Radio Engineering Hacks
Posted by Kirk Harnack [TWiRT] on Mar 5, 2014 1:51:00 PM
hack n. An inelegant but effective solution to a problem.
Often there’s more than one way to solve an engineering problem. There is usually the normal approach, and then there are one or more “hacks”. Some hacks are elegant and others – not so much.
In this episode, Chris Tobin and Kirk Harnack discuss radio engineering hacks – unusual yet effective ways to fix and use broadcast equipment.
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Announcer: This week in Radio Tech Episode 202 is brought to you by Axia Audio and Telos Systems, together bringing IP audio studios and connections within your reach for superb audio and easy configuration. On the web at Telosalliance.com.
Often there's more than one way to solve to an engineering problem, the normal approach followed by one or more hacks. Some hacks are elegant, while others not so much. Chris Tobin and Kirk Harnack discuss radio engineering hacks, unusual but effective ways to fix and use broadcast equipment.
Kirk: Hey, welcome into This Week in Radio Tech. I'm Kirk Harnack your host and really glad you're here today. We've got an interesting show for you, a little different subject matter. Kind of a light show, kind of light hearted. You know what? We're going to watch the chat room and see if you have something to chime in with as well.
By the way, if you're listening to this show right now, This Week in Radio Tech, if you're listening by means of a recorded podcast- in other words, you downloaded it. If you're watching it not live-let me encourage you to participate live. We do the show at 2:00 pm Eastern time on Thursdays. That's 1900 UTC, at least it is right now. I guess that changes when daylight savings comes along. But anyway, if you participate live you can be in our chat room. If you go to gfqlive.tv it'll pop up a chat room there and you can participate right in there. You can be anonymous, or you can say who you are, or use somebody else's name if you like. Yeah.
So this Show Number 202. I'm Kirk Harnack and thank goodness I'm not alone. We have with us Chris Tobin, the best-dressed engineer in radio. Welcome in, Chris.
Chris: Why thank you, Kirk. Yes, you are not alone and hopefully we'll have our guest come by shortly, if not it's just you and I, and we'll have a good time.
Kirk: Good deal. Hey, tell us what you're doing nowadays. I used to introduce you all the time as from CBS, and then I introduced you as being President of Musicam USA. You have probably found a niche where you're just doing a lot of people a lot of good right now. Tell us about that.
Chris: Yeah, what I basically am doing is I've started a solutions company, I guess that's the way to call it. It's for people who create content. I'm offering up solutions, both over analog, digital, IP. My experience is in both broadcasting TV and radio, and a lot of Internet stuff that I've done over the years. I'm still working with the folks at Musicam as getting their stuff out, that's part of the IP side of things. But I work with all the products, including the Telos Z/IP, the Comrex Access, TieLine, and help people build new facilities and transmitter sites.
I just recently worked with a guy who just put together a complete STL for six radio stations using three different IP radio links, and dozens of IP Codecs. The best part of it was, he was like, "Wow. I'm glad I spent all this money." I said, "Why?" He goes, "Those cheaper versions that you told me I'd definitely have a problem with, it happened during a storm." And I said, "Well, there you go. You get what you pay for."
Kirk: Actually let's talk about this for a second. Tell you what, let me finish the introductions.
Our show is brought to you by-They happen to be my employer and I appreciate them sponsoring the show and that is-the Telos Alliance. I'll tell you about some changes at the Telos Alliance, in terms of our public-facing side, that are very nice and they're going to be very helpful to you if you're a broadcast engineer, or someone interested in engineering, you're going to like the changes coming up. I'll tell you about those in just a few minutes.
This is our 202nd episode. I'm delighted to be here with Andrew Zarian and the GFQ Network. This the show where we talk about radio technology, everything from the microphone to the antenna at the top of the tower-that being the traditional radio, but now there are a lot of digital distribution methods as well, and we talk about those, too, as well.
Today's subject, the title of today's show is "Engineering Hacks." What have you as an engineer done, what have you had to do, in order to solve a problem that was inscrutable and maybe you found a good way to do it, maybe you found a hack. We didn't used to always call them hacks; we called them tips and tricks, and things like that. Now "hack" is the in-vogue word.
So hey, Chris Tobin, do you have the opportunity to open the chat room?
Chris: Yes, I do. Yes, I do.
Kirk: Because maybe I need to get a different chat client, but I'm not getting it to function for me very well. Oh, there it is. It just popped up. Okay, good deal. So we're in the chat room now. If you want to join the chat room, go to GFQlive.TV and you can see the chat room there.
