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Edirol R09, R09HR & R44 Mic Preamp Comparison

Aim

To compare the internal microphone preamplifiers of the Edirol R09, R09HR and R44 digital recorders using a pair of low noise stereo microphones (Audio Technica AT3032), recording in a quiet environment (domestic indoors) so background noise levels of the systems can be more easily compared.

Methods

Using the following...

Notes: The ART Phantom II (shown above) was used to provide Phantom power to the AT3032 microphones as the R09 and R09HR do not have 48V phantom power. This power-supply (2 x 9V batteries) does not add any significant noise to the throughput signal. The ART Phantom II was also used with the R44, rather than use the R44's phantom power, to make comparisons and signal chains as equivalent as possible. However, as the adapter cable shown connected to the R09HR in the shot above could not be used with the R44, the two short black XLR cables were used instead. This meant that the R44 received a balanced signal while the R09 and R09HR did not.

1. Levels

I attempted to match all recorders so that the peak-meters hit the same max levels = -12 dB. The recorder settings used were:

All recorders: Low cut off, plugin power off, screens minimum brightness, 44.1 kHz @ 24 bit.

2. Microphones & Signal chain

The microphones were fixed in stands and not moved during the test, all recorders recorded from the same mics (AT3032), in the same positions.

3. Source

In order to standardise the source material for the recording I played a standard test file (of layered Sampled Piano and Synthesizer notes) on a Hi-Fi system consisting a Rotel CD and Amplifier. This was not exhibiting any noticeable hiss (even when my ear was 5 cm from the tweeter) at the playback volume used. The original recording had no noise between the signal components.

Here's what the perfect recorder (and microphones) would look like as this is the source audio file spectrograph. The spectrograph shows the audible frequency spectrum, on the vertical axis (20 Hz at the bottom to 20,000 Hz at the top) and time on the horizontal axis. Of particular note is the inky-black background, this means there is no noise. Noise shows up as a grey speckling (as seen in the next section). Recorded information shows as colored bands, that's OK, you want that :)

Download the test recording here (2.8 Meg WAV file).

Results

Here is the spectrographs of all the recordings. In particular look at the decreasing contrast between the background and the recorded sounds as you move from top (best) to bottom (worst) below. Please note the low frequency information was 'rumble' present in the background noise of the room used and is typical of any recording environment outside a professionaly constructed studio.

You can download the .WAv or .MP3 (320 kbps) files from the above spectrographs below:

R44

R09HR

R09

More detail

In this recording I located the mechanical sounds of the CD player starting up at the beginning of the recording ("chik - ddddddddd"), you will probably only be able to hear this if you are wearing headphones. As you can see below the R09 has significantly more background noise when compared to the R09HR and R44 recorders.

Download the CD Player noise here (800 k wav file).

Conclusions

As with any test you see on the internet your first question should be how relevant is this to 'real world' conditions? Here are my thoughts -

I was pleasantly surprised to find that the internal mic-preamp on the R09HR was, from an audible noise perspective, very similar to the R44 (the R09HR perhaps being just a tiny bit worse, or it could be level differences). The R09 was a distant third. I will note however that the line-in on the R09 is very good and if you are using an external mic preamp you would have no issues with an R09 getting very low noise recordings.

One area not shown here is that the R44 does perform better than the R09 or R09HR in terms of digital noise perspective, but these noises are not audible so I won't go into detail here. While all three would be good for recording live bands, the R09HR and R44 would be better if acoustic instruments were being recorded.

Scott Fisher

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