I'm catching up on emails as I've been in hospital for a few days. I've got
a Tascam DR-100 mark I and it's only good at one thing which is recording
from line input where I can't fault it. I found the built in mics and the
mic inputs unusable for nature recording. The XLR sockets may be a draw, but
they are unbalanced and no better quality than 3.5's. You can't get wildlife
quality from just a pocket recorder. They may be just OK for music practice
sessions, but recording quality music is a whole new ball game.
I bought an SQN mixer from eBay and made an adaptor to the 3.5mm Tascam line
input at (from memory) -6dB. I would doubt if any pocket recorder would have
a clean mic input, and the criterion here is that you *can* hear mic hiss
clearly. Mic hiss is the noise you can't avoid.
My mic hiss is from old MKH series mics which are still very close to state
of the art. My guess is that any mic input amp on any pocket recorder will
not be up to the job. The reason for saying this is that matching the "noise
impedance" of a mic to an amplifier is the crucial element. This is rarely
quoted and it is not the input or output impedance that counts, but the
optimum noise match. If you plug a low impedance mic into a medium impedance
input, the noise should fall proportionately, if not there is a noise
impedance mismatch. Theoretically, reducing the input impedance further
should increase the proportional noise. Also look for mic sensitivities
above 20mV/Pa.
The simplest match is with a transformer, but they are deprecated nowadays
except for RF transformers in the MKH series. As far as I can tell, the cost
of a low noise matching solid state input mic amp or mixer is at least as
much as a good pocket line-in recorder, like the Tascam.
My advice would be to spend out on good mics and then try to match their
quality with the attached gear. The excess noise spec should be around 12dB
or 13dB A-weighted, or in the low 20's ITU-R468 weighted. Any mic quoting
less than that either costs around $5000 and is unsuitable for field use or
has been measured with the capsule disconnected, which is not helpful unless
you intend to use it with the capsule disconnected, :-)
David Brinicombe
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