Andrew Zarian, maybe you can tell us another way to join the chat room and participate in the shows on CFQ Network.
Andrew: If you have an IRC client you can put in "IRC.GFQnetwork.com" in your IRC client, and the chat is GFQ Network.
Kirk: Ah, okay, GFQ Network. Good deal. So engineering hacks. I was talking with Chris Tobin, our other co-host-and by the way, I should also mention, we have a scheduled guest. It's Dave Supplee with Cumulus Media. I've known Dave for years and years. He builds lots of studios for Cumulus. He's like their go-to guy to put a studio together, when they need to build a new one or refurbish one.
He got called away at the last minute to go to a transmitter site. He's trying to join us from the transmitter site now, but I'm not sure he's going to be able to, if the coverage or the Internet connection out there is going to be good enough for him. If he's not here today, I want to have him back on another show, maybe from one of the studios that he's built, because Dave's a great guy to talk to and understand his studio hacks. He's going to give us some good information about that and what he's had to do to get things on the air.
Chris Tar and Tom Ray one of them may want to join us a little later in the show, we'll see. But right now Chris Tobin is with us, so let's get started with "Engineering Hacks."
We are talking with Chris Tobin about what he's doing now. Chris, I think what you're doing here, if I understand it right, is something that's really necessary in today's world. We're dealing with some new technologies that not all the information is so easily available, or it's not part of our engineering tribal knowledge, or our experience yet. So you help people get IP solutions, especially, working for them. So give us some example of what you're doing for folks.
Chris: Well let's see, recently that STL setup we did was with 5.8 gigahertz unlicensed radio links. In their particular location where they are they can away with it. This distance between the studio and transmitter facility is just under two miles, so they over built the link budget, which is the power of the signal between the two antennas. It was enough to cover any rain fade, as well as probably any interference.
One of the things I did was working with them to explain to their customer-Now remember this phrase, because I tell this to everybody.-"You get what you pay for." There is a cost to doing things the right way. There is a cost to ensuring what we all understand, or used to understand, as the five nines of reliability, or the ability to be up and running, always on to meet your needs.
So if you're a radio station, television station, or maybe you're an Internet content provider that has the need to be always there for you customers or your listeners, your viewers, whatever you want to call them, there is a price to pay. So what I'm about to explain comes with a price, because there will be people listening and watching this right now saying, "Oh my goodness, if you do that it's going to cost you X." Yes it does, but on the flip side the result you get is what you need.
So this 5.8 gigahertz link, traditionally most people get two radios. They're transceivers, so they both transmit and receive, create a link and it's two antennas point-to-point, or a single antenna on each end. However, in recent years, because of the congestion and just overall RF in the world-I mean, if we could see RF signals we wouldn't be able to walk the streets.
Kirk: You're right, it's true.
Chris: What if we could see them.
Chris: Take a spectrum analyzer, put a piece of wire on it and look at the spectrum.
Kirk: It's crazy.
Chris: Right. So what I've doing with folks-and I've done this for many years, but now it's become in vogue. Five years ago everyone would have laughed at you for doing it. I am buying antenna systems and designing them with dual polarization. So now what you have is-the popular term nowadays is MIMO, multiple in multiple out antenna designs. Your cell phone has a MIMO antenna system.
By doing that you now have a horizontal and vertical polarized signal going between the two end points and if there is any interference the odds of it interfering enough to create bit error that, maybe collapses your link, can be minimized. Think of it like common mode rejection on an audio cable, right? You have a balanced wire or you have an unbalanced, so think of the dual polarization as sort of like a balanced wire connection. I'm being very broad strokes on this, but just to sort of give you an idea of why you spend the extra dollars to create this link.
Now this technology's been around a long time, because it's used by a lot of folks in the petroleum industry. That's how they connect all those rigs, out to sea, back to the mainland. It's through this technology, usually 5.8 gig or 3.2 gig, or one of the other bands depending on where you are in the world, but it's the technology the frequencies are still thing. If you license it, you have something to argue over if somebody interferes with you. That's basically all it gives you. If you unlicensed you're at the mercy of whatever you design.
That's what I've been working with and lot of folks, a lot of radio stations are starting to realize that this technology does make sense and forego putting in the traditional, say, terrestrial T1 connection, or terrestrial point-to-point equalized lines-those things are still around, still available-and using the IP.
