Mics and noise

[Tobiah]

I have only two pairs of microphones. The first pair
are NT1-A's and the second are a recently acquired pair
of "cheap Chinese dynamics" to quote Mr. Dorsey.

I got the latter pair, because I heard about people
talking about the more 'open' sound of an omni, while
all I had were the Rode cardioids. I have three options
for preamp. Mackie VLZ-Pro, a Tascam HD-P2, and an
M-Audio fast track ultra. Now, I've been pleased with these,
and one is pretty much as good as another. They all sound
a little different than each other, with the one sounding
the most different to me being the Mackies. Not definitely
better, just different. They all record weak signals out
of the Rode's without introducing any detectable noise.
They all have slightly different colors.

So I tested out the omnis, and found that when I place them around
two feet from my classical guitar, I have to crank the gain
on these preamps all the way up - the Tascam not being up
for the job gain-wise. Of course along with this came a
nice fuzzy blanket of noise. Enough that I could never consider
using these new mics for anything I do. I suppose a Rocker
shouting into the mic would do better.

So I figured that the noise I'm hearing is all from the preamps,
since in theory the dynamics introduced little as far as I can figure.
The Rode's require about 50% gain on the same preamps. I thought it
must be that at 60dB gain, these preamps can not deliver noise-free
signals.

That leads me to the thrust of the question. Obviously the NT1-As must
be putting out more signal in response to the movement of the
diaphragm than the cheapie omnis. How much of this is due to
the larger diaphragm, and how much is the signal actually
being raised inside the mic? If a good portion of it is inside the
mic, then why don't they take that voodoo and put it into the
preamp itself?

Also, is there an omni pattern mic in the very low multiples of $100
that would give me the ultra-low noise level (not detectable even
at high frequencies) that the Rode's are affording me?

I suppose another question would be where to look specifically
for a couple of channels of mic preamp that have superlative
performance where it comes down to high-gain/low noise applications?

Thanks,

Tobiah


---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com

[PStamler]

On Monday, July 14, 2014 6:14:20 PM UTC-6, Tobiah wrote:
> I have only two pairs of microphones. The first pair
>
> are NT1-A's and the second are a recently acquired pair
>
> of "cheap Chinese dynamics" to quote Mr. Dorsey.
>
>
>
> I got the latter pair, because I heard about people
>
> talking about the more 'open' sound of an omni, while
>
> all I had were the Rode cardioids. I have three options
>
> for preamp. Mackie VLZ-Pro, a Tascam HD-P2, and an
>
> M-Audio fast track ultra. Now, I've been pleased with these,
>
> and one is pretty much as good as another. They all sound
>
> a little different than each other, with the one sounding
>
> the most different to me being the Mackies. Not definitely
>
> better, just different. They all record weak signals out
>
> of the Rode's without introducing any detectable noise.
>
> They all have slightly different colors.
>
>
>
> So I tested out the omnis, and found that when I place them around
>
> two feet from my classical guitar, I have to crank the gain
>
> on these preamps all the way up - the Tascam not being up
>
> for the job gain-wise. Of course along with this came a
>
> nice fuzzy blanket of noise. Enough that I could never consider
>
> using these new mics for anything I do. I suppose a Rocker
>
> shouting into the mic would do better.
>
>
>
> So I figured that the noise I'm hearing is all from the preamps,
>
> since in theory the dynamics introduced little as far as I can figure.
>
> The Rode's require about 50% gain on the same preamps. I thought it
>
> must be that at 60dB gain, these preamps can not deliver noise-free
>
> signals.
>
>
>
> That leads me to the thrust of the question. Obviously the NT1-As must
>
> be putting out more signal in response to the movement of the
>
> diaphragm than the cheapie omnis. How much of this is due to
>
> the larger diaphragm, and how much is the signal actually
>
> being raised inside the mic? If a good portion of it is inside the
>
> mic, then why don't they take that voodoo and put it into the
>
> preamp itself?
>
>
>
> Also, is there an omni pattern mic in the very low multiples of $100
>
> that would give me the ultra-low noise level (not detectable even
>
> at high frequencies) that the Rode's are affording me?
>
>
>
> I suppose another question would be where to look specifically
>
> for a couple of channels of mic preamp that have superlative
>
> performance where it comes down to high-gain/low noise applications?

