Internal mics of DV mini camcorders - friend or foe?

Internal mics of DV mini camcorders – friend or foe?

DV mini camcorders do not have a good record as far as sound is concerned. The gurus recommend ignoring these “toys” completely and the use of external mics instead.
We wanted the complete picture and used the Analyser Pro´s Average Module to examine a SONY TRV 900 camcorder. The external mic was an ultralinear Behringer ECM 8000 with 18 V beltfeed. The white noise was calibrated with a Behringer Ultra Curve 8024 to our monitor boxes.
First we wanted to look at the capabilities of the sound recording device, so we recorded white noise via the Behringer ECM 8000 and compared it with the recording of the internal mic.The dv files were captured into the PC, then the respective wav files were loaded into the Average Module of Analyser Pro.

Here is the result:

The blue curve shows the result of the recording device’s general performance. This curve is quite rough with heightened low frequencies resulting in a just about fair performance (The deviance of 18 V feed vs. 48 V of the ultralinear mic is not the topic here; please refer to the respective workshop topic).
The curve of the internal mic shows a well-established peak at 2000 Hz for clarity of speech and a typical plateaued peak in the high frequencies for crispness. As was to be expected, the low frequencies have been purposedly lowered.The result shows a mic which performs better than its reputation.
It gets even better when we make visible how the sophisticated engeneering of the mic compensates for the waknesses of the recording device:

This graph needs some explanation: We drew the red curve manually, subtracting the values when yellow was less than blue, and adding when yellow was greater than blue, because the mic indeed corrects quite nicely the recording device. The resulting red line shows a reasonably good performance with accentuated frequencies around 2000 Hz and a plateau around 8000 Hz as is common for mics geared for speech. (The noise level is another question here).
As far as the common suggesting to use a high quality external mic with a DV camcorder is concerned, we did the test with a SONY ECM S959C as follows.

One can clearly see that the use of an expensive external mic makes no sense at least as far as frequency response is concerned.
When you really want to achieve a significant difference, use an external mic and an external digital recording device.

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