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Small Diaphragm Condensers

Discussion in 'Recording' started by gambit, Aug 10, 2004.

  1. gambit

    gambit Active Member

    I am looking to buy one (maybe a matched pair?) primarily for recording acoustic instruments and wondered if you could help me understand the various polar plots that I have seen.

    For example AVENSON AUDIO STO-2 shows this plot (from Mercenary):

    http://store1.yimg.com/I/mercenary-audio_1804_16841278

    Whereas a cheaper SE Electronics shows:

    http://www.seelectronics.com/web/cm_se1_gra.htm

    (NOTE: The first is Omni pattern, the second cardoid - I am pretty happy with the difference between these)

    What should a good plot look like?

    Thanks in advance.

    G.
     
  2. Kurt Foster

    Kurt Foster Distinguished Member

    These are frequency response plots, not polar plots. Whether they are for omni or cardioiod is of no consequence in this case... although omni's tend to display flatter more accurate response.. So in a way, you are comparing apples and oranges.

    A better comparison would be using either omni or cardioid patterns for both mic measurements.

    The first plot shows a roll off in the high frequency response starting at 7Khz., the second plot shows a rise in the high frequency response starting at 500 Hz. and continuing to 13KHz. and then rolling off to flat at 20KHz. The ideal would be a plot that was perfectly "flat" with no rise or dips.

    It's interesting that the plot for the STO-2 is measured at 0 dB while the SEA 1 is measured at what appears to be -50dB. These kind differences in measuring methods can render a comparison, moot.

    Judging from this alone, one could surmise that the SE1A will be a brighter sounding mic (in the shown configuration).

    A word about this .... use your ears. What something looks like on paper often will have nothing to do with what it sounds like, often due to the previously mentioned differences in measurement. Because of this, I have seen gear that spec'd out wonderfully but sounded very bad.. If you are going to compare specs, be sure all elements are on a level playing field.
     
  3. gambit

    gambit Active Member

    Thanks for the quick reply Kurt!

    I wasn't sure what to call them as I've seen both terms used. I assume a Polar Plot refers to the response around the axis as seen in the circular charts. These would surely just show the pattern not any useful information.

    Thanks for pointing out the difference in the measurements - kind of worrying really. Unfortunately I don't have the luxury of using my ears as I have found shops in this country rarely take you seriously unless your spending upwards of 3-5K, not buying the odd mic as and when you can afford it.

    One more point would this graph worry you as much as it does me?

    G.
     
  4. Kurt Foster

    Kurt Foster Distinguished Member

    The plot at the top is a polar plot. The bottom is a freq plot. Is it a problem? Not really. That has to be more an approximation instead of the actual response. It's too flat.

    It being measured at -50 dB is not as much of an issue, if it is not being compared to something else at another value (like 0 dB).
     

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