• Input attenuation set to 90dB, modulometer shows 0dB, this means that the sound has a pressure level of 90dB SPLpeak ≈ 80 dB SPL.
• Input attenuation set to 74dB, modulometer shows –12dB, this means that the sound has pressure level of (74 –12) 62dB SPLpeak ≈ 52dB SPL

Finally, if you know that you are going to make a recording of a sound level of 90 dB SPL (100 dB SPLpeak) then you can pre-adjust your machine by setting the level pot to the 100 dB position and in this way, your recording will not overload and you will record at about 0 dB on the modulometer.

NAGRA ARES-M
Q: When I press the "On" key the red LED lights but nothing happens - Why?
A: If the batteries of the ARES-M are just on the boarder of being completely consumed, there is a short period of time when pressing the "ON" power key on the front panel will still initiate the power-up sequence. However the display will not light up and the machine will appear to be faulty. To resolve the problem, simply replace the batteries paying careful attention to the polarity.

Q: What is the low cut and how does it work? 
A: The ARES-M is equipped with a analogue low cut filter integrated within the microphone pre-amplifier. This filter can be turned ON of OFF as desired.

Frequency response curve of the External microphone pre-amplifier (flat and Low cut 220Hz):


The frequency of the cut is at 200Hz with a gradient of 40 dB / octave.
This filter can be activated for each microphone type, as defined in the USER list (DYN, NAGRA,COND……)
It is specially useful for recordings made using directional microphones outside in windy conditions, such as the stereo NAGRA microphone. In fact, cardioïd (speed capsules) such as the NAGRA microphone are susceptible to vortexes induced by wind moving round the microphone capsule, contrary to omni-directional (pressure) capsules, which are not.
Note however that the NAGRA microphone is equipped with a fine silk screen directly behind the grill / basket carefully positioned to compensate for these vortexes and “pop” effects. It is also recommended to use the external foam windshield whenever one works outside when unexpected wind noise may be encountered.


Q: How much noise is there on the mic pre-amps of the ARES-M?
A: The microphone pre-amplifier of the ARES-M was designed to accept the very best electret microphones. This insinuates that the pre-amplifier noise is guaranteed to be lower than the noise generated by the best electret microphone compatible with the ARES-M. It goes without saying that the pre-ampifier of the ARES-M is not able to exploit the entire dynamic range offered by a traditional condenser microphones such as a Neumann, Schoeps or Sennheiser phantom powered microphones. It cannot therefore be compared with the microphone pre-amplifiers of the NAGRA V or even the ARES-BB+ where limitations of space, price and power consumption do not enter the equation, unlike in the ARES-M. The measurements below allow you to get an idea of the excellent quality of this little pre-amplifier.

Measurement description:
In these measurements, we measure the gain of each channel precisely (with the level and sensitivity adjustments set to the maximum position).
We have measured the noise on the outputs, and we reduced the noise on the input by dividing the value obtained by the gain, so as to reference all the measurements and calculations to the same point.
The measurements were carried out linear ASA A-weighted from 22Hz to 22kHz.
These measurements are compared to the noise of equivalent resistive loads (2kΩ for electret microphones). The measurements are also referenced to the intrinsic noise generated by the external microphones.
Measurement made with ARES-M set to “COND” or “NAGRA

Gain of both channels: 315.8

Output noise with a 2000Ω load on the input:

Unoise ASA-A Ch1 0.4 mV Unoise Lin. Ch1 0.66 mV
Unoise ASA-A Ch2 0.42 mV Unoise Lin. Ch1 0.7 mV

Noise reduced on the input: (read “U’ “ for “U reduced on the input”)

U’noise ASA-A Ch1 1.26 µV U’noiseL Lin. Ch1 2.1 µV
U’noise ASA-A Ch2 1.33 µV U’noise Lin. Ch1 2.21 µV

Noise of a 2 kΩ resistive load (calculated):

Unoise ASA-A of 2kΩ 532µV Unoise Lin. of 2kΩ 0.844µV
Noise factor of preamplifier with 2000 Ω source 7.5 dB

Noise reduced on the input using a microphone fitted with Sennheiser KE-420 capsules (diameter 10 mm)

U’noise Mic A ASA-A Ch1 4.18 µV
U’noise Mic A ASA-A Ch2 3.95 µV

Noise reduced on the input using a SONY ECM-MS907 (diameter 14.3 mm)

U’noise Mic B ASA-A Ch1 1.43 µV
U’noise Mic B ASA-A Ch2 1.43 µV

Noise reduced on the input using the Nagra mike delivered with the machine:

U’ Mic C ASAA Ch1 4.75 µV
U’ Mic C ASAA CH2 5.54 µV

Conclusions:

It can be clearly seen that in all the cases the intrinsic noise of the microphones is greater then the noise of the pre-amplifier itself. The Sennheiser KE 10-420 capsules are of excellent quality and can be mounted into the support of the NAGRA microphone on the ARES-M without any problem. They are not used as standard as their price is prohibitive for microphones which are delivered free of charge with the unit.

