Nagra Mezzo vs Tascam DR05 V1

Sound quality comparison

Table of contents

  1. Foreword
  2. Scene by scene analysis
    1. 2018-07-22 08:16 South, Etang de Giat, Saint-Agoulin
    2. 2018-07-22 08:26 South, Etang de Giat, Saint-Agoulin
    3. 2018-07-22 08:55 Center east, Etang de Giat, Saint-Agoulin
    4. 2018-07-22 08:58 Center east, Etang de Giat, Saint-Agoulin
    5. 2018-07-22 10:21 West of Les Sagnes, Saint-Agoulin
    6. 2018-07-22 10:22 West of Les Sagnes, Saint-Agoulin
    7. 2018-07-23 08:01 North-west of Les Vergers, Artonne
    8. 2018-08-01 20:51 Cemetery, Saint-agoulin
  3. Conclusion
  4. License / Author

Foreword

Here, we are comparing the output sound quality of the following devices : * Nagra Mezzo, * Tascam DR05 V1. For this, we simply made simultaneous field recordings of the same audio scenes (soundscapes) by starting all the recorders at the same times. With some various settings each time. All recordings have been made : * at 48kHz sampling rate, * some as 24 bit-WAV, some as 320 kbps MP3. Then, they were : 1. loaded into the Audacity software, 2. cut down to a special time range, * for selecting the target signal event (often a bird call or song note), * for device to device time matching, 3. and finally converted to 32 bit-WAV files. All in all, they suffered : * no post-processing, * exactly the same preparation steps. For every audio scene, you'll find : * the date and time of recordings, * the place where it was recorded (in Auvergne region, center-south of France), * some words about the audible sound sources (birds, human activities, wind, ...), * for each recording : - the name of the device used, - the device settings used for the recording (see the abbreviations used below), - a link to the original audio file analysed (for downloading if needed : right-click, then 'save link target'), - a player to listen to an MP3 (VBR 3) 0 dB RMS normalised version of the analysed recording (to get a decent volume). * 3 spectrograms for each recording : - a raw one (only "amplified" through a multiplication by 50, for better constrast ; unit = power spectral density), - a "normalised" one (reference = max. of the spectrograms of all the recordings ; unit = dB, in some kind of Full Scale variant, but the "full scale" is here that of the actual sample values, not the one of the max possible value for 24bit samples), - a "SNR" = Signal to Noise Ratio one, computed by dividing the whole raw one by the temporal mean of the raw one during the "noise" time range (see below) ; unit = dB. - note: the orange box on each spectrogram shows the time range selected for extracting the "pure" noise average (approximately no audible signal inside). * 3 PSDs plots (power spectral density, extracted from the raw spectrograms) for each recording : - a "normalised" one (reference = max. of the raw spectrograms of all the recordings, but only during the "signal" time range, and only in the "signal" frequency band, highlighted through 2 pink boxes on the spectrograms ; unit = dB, like the norm'ed spectrogram), - the device by device difference (of the normalised PSD) to the 1st one, - a "SNR" = Signal to Noise Ratio one, computed by dividing the temporal mean of the raw spectrogram during the "signal" time range (pink box), by the temporal mean of the same spectrogram during the "noise" time range (orange box) ; unit = dB, * some comments after analysing the spectrograms and PSDs, as well as listening to the recordings (note: for "ear" = subjective comparison, some simple amplification was achieved, in order to get roughly the same "perceived" signal volume, = bird song or call volume). Note: The simple signal processing computations (spectrogram, PSD, amplification, division, mean, ...) are run through Python 3.5 code, using SciPy 1.1 and NumPy 1.14 libraries (see the last line of this page for more details and access to the source code). Device settings abbreviations (note: on/off settings are all 'off' unless specified) : - r : sample rate (kHz) ex: r=48 - wav : recorded in Wave format, with this bit depth / resolution (bit). Ex : wav=24 - mp3 : recorded in MP3 format, with this bit rate (bps). Ex : mp3=320 - g : mic. gain (% of the possible range, or dB, or a=auto=agc). Ex: g=50%, g=16dB, g=a - hn : device in hand (on/off). Ex hn=on - mp : electronic microphone pad (on/off). Ex mp=on - ws : physical windscreen (on/off). Ex: ws=on - mpw : microphone power (on/off). Ex: mpw=on - hpf : high-pass filter, with given threshold (Hz). Ex: hpf=200 Finally, for this device comparison, * only device-embedded microphones where used (no external one), * care was taken to avoid any dust or other obstacle around the microphones, * the 'external microphone power' setting was always set to off. And last precision : the latest available firmware (1.3.1.8) had been installed on the Nagra Mezzo before starting the field recordings.

