Soundcards and plugin-power mic's

I have an inexpensive plugin-power mic that I use with my minidisc recorder.
It gives excellent results. I can place the recorder in the middle of a
room and record the voices of all those present, even a telephone
speakerphone.
The same mic, plugged in to a front panel mic input on a PC (realtek HDA
889A) results in much much lower levels. This is with the mixer record
level set at 100% and mic boost at +20dB. Maximum boost (+30dB) results in
hum/distortion.


Do PC soundcards provide plugin-power? If not, is it possible to wire the
panel to provide it?

Or is this disparity just down to the superior recording capability of the
minidisc recorder?

Any advice gratefully recieved.

 

I know nothing about minidisc recorders, but I guess you have an
electret microphone. You can easily make up a cable to power it
with a battery and a couple other components. Here's one suggestion,
plenty more out there:
http://www.epanorama.net/documents/audio/electret.html

 

The mic input might be taking a 'wanderous route' around other noisy
signals and source I/O switching employed so that connectors can be
reused for multichannel audio outputs, depending on OS control panel
settings. Check it is indeed set for microphone, and also whether there
is a difference trying the microphone connector at the rear of the PC.
Also I've come across sound chipsets that have a jumper to connect, to
enable the 'plug in power' voltage source.

Failing that, if you wire the line level (or failing that, headphone)
output of your recorder into your PC's line input connector (rather than
the microphone socket) - and place the recorder in 'record-pause' mode
(so that you get a monitoring signal of the plugged in microphone - you
may need an MD inserted), then the results could be a lot better.
Especially if you can fiddle with manual recording level settings on the
recorder.

--
Adrian C

 

Thank Robs. Using terminology found there, I searched a little more and
found some similar solutions.

 

I have tried front and rear inputs, with and without a 1m stereo extension
lead. It makes no discernible difference. I don't appear to have any
hardware switch for plug in power either.

Never thought of that and it works great! The minidisc outputs on line-out
whilst recording (whether paused or not).

Thanks.

 

The standard mic input to a PC is for a mono mic that requires power. Is
your mic mono or stereo?

 

That puts me in my ignorant place - I always thought they expected a
regular dynamic mic. but a quick search shows that Soundblasters do
indeed put +5V on the ring of the TRS, or both tip and ring for newer
cards that support stereo mics.

 

It wants 2-10V on the ring (middle conductor). Apparently sound cards
often have a jumper with which to enable this. If not you could
probably take +5V from one of the molex power connectors inside the
case, although it might be a bit noisy.

 

It's advertised as being compatible with laptop mic inputs which are
mono, using the extra connector on the 'stereo' jack plug to provide
power. It should work with the mic input of generic sound cards.