!/ That is a relevant question - you have to identify the noise by it's
character. When working with a mic in the lab for several days, you learn
to hear what the noise sounds like, just like you learn to hear what a
certain bird sounds like. Usually it is not difficult, but I admit that I
make temporary mistakes.
A simple way to learn the difference is to put an attenuator on the mic and=
lower the mic self noise until you start to hear the MD / DAT /Edirol
/whatever mic amp noise. Then you can hear the difference.
The FET-IC which I use for all mics has a noise which is low in frequency,=
while the MD/DAT/Edirol inputs have a noise which is much more like white
noise. Sometimes you can hear how the mic noise and the preamp noise is
added, so that a low frequency noise from the mic is added to a high
frequency noise from the mic amp.
2/ When reading noise figures, consider that "A-weighted" noise or
"CCIR-weighted" noise means that one has compensated for the frequencies
which are most audible to the human ear.
For naturesound recordists there should be another way to "weight" a noise,=
compensating for the noise which is most masked by nature atmosphere. A
high frequency noise can be audible "on top" of the atmosphere, while a low=
frequency noise is masked by it and not possible to hear at all.
3/ When I send my postings on this list, I don't feel that I am understood.=
I do not succeed in finding the right words for my logic. Let me try this o=
ne:
Suppose a microphone has a self noise of 16 db(A). Fine. That cannot be
changed by any pre-amp.
Then the question must be: "How sensitive (output =3D mv/Pa) must that
microphone be to "noise-dominate" over the MD/DAT/ Etc mic input noise?
That is the question which needs to be answered!
I mean - the noise you hear should always come from the mic!!! The mic must=
always be the weakest link in the chain!
4/ Sensitivity must be presented as mV/Pa, NOT -db, whatever - as there is=
too much cheating on the market, using different reference levels for the
db measuring.
I spent two hours on the web a few days ago (with broadband- finally!! here=
in the woods!!) - to straighten out my questions about "sensitivity"
expressed as "db". I found myself in a total mess of different standards.
If you like to try - please visit
http://www.acoustics-noise.com/dBA-B-C-D-U-G-U-AU-tables.shtml for example.
When the data sheet says: "10 mv/Pa at 1000 Hz" - fine, that is a fact! One=
can understand it. But when it says: "Sensitivity -64" db or something, I
don't care about it. I don't see any good reason why somebody should leave=
an established and accurate expression (mV/Pa) in favor of a strange figure=
(db), unless there is fraud going on.
We must all understand that: When one manufacturer starts manipulating with=
data, even lying, all the others have to follow. Or die.
Example: Walt helped me to buy a CAD 179. It is a good mic for it's price,=
though bulky and ugly and not good for field work. But it's noise
presentation?? It says 10 db(A)!!! No way!! In it's omni-position, it is
much noisier than a MKH20 which presents the same 10db(A), and the noise is=
more "sparkling"!
Even Neumann presents a similar (China made) mic with a self noise of
7db(A). So why is it audibly noisier than a MKH??
Klas.
At 14:41 2005-05-11, you wrote:
>Klas
>How are you Mic picking noise from pre-amp noise?
>
>Klas Strandberg wrote:
>
> > A Telinga microphone boosts sensitivity and low noise. It sacrifices hi=
gh
> > sound pressure level and in one case (stereo DATmic) also linearity.
> >
> > Other mic's don't do that. Therefore, if you want to combine "the Telin=
ga
> > qualities" with high sound pressure level and linearity, - you are
> > stuck in
> > the Sennheiser MKH system. There is no way around this problem.
> >
> > I don't know about the Rode mic's, except that they are made by a
> > Swede who
> > emigrated to Australia and sold here, too, in shops for musical
> > instruments
> > and vocals.
> >
> > What I know about microphone tests is that is is soooo easy to make
> > errors.
> > Even the most careful tests which I (and J=F6rgen) have made, have
> > proved to
> > be wrong after a few days only. It is like you have to "get acquainted"
> > with a certain microphone over a long time before you can judge about
> > it. I
> > have listened to mic noise one evening and judged it as okay, next day =
I
> > find it too high... And vice versa!
> > And most of the tests which I do have to be repeated over and over agai=
n.
> > Only when I get the same result at least five, six times - then I am
> > pleased with the reliability.
> >
> > I can only claim two things:
> >
> > If you hear microphone noise, then you cannot lower this noise by using=
a
> > preamplifier. It is there, and all you can do is amplify it.
> > If you hear MD / DAT amplifier noise, you have the wrong microphone for
> > nature sound recording. Or - rare - you have a very, very bad microphon=
e
> > preamp, must worse than any common MD mic input.
> >
> > I tested again today: Used a 10 mm PIP electret and a EM23PIP into
> > different Sharp MD's which I have + the Edirol R1. The noise I could he=
ar
> > came from the microphone FET and not from the MD / Edirol mic input amp=
.
> >
> > A preamp into the line inputs will only amplify this FET noise.
> >
> > I don't deny that others have other experiences, but I can't explain it=
.
> >
> > When reading data sheets with noise figures and frequency curves, don't
> > forget that those figures were measured with a brand new microphone,
> > inside, room-temperature and a suitable humidity. Age, low temp, impact
> > from use in humid areas, dust and bacteria (even fungus!) will affect
> > those
> > figures by many db.
