[Tobiah]

I bout a pair of Rode NT1-A's for recording quieter
sounds because I heard that it had the lowest noise
out there. I'm quite happy with them, but I got to
thinking. Isn't the important thing the signal to
noise ratio, rather than the actual amount of noise
that the mic puts out? It seems that a significantly
more sensitive mic, with slightly higher noise would
actually be a better choice for recording quiet sounds.

Thanks,

Toby

[Laurence Payne[_2_]]

On Wed, 14 Jan 2009 10:03:42 -0800, Tobiah wrote:

I bout a pair of Rode NT1-A's for recording quieter
sounds because I heard that it had the lowest noise
out there. I'm quite happy with them, but I got to
thinking. Isn't the important thing the signal to
noise ratio, rather than the actual amount of noise
that the mic puts out? It seems that a significantly
more sensitive mic, with slightly higher noise would
actually be a better choice for recording quiet sounds.

Yup. And when the NT1-A was being recommended as a "quiet" mic, it
was the s/n ratio they were talking about.

[Don Pearce[_2_]]

On Wed, 14 Jan 2009 10:03:42 -0800, Tobiah wrote:

I bout a pair of Rode NT1-A's for recording quieter
sounds because I heard that it had the lowest noise
out there. I'm quite happy with them, but I got to
thinking. Isn't the important thing the signal to
noise ratio, rather than the actual amount of noise
that the mic puts out? It seems that a significantly
more sensitive mic, with slightly higher noise would
actually be a better choice for recording quiet sounds.

Thanks,

Toby

No. What matters (and what the mic manufacturers quote) is the
equivalent noise level of the mic. In the case of the NT1-A it is 5dB.
This figure takes everything into account. The only thing that the
sensitivity of the mic does is determine the position of the gain
control on the preamp. As long as the amp has enough gain that you can
reach the position you need, then all is well.

d

[Tobiah]

On Wed, 14 Jan 2009 18:46:15 +0000, wrote:

On Wed, 14 Jan 2009 10:03:42 -0800, Tobiah wrote:

I bout a pair of Rode NT1-A's for recording quieter
sounds because I heard that it had the lowest noise
out there. I'm quite happy with them, but I got to
thinking. Isn't the important thing the signal to
noise ratio, rather than the actual amount of noise
that the mic puts out? It seems that a significantly
more sensitive mic, with slightly higher noise would
actually be a better choice for recording quiet sounds.

Thanks,

Toby

No. What matters (and what the mic manufacturers quote) is the
equivalent noise level of the mic. In the case of the NT1-A it is 5dB.
This figure takes everything into account. The only thing that the
sensitivity of the mic does is determine the position of the gain
control on the preamp. As long as the amp has enough gain that you can
reach the position you need, then all is well.

d

What then, is 'equivalent noise'? I thought that it meant that when
you power on the mic when there are no sounds present, there is some
output on the wire in the form of noise, and we were measuring the
strength of that noise. If this is the case, then if the mic is
not very sensitive, I'll have to crank the preamp, which will amplify
the noise.

Thanks,

Toby

[Scott Dorsey]

In article ,
Tobiah wrote:
I bout a pair of Rode NT1-A's for recording quieter
sounds because I heard that it had the lowest noise
out there. I'm quite happy with them, but I got to
thinking. Isn't the important thing the signal to
noise ratio, rather than the actual amount of noise
that the mic puts out?

The signal to noise ratio of a microphone is the ratio between the loudest
sound it can reproduce and the noise floor of the microphone. As long as
you are only recording soft things, you care only about the noise floor and
not the clipping point.

It seems that a significantly
more sensitive mic, with slightly higher noise would
actually be a better choice for recording quiet sounds.

That would be the case IF the preamp noise floor was higher than the mike
noise floor. And that depends on how good your preamp is. With a quality
modern preamp, the microphone will be the dominant noise source, even with
a low-output mike like a 635A. With a typical modern video camera, the
preamp noise will be much higher than even a noisy high-output mike.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Tobiah]

On Wed, 14 Jan 2009 14:06:51 -0500, Scott Dorsey wrote:

In article ,
Tobiah wrote:
I bout a pair of Rode NT1-A's for recording quieter
sounds because I heard that it had the lowest noise
out there. I'm quite happy with them, but I got to
thinking. Isn't the important thing the signal to
noise ratio, rather than the actual amount of noise
that the mic puts out?

