I went down to fix dinner and realized that my logic is wrong about
being able to deduce any Mic Pre noise figure from the test. Sorry.
With the NT3, if the noise through the HiMD mic pre and the
workaround MP-2 is the same, what we're hearing is likely the noise
just from the NT-3.,..I have to go back to making dinner, but why
does the NT-4 through the workaround MP2 have less noise? Where would
the noise be coming if not from the HiMD mic pre? Rob D
Rob D: wrote and realized soon afterwards,..
>
>
>At 12:22 PM +0200 4/21/05, Klas Strandberg wrote:
>> >Since the 957 already terminated in an 1/8th mini jack, and uses
>>>plug-in power? Or maybe it's battery operated? I'm not sure how much
>>>you'd gain by adding a preamp. I think we're mainly referring to
>>>phantom powered mics using external preamps. That being said, I know
>>>often the minidisc mic input isn't the cleanest, and if you can go in
>>>line level, you'll bypass some of the noise.
>>
>>
>>I clam that that statement is common but wrong.
>>Give me some proof!
>>
>>Klas.
>>
>
>m("sbcglobal.net/vwp2?.tok","//f2.pg.briefcase.yahoo.com/bc/rob_danielson");=bcmKTRVBNxZgHObW&.dir=/Tests&.dnm=CompareMiniDiscMicPreNoise.mov&.src=bc">http:=bcmKTRVBNxZgHObW&.dir=/Tests&.dnm=CompareMiniDiscMicPreNoise.mov&.src=bc
>
>Right-click on the paper-looking document and select, "Download
>linked files as,.." option.
>
>I've uploaded the above 2.3 mb QuickTime movie that compares the
>resultant noise from Rode Nt3 and Nt4 mics using a HiMD mic input
>jack and the same mics routed through a Sound Devces MP-2 outboard
>preamplifier into the HiMD's line input. The recordings were made at
>16/44.1; the QuickTime movie has an IMA:4 compressed sound track so
>that more people can download it. Again, these tests are for quiet
>location recording situations where high gain is more likely to be
>used. The files are well saturated and loud, be sure to adjust
>playback volume to a comfortable level
>
>To my ears, the NT3 presents a fairly close match between internal
>and external preamp noise which suggests to me that an "effective
>self-noise" rating for the NH-900 HiMD recorder's mic pre _with this
>particular mic_ is in the ballpark of 16 dBA. [The self noise
>equivalent for the MP-2 (with some conservative assumption involved)
>is in the area of 5dBA, so its very unlikely to be adding noise.]
>
>I say only for "this particular mic" because, as we found before,
>sensitivity (output) and other factors come into play. You will note
>that I had to boost the playback level of the NT4's recording 14dB to
>match the playback level of the NT3's recording. Even though both
>mics have very close self noise specs (16dBA for the NT4 and 17dBA
>for the NT3), the noise component in the NT-4's recording is also
>increased 14dB to match playback leve with the NT3's. The addition
>of noise from the HiMD mic pre can be confirmed by looking at the NT4
>signal routed through the MP2 where we hear less noise than that from
>the recording where the NT4 is connected to the HiMD recorder's mic
>pre.
>
>The NT3's recording (apparently taking advantage of effective higher
>output) exhibits about the same noise as the recording made when the
>NT3 routed through the MP2. This suggests to me that a HiMD mic
>preamp is more likely to introduce significant noise when the record
>level is high and the mic does not have high output. This is
>consistent with our theory of why the Shure 183 performed well with
>22.5dBA noise in the prior test with its high sensitivity of 42 mv/Pa.
>
>So, there is no simple way to put MD mic preamp noise into a general
>"effective self noise" number because performance is the result of
>speciifc mic-preamp combinations. If you need further proof of this
>phenomenon, according to Rode, the NT3 and the NT4 have equal
>sensitivity (12 mv/Pa). Their output impedance is also matched at
>200 ohms.
>
>I tested the mics from the first test again and I feel the results of
>the first test are very reliable. That's is available as a small
>.mov now:
>
>http://www.micbooster.com/movies/TransMic&PreTestSor3_IMA.mov
>
>People commented on the appreciable leap in quality that happened
>with the NT1A/Mp2 in the first test so I'm testing some higher end
>mic-pre combos. Rob D.
>
>
>
>
>
>
>
>"Microphones are not ears,
>Loudspeakers are not birds,
>A listening room is not nature."
>Klas Strandberg
>Yahoo! Groups Links
>
>
>
>
--
Rob Danielson
Film Department
University of Wisconsin-Milwaukee
________________________________________________________________________
________________________________________________________________________
|