Dec 18, 2023
RF noise rejection is a pretty complicated thing. We try to make sense of it...
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“When the going gets weird, the weird turn professional.”
Hunter S Thompson
Summary
In this episode of The Pro Audio Suite, professional audio experts
George Wittam, Robert Marshall, Darren Robertson, and Andrew Peters
explore the concept of RF technology in microphones and its
benefits like noise rejection and immunity to humidity. They
consider whether RF technology should factor into buying decisions
when it comes to shotgun mics. The team also discuss the advantages
and disadvantages of different types of mics including small
diaphragm and pencil condenser mics. They share their top pick for
the best value shotgun mic—the NTG 5 from Road—and discuss the
impressive feats of engineering that go into manufacturing low
noise mics. Lastly, they discuss the stark cost differences between
mic capsules and complete kits before considering the features of
the V4U model.
#ProAudioSuite #ShotgunMicTechnology #RFMicrophone
Timestamps
(00:00:00) Introduction
(00:00:44) RF Microphone Technology
(00:07:04) Shotgun Mics for VO
(00:12:42) Small vs Large Mic Models
(00:17:55) Mic Capsules & Their Uses
Transcript
Speaker A: Y'all ready be history, get started welcome.,Speaker B:
Hi. Hi.,Speaker C: Y'all ready be history, get started
welcome.,Speaker B: Hi. Hi. Hello, everyone to the pro audio
suite.,: These guys are professional. They're motivated with tech.
To the Vo stars, George Wittam, founder of Source elements Robert
Marshall, international audio engineer Darren Robbo Robertson and
global voice Andrew Peters. Thanks to Triboo, austrian audio making
passion heard source elements George the tech wisdom and Robo and
AP's international demo. To find out more about us, check Thepro
audiosuite.,Speaker B: Com line up learner. Here we go.,Speaker C:
And of course, don't forget the code. Trip a p two hundred and that
will get you two hundred dollars off your tribooth. Now, we're
going to talk microphones today because there's one thing I don't
think we've ever discussed, or not in depth anyway. Is RF on a
shotgun mic? Now I'm assuming rf is radio frequency, but for
anybody like me, what does it actually really mean? And should it
be something that we consider when we're buying a shotgun
mic?,Speaker A: You mean the fact that the microphone uses what
they call an RF technology? Is that what you're referring? Sure.
I'm sure Robert would know more about the details without me having
to google it. I read about RF microphones for a few times and I
think one of the side effects of a mic being RF technology, which
by the way, has nothing to do with transmitting a radio signal,
right. It's the ability for the microphone to reject noise. I don't
know if I've ever heard of a four hundred and sixteen, for example,
which is using this RF technology as having an issue. Picking up
radio frequency noise. If anybody else has heard of that, if you've
had a mic, a four hundred and sixteen picking up RFI, let me know.
But one of the advantages of that technology is it's very highly
immune to humidity.,Speaker C: Yeah, that's what I heard.,Speaker
A: And why that exactly is, is definitely beyond my pay
grade.,Speaker C: Isn't it something to do with the way inside the
microphone? Each part talks to itself, like talks to each other. It
uses like a radio frequency inside the microphone to communicate
with itself. That's my vague recollection of what it actually
is.,Speaker A: That is certainly plausible. I just wish I was more
understanding of the technology.,: So we're talking about it
rejecting radio frequencies, is that what you're saying? Like a
shielded cable would reject?,Speaker C: Yeah, I think that's what
it does. And if anyone's listening, we should do what everybody
else does on their YouTube things. Leave us a comment in the
comments section.,Speaker A: Can I do story time and read it to
you?,Speaker C: Yes, do story time. Oh, I'm sitting comfortably,
George.,: But read it in your best bedtime story voice,
George.,Speaker A: Okay, yeah, well it would have to be in a german
accent.,Speaker C: I'm not going to do that.,Speaker A: A bedtime
german accent?,: No, that's scary.,Speaker C: That's really scary
actually.,Speaker A: But there is a whole white paper from
Senheiser and it's written by Manfred Hibbing and it's Sennheiser's
professor. MkH condenser microphone sorry everybody, I'm sorry, but
basically what it says is that high rf frequency solves a problem.