Now, what's the benefit? The upside to this is, not only do you put your audio across it with your codecs, but you can also extend your LAN if you choose, or you can create your own VLAN and now you have a VLAN STL link that gets you to your transmitter site, so you can do many things.
In today's technology you can have all kinds of fail levels, because in the IP world you can buy boxes, routers that will fail safe or fail over to another IP circuit. So if you're really ambitious you can do two radio links and set yourself up with routers that will fail back and forth.
So there's a lot of stuff you can do and it's actually relatively inexpensive when you do the total cost of ownership over a period of, say, five years, three years depending on how you used to do [phone] lines. You know, for T1s these days you can still spend close to $600 a month for a T1. That's only 1.544 megabits in each direction. $600 a month, do the math, if you make a one-time purchase, now you own the link, and the cost of increasing or decreasing the data rate, there is none. It's your pipeline, you built it out.
So that's what I've been working a lot on lately. Then I'm working with some folks in the video world with the same principals. I'm doing some wireless stuff with cellular, which has been a real treat. If you want to do anything with cellar technology be very careful. You're at the mercy of monopolies and anyone who tells you you're not is an idiot. The technology, LTE, does work. The problem is the phone companies don't put it to its best use and broadcasters do get the short end of the stick.
Kirk: Speaking now of the whole subject of IP radios, and I'm about to implement some IP radios-from my first hands-on time, other than in the lab at Telos and Axia-down in Mississippi, very low population density. I'm not anticipating RF issues, interference issues.
Talk about the difference of licensed IP radios and unlicensed IP radios. Where do you have to go to a licensed plan, and really plan it out well?
Chris: Well, the licensed plan is basically you have your STLs on the 950 Megahertz band. You have licensed frequencies in order to coordinate between the users. If you're in a metropolis or a metropolitan area like, say, New York City, Chicago, Boston, you do a spectrum check and if 5.8 gig is busy-it very much might be- then you may want to go with licensed. Then you apply for a license and you protect yourself in that way. Hopefully, the coordination between those frequencies is done properly and you're okay to go.
Unlicensed is just like your Wi-FI at home. It's like your Wi-FI router you buy for home. [inaudible 12:08]
Kirk: So here's a question. I tend to not live in areas that are population dense as you do, so here in Nashville, and I live in a suburb of Nashville, so there's not much Wi-FI, either at 2.4 or 5.8 Gig going on around here. We all know of this technique called "Spread Spectrum." Within a channel area, spread spectrum, and that allows more than one user to use a given piece of bandwidth at a time and generally, up to a point, they don't interfere with each other. So I can have a Wi-FI hotspot in my house on the same frequency as one next door, 100 feet away, and it's generally quite usable. You don't notice a problem.
Do you have a rule of thumb or when do you need to think about, "You know what? Let's move your Wi-FI hotspot to a different frequency, because I can see that that's clear?" Or, sometimes I stay in a hotel in Cleveland, Ohio when I'm visiting Telos and out the backside of this hotel there's a big apartment building. When you turn on your computer and you search for a Wi-FI spot and there's 73 of them because there's this huge apartment complex right next door. So what's usable in a situation where there are all these users on the air?
So of course, I realize we're talking about broadcast here so I assume that you don't want to get your email 90% of the time. You want your audio to be there 99.999% of the time. How do you make that value judgment about a frequency and if it's overused, in the light of spread spectrum and perhaps polarization possibilities, optimizations?
Chris: Right. Well, first of all let's visit this. Wi-FI, we'll just use the phrase "Wi-FI", has in it inherently in the design for the IEEE 802.11 of an A, a C, a B, and D, and E has in it, by design, the ability to look at channels and move around, and decide what will happen. It's sort of like a first come, first serve-I forget, there's a name for it and I can't find it right now. There's an actual term for that technology that's part of the frequency hopping. So if you're in a hotel and you're on a 2.4 Gig Wi-Fi system the odds are you won't be able to get away from the interference of everybody who's operating without any managed Wi-Fi. Okay?
So there's the two things you have to watch out for. The managed Wi- Fi will get you connected and then follow you throughout the Wi- Fi bubble, I'll call it that. Then you have Wi-Fi that's just thrown up. People put up a hot spot or an access point on the floor and off it goes and then they hope for the best. There's no way to guarantee you're not going to get interference. That's just the way it goes.
If you're lucky, 5.8 Wi-Fi has more channels, less overlap on different frequencies, so the chance of you losing bandwidth enough to fail so you'll not get mail and other things is minimal, but that will eventually grow out and people will start having problems. Those are the two things to watch out for.