The signal to noise ratio of a microphone is the ratio between the loudest
sound it can reproduce and the noise floor of the microphone. As long as
you are only recording soft things, you care only about the noise floor and
not the clipping point.

Oh, right. S/N is not what I'm after.


It seems that a significantly
more sensitive mic, with slightly higher noise would
actually be a better choice for recording quiet sounds.

That would be the case IF the preamp noise floor was higher than the mike
noise floor.

Wait, let's assume that the preamp is magic, and creates zero noise.
As I turn up the preamp, I hear more and more of the noise created
by the microphone. If two mics create the same amount of noise,
but one is far more sensitive, then the sensitive one will allow
me to create recordings with a lower noise floor.

What I'm getting at, is that if the 5dB measurement of the NT1-A is
a measurement of the strength of the noise from the mic, then another
mic that has a 6dB rating, but is quite a bit more sensitive, would
actually be a better choice where noise is concerned.

?

[Don Pearce[_2_]]

On Wed, 14 Jan 2009 10:53:04 -0800, Tobiah wrote:

On Wed, 14 Jan 2009 18:46:15 +0000, wrote:

On Wed, 14 Jan 2009 10:03:42 -0800, Tobiah wrote:

I bout a pair of Rode NT1-A's for recording quieter
sounds because I heard that it had the lowest noise
out there. I'm quite happy with them, but I got to
thinking. Isn't the important thing the signal to
noise ratio, rather than the actual amount of noise
that the mic puts out? It seems that a significantly
more sensitive mic, with slightly higher noise would
actually be a better choice for recording quiet sounds.

Thanks,

Toby

No. What matters (and what the mic manufacturers quote) is the
equivalent noise level of the mic. In the case of the NT1-A it is 5dB.
This figure takes everything into account. The only thing that the
sensitivity of the mic does is determine the position of the gain
control on the preamp. As long as the amp has enough gain that you can
reach the position you need, then all is well.

d

What then, is 'equivalent noise'? I thought that it meant that when
you power on the mic when there are no sounds present, there is some
output on the wire in the form of noise, and we were measuring the
strength of that noise. If this is the case, then if the mic is
not very sensitive, I'll have to crank the preamp, which will amplify
the noise.

Thanks,

Toby

Equivalent noise is the amount of actual acoustic environmental
background noise you would need to get an equivalent to that produced
within the mic. The actual level of noise, and the level of the signal
are not important. The way they relate to each other is the key. If
you have a sound level of 30dB and a mic noise level of 5dB, you get
a 25dB signal to noise ratio. The same sound level with a mic having
17dB noise level leaves you just a 13dB signal to noise ratio, which
is much worse. The actual sensitivity of the mic doesn't appear in
this calculation.

Where it can be important is with a really poor pre-amp, which has
equivalent noise of its own which is comparable to or even greater
than that of the mic. This is unlikely to happen in practice with a
mic like the NT1-A, because the mic itself contains the first stage of
the pre-amp.

There is one highly regarded pre-amp - the RNP - which has an
appallingly bad noise performance and should never be used for
amplifying low level signals.

d

[Scott Dorsey]

Tobiah wrote:

Wait, let's assume that the preamp is magic, and creates zero noise.
As I turn up the preamp, I hear more and more of the noise created
by the microphone. If two mics create the same amount of noise,
but one is far more sensitive, then the sensitive one will allow
me to create recordings with a lower noise floor.

The noise is specified in terms of the acoustical level. Look on the
data sheet and it will say something like "Noise level 35 dB SPL unweighted
by ISO method." This means that if you have a perfect preamplifier, a
sound of 35 dB SPL is going to be about as loud as the noise floor of the
microphone. Doesn't matter how much gain you have or what the mike
sensitivity is... that sound level will be at the mike noise floor.

If one mike is more sensitive than another, you turn the gain up on the
preamp of the other and you don't worry about it.

What I'm getting at, is that if the 5dB measurement of the NT1-A is
a measurement of the strength of the noise from the mic, then another
mic that has a 6dB rating, but is quite a bit more sensitive, would
actually be a better choice where noise is concerned.

No, that's not how noise is measured.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Tobiah]

On Wed, 14 Jan 2009 19:43:32 +0000, wrote:


Equivalent noise is the amount of actual acoustic environmental
background noise you would need to get an equivalent to that produced
within the mic.