As a very general rule, condenser mics typically produce 10-15dB more signal for a given SPL than dynamic mics. That's why you're having to crank your preamps when recording through the dynamic mics. Eibbon mics are typically 5-10dB lower than moving-coil dynamics.

Why don't they stick some of that amplification into your cheap dynamic mics? A couple of reasons:

(1) If they did, the mics would no longer be cheap. Dynamic mics are actually pretty cheap to build: a magnet, a diaphragm, a moving-coil assembly. Maybe a transformer and/or a humbucking coil. There are no active electronics in dynamic mics. (There are in some ribbon mics, but they're usually a good deal more expensive than their passive brethren.)

(2) A low output is sometimes useful when you're close-miking loud instruments (like guitar amps or drums) and want to avoid preamp overload.

(3) Passive moving-coil dynamic mics are usually pretty rugged and hard to break.

So is there a super-quiet mic preamp out there that can make a quiet recording with your cheap dynamic mics. Not really, because a lot of what you're hearing is the inherent noise of the microphone itself (or the resistances inside it), and even a perfectly noiseless preamp would amplify that. The Mackie Onyx is actually fairly quiet; you might get a fancy preamp that was a dB or so quieter with the dynamic mic, but that's about it.

So keep them in your kit for miking noisy instruments, and use the Rodes for quiet things. Oh, a quiet omni (which means one with head-amp gain comparable to the Rode's)? Try the Oktava MC012 with the cardioid capsule.

Peace,
Paul
Peace,
Paul

[Adrian Tuddenham[_2_]]

PStamler > wrote:

> On Monday, July 14, 2014 6:14:20 PM UTC-6, Tobiah wrote:
> > I have only two pairs of microphones. The first pair
> >
> > are NT1-A's and the second are a recently acquired pair
> >
> > of "cheap Chinese dynamics" to quote Mr. Dorsey.
> >
> >
> >
> > I got the latter pair, because I heard about people
> >
> > talking about the more 'open' sound of an omni, while
> >
> > all I had were the Rode cardioids. I have three options
> >
> > for preamp. Mackie VLZ-Pro, a Tascam HD-P2, and an
> >
> > M-Audio fast track ultra. Now, I've been pleased with these,
> >
> > and one is pretty much as good as another. They all sound
> >
> > a little different than each other, with the one sounding
> >
> > the most different to me being the Mackies. Not definitely
> >
> > better, just different. They all record weak signals out
> >
> > of the Rode's without introducing any detectable noise.
> >
> > They all have slightly different colors.
> >
> >
> >
> > So I tested out the omnis, and found that when I place them around
> >
> > two feet from my classical guitar, I have to crank the gain
> >
> > on these preamps all the way up - the Tascam not being up
> >
> > for the job gain-wise. Of course along with this came a
> >
> > nice fuzzy blanket of noise. Enough that I could never consider
> >
> > using these new mics for anything I do. I suppose a Rocker
> >
> > shouting into the mic would do better.
> >
> >
> >
> > So I figured that the noise I'm hearing is all from the preamps,
> >
> > since in theory the dynamics introduced little as far as I can figure.
> >
> > The Rode's require about 50% gain on the same preamps. I thought it
> >
> > must be that at 60dB gain, these preamps can not deliver noise-free
> >
> > signals.
> >
> >
> >
> > That leads me to the thrust of the question. Obviously the NT1-As must
> >
> > be putting out more signal in response to the movement of the
> >
> > diaphragm than the cheapie omnis. How much of this is due to
> >
> > the larger diaphragm, and how much is the signal actually
> >
> > being raised inside the mic? If a good portion of it is inside the
> >
> > mic, then why don't they take that voodoo and put it into the
> >
> > preamp itself?
> >
> >
> >
> > Also, is there an omni pattern mic in the very low multiples of $100
> >
> > that would give me the ultra-low noise level (not detectable even
> >
> > at high frequencies) that the Rode's are affording me?
> >
> >
> >
> > I suppose another question would be where to look specifically
> >
> > for a couple of channels of mic preamp that have superlative
> >
> > performance where it comes down to high-gain/low noise applications?
>
> As a very general rule, condenser mics typically produce 10-15dB more
> signal for a given SPL than dynamic mics.
>That's why you're having to
> crank your preamps when recording through the dynamic mics. Eibbon mics
> are typically 5-10dB lower than moving-coil dynamics.