So traveling Wi-Fi or even in your home. Like, I have in my home two routers and one of them is Wi-Fi 5.8 and one's 2.4. I can't tell you how many times the 2.4 one just collapses. I can be sitting there with my laptop, and it's just like, "Yeah, I'm not connecting. I've got some kind of bandwidth I can't make out what it is because it's just all noise."
Kirk: But you're in a high-density area.
Chris: Oh, yes. I can get one of those NetStumblers, or there's many products out there that can look at the Wi-Fi spectrum, and yeah, I can see. Like, right now if I turn it on, I can look at it and see 25 hotspots. Thank goodness, they're all secure, so people aren't being stupid about it, giving away their bandwidth, but they're there.
Kirk: It didn't used to be that way.
Chris: You could enjoy Internet from your neighbors without them knowing it.
So when it comes to radio stations or TV facilities and you're going to do linking, transmitter to studio to studio, depending on where you are, the 5.8 will work just fine and if you do a dual polarization. There are certain products that are out there that spectrum-what do you call it-the OFDM stuff, their boxes are designed-and you can turn it on or off-to jump between frequencies to minimize interference. They actually have algorithms in them to sort of minimize it.
Kirk: That kind of frequency hopping that you're talking about now, where it listens to see what's out there it's, "Oh, well, this channel's really tied up, let me go to another. Oh, this is pretty empty, I'll go over here," automatically. That is different than spread spectrum where you're hopping within a given channel range.
Chris: But, Wi-Fi does spread spectrum too, and it's all predetermined timeslots, the whole bit. Yeah, spread spectrum is just the broad term these days. Years ago it was just basically one thing, now it's become a huge algorithm based design. That's why you'll see a lot of these 5.8 radio links tout low interference or you're ability to do this and to do that. Because now they've got algorithms they've written in to that spread spectrum timeslot generator, and it says, "Okay, we're going to do this, we're going to go on to this and see what energy bits we have, and we'll move back and forth. It's pretty cool and when you start getting into it it's like, "Whoa." And depending on your link-The trick is or what people forget, if you have a link in the IP world, IP radio, you're link is one mile in distance from Point A to Point B. Depending on how you design that radio, on what bandwidth and modulation you choose, will dictate the bandwidth you get. It's not assumed you'll get 100 megabits if your radio is designed for 100 megabits; you've got to be careful with that.
The same is true if you go with that same radio set up and go six miles out. You're not going to get 100 megabits unless you design it accordingly, which means you have to have enough link budget, RF signal, to get between the points.
So these are the things you have to look at, and it gets more detailed. Like, I just did a four-mile link between a studio and transmitter, and thank goodness there's literally flat land between the two locations so there's no fail zones issues to work on, or anything else. But, that four miles, I had to determine which form of modulation would work to get me the 100 megabits I needed, because I was pushing it at the edge, because I was only using a two-foot flat panel in the studio side, because they were not allowed to put a two-foot dish on the [inaudible 18:21]
Kirk: Oh, really?
Kirk: So you have site issues there.
Chris: Well, site issues in the sense of aesthetics. The window was clean, there was no Mylar, no lead-based-not lead these days, it's something else that they call it-they put the film in for the building heat. What we did was, at the transmitter site, since we had no issue with aesthetics, we put a four-foot dish out there.
Now, some people say, "That'll work, that makes up the difference." Yes and no, it does give you a little more to work with, but remember, the four-foot dish is going to benefit more. That transceiver is going to be much better than the one at the studio that's got the two-foot flat panel. But it helps you to design what you can work with and that's what's nice about IP. You dictate the guard bands, or the parameters by which you operate under. Whereas in the past if you had a T1 you were basically at the mercy of the phone company doing the proper clocking and everything else involved, and you hope that your . . .
Kirk: That's a good point. Something else that I would point is, if you have a T1 you have 1.5, whatever it is, megabits per second, that's what you have. You may have other faster services available, IP services from various carriers now, but if you could do your own IP radio and you can get a clear path, even if you have to do a hot point somewhere, if it's your equipment, especially if it's licensed, but even to some degree if it's not licensed, you may have the opportunity to have a much bigger pipe between where you are and where you want to be.