There we have it. That way of measuring includes the sensitivity
of the mic, because the sound going into the mic would have to
be louder with a less sensitive mic, which would raise the noise
rating. So then, I see why we can just call the NT1-A the quietest
mic and leave it at that.

Thanks everyone. I've learned something.

Toby

[Randy Yates]

Tobiah writes:

On Wed, 14 Jan 2009 19:43:32 +0000, wrote:


Equivalent noise is the amount of actual acoustic environmental
background noise you would need to get an equivalent to that produced
within the mic.

There we have it. That way of measuring includes the sensitivity
of the mic,

Exactly. Your notions, Tobiah, were correct from the start. I'm not sure
why no one here has confirmed that. The only part you were missing is
that the specified noise is actually "equivalent noise."
--
% Randy Yates % "Bird, on the wing,
%% Fuquay-Varina, NC % goes floating by
%%% 919-577-9882 % but there's a teardrop in his eye..."
%%%% % 'One Summer Dream', *Face The Music*, ELO
http://www.digitalsignallabs.com

[Tobiah]

On Wed, 14 Jan 2009 16:01:28 -0500, Randy Yates wrote:

Tobiah writes:

On Wed, 14 Jan 2009 19:43:32 +0000, wrote:


Equivalent noise is the amount of actual acoustic environmental
background noise you would need to get an equivalent to that produced
within the mic.

There we have it. That way of measuring includes the sensitivity
of the mic,

Exactly. Your notions, Tobiah, were correct from the start. I'm not sure
why no one here has confirmed that. The only part you were missing is
that the specified noise is actually "equivalent noise."

Actually I was quite mistaken. I thought that the 5dB was relative to
the voltage coming out of the mic when no sound was there. That caused
me to assume that a slightly more noisy mic that was far more sensitive
would be better for lower relative noise. This is not the case. Like
Don says, the equivalent noise rating takes everything into account.

Toby

[Don Pearce[_2_]]

On Wed, 14 Jan 2009 11:34:41 -0800, Tobiah wrote:

On Wed, 14 Jan 2009 14:06:51 -0500, Scott Dorsey wrote:

In article ,
Tobiah wrote:
I bout a pair of Rode NT1-A's for recording quieter
sounds because I heard that it had the lowest noise
out there. I'm quite happy with them, but I got to
thinking. Isn't the important thing the signal to
noise ratio, rather than the actual amount of noise
that the mic puts out?

The signal to noise ratio of a microphone is the ratio between the loudest
sound it can reproduce and the noise floor of the microphone. As long as
you are only recording soft things, you care only about the noise floor and
not the clipping point.

Oh, right. S/N is not what I'm after.


It seems that a significantly
more sensitive mic, with slightly higher noise would
actually be a better choice for recording quiet sounds.

That would be the case IF the preamp noise floor was higher than the mike
noise floor.

Wait, let's assume that the preamp is magic, and creates zero noise.
As I turn up the preamp, I hear more and more of the noise created
by the microphone. If two mics create the same amount of noise,
but one is far more sensitive, then the sensitive one will allow
me to create recordings with a lower noise floor.

What I'm getting at, is that if the 5dB measurement of the NT1-A is
a measurement of the strength of the noise from the mic, then another
mic that has a 6dB rating, but is quite a bit more sensitive, would
actually be a better choice where noise is concerned.

?

The one with the 5dB rating. Let's try another explanation.

Suppose we have two mics, both with a 5dB noise rating, but one much
more sensitive than the other. You will get more signal out of the
more sensitive one, but you will also get more noise (in exactly the
same proportion). If you amplify the less sensitive one so the signal
is the same as the other, the noise will then be the same too.

d

[Mike Rivers]

Tobiah wrote:
I bout a pair of Rode NT1-A's for recording quieter
sounds because I heard that it had the lowest noise
out there. I'm quite happy with them, but I got to
thinking. Isn't the important thing the signal to
noise ratio, rather than the actual amount of noise
that the mic puts out?

For a given signal level, the mic's noise is a major contributor to the
signal-to-noise ratio. The thing is that nature sounds are so quite that
when calculating the S/N, you have one small number divided by another
small number.

[Mike Rivers]

Don Pearce wrote:

No. What matters (and what the mic manufacturers quote) is the
equivalent noise level of the mic. In the case of the NT1-A it is 5dB.
This figure takes everything into account.

