose your volume setting with caution !!!!
Directional listening
In normal daily life people use various mechanisms to locate sources of sound.
Firstly, a sound from the right side of the listener not only reaches the right ear but, attenuated and delayed, is also heard by the left ear. The level of attenuation and the delay time of this crossfeed signal provide important directional information.
Secondly, the soundwaves are partly absorbed and partly reflected by the tissues of the head. Reflections at the oracles (pinnae) interfere with the soundwaves that directly enter the ear-channel and amplify or attenuate specific frequency components. Since these reflections depend on the direction of the soundwave the “color” of the sound changes with the direction of the source.
Thirdly, reflections of the soundwaves from the walls, ceiling and floor of our listening room produce reverberation that conveys an extra feeling of space.
The information obtained by these mechanisms is further refined by movements of the head. Changes in sound levels, delay times and sound color refine the sense of direction.
Listening by headphones
All these mechanisms are missing when we listen to music by headphones. The sound at the right ear will no longer reach the left ear and pinnae-reflections no longer interfere with the original soundwave. Moreover, the headphones are directly attached to our head, and so head movements no longer add information. Reverberation is also not present.
As a result, the sound heard by headphones seems to stick to the inside of our head and to our ears and an unnatural soundfield is created. The brain misses logical clues for direction and this subconsciously results in mental stress. Some people cannot tolerate this stress and are unable to use headphones.
The natural crossfeed filter
In principle, digital soundprocessors can simulate all the mechanisms for directional listening but the results are, thus far, not very satisfactory. In particular, pinnae-reflections are very complex and listener-specific and impossible to simulate accurately.
Fortunately, the main directional information is provided by the time delay and level of attenuation of the sounds that reaches the opposite ear. The CORDA ARIA can electronically simulate this process and, with appropriate attenuation and delay, add some of the right audiosignal to the left channel and vice -versa. This considerably reduces the adverse symptoms of headphone listening.
A unique feature of the crossfeed circuitry of the CORDA ARIA is that it “recognizes” the virtual positions of the instruments and singers in a recording. The sound of an instrument in the middle of the soundstage will be equally present in both audio-channels and isn’t given any crossfeed. A crossfeed signal is only generated for instruments that are not placed at the center. The more off-center the instrument is placed, the stronger the crossfeed and the longer its delay. This feature is called “natural crossfeed”.
The crossfeed filter of the CORDA ARIA is activated with the switch at the middle of its front side in upper position. In the lower position the amplifier runs in normal stereo mode.
With the crossfeed filter activated the sound level of the ARIA is slightly reduced. This is easily compensated using the volume dial.
Notes:
Technical data
Measures:23.1 x 18.7 x 8.7 cm
Weight:2.2 kg.
Power supply:100..120V / 200..240 Volts mains.
Voltage range is selectable.
Power uptake:5 Watts
Maximal amplification (1 kHz):10 dB
Maximum output voltage:13 Volts (4.5 Volts analog input)
2.8 Volts (maximum level digital input)
Maximum output current:250 mA / channel
Input impedance:12 kOhm
Output impedance:0 Ohm
Digital resolution (USB)16 bit
Sampling frequencies (USB)32 / 44.1 / 48 kHz
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