So when the replacement of electronic valves by transistors
commenced at the end of the fifty s, this change was also under
consideration for condenser microphones. Reduced size, low supply
voltages and lower power consumption were regarded as great
benefits as well as being able to use simpler microphone cables.
However, there was a basic problem. Direct replacement of the valve
by a transistor was not possible due to the mismatch between the
high impedance of the condenser capsule and the low input impedance
of the transistor. Hence, for optimal matching, the capsule
impedance needed to be drastically reduced. And then they go on to
explain the impedance of capsules, et cetera, et cetera. So down to
the next paragraph. How does RF microphone technology actually
work? The principle is simple. After all that.,Speaker C: Yeah,
sure it is.,Speaker A: Sound waves deflect the diaphragm of the
condenser capsule and change the capacitance between the diaphragm
and the nearby back electrode, or backplate. Contrary to the more
common low frequency AF condenser method, the capacitance
variations are not converted directly into audio signals, but
modulate a high frequency radio frequency signal generated by an
oscillator inside the microphone. This signal is then immediately
demodulated inside the microphone, thus recreating the audio
signal, but with a very low source impedance that is well suited
for driving a transistor amplifier. Thusly, an RF condenser
microphone is basically comprised of a transmitter and a receiver
that are directly wired together. The RF signal is therefore kept
inside the microphone only the audio signal is supplied to its
output just like all other microphones. So yeah, what you were
saying was pretty much usual for me.,Speaker C: What
happened?,Speaker A: He picked it up through osmosis somewhere
along the way.,Speaker C: That's right.,: Can I just say, Robert
would make that a lot.,Speaker C: Yes.,Speaker A: Yeah, sure. The
thing with humidity, and here's a little paragraph about this,
there is no other important benefit of the RF principle for
practical use, the low electrical impedance of the capsule provides
outstanding immunity against detrimental effects due to humidity,
because even then, the leak resistance is very much larger than the
capsule impedance. Thus, Mkh microphones, which I understand, all
of those, all Mkh mics are RF mics. They're well suited for outdoor
use. So this is why mkh mics, no matter whether they are the mkh
four one five, forty one six, and I'm paraphrasing here, or any of
the mkh stuff like the mkh forty. There's the eight thousand
series, right? They have the eighty third. Eighty, twenty, eighty,
thirty, eighty, forty, fifty, eighty, sixty. They have a whole new
line. All of them are using this technology. And the reason for why
it still persists to this day is it's excellent outside and thereby
it's also excellent in a sweaty, hot, muggy voiceover
booth.,Speaker C: If it's four x three x six. Yes, indeed.,Speaker
A: Especially if it's four x three x six. Absolutely.,:
Yeah.,Speaker C: Talk about that outdoors, though, because this was
something else where I got stuck in the rabbit hole that I
mentioned before we started recording. Then there was a discussion
about using shotgun mics inside. Now, this is basically for drama
and stuff like that. So a boom op using a mic where they wouldn't
use a shotgun inside, they would use a pencil. Small diaphragm,
pencil condenser.,Speaker A: Yeah.,Speaker C: Now, if that's the
case, if you're a field audio guy, why would you not use a pencil
condenser as a voiceover person inside?,Speaker A: I don't know. I
did have a pair, and I still do have a pair of pencil condensers,
the classic octava mics that are so popular. And I used to use them
to try to do field recordings. And I didn't know that much about
mics at the time. And I would get the dreaded, we sometimes call it
motorboating. It was like this.,: Yeah.,Speaker A: Fluttering
sound. And I didn't know why it was happening. I just knew it would
happen. And it would always happen if I was outdoors and sometimes
I was like, in a really humid environment and it would get really
bad. And I was like, oh, no, the mic's bad. And then I'd bring the
mic home and I'd pull it out of the box later and would be
perfectly fine.,: Yeah.,Speaker A: So because with af microphones
or audio frequency condensers, because they store a charge on a
high impedance capsule, it's easy for that charge to find a way and
leak across the insulation by riding on water molecules which cause
those motorboat or crackling effects. So I don't know. I mean, I
think it's just another added benefit of an RF mic is that you're
just never going to have that problem. But Neumann, large diaphragm
condenser mics where you have two diaphragms extremely close to
each other, even if it's a cardioid, there's still two. There's the
diaphragm in the front that takes the sound wave and then there's
one on the back that picks up the signal, creating the changes in
capacitance, blah, blah, blah. And those are so close together that
water molecules actually transmit the electricity.,: Yeah.,Speaker
C: It's amazing.,Speaker A: And create the static.,: Yeah.,Speaker
C: Do you know anybody who does use any pencil Mic for doing
voiceover in their. I do.,Speaker A: I know people that use the
eighty series or the eight thousand series, but those are MKh mics.