I'm not sure about the meaning of "equivalent noise" of the mic. What
matters to me is how much noise the mic puts out when it's as isolated
from acoustic sound as it can be. No argument that the NT-1A is pretty
darn quiet. But if it's also not very sensitive (and as far as I know
its sensitivity is "about normal") then for a given SPL, the S/N ratio
won't be as good as for a mic with higher sensitivity.

I don't know if there's a corollary to equivalent input noise for
microphones. EIN is the noise level (in dBsomething) minus the gain (in
dB). I'm not sure how you'd figure or define that when the noise is in
volts and the gain is in millivolts/pascal.

[Chris Hornbeck]

On Wed, 14 Jan 2009 13:31:52 -0800, Tobiah wrote:

I thought that the 5dB was relative to
the voltage coming out of the mic when no sound was there. That caused
me to assume that a slightly more noisy mic that was far more sensitive
would be better for lower relative noise. This is not the case. Like
Don says, the equivalent noise rating takes everything into account.

A big helping of the confusion needs to land in the plate of the
term "dB" itself. "dB" is very powerful, universal and flexible,
but because it is, can lead to confusion when not *exactly*
specified.

Ferinstance, your mic noise spec is (and must!) be called "dB SPL"
because it is a reference to an actual sound level. The microphone
is as noisy in a perfectly quiet room as a perfectly quiet microphone
in a room with a 5 dB SPL room noise level. That's just one of
gazillions of uses of the "dB" term.

Another use of "dB" might be to specify the mic preamp. A really
quiet mic preamp might be said to have a "noise factor" of 1 dB,
meaning that it increases the noise level coming into itself
by 1 dB. In this case, the "dB" term has no other letters associated
and the term is dimensionless, a pure ratio.

So, we all need to read the term "dB" with an interpreter engaged,
first deciding if a pure ratio is appropriate; then, if not,
trying to figure out WTF the number is relative to. Pardon my
dangling participle.

All the best fortune,
Chris Hornbeck

[Chris Hornbeck]

On Thu, 15 Jan 2009 01:06:32 GMT, Mike Rivers
wrote:

I don't know if there's a corollary to equivalent input noise for
microphones. EIN is the noise level (in dBsomething) minus the gain (in
dB). I'm not sure how you'd figure or define that when the noise is in
volts and the gain is in millivolts/pascal.

If I'm following you correctly (first time for everything!) the
spec of microphone noise in SPL *is* that corollary. Sensitivity
and all "voltage stuff" fall out.

But maybe you're after something deeper? (And out of my depth!)

Much thanks, as always,
Chris Hornbeck

[Mike Rivers]

On Jan 14, 8:42 pm, Chris Hornbeck
wrote:

But maybe you're after something deeper? (And out of my depth!)

I was after an explanation of what it means, and I think I got it from
further posts. It's the SPL that would give the output level of the
measured noise if the mic were otherwise noiseless. Thus, you're
comparing SPL to SPL, not SPL to volts.

Frankly, my dear, I don't give a damn. If I hear too much noise and
not enough subject matter, I move the mic closer (or tell the speaker
to talk louder). If the subject bites, stings, or flies away if I were
to try to get too close, if I really need that sound, I'll buy the
sound effect CD. g

[Randy Yates]

Tobiah writes:

On Wed, 14 Jan 2009 16:01:28 -0500, Randy Yates wrote:

Tobiah writes:

On Wed, 14 Jan 2009 19:43:32 +0000, wrote:


Equivalent noise is the amount of actual acoustic environmental
background noise you would need to get an equivalent to that produced
within the mic.

There we have it. That way of measuring includes the sensitivity
of the mic,

Exactly. Your notions, Tobiah, were correct from the start. I'm not sure
why no one here has confirmed that. The only part you were missing is
that the specified noise is actually "equivalent noise."

Actually I was quite mistaken. I thought that the 5dB was relative to
the voltage coming out of the mic when no sound was there. That caused
me to assume that a slightly more noisy mic that was far more sensitive
would be better for lower relative noise. This is not the case.

We have a communication problem. I've already stated that the "part you
were missing" is the interpretation of 5 dB. You were taking it as an
electrical power level, perhaps in dBV. This is why Chris Hornbeck's
post on "dB" is quite appropriate.