It is a bit more complicated than that. The *voltage* from a moving
coil microphone or a ribbon is low; but the source impedance is also
low, which means that a transformer could be used to step up the voltage
as long as the input impedance of the pre-amp was high enough to avoid
loading it down. That is one way of improving the signal-to-noise
ratio. Nowadays transformers are out of fashion, so an alternative
method is to design the pre-amp specifically for low impedance/low
voltage mics, but you need to be certain that the designer has done the
job properly and not just bunged a loading resistor across a high
impedance input.

All microphones have an inherent background noise level which is made up
of two main components: 1) 'Brownian' noise due to movement of air
molecules against the diaphragm. 2) 'Johnson' noise due to thermal
movement of the electrons in the source resistance of the microphone
circuit.

In capacitor mics the noise situation is very complicated, but in moving
coil mics it is controlled by two major design factors: A large
diaphragm gives a better S/N ratio because it averages out the Brownian
noise over a larger area and simultaneously picks up more energy from
the sound waves. A more efficient magnetic system gives better
conversion of the available sound energy into electrical energy, so the
Johnson noise is then of less consequence.

In a microphone intended for hand-holding, there is insufficient space
to accommodate a large diaphragm, quite apart from the acoustic problems
it causes - and, until recently, the weight of a really efficient magnet
system would have made a very efficient mic unacceptably heavy. Recent
magnetic developments have been used to make mics smaller, cheaper and
lighter, rather than more efficient; which is common sense from the
manufacturer's point of view because the majority of those mics will be
bought for close -micing applications which do not require low
background noise levels.

The basic message is that a small, cheap hand-held moving-coil mic will
be inherently noisy, even if it is connected to the best possible
pre-amp. Some years ago, Igor M. and I did some tests on one of the
popular Shure models, reducing the pre-amp noise to well below the
Brownian+Johnson noise level We found that the residual noise was still
far too high to allow the microphone to be used for good recordings of
quiet speech.


--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

[Mike Rivers[_2_]]

On 7/14/2014 8:14 PM, Tobiah wrote:

> Obviously the NT1-As must
> be putting out more signal in response to the movement of the
> diaphragm than the cheapie omnis. How much of this is due to
> the larger diaphragm, and how much is the signal actually
> being raised inside the mic?

How about Door Number 3: A condenser mic inherently has a higher voltage
output than a dynamic. The "preamp" inside the mic isn't to boost the
signal level, it's to convert the very high source impedance of the
capsule to something that you can connect to the outside world. In the
process, it often lowers the voltage rather than raising it. Studio and
broadcast condenser mics have always had higher output level for a given
SPL than moving coil dynamics and ribbons, and in the early days, mic
preamps had more gain than what's typical today.

What happened was The Home Recording Revolution. The 75-80 dB gain mic
preamps became around 60 dB, with some products with gain as low as 45
dB. This was necessary to make them cheap. Originally, the small handful
of hobbyist recordists who could afford a real condenser mic found the
high output level bothersome - that they had to turn the gain nearly all
the way down to avoid distortion worried them. So the manufacturers
complied, and the lower cost condenser mics, to better match the gear
with which they were expected to be used, had lower sensitivity than the
classic mics so they were closer, in use, to the dynamics that most
people were using.

> If a good portion of it is inside the
> mic, then why don't they take that voodoo and put it into the
> preamp itself?

Then it would no longer be a cheap preamp. The "active ribbon" mic
design is becoming popular, with a phantom powered preamp built into the
mic to bring its level up to that of a hot dynamic or mass-market
condenser mic. This has created a market for a "pre-preamp" such as the
Cloudlifter from Cloud Microphones, and there are some other similar
devices. The Cloud is really good. I don't know about the cheaper
similarly functional units.