So I believe all the eight thousand series Mkh mics are also
rf.,Speaker C: Is that the eighty fifty?,Speaker A: Is that like
the eighty fifty? The eighty twenty, eighty thirty are tiny little
stubby capsules. I mean, they're mini because I guess they have the
most condensed electronics and boy, are they expensive.,:
Yes.,Speaker A: This is a stereo set. So I'm looking at two
thousand eight hundred for a stereo set.,Speaker C: Don't look at
the chefs then.,Speaker A: Yeah, I know. Chef takes to another
level, right?,Speaker C: Yes.,Speaker A: But yeah, the MKH forty is
going to be about one thousand four hundred us. So if somebody's
comparing mics and they look at this minuscule, laughably small mic
and then they think, why would I ever use that over a four hundred
and sixteen? Well, that's because it doesn't have the negative
effects of a shotgun microphone.,: Yeah.,Speaker A: Doesn't have
any of the negatives. It doesn't have the negatives in terms of off
axis phase problems.,: Yes.,Speaker A: You get a way more accurate
pattern as you go off axis. Right. So that's one reason it's
certainly very nice to work with, because it's so small.,:
Yeah.,Speaker A: So it's never going to get in the way. But they're
going to be extremely pop sensitive. Right. Because the capsule is
right there at the grille. It's right in the front. Like any pencil
mic. They work great on voice, but they pop like a mofo. Yeah, they
pop really bad. So you have to have good mic technique and maybe a
good pop screen. But they are quite an upgrade. Some really have
found them to be quite an upgrade. Like an eighty forty from a
forty one six.,Speaker C: Yeah.,Speaker A: I would go with the
eighty fifty because that's a super cardioid. That would be my
choice if I was going this direction.,Speaker C: Yeah, it's
interesting. It's funny with shotguns and we were talking about
this also before we jumped on because the road kit I set my
daughter up with for her travels, I gave her the NTG three and we
were just doing some testing a few hours ago just to make
sure.,Speaker A: That is an RF mic too.,Speaker C: I believe it is
an RF mic, but also it's quite bottom end.,Speaker A: It's eqed
very differently. It is a very different tone from.,Speaker C: The
forty one six, which I think for location is perfect because the
further you get away from the source, the sound source, the thinner
the audio gets. But if they've got that sort of hype bottom end, it
actually keeps some of that in there in the sound, which is great
for that kind of work. But it also sounds really good on a female
voice. I mean, she sounds great on that ntG three. But when I put
it up in front of me, I had one for a while, mud central. It just
didn't work.,Speaker A: Muddy?,Speaker C: Oh yeah, it wasn't
good.,Speaker A: You lose articulation. It doesn't have a crisp
attack. It's very, yeah. There's another mic that's really popular
because of its price point and that's the Cinco d two. Have you
heard of that one?,Speaker C: No.,Speaker A: Very cheap shotgun
mic. And of course it looks a lot like a forty one six. Of course,
same color, same shape, same size, same everything. So of course it
gets sold all over the Amazons and stuff as a cheap forty one six.
But it sounds nothing at all like a forty one six. Nothing at all.