Where you were right is in your notion that IF the stated specification
were one of ELECTRICAL noise power (e.g., 5 dBV), THEN the mic
sensitivity is indeed required in order to arrive at a SNR for a given
acoustic power input since it relates the input acoustic power to an
electric power level.
--
% Randy Yates % "...the answer lies within your soul
%% Fuquay-Varina, NC % 'cause no one knows which side
%%% 919-577-9882 % the coin will fall."
%%%% % 'Big Wheels', *Out of the Blue*, ELO
http://www.digitalsignallabs.com

[Don Pearce[_2_]]

On Thu, 15 Jan 2009 01:06:32 GMT, Mike Rivers
wrote:

Don Pearce wrote:

No. What matters (and what the mic manufacturers quote) is the
equivalent noise level of the mic. In the case of the NT1-A it is 5dB.
This figure takes everything into account.

I'm not sure about the meaning of "equivalent noise" of the mic. What
matters to me is how much noise the mic puts out when it's as isolated
from acoustic sound as it can be. No argument that the NT-1A is pretty
darn quiet. But if it's also not very sensitive (and as far as I know
its sensitivity is "about normal") then for a given SPL, the S/N ratio
won't be as good as for a mic with higher sensitivity.

No, you have that wrong, Mike. You get all the S/N ratio facts out of
the mic noise spec (assuming you aren't wrecking it with a bad
preamp). All you need to do to compensate various mic sensitivities is
change the gain setting of the pre-amp. Since the mic noise goes up
and down with the signal, the S/N ratio is unchanged.

I don't know if there's a corollary to equivalent input noise for
microphones. EIN is the noise level (in dBsomething) minus the gain (in
dB). I'm not sure how you'd figure or define that when the noise is in
volts and the gain is in millivolts/pascal.

If you know the sensitivity of the microphone, you can use this with
the noise figure to give you an Ein number. Not a very useful number,
though as you need to use the mic gain again to work out what that
means in equivalent acoustic terms.

d

[Eric B]

What a bizarre discussion! Frankly, it has gone over the edge into the
angels on the head of a pin level of absurdity.
The self noise of a condensor mic is bounded by the size of the
diaphragm and the impedance of the materials insulating the diaphragm
from the backplate (including air- a variable). Presuming the design
and manufacture haven't introduced noise producing electronic
mistakes, that is it! Specsmanship probably has weighted that 5dB
noise figure. The sensitivity of condensor mics tends to be a
categorical thing. They are all about the same, and all hotter than
dynamics or ribbons.
The far more important factor is that in no real world situation is
the ambient noise ever anywhere near as low as that. In the quietest
isolation room it is never that quiet, and if you put a living human
in the space, they make noise- wait, that's what you are recording. If
you attach the microphone to a stand, no matter how good the shock
mount, there will be structure borne vibrations that are great enough
to mask that level of "self" noise.
The real questions are- does it sound good and does it pick up those
quieter sources in a way that is useful to you? I bet it sucks for
kick drum and can't be used in the wind and won't do supersonics at
all. The bass proximity effect is probably severe. Is it 'flat? No!
The resonance of a large (1"?) diaphragm will be around 1K to 1200Hz.
It will be less directional at that frequency and have a 'presence
peak'.' Does it sound real? (Ha!) Does it sound good? Aren't these the
questions to ask about a microphone?
From what I hear it is a pretty good mic. How is it working for you?
Best regards,
Eric B

[Ty Ford]

On Thu, 15 Jan 2009 08:08:08 -0500, Eric B wrote
(in article
):

What a bizarre discussion! Frankly, it has gone over the edge into the angels

on the head of a pin level of absurdity.
The self noise of a condensor mic is bounded by the size of the diaphragm
and the impedance of the materials insulating the diaphragm from the
backplate (including air- a variable). Presuming the design and manufacture
haven't introduced noise producing electronic mistakes, that is it!

And, therein, lies the rub.

As a regular part of my mic reviews, I do comparisons of the new mic with
others using matched GML preamps.

Some mics spec a certain selfnoise, but their sensitivity is lower than other
mics that spec a higher selfnoise. When you adjust the preamp for equivalent
loudness (and, BTW, the GML preamps are extraordinarily quiet and neutral)
the lowest selfnoise figure doesn't always win if selfnoise is the only thing
you're interested in.

The Neumann TLM 103 (and new TLM103D) have the advantage of very low
selfnoise and high sensitivity. I'm guessing they may not have the headroom
of other mics, which is where that high sensitivity becomes part of a
tradeoff with headroom.