> Also, is there an omni pattern mic in the very low multiples of $100
> that would give me the ultra-low noise level (not detectable even
> at high frequencies) that the Rode's are affording me?

There are some omni condensers that aren't too expensive. Look into
Oktava, which has an omni capsule available, but be sure to buy a
genuine one, not a Chinese copy or un-QC'd original.

--
For a good time, visit http://mikeriversaudio.wordpress.com

[Sean Conolly]

"Tobiah" > wrote in message
...
>I have only two pairs of microphones. The first pair
> are NT1-A's and the second are a recently acquired pair
> of "cheap Chinese dynamics" to quote Mr. Dorsey.
>
> I got the latter pair, because I heard about people
> talking about the more 'open' sound of an omni, while
> all I had were the Rode cardioids. I have three options
> for preamp. Mackie VLZ-Pro, a Tascam HD-P2, and an
> M-Audio fast track ultra. Now, I've been pleased with these,
> and one is pretty much as good as another. They all sound
> a little different than each other, with the one sounding
> the most different to me being the Mackies. Not definitely
> better, just different. They all record weak signals out
> of the Rode's without introducing any detectable noise.
> They all have slightly different colors.
>
> So I tested out the omnis, and found that when I place them around
> two feet from my classical guitar, I have to crank the gain
> on these preamps all the way up - the Tascam not being up
> for the job gain-wise. Of course along with this came a
> nice fuzzy blanket of noise. Enough that I could never consider
> using these new mics for anything I do. I suppose a Rocker
> shouting into the mic would do better.
>
> So I figured that the noise I'm hearing is all from the preamps,
> since in theory the dynamics introduced little as far as I can figure.
> The Rode's require about 50% gain on the same preamps. I thought it
> must be that at 60dB gain, these preamps can not deliver noise-free
> signals.
>
> That leads me to the thrust of the question. Obviously the NT1-As must
> be putting out more signal in response to the movement of the
> diaphragm than the cheapie omnis. How much of this is due to
> the larger diaphragm, and how much is the signal actually
> being raised inside the mic? If a good portion of it is inside the
> mic, then why don't they take that voodoo and put it into the
> preamp itself?
>
> Also, is there an omni pattern mic in the very low multiples of $100
> that would give me the ultra-low noise level (not detectable even
> at high frequencies) that the Rode's are affording me?
>
> I suppose another question would be where to look specifically
> for a couple of channels of mic preamp that have superlative
> performance where it comes down to high-gain/low noise applications?

Adding to what others have said...

With my own VLZ I consider the mic pre's to have about 50db of usable gain,
and the noise floor becomes obtrusive after that. Having a cheap mic with
(probably) lower sensitivity and higher internal resistance is just going to
make it worse. A combination better suited to a guitar cabinet than a
acoustic guitar.

Sean

[Scott Dorsey]

In article >, Tobiah > wrote:
>
>So I tested out the omnis, and found that when I place them around
>two feet from my classical guitar, I have to crank the gain
>on these preamps all the way up - the Tascam not being up
>for the job gain-wise. Of course along with this came a
>nice fuzzy blanket of noise. Enough that I could never consider
>using these new mics for anything I do. I suppose a Rocker
>shouting into the mic would do better.

There should be no "of course" here. You have just discovered the difference
between cheap preamps and high-end preamps. With a better preamp, you can
run it at full gain and not worry so much.

>So I figured that the noise I'm hearing is all from the preamps,
>since in theory the dynamics introduced little as far as I can figure.
>The Rode's require about 50% gain on the same preamps. I thought it
>must be that at 60dB gain, these preamps can not deliver noise-free
>signals.

The dynamic mikes will introduce some noise, just because of the resistance
of the windings. The degree to which this is a problem depends on the design
of the mike. It's a problem... you use a larger gauge wire on the voice coil
to reduce noise, and then you get a heavy coil and the high frequency response
is reduced because the diaphragm has to move all that mass. You don't get
something for nothing.

>That leads me to the thrust of the question. Obviously the NT1-As must
>be putting out more signal in response to the movement of the
>diaphragm than the cheapie omnis. How much of this is due to
>the larger diaphragm, and how much is the signal actually
>being raised inside the mic?

