Hi Rob,
Thanks for making these tests and uploading the results. The -130.7dB for =
NT-2A is with a 10dB safety margin so perhaps the shape of the noise floor =
of mic and preamp is a factor in audibility. It could be the flatter the no=
ise floor of both mic and preamp the more likely the lower end of the 6-10d=
B range will be adequate. The calculated output noise figures would only ev=
er be valid in an environment where the noise level was below the noise flo=
or of the mic so these "tick" tests
Looking at the original pink noise files the difference in level between th=
e NT-2A and NT-1A is 1.5dB peak, 1.3dB average and 1.3dB rms which reflect=
s the 2dB difference in sensitivity indicated by the manufacturers specs. =
Using a pink noise calibration tone to match levels is potentially more rev=
ealing that trying to match apparent levels. The differences in tonal balan=
ce are inherent in the design of mics and preamps so when comparing equipm=
ent we should be preserving these differences rather than trying to negate =
them. I'd personally boost the NT2-A by around 1.3-1.4dB to do comparisons.
The differences between the mics are quite interesting - the NT-1A's sound =
rather "thin" compared with NT-2A which seems to have more emphasis on the =
low frequencies. I definitely agree the NT-2A has more noise but that is bo=
rne out by the specs.
cheers
Paul
On 09/04/2010, at 7:33 AM, Rob Danielson wrote:
>
> Hi Paul--
> Here are some test materials in a folder to download. I recorded both
> mics with 58.6 dB of Gain with a SD 744T recorder.
>
> http://tinyurl.com/y8haout
>
> The Hz response on the two mics is very different. Mic self-noise,
> high in register with both mics, is not significantly different in
> color.
>
> Using RMS matching of pink noise is the only way I know of to match
> playback levels when the tonality of the two mics differs as
> significantly as these do. With the additional LF response it has,
> the less sensitive NT2-A needed only .5dB of additional gain to match
> the NT1-A (pink noise RMS). You can easily hear the additional LF
> response in the room tone/tick section as well and there's not much
> LF there to work with!
>
> I we assume as Rane Table 3 suggests that the mic pre in the 744T
> [measured at -130dBu (A weighted)] is quiet enough for an NT1-A mic
> (which we also know from other tests), then I don't understand why
> Rane Table suggests a quieter pre is needed to become transparent
> behind the NT2-A. When the signal output of the two mics is matched,
> the sonograms I've made indicate that the NT2-A has slightly more
> effective self-noise noise, not less. In my experience, this usually
> means the pre can be slightly noisier, not less. If I've missed
> something glaring, I'm ready fer educatin' Rob D.
>
>>
>> At 5:03 AM +1100 4/1/10, Paul Jacobson wrote:
>>>
>>
>>> On 31/03/2010, at 5:19 PM, Rob Danielson wrote:
>>>>
>>>> Rode NT-1A 25 5 -118.83 -128.8 dBu YES, A-weighted
>>>> Rode NT-2A 16 7 -120.70 -130.7 dBu?? Side by
>>>> side, the 2A is noisier than the 1A. In practice one could get by
>>>> with a slightly "noisier" pre, not a "quieter" one and one would not
>>>> need -130.7 dBu (A weighted).
>>>
>>> There is no question that the NT-2A has a higher level of
>>> self-noise, but based on the published specs if you recorded both
>>> the NT-1A and NT-2A at identical gain settings on the same recorder
>>> the recorded mic noise floor of the NT-2A _should_ be lower in terms
>>> of of dbFS than the recorded noise floor of the NT-1A. I'd be
>>> interested to see your results of such an unadjusted comparison.
>>
>> Hi Paul--
>>
>> Its on the test "to-do" list. I'm not following how rec gain makes a
>> difference in mic self-noise performance and the resulting recording
>> if a sufficiently quiet pre is used. Such a pre would be necessary to
>> compare the self-noise performance of the two mics.
>
>
>
> --
>
>
>
> ------------------------------------
>
> "While a picture is worth a thousand words, a
> sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause
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>
>
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