The Sony MZ-RH1 Hi-MD recorder has several advantages over earlier
minidisc models:
--Date and time stamp for each track you record
--Manual record settings are remembered for the next session (other
Hi-MDs default to automatic gain control at power-up)
--Aluminum body is more durable than plastic
--OLED display is very easy to read in dim light
--Controls and display are on the top edge of the recorder. This
makes the recorder easy to monitor when it's standing upright in a
pocket, clipped to a belt, or in a shoulder bag.
The self-noise of the Sony MZ-RH1 preamp compares well with other
popular recording devices in its price range. For tests conducted
under comparable conditions, see
http://www.avisoft.com/recordertests.htm
The preamp of the Sony Hi-MD recorders seems to be the same in all
models. Read the test comparing the MZ-RH1 and MZ-NH700 (now
discontinued) here to see the similarity in performance:
http://www.wildlife-sound.org/equipment/himd/rh1.html
One point raised by this test is that it appears the MZ-RH1's OLED
display generates extra electronic noise compared to the LCD display
of the MZ-NH700. This noise is low enough to be masked by noise from
other sources (your mic, for example). But it's troubling to think
that the latest model is noisier than the original.
A second test found extra noise is added when the MZ-RH1's motor turns
the Hi-MD disc (the motor is cycled on and off during recording to
conserve battery power).
http://beale.best.vwh.net/measure/audio/RH1-noise/index.html
This power cycling is common to all Hi-MD recorders, so it's likely
that all Hi-MDs suffer this flaw. Again, the extra noise added is
small, and is likely to be masked by noise from other sources.
The Hi-MD format has an Achilles Heel: There is no way to recover data
from a corrupted Hi-MD disc. No tools or procedures exist to help you
when the disc can't be read.
The most common disc problem is caused by low power at the end of a
recording. The Hi-MD machine waits until recording is stopped to write
the table of contents (TOC) entry. This information tells the Hi-MD
where on the disc the recording is stored. When there isn't
enough power to write the TOC, the entire recording is permanently lost.
A recorder that uses flash memory has problems when the battery power
runs low, too. The difference is that there are many effective,
inexpensive recovery tools to retrieve data from flash memory. When
these don't work, there are commercial services that specialize in
data recovery from flash memory.
So if you plan to use a Hi-MD recorder, keep close watch on the power
level of the battery.
Another shortcoming is that all Hi-MD machines record in stereo mode
only. If the input plug is monaural, the audio is recorded on the left
channel, and the right channel is silent. In addition, the record
level for the left and right channels can't be adjusted independently.
The Sony MZ-RH1 uses a rechargeable lithium ion battery called the
Sony LIP-4WM. The battery is about the size of a stack of three sticks
of chewing gum, and weighs about 10 grams. The battery will power the
recorder for about 5 hours of WAV recording or 8 hours of Hi-SP
recording. Replacement batteries cost about $15 on eBay, so it's easy
and relatively inexpensive to carry several days' worth of battery
power in your pocket.
I am not aware of any way to recharge the LIP-4WM battery outside the
Hi-MD recorder. It may not be practical to recharge several batteries,
one at a time in the recorder, at the end of a long day in the forest.
A longer lasting power alternative is to run the Hi-MD recorder from a
small external battery. The external battery attaches to the USB port
of the recorder. One example is the $25 Lenmar Li-Ion Battery Model
PPU1700B (5 V, 1700 mAh). That's 4.5 times the mAh provided by the
LIP-4WM battery. As a result, the PPU1700B adds 20+ hours of record
time to MZ-RH1.
--oryoki
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