The current gain inside a condenser mike is somewhere between 10,000 and a
million times. It's a _lot_ of current gain in those electronics.

>If a good portion of it is inside the
>mic, then why don't they take that voodoo and put it into the
>preamp itself?

You can't run a high-Z connection very far, and in the case of the condenser
mike, the stuff coming right off the capsule is so high impedance that you
can only run it an inch or so. So you have to have some impedance matching
electronics inside the case and the end result of that matching is a lot of
power gain.

>Also, is there an omni pattern mic in the very low multiples of $100
>that would give me the ultra-low noise level (not detectable even
>at high frequencies) that the Rode's are affording me?

Actually, you will find the noise of those Rode mikes is much worse at low
frequencies... it is mostly a rumble.

I don't know what is available in terms of inexpensive omni condensers any
more. There used to be a bunch of them, like the Shure SM-80, but so much
of that stuff has been discontinued. The huge wave of cheap Chinese mikes
has driven so much of that mid-grade stuff off the market. You could try
something like the AT8010, though I have never used it for anything serious.

>I suppose another question would be where to look specifically
>for a couple of channels of mic preamp that have superlative
>performance where it comes down to high-gain/low noise applications?

Try the John Hardy, perhaps?
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Dave Plowman (News)]

In article >,
Mike Rivers > wrote:
> What happened was The Home Recording Revolution. The 75-80 dB gain mic
> preamps became around 60 dB, with some products with gain as low as 45
> dB. This was necessary to make them cheap. Originally, the small handful
> of hobbyist recordists who could afford a real condenser mic found the
> high output level bothersome - that they had to turn the gain nearly all
> the way down to avoid distortion worried them. So the manufacturers
> complied, and the lower cost condenser mics, to better match the gear
> with which they were expected to be used, had lower sensitivity than the
> classic mics so they were closer, in use, to the dynamics that most
> people were using.

Going back a few years to when mics like the AKG C28 and Neumann U77 were
current, on close mic setups it was sometimes necessary to use the line
input. And that on a Neve...

--
*Sherlock Holmes never said "Elementary, my dear Watson" *

Dave Plowman London SW
To e-mail, change noise into sound.

[Scott Dorsey]

Dave Plowman (News) > wrote:
>In article >,
> Mike Rivers > wrote:
>> What happened was The Home Recording Revolution. The 75-80 dB gain mic
>> preamps became around 60 dB, with some products with gain as low as 45
>> dB. This was necessary to make them cheap. Originally, the small handful
>> of hobbyist recordists who could afford a real condenser mic found the
>> high output level bothersome - that they had to turn the gain nearly all
>> the way down to avoid distortion worried them. So the manufacturers
>> complied, and the lower cost condenser mics, to better match the gear
>> with which they were expected to be used, had lower sensitivity than the
>> classic mics so they were closer, in use, to the dynamics that most
>> people were using.
>
>Going back a few years to when mics like the AKG C28 and Neumann U77 were
>current, on close mic setups it was sometimes necessary to use the line
>input. And that on a Neve...

I've had to use the line input on an RE-20, even.

Maybe that's a sign your bass amp is too damn loud....
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[hank alrich]

Scott Dorsey > wrote:

> Dave Plowman (News) > wrote:
> >In article >,
> > Mike Rivers > wrote:
> >> What happened was The Home Recording Revolution. The 75-80 dB gain mic
> >> preamps became around 60 dB, with some products with gain as low as 45
> >> dB. This was necessary to make them cheap. Originally, the small handful
> >> of hobbyist recordists who could afford a real condenser mic found the
> >> high output level bothersome - that they had to turn the gain nearly all
> >> the way down to avoid distortion worried them. So the manufacturers
> >> complied, and the lower cost condenser mics, to better match the gear
> >> with which they were expected to be used, had lower sensitivity than the
> >> classic mics so they were closer, in use, to the dynamics that most
> >> people were using.
> >
> >Going back a few years to when mics like the AKG C28 and Neumann U77 were
> >current, on close mic setups it was sometimes necessary to use the line
> >input. And that on a Neve...
>
> I've had to use the line input on an RE-20, even.
>
> Maybe that's a sign your bass amp is too damn loud....
> --scott

"Can you hear the kick drum yet?"