Yeah, it's a very flat mic. Very flat, very dull. So when somebody
sends me that sample, I know immediately I'm going to have to help
the top end. And when I do that, up comes the noise. And that's the
other problem with small diaphragm mics. Making a small diaphragm
pencil or shotgun mic sound as low noise as a large diaphragm mic
is no small feat. No, it's very difficult to do. So. That's another
problem. You're never going to get a small capsule mic to be as
quiet from a self noise perspective as you will a large diaphragm
mic, even a cheaper diaphragm. Well, let's look at the rode nt one
four or so db self noise. You're never ever going to find a small
diaphragm mic with that kind of a measurement.,: Yeah.,Speaker A:
What's funny is I'm reading the specs right now from the Senheiser
mkh. Eighty fifty. They don't even quote the self noise.,Speaker C:
Interesting.,Speaker A: Which to me is a way of saying it ain't so
great, but it doesn't matter. This is a location mic. You're going
to use it outside so it doesn't need to be that quiet.,:
Yeah.,Speaker A: But still, it's a one thousand four hundred
dollars mic and they don't quote the spec. So I find that kind of
fascinating.,Speaker C: Yeah, but if you're buying a shotgun, and I
know we've banged on about this before, but I still reckon the best
value, the best bang for buck in any shotgun mic is the NTG five
from road.,Speaker A: Yeah, it sounds once they got over there they
had some growing pains with that. They did. We definitely had a few
people with some issues and it seems that that has been sorted
because I haven't heard of any of those kind of complaints of noise
or whatever for well over a year now. It's been more than a year or
two.,: I was a victim of one of those. The first one they sent me I
had problems with, but sent it back and got a brand new one and
haven't had any problems with it since. Full credit to road
all.,Speaker A: I never ever had a problem replacing a mic.,: Yeah,
and full credit to road. All I sent back was the actual mic and I
got a whole new, whole new kit when they sent me back the new one.
Typical of road.,Speaker A: Really.,Speaker C: So you got a nice
little shock mount for your forty one sixes?,: Yeah, I've now got
two of their shock mounts, which is kind of nice.,Speaker A: Well
those are cool, man. If you were to go buy those pistol grip shock
mounts with the rycoat style Lyre mount and everything, those are
going to be one hundred dollars plus easily.,Speaker C:
Easily.,Speaker A: And then the windscreen and everything else. I
mean it's like one hundred and fifty dollars kit plus the mic.,:
Yeah.,: And I do like it. It's standard fare in my room here. That
or the austrian audio one or.,Speaker C: The other of the two.
Yeah.,Speaker A: Mine pretty much lives permanently in my kit for
going on the road and traveling. I have a pelican hard case and the
ten TG five lives in there. It's just always there, ready to go.,:
Yeah. Well, you know what I need to figure out now, thinking about
that is cutting the foam in the road kit for my english channel so
that the NTG five fits in there and then I've got it all in one
case that's what I need to figure out.,Speaker A: Oh yeah. It
seemed that there was enough space in there to squeeze in a shotgun
mic.,: Absolutely. Just pick up the bag and away you go.,Speaker A:
That'd be a sick kit, wouldn't it? Oh, man.,Speaker C:
Fantastic.,Speaker A: I did actually dig around and I went on the
recording hacks website, which is a great database of microphones
recordinghacks. Com. And while it's missing mics here and there for
sure, it does have pretty much all the Neumans and Sennheisers and
the bigger brands and stuff. And I found the eighty fifty and they
actually do list a self noise rating of thirteen DBA weighted. So
the Sennheiser four hundred and sixteen is like sixteen, I believe.
