From Newsgroup: rec.audio.pro

The Rode NT1-A lists an "Equivalent Noise Level" of 5 dBA.

So I can look at that figure, and compare it to other mics.
But then I thought, what about sensitivity? If the noise
figure measures the raw noise level coming into the preamp,
then a high sensitivity mic would have a larger signal to
noise ratio, making the self noise figure meaningless on
its own. Or does the noise figure take that into account
somehow?


Toby
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From Newsgroup: rec.audio.pro

A more focused Google search got me the answer the
second time, sorry. The noise figure indicates the
level of acoustic sound that would create the same
signal level as the noise, so sensitivity is indeed
accounted for.


Toby

On 12/4/25 07:40, Tobiah wrote:

The Rode NT1-A lists an "Equivalent Noise Level" of 5 dBA.

So I can look at that figure, and compare it to other mics.
But then I thought, what about sensitivity?-a If the noise
figure measures the raw noise level coming into the preamp,
then a high sensitivity mic would have a larger signal to
noise ratio, making the self noise figure meaningless on
its own.-a Or does the noise figure take that into account
somehow?

Toby

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From Newsgroup: rec.audio.pro

Still not the entire picture though, when a lower sensitivity
mic requires more preamp gain, and therefore introduces some
extra noise there. So you really have to know the sensitivity
of the mic to get the entire picture regarding noise.
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From Newsgroup: rec.audio.pro

Tobiah <toby@tobiah.org> wrote:

The Rode NT1-A lists an "Equivalent Noise Level" of 5 dBA.

So I can look at that figure, and compare it to other mics.
But then I thought, what about sensitivity? If the noise
figure measures the raw noise level coming into the preamp,
then a high sensitivity mic would have a larger signal to
noise ratio, making the self noise figure meaningless on
its own. Or does the noise figure take that into account
somehow?

I presume they mean that the noise coming from the mic connector is
equivalent to a sound pressure level of 5 dBA. That is useful because
it tells you the signal to noise ratio of the mic at any given sound
pressure level (assuming it is connected to a 'perfect' pre-amp).

What it does not tell you is the actual electrical output power at that
sound level, so the overall noise level of the whole microphone channel
(mic + pre-amp) can't be calculated. Perhaps that figure is hidden
elsewhere in the specification?

As long as the pre-amp noise is more than 6dB below the mic noise and
similar in character, there is little point in spending a lot of money
on a quieter pre-amp. You can check that by measuring (or listening to)
how the noise changes when you disconnect the mic and connect a dummy
plug with a resistor across the pins, with the same resistance as the
mic's output impedance.
--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk
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From Newsgroup: rec.audio.pro

Tobiah <toby@tobiah.org> wrote:

Still not the entire picture though, when a lower sensitivity
mic requires more preamp gain, and therefore introduces some
extra noise there. So you really have to know the sensitivity
of the mic to get the entire picture regarding noise.

That's correct.

I am very suspicious of their specifications: they claim it is a
velocity microphone with a cardioid polar pattern - which is impossible.
--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk
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From Newsgroup: rec.audio.pro

On 12/4/25 08:38, Liz Tuddenham wrote:

Tobiah <toby@tobiah.org> wrote:

Still not the entire picture though, when a lower sensitivity
mic requires more preamp gain, and therefore introduces some
extra noise there. So you really have to know the sensitivity
of the mic to get the entire picture regarding noise.

That's correct.

I am very suspicious of their specifications: they claim it is a
velocity microphone with a cardioid polar pattern - which is impossible.

For what it's worth, Google's AI spat this out:

Yes, a velocity microphone can be a cardioid, but a standard velocity (or pressure-gradient) microphone has a bidirectional pattern, and a cardioid pattern is achieved by adding a pressure component. To create a cardioid pattern, engineers add a pressure-sensitive element to a velocity microphone, which is done by design in multi-pattern microphones.