Scene by scene analysis

2018-07-22 08:16 - South, Etang de Giat, Saint-Agoulin

Sounds from :

* Emberiza citrinnela (song), * Corvus corone (call).

Recordings :

Device DR05 v1 Mezzo
File DR05-00514-start11.95-dur3.46.wav MZ-00001-start11.685-dur3.46.wav
Settings r=48 mp3=320 g=75% r=48 mp3=320 g=75%
Listen

Analysis comments :

DR05 really better (confirmed by ears) : * \>3dB better SNR (Emberiza 5+6.3kHz), * -3 to -14dB noise below 270Hz, * -3 to -4dB noise in [270Hz, 4kHz], * -2 to -3dB noise above 4kHz.

Spectrograms and PSDs :

2018-07-22 08:26 - South, Etang de Giat, Saint-Agoulin

Sounds from :

* Emberiza citrinnela (song), * Corvus corone (call), * Ephippiger sp (song).

Recordings :

Device DR05 v1 Mezzo
File DR05-00519-start9.781-dur2.914.wav MZ-00005-start9.670-dur2.914.wav
Settings r=48 wav=24 g=100% r=48 wav=24 g=25%
Listen

Analysis comments :

DR05 really better (confirmed by ears) (but low mic. gain setting on Mezzo) : * +3 to +8dB better SNR (Corvus 1.5kHz, Emberiza 5+6.3kHz, Ephippiger 10-12kHz), * -4 to -10dB noise below 270Hz, * -4 to -6dB noise in [270Hz, 4kHz], * at least -3 to -5dB noise above 4kHz. Mezzo does not even "see" Ephippiger sp at 10-12kHz (very strange : can't have been that much further of Mezzo mics, 'cause my 2 hands were only separated by 30cm !? May be too low mic. gain setting).

Spectrograms and PSDs :

2018-07-22 08:55 - Center east, Etang de Giat, Saint-Agoulin

Sounds from :

* Emberiza citrinella (call).

Recordings :

Device DR05 v1 Mezzo
File DR05-00522-start32.068-dur1.147.wav MZ-00008-start31.945-dur1.148.wav
Settings r=48 mp3=320 g=50% r=48 mp3=320 g=50%
Listen

Analysis comments :

DR05 a bit better, but not really audible : * +2dB better SNR (Emberiza 5kHz), * -1dB noise below 270Hz, * -2 to -4B noise in [270Hz, 4kHz], * at least -3 to -5dB noise above 4kHz. But Mezzo produces slightly better spectral line separation ?

Spectrograms and PSDs :

2018-07-22 08:58 - Center east, Etang de Giat, Saint-Agoulin

Sounds from :

* Acrocephalus scirpaceus (short part of song).

Recordings :

Device DR05 v1 Mezzo
File DR05-00523-start38.868-dur0.966.wav MZ-00009-start38.823-dur0.967.wav
Settings r=48 mp3=320 g=75% r=48 mp3=320 g=75%
Listen

Analysis comments :

Mezzo a bit better for main spectral line, but DR05 preserves secondary ones (better "separation"): * Mezzo : +1dB better SNR at 4kHz, * but -2dB lower SNR at 2kKz (not really audible), * -2dB to -4dB noise at all frequencies (confirmed by ears).

Spectrograms and PSDs :

2018-07-22 10:21 - West of Les Sagnes, Saint-Agoulin

Sounds from :

* Saxicola torquata (alarm calls), * motorway 1km west.

Recordings :

Device DR05 v1 Mezzo
File DR05-00525-start18.729-dur0.944.wav MZ-00012-start18.530-dur0.946.wav
Settings r=48 mp3=320 g=75% r=48 mp3=320 g=75% ws=on
Listen

Analysis comments :

Windscreen very efficient on Mezzo ! * Very similar SNR. * but less LF noise with Mezzo, thanks to windscreen (at least -6dB under 300Hz), * but better detection by DR05 of the 10kHz harmonic spectral line (around +3dB), and even the 15kHz one (may be 1dB ?) (not audible for me).