Okay, so they managed to shave three db of the self noise.,Speaker
C: I think the NTG three is about the same. About twelve or
thirteen from memory.,Speaker A: Yeah. That's good. I mean, it's
going to be hard to find a lower value than that. I haven't seen. I
mean, maybe Sheps has something quieter. Possibly. I haven't
looked, but. S-C-H-O-E-P-P-S. Is that how you spell.,: Am I
thinking of the engineer or the. Is it double P?,Speaker A: Well,
yeah, it's confusing because you have the mic called sheps.,:
Yes.,Speaker A: And you have the engineer, and I.,: Can'T remember
whether it's double P for the engineer or double P for the mic. One
of them has two.,Speaker A: I guess I kez guessed it right. It's
S-C-H-O-E-P-S. So the CMC five, which is one of the quintessential
chefs shotgun mics, is. It's got one, two, three, four, five, six,
seven, eight, nine, ten, eleven, twelve, thirteen, fourteen,
fifteen, sixteen, seventeen, eighteen, nineteen. Different capsule
options.,: Wow.,Speaker C: Bloody hell.,: Wow.,Speaker A: They have
this huge array of capsules that thread onto the body depending on
what you're doing. So let's look at a cardioid. Let's look at a
super cardioid, the mk forty one. It does not list a noise spec.,:
Right?,Speaker A: There's no noise spec listed anywhere.
There.,Speaker C: Kind of old school, isn't. It's like the old cmv
microphones from Neumann back in the. Would have been thirty s.
Forty s where you got the bottle. And instead of having a switch to
go from cardioid figure eight to omni or whatever, you unscrewed
the capsule and put new capsule on the top.,Speaker A: Yeah. Right.
Yeah. Well, actually my mkhs. Sorry, my octavus. Same deal. I have
three capsules per mic, but that whole kit with two mics and all
the capsules costs less than one of these capsules.,Speaker C:
Yes.,Speaker A: You start realizing the difference in cost is
pretty stark. I mean, they said the capsules are anywhere from
eight hundred dollars to one thousand four hundred dollars for one
capsule.,: Yeah.,Speaker C: I do like the idea of the ships. The
shotgun, that's blue. I mean if you had that in the booth and as
soon as you see that color, you go, oh, okay, somebody's serious.,:
Yeah.,Speaker A: Have you ever seen their v four u model? It has a
blue bottle and then the grille has this very cool deco style
grille. It's very cool looking. Look it up sometime for you. And
it's a neat looking mic and it has a quirky thing. It's that the
capsule has a slightly hinged head so you can tilt the capsule
forward and back a little bit. Like ten degrees, twenty
degrees.,Speaker C: Oh God, that looks good.,Speaker A: But it's a
cool looking mic.,Speaker C: That is very tasty. Yeah, don't Google
Robbie, you'll get blow your machine up.,: Well, I'm doing it on my
iPad, but it's saying there's some problem with the website and I
can't get on there. So I don't know what's going on.,Speaker A: V
four U is three thousand dollars retail. And then it has a pretty
flat response curve. I mean it has a small presence rise at four k,
which is typical, but it's only like two or to three db rise. So
it's pretty flat.,Speaker C: That is insane.,Speaker A: I remember
trying it at one of the nams or whatever and being like, wow,
that's a cool sounding mic.,Speaker C: It looks really neat, very
tasty.,Speaker A: Oh, that's how much it costs.,Speaker C: Okay.
Yeah, I might get one in the next lifetime. Yeah, I was in Tokyo
and I saw a dunhill store and I went in there and they had these
linen bucket hats and caps and stuff. I thought, wow, they're
really cool. And I was looking at the price and tried on the bucket
hat and it's like, yeah, I'll get that. So I said, yeah, I'll take
this one. I said, actually, I might even get the cap as well. And
the guy's looking at me going, no, you don't need the cap as well.
Just take this hat. That's all you need. I'm like really doing
yourself out of a sale here.,: Okay, whatever.,Speaker C: So I
bought the thing and I'm walking back to the hotel and then I'm
doing the calculation in my head and thinking I just got a bargain
of thirty five dollars. I sort of went, hang on a minute. I got the
digital point in the wrong spot.,Speaker A: I just paid three off
of zero.,Speaker C: Three hundred and fifty bucks for a bucket
hat?,: Yeah, right.,Speaker C: Dear, oh dear, oh dear. Anyway,
yeah, well, that was fun.,Speaker B: Is it over?,: The pro audio
suite with thanks to tribut and austrian audio recorded using
source Connect, edited by Andrew Peters and mixed by Robo. Got your
own audio issues? Just askrobo. Com tech support from George the
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