If you're trying to mic lots of really loud things, you don't really need to
worry about selfnoise that much. OTOH, if you're micing a celtic harp or
other quite sources, it does come into play.

Did I mention the TLM103D is friggin' quiet? I have some samples he
http://idisk.mac.com/tyreeford-Publi...dD-01?view=web

Regards,

Ty Ford


--Audio Equipment Reviews Audio Production Services
Acting and Voiceover Demos http://www.tyford.com
Guitar player?:http://www.youtube.com/watch?v=yWaPRHMGhGA

[Arny Krueger]

"Ty Ford" wrote in message
al.NET
On Thu, 15 Jan 2009 08:08:08 -0500, Eric B wrote
(in article
):

What a bizarre discussion! Frankly, it has gone over the
edge into the angels

on the head of a pin level of absurdity.
The self noise of a condensor mic is bounded by the
size of the diaphragm and the impedance of the materials
insulating the diaphragm from the backplate (including
air- a variable). Presuming the design and manufacture
haven't introduced noise producing electronic mistakes,
that is it!

And, therein, lies the rub.

As a regular part of my mic reviews, I do comparisons of
the new mic with others using matched GML preamps.

Some mics spec a certain selfnoise, but their sensitivity
is lower than other mics that spec a higher selfnoise.
When you adjust the preamp for equivalent loudness (and,
BTW, the GML preamps are extraordinarily quiet and
neutral) the lowest selfnoise figure doesn't always win
if selfnoise is the only thing you're interested in.

The Neumann TLM 103 (and new TLM103D) have the advantage
of very low selfnoise and high sensitivity. I'm guessing
they may not have the headroom of other mics, which is
where that high sensitivity becomes part of a tradeoff
with headroom.

If you're trying to mic lots of really loud things, you
don't really need to worry about selfnoise that much.
OTOH, if you're micing a celtic harp or other quite
sources, it does come into play.

Did I mention the TLM103D is friggin' quiet? I have some
samples he
http://idisk.mac.com/tyreeford-Publi...dD-01?view=web

Dynamic range is a very good but not exceptional 73dB, if the hum at 60 and
120 Hz is removed.

Begs the question whether the NT1A would give a more or less quiet recording
under identical conditions.

[Chris Whealy]

Tobiah wrote:
I bout a pair of Rode NT1-A's for recording quieter sounds because I heard that it had the lowest noise out there. I'm quite happy with them, but I got to thinking. Isn't the important thing the signal to noise ratio, rather than the actual amount of noise that the mic puts out? It seems that a significantly more sensitive mic, with slightly higher noise would actually be a better choice for recording quiet sounds.

Thanks,

Toby

I would recommend that all interested parties (and there seem to be
quite a few) read chapter 7 of John Eargle's "The Microphone Book"
(Second Edition)

Chris W

--
The voice of ignorance speaks loud and long,
But the words of the wise are quiet and few.
---

[Mike Rivers]

Eric B wrote:
What a bizarre discussion! Frankly, it has gone over the edge into the
angels on the head of a pin level of absurdity.

That's the way it goes on the 'net when someone asks a question without
already knowing the answer.

There does seem to be some attempt to clarify the difference between
electric dB and acoustic dB and
how the electrical noise (which comes out of a mic) can be related to
acoustic input that produces the same
amount of noise.

For most real world recording applications, comparing numbers that are
much smaller than the sound
level of the source you want to record is rather insignificant. However,
for recording very quiet sources
in the presence of near silence (a Foley stage is a good example) a
quieter mic is likely to give better
results than a noisier one.

[Richard Kuschel]

On Jan 15, 8:35 am, Mike Rivers wrote:
Eric B wrote:
What a bizarre discussion! Frankly, it has gone over the edge into the
angels on the head of a pin level of absurdity.

That's the way it goes on the 'net when someone asks a question without
already knowing the answer.

There does seem to be some attempt to clarify the difference between
electric dB and acoustic dB and
how the electrical noise (which comes out of a mic) can be related to
acoustic input that produces the same
amount of noise.

For most real world recording applications, comparing numbers that are
much smaller than the sound
level of the source you want to record is rather insignificant. However,
for recording very quiet sources
in the presence of near silence (a Foley stage is a good example) a
quieter mic is likely to give better
results than a noisier one.