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From Newsgroup: rec.audio.pro

Tobiah <toby@tobiah.org> wrote:

On 12/4/25 08:38, Liz Tuddenham wrote:

Tobiah <toby@tobiah.org> wrote:

Still not the entire picture though, when a lower sensitivity
mic requires more preamp gain, and therefore introduces some
extra noise there. So you really have to know the sensitivity
of the mic to get the entire picture regarding noise.

That's correct.

I am very suspicious of their specifications: they claim it is a
velocity microphone with a cardioid polar pattern - which is impossible.

For what it's worth, Google's AI spat this out:

Yes, a velocity microphone can be a cardioid,...

No it can't, not without an additional pressure component - at which
point it ceases to be a velocity microphone.

...but a standard velocity (or
pressure-gradient) microphone has a bidirectional pattern, and a cardioid pattern is achieved by adding a pressure component. To create a cardioid pattern, engineers add a pressure-sensitive element to a velocity
microphone, which is done by design in multi-pattern microphones.

The polar pattern of a cardioid microphone is indeed made up of a
velocity and a pressure response but a "velocity" (Fig-8) microphone has
only the velocity component and a "pressure" (Omnidirectional)
microphone has only a pressure component. If you buy a microphone that
is advertised as a "velocity" microphone, you expect to get one with a
Fig-8 pattern..
--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk
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From Newsgroup: rec.audio.pro

In article <10gsa0o$d26a$1@dont-email.me>, Tobiah <toby@tobiah.org> wrote: >The Rode NT1-A lists an "Equivalent Noise Level" of 5 dBA.

This is meaningless and cannot be compared between other microphones because
no two manufacturers measure under the same conditions.

So I can look at that figure, and compare it to other mics.
But then I thought, what about sensitivity? If the noise
figure measures the raw noise level coming into the preamp,
then a high sensitivity mic would have a larger signal to
noise ratio, making the self noise figure meaningless on
its own. Or does the noise figure take that into account
somehow?

The noise level should be the noise just of the microphone, which under
most conditions is going to swamp the noise of the preamp unless the
microphone sensitivity is so very very low.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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From Newsgroup: rec.audio.pro

In article <10gsdth$edds$1@dont-email.me>, Tobiah <toby@tobiah.org> wrote:

Yes, a velocity microphone can be a cardioid, but a standard velocity (or pressure-gradient) microphone has a bidirectional pattern, and a cardioid pattern is achieved by adding a pressure component. To create a cardioid pattern, engineers add a pressure-sensitive element to a velocity microphone, which is done by design in multi-pattern microphones.

This is meaningless.

A velocity microphone is inherently a figure-8. A pressure microphone is inherently an omni. A combination of the two gives you cardioid, hypercardiod, and wide cardioid depending on the ratio.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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From Newsgroup: rec.audio.pro

Scott Dorsey <kludge@panix.com> wrote:

In article <10gsa0o$d26a$1@dont-email.me>, Tobiah <toby@tobiah.org> wrote: >The Rode NT1-A lists an "Equivalent Noise Level" of 5 dBA.

This is meaningless and cannot be compared between other microphones because no two manufacturers measure under the same conditions.

So I can look at that figure, and compare it to other mics.
But then I thought, what about sensitivity? If the noise
figure measures the raw noise level coming into the preamp,
then a high sensitivity mic would have a larger signal to
noise ratio, making the self noise figure meaningless on
its own. Or does the noise figure take that into account
somehow?

The noise level should be the noise just of the microphone, which under
most conditions is going to swamp the noise of the preamp unless the microphone sensitivity is so very very low.

The resistive component of the source impedance of the microphone is
another source of noise. From the Rode NT1-A specification I have
calculated this to be about 10dB below the noise level they quote, so it
is insignificant in this case. In some other mics, which were intended
for close singing, the resistance of the moving coil was the biggest
noise source.

It would be instructive to test it in a vacuum and see how much of the
total noise is caused by Brownian motion of the air molecules. This
becomes a significant limiting factor with small diaphragm area mics.
--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk
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