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Re: [micbuilders] Rode NT1A matching

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  • Rob Danielson
    ... The right mic was so off to my ears compared to the other NT1A s I had heard that I just sent it back to the store . The replacement they sent was a much
    Message 1 of 24 , Apr 30, 2005
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      At 1:02 PM -0700 4/30/05, <ebenj@...> wrote:
      >..
      >
      >> these two NT1A's are not well-matched.
      >Do you say that just because of the differences observed in these
      >recordings? Or have you found that to be true elsewhere, as well? I have
      >two NT-1As and I find them to be pretty well matched. I should be more
      >specific. The frequency response curves lie almost on top of each other up
      >to about 3.5 kHz. Above that point one of them increases slowly in
      >sensitivity until it they are about 2.8 dB apart at 9 kHz, and then the
      >sensitivity becomes more equal until they again have the same sensitivity
      >above 15 kHz. Perhaps that would not qualify as well-matched, but for
      >microphones it seems pretty good to me.
      >
      >
      >Eric
      >

      The "right" mic was so off to my ears compared to the other NT1A's I
      had heard that I just sent it back to the store . The replacement
      they sent was a much better match. I emailed Peter at Rode before we
      made a larger order and he said they could provide dealers with
      consecutive numbers but none of the dealers I spoke with would mess
      with it. Rode may be just stamping bodies anyway? I haven't tested
      all the new units yet, I should do that. I have more confidence in
      what I can learn by opening several up in a big quiet place and
      listening to them side by side than what I can do with a speaker and
      sine tones. But you have real bench and know what you're doing. Rob
      D.

      --
    • Jason May
      Rob, it seems to me that perhaps some of what your hearing is a result of the phase inaccuracy inherent in cardioid mics (I believe bob cain suggested this
      Message 2 of 24 , May 1, 2005
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        Rob, it seems to me that perhaps some of what your hearing is a result of
        the phase inaccuracy inherent in cardioid mics (I believe bob cain suggested
        this earlier). For your application, I would strongly suggest some B&K
        Omni¹s (or even earthworks perhaps though they might be a bit noisy) and an
        extremely phase accurate preamp. Also, the very wide spacing you used will
        present it¹s own phasing problems. I know my suggestions probably aren¹t of
        much help, but I thought I¹d share my thoughts. It does sound like a
        beautiful area to record. Thanks for the experiment, always interesting.



        Jason


        [Non-text portions of this message have been removed]
      • Rob Danielson
        ... Thanks for the suggestions, Jason. A few folks do use B&K s in the field, I ve wanted to hear how they sound with the gain cranked up for years. Maybe
        Message 3 of 24 , May 1, 2005
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          At 3:40 PM -0400 5/1/05, Jason May wrote:
          >Rob, it seems to me that perhaps some of what your hearing is a result of
          >the phase inaccuracy inherent in cardioid mics (I believe bob cain suggested
          >this earlier). For your application, I would strongly suggest some B&K
          >Omni¹s (or even earthworks perhaps though they might be a bit noisy) and an
          >extremely phase accurate preamp.

          Thanks for the suggestions, Jason. A few folks
          do use B&K's in the field, I've wanted to hear
          how they sound with the gain cranked up for
          years. Maybe someday. I do use mbho 603/D100's
          and mkh20s omnis and they perform identically in
          this regard.

          I do agree the muddiness does sound like its from
          sort of interferece of which phase cancellation
          is a type. But any phasing you're hearing would
          be identical to that if the mics were 5" apart
          because the left and right signals are discrete,
          at least in excess of 110dB. My guess is that
          phase inaccuracies from the MP2 mic preamp would
          be well documented as its a very popular pre for
          making M-S recordings and M-S relys on phase
          relations for imaging. Perhaps northerners have
          to develop a liking for sparseness and air. Rob D.

          > Also, the very wide spacing you used will
          >present it¹s own phasing problems. I know my suggestions probably aren¹t of
          >much help, but I thought I¹d share my thoughts. It does sound like a
          >beautiful area to record. Thanks for the experiment, always interesting.
          >
          >
          >Jason
          >

          --
          Rob Danielson
          Film Department
          University of Wisconsin-Milwaukee
        • ebenj@pacbell.net
          From: Rob Danielson ... Now this shoots down the theory that I was working up which was that it has something to do with the pressure
          Message 4 of 24 , May 1, 2005
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            From: "Rob Danielson" <type@...>

            >I do use <snip> mkh20s omnis and they perform identically in this regard.
            Now this shoots down the theory that I was working up which was that it has
            something to do with the pressure gradient pattern of the NT-1As and the
            concomitant proximity effect. If you hear more or less the same thing with
            omnis then I have to discard that theory.

            >I do agree the muddiness does sound like its from sort of interferece of
            which phase cancellation
            >is a type.
            I wonder if it could simply be a case of the incorrect playback level? By
            incorrect, I simply mean that the playback level may be higher than the
            actual acoustic level at the recording site.

            Let me get back on my stump and think out loud. It is known that the growth
            of loudness is not the same at low frequencies as it is at mid frequencies.
            We tend to think of dB SPL (Sound Pressure Level) as representing loudness
            (a perceptual phenomenon) but it doesn't. Phons are a measure of loudness
            level and they have approximately the same size as dB but they are
            nonlinearly related to the acoustic level in dB, particularly at low
            frequencies. I think that most people in this forum know that the threshold
            of hearing is higher at low frequencies than at mid frequencies (about 0 dB
            SPL at 1 kHz, 76 dB SPL at 20 Hz!), but what they may not know is that once
            the threshold is passed at low frequencies, the sound grows louder (in
            phons) at a more rapid rate at low frequencies than at mid frequencies.