Remember that these noise figures may be measured by different
methods. Some are dBSPL some are dBSPL(A) which is filtered. A non
filtered specification will read higher noise. Even others are
measured by other standards.

[[email protected]]

On Jan 15, 10:33*am, Chris Whealy wrote:
I would recommend that all interested parties (and there seem to be
quite a few) read chapter 7 of John Eargle's "The Microphone Book"
(Second Edition)

There's also some relevent information at:
http://www.rane.com/note148.html

An interesting point arose from re-reading that page. Mic
sensitivities are often specified in mV/Pa. Another way of expressing
that is dBV/Pa. 10 mV/Pa (e.g. from the Earthworks SR20's spec sheet)
= -40dbV/Pa. 1.85 mV/Pa (e.g. from the Shure SM-58 spec sheet) = -54.7
dBV/Pa. But the Rane page does not use dBV (ref = 1 V), they use dBu
(ref = 0.775). dBu and dBV differ by about 2.2 dB. Several posters
have noted that careless notation of dB can be a problem, and here's
one reason. I've seen some specs that only list sensitivity in "dB",
which is meaningless without a reference level. Is it dBV/Pa or dBu/
Pa, or something else? Many pitfalls!

10 mV/Pa = -40 dBV/Pa = -37.8 dBu/Pa.

[Ty Ford]

On Thu, 15 Jan 2009 10:31:04 -0500, Arny Krueger wrote
(in article ) :

"Ty Ford" wrote in message
al.NET
On Thu, 15 Jan 2009 08:08:08 -0500, Eric B wrote
(in article
):

What a bizarre discussion! Frankly, it has gone over the
edge into the angels

on the head of a pin level of absurdity.
The self noise of a condensor mic is bounded by the
size of the diaphragm and the impedance of the materials
insulating the diaphragm from the backplate (including
air- a variable). Presuming the design and manufacture
haven't introduced noise producing electronic mistakes,
that is it!

And, therein, lies the rub.

As a regular part of my mic reviews, I do comparisons of
the new mic with others using matched GML preamps.

Some mics spec a certain selfnoise, but their sensitivity
is lower than other mics that spec a higher selfnoise.
When you adjust the preamp for equivalent loudness (and,
BTW, the GML preamps are extraordinarily quiet and
neutral) the lowest selfnoise figure doesn't always win
if selfnoise is the only thing you're interested in.

The Neumann TLM 103 (and new TLM103D) have the advantage
of very low selfnoise and high sensitivity. I'm guessing
they may not have the headroom of other mics, which is
where that high sensitivity becomes part of a tradeoff
with headroom.

If you're trying to mic lots of really loud things, you
don't really need to worry about selfnoise that much.
OTOH, if you're micing a celtic harp or other quite
sources, it does come into play.

Did I mention the TLM103D is friggin' quiet? I have some
samples he
http://idisk.mac.com/tyreeford-Publi...dD-01?view=web

Dynamic range is a very good but not exceptional 73dB, if the hum at 60 and
120 Hz is removed.

Begs the question whether the NT1A would give a more or less quiet recording
under identical conditions.



I've had that opportunity, having an NT1-a here back then. I do remember I
like the osund of the TLM 103 better. I may have referred to the gain
structures in my review.

Ty Ford


--Audio Equipment Reviews Audio Production Services
Acting and Voiceover Demos http://www.tyford.com
Guitar player?:http://www.youtube.com/watch?v=yWaPRHMGhGA

[thepaulthomas]

On Jan 15, 7:33*am, Chris Whealy wrote:
Tobiah wrote:
I bout a pair of Rode NT1-A's for recording quieter sounds because I heard that it had the lowest noise out there. *I'm quite happy with them, but I got to thinking. *Isn't the important thing the signal to noise ratio, rather than the actual amount of noise that the mic puts out? *It seems that a significantly more sensitive mic, with slightly higher noise would actually be a better choice for recording quiet sounds.

Thanks,

Toby

I would recommend that all interested parties (and there seem to be
quite a few) read chapter 7 of John Eargle's "The Microphone Book"
(Second Edition)

Chris W

--
The voice of ignorance speaks loud and long,
But the words of the wise are quiet and few.
* * * * * * * * * * * * * * * * * * * * *---

I think you meant John Eargle's 'The Microphone Handbook'.