Spectrograms and PSDs :

2018-07-22 10:22 - West of Les Sagnes, Saint-Agoulin

Sounds from :

* Saxicola torquata (alarm calls), * motorway 1km west, * some wind.

Recordings :

Device DR05 v1 Mezzo
File DR05-00526-start15.657-dur0.836.wav MZ-00013-start15.649-dur0.835.wav
Settings r=48 mp3=320 g=50% r=48 mp3=320 g=50% ws=on
Listen

Analysis comments :

Lower gain. Windscreen quite efficient on Mezzo, but better feeling with DR05 ! * Very similar SNRs, * but less LF noise with Mezzo, thanks to windscreen (at least -6dB under 300Hz), * but slightly better detection by DR05 of the 10kHz harmonic spectral line (may be 1dB ?). Stangely, subjectively far more HF noise with Mezzo, givin a poorer ear perception of the signal !

Spectrograms and PSDs :

2018-07-23 08:01 - North-west of Les Vergers, Artonne

Sounds from :

* Sylvia atricapilla (short part of song), * church bell ringing.

Recordings :

Device DR05 v1 Mezzo
File DR05-00527-start42.358-dur2.328.wav MZ-00015-start42.199-dur2.328.wav
Settings r=48 mp3=320 g=75% r=48 mp3=320 g=75%
Listen

Analysis comments :

Quiet scene, better perception with DR05 : * DR05 has a slightly better SNR (1 to 2dB), * but more LF noise below 370Hz (3 to 5dB) and above 5kHz (about 2dB).

Spectrograms and PSDs :

2018-08-01 20:51 - Cemetery, Saint-agoulin

Sounds from :

* Passer domesticus (song), * no wind.

Recordings :

Device DR05 v1 Mezzo
File DR05-00534-start1.570-dur1.374.wav MZ-00018-start1.545-dur1.374.wav
Settings r=48 wav=24 g=100% r=48 wav=24 g=100% ws=on
Listen

Analysis comments :

Maximum gain, Mezzo with windscreen, very quite scene (better ear perception with DR05) : * DR05 has a slightly better SNR (1 to 2dB), * and less LF noise below 2kHz (-2 to -6dB).

Spectrograms and PSDs :

Conclusion

The above described parallel field tests and objective analyses show some contrasting results when comparing the Nagra Mezzo to the Tascam DR05 v1. But all in all, the Tascam DR05 v1 very often "displays" : * a better signal to noise ratio (+1 to +2dB), * far less low-frequency noise below 300Hz (-1 to -14dB), * less medium-frequency noise below 2kHz (-1 to -4dB), * a slighltly better medium to high frequency lines separation, * a better "ear feeling", mainly due to less LF noise. The Mezzo windscreen is - not surprisingly - quite efficient at lowering the low frequency noise ... when the wheather is windy. But the effect would be same on the DR05. During these tests, the high pass filter option (no more than the auto. gain control one) was not activated ... as I don't want to hide any possible low frequency signal at recording time (of course, I often apply this kind of filter ... when post-processing the recordings, when I'm sure it won't destroy any interesting detail). For some background about me, * although I'm not an audio signal processing expert, I'm a computer science engineer and thus know more than some basics about it, as well as about sound physics, * as an active nature watcher, more specificaly dedicated to ornithology, I also have a long experience and passionnate practice of nature soundscapes live analysis by ear, * and thus an excellent knowledge of the various calls and songs of most of the species of birds that can be encountered at least in the center of France ; * thanks to this, among others, - I have been an active contributor to the french Museum National d'Histoire Naturelle common birds monitoring program called STOC EPS since 2002, - I'm also an active contributor of the LPO Auvergne Distance Sampling group created in 2016 by François Guélin, - I've been providing since 2015 serious training courses, applied field sessions and online exercises about recognising common bird species by ear (see my training, reference and exercice material (in french) about this), * I've come to recording nature soundscapes only some years ago, as a non-top-priority activity, targetting more convenience and pocket handling than high fidelity, * but I felt recently a need to improve the sound quality of my recordings.

License / Author

© 2018 Jean-Philippe Meuret (around 50 hours worked).

The whole contents of this document is under the full responsibility of the author.

You must not distribute in any way any part of it without the author's authorisation.

This page was generated on 2018-10-31 22:19:21