            So a 76 dB SPL 20 Hz tone is equally at loud as a 0 dB SPL 1 kHz tone. But
            the loudness of the 20 Hz tone grows more rapidly such that at 100 dB SPL
            they are about equally loud. In other words, the 20 Hz tone increases as
            much in loudness with a 24 dB change in level as the 1 kHz tone did with a
            100 dB increase in level.

            Back to the question of what is causing the loss of clarity? That is the
            question, isn't it? If the low-frequency sounds are perceived as being
            louder than they actually were on-site at the time of the recording, then
            they exert a greater masking influence on the sounds above and below them in
            frequency. That masking of higher-frequency spectral components could be
            perceived as a loss of clarity.

            Well, it's a theory.

            Eric
          • Rob Danielson
            ... And thus an explanation of why a biamp d speaker system allows the (non sub) woofer to portray significantly greater clarity in the mystery range? That is
            Message 5 of 24 , May 1, 2005
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              At 4:48 PM -0700 5/1/05, <ebenj@...> wrote:
              >From: "Rob Danielson" <type@...>
              >
              >>I do use <snip> mkh20s omnis and they perform identically in this regard.
              >Now this shoots down the theory that I was working up which was that it has
              >something to do with the pressure gradient pattern of the NT-1As and the
              >concomitant proximity effect. If you hear more or less the same thing with
              >omnis then I have to discard that theory.
              >
              >>I do agree the muddiness does sound like its from sort of interferece of
              >which phase cancellation
              >>is a type.
              >I wonder if it could simply be a case of the incorrect playback level? By
              >incorrect, I simply mean that the playback level may be higher than the
              >actual acoustic level at the recording site.
              >
              >Let me get back on my stump and think out loud. It is known that the growth
              >of loudness is not the same at low frequencies as it is at mid frequencies.
              >We tend to think of dB SPL (Sound Pressure Level) as representing loudness
              >(a perceptual phenomenon) but it doesn't. Phons are a measure of loudness
              >level and they have approximately the same size as dB but they are
              >nonlinearly related to the acoustic level in dB, particularly at low
              >frequencies. I think that most people in this forum know that the threshold
              >of hearing is higher at low frequencies than at mid frequencies (about 0 dB
              >SPL at 1 kHz, 76 dB SPL at 20 Hz!), but what they may not know is that once
              >the threshold is passed at low frequencies, the sound grows louder (in
              >phons) at a more rapid rate at low frequencies than at mid frequencies.
              >
              >So a 76 dB SPL 20 Hz tone is equally at loud as a 0 dB SPL 1 kHz tone. But
              >the loudness of the 20 Hz tone grows more rapidly such that at 100 dB SPL
              >they are about equally loud. In other words, the 20 Hz tone increases as
              >much in loudness with a 24 dB change in level as the 1 kHz tone did with a
              >100 dB increase in level.
              >
              >Back to the question of what is causing the loss of clarity? That is the
              >question, isn't it? If the low-frequency sounds are perceived as being
              >louder than they actually were on-site at the time of the recording, then
              >they exert a greater masking influence on the sounds above and below them in
              >frequency. That masking of higher-frequency spectral components could be
              >perceived as a loss of clarity.
              >
              >Well, it's a theory.
              >
              >Eric
              >

              And thus an explanation of why a biamp'd speaker system allows the
              (non sub) woofer to portray significantly greater clarity in the
              mystery range? That is certainly true. I like your hunch that the
              disproportionate amount of work that the speaker (capsule too?) is
              being asked to do at the lowest Hz's is behind it somehow. Try this
              blind test: Take a recording with lots of inherent low end pink noise
              (or the demo) use parametric EQ to momentarily create a big (~+18dB)
              boost at 20Hz. Now do the same at ~60Hz. Go back and forth making
              temporary boosts and pay attention to what you can hear during the
              boosts in the mystery range. Maybe use headphones?

              We use the term "coloration" to refer to a faint "tuning" of the
              signal created by a mic, pre, and a-d. At the mic capsule level, do
              some the phenomena thought to be responsible for this do their thing
              in these 3 lowest octaves? It strikes me that what we have in common
              here-- inside and outside, city and remote-- is that with high gain,
              the mics are getting, proportionally, a lot of very low frequency
              content. Look at the first curve in the demo- that's the spectrum
              coming through the mixing chain. I added a sharp -12dB cut at 20hz
              too that's not showing on the eq curves too. Anechoic chamber anyone?
              Rob D.



              --
            • Rob Danielson
              I came across Eric s graph comparing messured noise from NT1-A and other mics. I ve been wondering if the increasing lower end distortion could also be
              Message 6 of 24 , May 11, 2005
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                I came across Eric's graph comparing messured noise from NT1-A and
                other mics. I've been wondering if the increasing lower end
                distortion could also be contributing to the muddiness or is the
                percentage of the signal that is distorted too low?

                http://f3.grp.yahoofs.com/v1/YJ-BQoSF64dBBaVp9-4YBFeFtno1hLyh0q9eEUPqYPL5dQ9pPEFhYstdfZCPKJloVX6vft4GeL9QiISUESxVDWuhWMaKqKCprtMUECkEKeB_6DEQE3XA-l8W/Mic%20Measurements/comparison%20of%20microphone%20noise.pdf

                Can distortion produce simplified bands like the eaggerated tones? Rob D.
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