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The Pro Audio Suite


A must listen Podcast if you're in audio or voice over. Our panel features industry professionals, George 'The Tech' Whittam, Robert 'Source Connect' Marshall, Andrew 'Realtime Casting' Peters and Darren 'Voodoo Sound' Robertson, plus special guests.

Each week we dive into topics that will resonate with Professionals and home studio owner alike...

Dec 18, 2023

RF noise rejection is a pretty complicated thing. We try to make sense of it...

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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 tech don't forget to subscribe to the show and join in the conversation on our Facebook group. To leave a comment, suggest a topic, or just say g'day. Drop us a note at our websiteproudiosuite. Com.