Q: What are the levels of the line inputs?
A: The line inputs of the ARES-M are asymmetrical and present an input impedance of about 60 kΩ.
They allow the entire dynamic range of the machine to be used, typically 95 dB ASA weighted when measured on the USB output, or 92 dB ASA weighted on the analogue outputs.

Two sensitivities are available: Line H (for High level inputs) and Line L (for low level inputs). The Line H position allows 0 dB to be recorded throughout the input voltage range of 300 mV to 4.9V and the Line L from 19 mV to 310 mV.

The adjustment zone (using the level adjustment keys) ranges from +20 dB to –12 dB in the Line H mode and –3 dB to –35 dB in Line L (referenced to 1V).

As an example, one can say that if the modulometer indicates –10dBfs and that the level adjustment is set to –12 dB, then the input level is 12db – 10 dB= -22 dB with respect to 1 V or in other words 794 mV.

The following drawing clarifies the above.



Q: How are the input gains set-up on the ARES-M?
A: The input of the ARES-M has 3 principal stages. The analogue microphone pre-amplifier “front end”, the PGA (Programmable Gain Amplifier) and the DGA (Digital Gain Adjustment).
Different adjustments are available at all three stages. Only one, the “recording level” is readily accessible from the front panel by the user (using the left/right keys).



The microphone pre-amplifier stage has two selectable sensitivity settings which correspond to a typical dynamic microphone (34 dB) and the NAGRA microphone (19 dB); this selection is made in the “Screwdriver” menu in the “Input device manager”.
Dynamic microphone sensitivity is low and needs more gain than a condenser or electret microphone. So, if a dynamic microphone is used, 34 dB gain is needed, and if a condenser microphone such as the NAGRA one, or any other external condenser microphone (such as the SONY ECM MS907 Stereo microphone) then 19dB gain should be selected. The correct selection of this gain will avoid the saturation of the PGA and DGA stages.

In the Codec section of the machine the first stage is equipped with a PGA adjustable gain setting allowing the modulometer to be calibrated to give an accurate indication of SPL (Sound Pressure Level). This setting is available in 3 dB steps and is also found in the Screwdriver menu and allows a range of 24 dB variation. This value is factory set to 9 dB for the NAGRA microphone and 6 dB for an external dynamic microphone such as a Sennheiser MD21.

Finally, the MAIN RECORD LEVEL is the actual level that should be used to adjust the recording level during operation of the machine and is accessible using the Left and Right keys without any need for going into the menus. This task is achieved by the DGA, and the range of adjustment allows 0dB Full Scale to be displayed on the modulometer for 84 dB to 144 dB SPL. The normal range of acceptable input levels ranges from 84 dB to 110dB SPL. The range from 110dB to 144 dB SPL will not allow 0 dB to be indicated on the modulometer without risk of saturation of the codec.
84 dB is the usual setting for an interview in a quiet environment. 110 dB allows the recording of somebody shouting at a distance of about 40 cm from the microphone.
The zone from 110 to 144 allows the user to make a fade out or to record with headroom (by recording below the 0dB point on the modulometer).

Q: Why only 1 GB on-board? 
A: This size of memory is the best compromise between capacity and price.

Q: How much recording time does 1 GB memory give? 
A: In the compressed mode at 32 kbits/sec, 1GB will allow up to about 70 hours recording time. In PCM linear operation it will offer 1h30 of stereo at 48 kHz. Typically in broadcast environments one uses 128 kbits/sec per channel which equates to 17 hours of Mono or 8.5 hours in stereo.

Q: Why isn’t the memory removable? 
A: Removable memory devices have certain advantages, however the mechanics, choice of format and vulnerability to theft are all factors that discouraged us from using a removable media.

Q: How long does it take to download the memory? 
A: Using the USB port on the machine the entire contents of the memory can be copied to a PC / MAC in approximately 30 minutes.

Typically a 30 minute recording can transfer as follows:

1. Normal operation as today;
2. MPEG compression up to 384kb/s;
3. FAT 16 card formatting;
4. PCM Linear recording up to 48kHz stereo;
5. Markers can be inserted during playback and record;
6. Individual "take" erasure;
7. Voice start; and
8. Personalized templates.