--
shut up and play your guitar * HankAlrich.Com
HankandShaidriMusic.Com
YouTube.Com/WalkinayMusic

[Dave Plowman (News)]

In article >,
Scott Dorsey > wrote:
> >Going back a few years to when mics like the AKG C28 and Neumann U77 were
> >current, on close mic setups it was sometimes necessary to use the line
> >input. And that on a Neve...

> I've had to use the line input on an RE-20, even.

> Maybe that's a sign your bass amp is too damn loud....

Quite - but this was TV with a session big band. The RE-20 hadn't made it
to 'us' then - although may well have been used in pukka recording studios.

--
*Time is the best teacher; unfortunately it kills all its students.

Dave Plowman London SW
To e-mail, change noise into sound.

[Tom McCreadie]

Scott Dorsey wrote:
>I don't know what is available in terms of inexpensive omni condensers any

The modest priced Line Audio OM1 (made in Sweden) seems to be picking up
plaudits from the folks over on the Gearslutz web forum.
--
Tom McCreadie

[Trevor]

"PStamler" > wrote in message
...
>Oh, a quiet omni (which means one with head-amp gain comparable to the
>Rode's)? Try the Oktava MC012 with the cardioid capsule.

An Omni using a cardiod capsule?

Trevor.

[PStamler]

On Thursday, July 17, 2014 12:33:35 AM UTC-6, Trevor wrote:
> "PStamler" > wrote in message
>
> ...
>
> >Oh, a quiet omni (which means one with head-amp gain comparable to the
>
> >Rode's)? Try the Oktava MC012 with the cardioid capsule.
>
>
>
> An Omni using a cardiod capsule?

Typo -- I meant the omni capsule, of course. But actually, if you point the mic vertically, so direct sound hits the mic from the sides, you can fake an omni response with the Oktava's cardioid capsule. It's not *really* omni, but it's a good fake-out.

As somebody noted, if you're buying an Oktava, get it from www.oktava.com, not from a musical-instrument store. The latter's Oktavas are likely to be the ones that failed quality control tests, or Chinese knockoffs. You pay more at oktava.com, but you get the real thing.

Peace,
Paul

[Trevor]

"PStamler" > wrote in message
...
On Thursday, July 17, 2014 12:33:35 AM UTC-6, Trevor wrote:
> "PStamler" > wrote in message
> ...
>> >Oh, a quiet omni (which means one with head-amp gain comparable to the
>> >Rode's)? Try the Oktava MC012 with the cardioid capsule.
>
>> An Omni using a cardiod capsule?

>Typo -- I meant the omni capsule, of course. But actually, if you point the
>mic vertically, so direct sound hits the mic from the sides, you can fake
>an omni response with the >Oktava's cardioid capsule. It's not *really*
>omni, but it's a good fake-out.

That's not omni of course, just in a single plane rather than a spherical
pattern. And since it reduces the required output, increases the noise. And
you better not have a low, flat, hard ceiling! :-)

Trevor.

[PStamler]

On Sunday, July 20, 2014 11:14:22 PM UTC-6, Trevor wrote:
> "PStamler" > wrote in message
>
> ...
>
> On Thursday, July 17, 2014 12:33:35 AM UTC-6, Trevor wrote:
>
> > "PStamler" > wrote in message
>
> > ...
>
> >> >Oh, a quiet omni (which means one with head-amp gain comparable to the
>
> >> >Rode's)? Try the Oktava MC012 with the cardioid capsule.
>
> >
>
> >> An Omni using a cardiod capsule?
>
>
>
> >Typo -- I meant the omni capsule, of course. But actually, if you point the
>
> >mic vertically, so direct sound hits the mic from the sides, you can fake
>
> >an omni response with the >Oktava's cardioid capsule. It's not *really*
>
> >omni, but it's a good fake-out.
>
>
>
> That's not omni of course, just in a single plane rather than a spherical
>
> pattern. And since it reduces the required output, increases the noise. And
you better not have a low, flat, hard ceiling! :-)

All true -- but it's an occasionally useful emergency make-do.

Peace,
Paul