> >
> > Klas.
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > At 20:07 2005-05-09, you wrote:
> > >Hi Klas-- I apologize for my error. Were you able to download the
> > >test? There's a noticeable increase in noise with the NT-4 that I'd
> > >like to hear your thoughts about. The MP2 preamp does seem to lower
> > >the noise with the NT-4 and the curious thing is the NT3 and Nt4 both
> > >have very similar self noise (16 and 17dBA) and exact sensitivity
> > >specs (12dBA). I can email it to you too, its 2.3 mb. Rob D.
> > >
> > >At 6:47 PM +0200 5/9/05, Klas Strandberg wrote:
> > > >At 23:55 2005-05-04, you wrote:
> > > >>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 wou=
ld
> > > >>the noise be coming if not from the HiMD mic pre? Rob D
> > > >
> > > >
> > > >How wonderful isn't it with people who has such a free-running
> > brain that
> > > >it realized a previous error while fixing dinner....
> > > >
> > > >I still don't know for sure what is right and wrong in this topic,
> > but I
> > > >hope that my brain will solve it while making dinner next time. Have=
to
> > > >wash my car tomorrow. Perhaps then...?
> > > >
> > > >Until then I repeat: If you hear noise, you can never lower this
> > noise by
> > > >using a preamp.
> > > >
> > > >Klas.
> > > >
> > > >
> > > >
> > > >
> > > >>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?.","//f2.pg.briefcase.yahoo.com/bc/rob_danielson");=">http:=
tok
> > > >>
> > =3DbcmKTRVBNxZgHObW&.dir=3D/Tests&.dnm=3DCompareMiniDiscMicPreNoise.mov=
&.src=3Dbc
> > > >> >
> > > >> >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 inpu=
t
> > > >> >jack and the same mics routed through a Sound Devces MP-2 outboa=
rd
> > > >> >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 qui=
et
> > > >> >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 intern=
al
> > > >> >and external preamp noise which suggests to me that an "effectiv=
e
> > > >> >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 befor=
e,
> > > >> >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 bo=
th
> > > >> >mics have very close self noise specs (16dBA for the NT4 and 17d=
BA
> > > >> >for the NT3), the noise component in the NT-4's recording is als=
o
> > > >> >increased 14dB to match playback leve with the NT3's. The addit=
ion
> > > >> >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 smal=
l
> > > >> >.mov now:
> > > >> >
> > > >> >http://www.micbooster.com/movies/TransMic&PreTestSor3_IMA.mov
> > <http://www.micbooster.com/movies/TransMic&PreTestSor3_IMA.mov>
> > > >> >
> > > >> >People commented on the appreciable leap in quality that happene=
d
> > > >> >with the NT1A/Mp2 in the first test so I'm testing some higher e=
nd
> > > >> >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
> > > >>
> > > >>
> > > >>
> > > >>"Microphones are not ears,
> > > >>Loudspeakers are not birds,
> > > >>A listening room is not nature."
> > > >>Klas Strandberg
> > > >>Yahoo! Groups Links
> > > >>
> > > >>
> > > >>
> > > >>
> > > >
> > > >Telinga Microphones, Botarbo,
> > > >S-748 96 Tobo, Sweden.
> > > >Phone & fax int + 295 310 01
> > > >email:
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >"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
> > >
> > >
> > >
> > >"Microphones are not ears,
> > >Loudspeakers are not birds,
> > >A listening room is not nature."
> > >Klas Strandberg
> > >Yahoo! Groups Links
> > >
> > >
> > >
> > >
> >
> > Telinga Microphones, Botarbo,
> > S-748 96 Tobo, Sweden.
> > Phone & fax int + 295 310 01
> > email:
> >
> >
> >
> >
> >
> > "Microphones are not ears,
> > Loudspeakers are not birds,
> > A listening room is not nature."
> > Klas Strandberg
> >
> >
> > *Yahoo! Groups Links*
> >
> > * To visit your group on the web, go to:
> > http://groups.yahoo.com/group/naturerecordists/
> >
> > * To unsubscribe from this group, send an email to:
> >
> >
> <=3DUnsubscrib=
e>
> >
> > * Your use of Yahoo! Groups is subject to the Yahoo! Terms of
> > Service <http://docs.yahoo.com/info/terms/>.
> >
> >
> >------------------------------------------------------------------------
> >
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> >Checked by AVG Anti-Virus.
> >Version: 7.0.308 / Virus Database: 266.11.8 - Release Date: 10/05/05
> >
> >
>
>
>--
>No virus found in this outgoing message.
>Checked by AVG Anti-Virus.
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>
>
>
>
>"Microphones are not ears,
>Loudspeakers are not birds,
>A listening room is not nature."
>Klas Strandberg
>Yahoo! Groups Links
>
>
>
>
Telinga Microphones, Botarbo,
S-748 96 Tobo, Sweden.
Phone & fax int + 295 310 01
email:
________________________________________________________________________
________________________________________________________________________
"Microphones are not ears,
Loudspeakers are not birds,
A listening room is not nature."
Klas Strandberg
------------------------------------------------------------------------
Yahoo! Groups Links
<*> To visit your group on the web, go to:
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<*> To unsubscribe from this group, send an email to:
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