[Chris Whealy]

thepaulthomas wrote:
On Jan 15, 7:33 am, Chris Whealy wrote:

I would recommend that all interested parties (and there seem to be
quite a few) read chapter 7 of John Eargle's "The Microphone Book"
(Second Edition)

Chris W

--
The voice of ignorance speaks loud and long,
But the words of the wise are quiet and few.
---


I think you meant John Eargle's 'The Microphone Handbook'.

Nope, I've got in front of me here.
Its definitely "The Microphone Book" Second Edition
ISBN-10: 0-240-51961-2

Chris W

--
The voice of ignorance speaks loud and long,
But the words of the wise are quiet and few.
---

[Randy Yates]

writes:

On Jan 15, 10:33*am, Chris Whealy wrote:
I would recommend that all interested parties (and there seem to be
quite a few) read chapter 7 of John Eargle's "The Microphone Book"
(Second Edition)

There's also some relevent information at:
http://www.rane.com/note148.html

An interesting point arose from re-reading that page. Mic
sensitivities are often specified in mV/Pa. Another way of expressing
that is dBV/Pa. 10 mV/Pa (e.g. from the Earthworks SR20's spec sheet)
= -40dbV/Pa. 1.85 mV/Pa (e.g. from the Shure SM-58 spec sheet) = -54.7
dBV/Pa. But the Rane page does not use dBV (ref = 1 V), they use dBu
(ref = 0.775). dBu and dBV differ by about 2.2 dB. Several posters
have noted that careless notation of dB can be a problem, and here's
one reason. I've seen some specs that only list sensitivity in "dB",
which is meaningless without a reference level. Is it dBV/Pa or dBu/
Pa, or something else? Many pitfalls!

Absolutely! Great post, tw!
--
% Randy Yates % "Ticket to the moon, flight leaves here today
%% Fuquay-Varina, NC % from Satellite 2"
%%% 919-577-9882 % 'Ticket To The Moon'
%%%% % *Time*, Electric Light Orchestra
http://www.digitalsignallabs.com

[Eeyore]

Tobiah wrote:

I bout a pair of Rode NT1-A's for recording quieter
sounds because I heard that it had the lowest noise
out there. I'm quite happy with them, but I got to
thinking. Isn't the important thing the signal to
noise ratio, rather than the actual amount of noise
that the mic puts out? It seems that a significantly
more sensitive mic, with slightly higher noise would
actually be a better choice for recording quiet sounds.

Indeed the noise should be referred to the sensitivity (or an acoustic
noise equivalent) to have any useful meaning.

I thought this was mostly the case. Look for some Pascals (Pa) in the
spec.

Graham

[Eeyore]

Tobiah wrote:

What then, is 'equivalent noise'?

Depends on the context you're using it.

Graham

[Eeyore]

Scott Dorsey wrote:

The signal to noise ratio of a microphone is the ratio between the loudest
sound it can reproduce and the noise floor of the microphone.

pedant mode on

That's the dynamic range.

pedant mode off

Regds, Graham

[Eeyore]

Tobiah wrote:

Oh, right. S/N is not what I'm after.

SNR is a widely abused term.

Graham

[Don Pearce[_2_]]

On Sat, 17 Jan 2009 11:55:29 +0000, Eeyore
wrote:



Tobiah wrote:

I bout a pair of Rode NT1-A's for recording quieter
sounds because I heard that it had the lowest noise
out there. I'm quite happy with them, but I got to
thinking. Isn't the important thing the signal to
noise ratio, rather than the actual amount of noise
that the mic puts out? It seems that a significantly
more sensitive mic, with slightly higher noise would
actually be a better choice for recording quiet sounds.

Indeed the noise should be referred to the sensitivity (or an acoustic
noise equivalent) to have any useful meaning.


I think all mics are specified in acoustic noise equivalent. It is the
only method that really makes sense, and needs no translation to
understand what it means. You only find Pascals in the sensitivity
spec.

d

[Scott Dorsey]

Richard Kuschel wrote:

Remember that these noise figures may be measured by different
methods. Some are dBSPL some are dBSPL(A) which is filtered. A non
filtered specification will read higher noise. Even others are
measured by other standards.

There are two standard methods, and several possible weightings. I have
seen numbers varying from 9 dB to 35 dB on the same microphone, depending
on the measurement method. And these were the honest measurements.... lots
of manufacturers use measurements that are les than honest.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."