In fact, this is what I'm doing in Mississippi. We have a transmitter site that doesn't really have the possibility to get any IP services out there, but we have a nice clear shot. We're doing a 950-Megahertz analog shot now from 40 feet up at the studio, and about 100 feet up at the transmitter site. Well, we're going to do that again for an IP hop, just with little Ubiquity dishes-If I get a chance to run over here and get one I will, and show it- and we'll get some IP connectivity out there. Now, we have a world of IP things to connect to, like our Nautel transmitter and the AUI display. We'll be able to look at that, so I'm delight about that possibility.
Hey, we were talking about-here's where we get back into hacks. So here is a Wi-Fi analyzer, a popular little application for Android, and I guess they have it for iPhone as well. I'm looking on Channel 6, and a lot of things come on Channel 6, right? On the 2.4 gig spectrum is my hotspot; I call it "Ghost of Otis." There's a long story there. So that's my hotspot and there's not much else in there.
I'm in the basement here, in the lab, but if I go upstairs we'll see several different hotspots on there from neighbors, but down here it doesn't matter. It turns out they're not using Channel 6, so that's good.
We talked briefly about licensed versus unlicensed. If you go to licensed you've got opportunities for other bands to go in. You wouldn't license yourself in the 2.4 gig band, I take it.
Chris: No. In the United States it's 3.6 gig.
Kirk: Ah, okay. Aren't there some other ones? Aren't there some real high ones, 11 or 17 gig?
Chris: Well, yeah. There's the 11 gig and the 23 gig that you can also do. Again, as I pointed out earlier, that's where you get what you pay for. So, if you want to go up there, you can, and you can do a lot with it, but then also remember the penalties. At 11 gig and 23 gig your link budget, rain fade, and many other things fall into play. So if you can do 3.6 and manage it properly then you're sort of right in the middle of where you want to be. Yeah, you can do that.
Kirk: But that's a good point. That rule of thumb is that the higher the frequency the less of an aberration in the path that it takes to decrease the signal.
Kirk: So a swarm of birds somewhere in the path at 23 gig can certainly hurt things. Of course, the more common thing is rain fade. If you get a lot of rain in that path, and it's going to wipe out a 23-gig path. It's going to hurt an 11-gig path, it won't do so badly with a 3.6-gig path, and not as badly with a 2.4-gig path, either.
Chris: Right. You have all of these conditions, but the nice thing is there are formulas and mathematics involve that you can calculate and figure it out. So you could always have a fail over something hardwired, so you have a DSL line, or a cable modem at your transmitter site [inaudible 22:45] If you can. If you have that luxury or maybe you do need to have one there for something else.
Kirk: Well here's a hack. This is what our previous guest we had on the show, Dave Anderson, is doing. At all of his transmitter sites, including some translator sites, he's up to 10 or 11 transmitter sites now. He tried to get wired Internet, whether it's DSL or cable, to every transmitter site. Plus, he gets a second Internet feed, and in some cases that separate Interned fed is a CradlePoint travel router, or point of sale router, with a Verizon 4G LTE USB modem on it, or the dedicated kind of router that has that built in. That's not his primary, but it works well enough, often enough, to where it's a good backup.
There's also a few cases where he can't get a second form of Internet to a transmitter site, because usually they're out in the boonies, or often times they are. So he'll find the nearest place that does have Internet that he can get access to. Maybe it's a fellow engineer, or a HAM radio operator, or a business that's friendly to the radio station, so they'll make an arrangement with that business, "Hey, let us put up a little 20- foot tower around back. We're going to pay for your Internet, but we're going to take some of it. We're going to put a Ubiquity, or some other brand of dish up, IP radio, and shoot it out to our transmitter site." Which at that point might only be three or four miles away, or eight miles away, it's not a 40- or a 100-mile shot all the way from the studio.
So you get it as far as you can go and then you hop it where it needs to go, if those common carriers or cable companies can't get it out there to you. I think that's a great hack to get two sources of Internet, if you're using it for STL, to you transmitter site by whatever means that it may take.
Chris: Absolutely. I've done that. CradlePoint's a great product to use. There's a couple of them out there, and I've done the exact same thing. Yeah, that's another thing. See, as I said earlier, you can control and design on how you want to do things. It's your design, your control.
Kirk: So we've been talking about some pretty sophisticated modern day hacks right now, but I want to roll back to a couple of old school hacks, okay?
Chris: Sure, I've got one.
Kirk: So, maybe you've got an audio console that has no way to do a mix- minus on it. Maybe you have an old-fashioned console where you've got a fader or knob, maybe it's a rotary knob fader, and you've got a switch above it for program or audition, but not both. You can put that audio in the program bus or in the audition bus, but you can't put it in both busses. There's no third bus, a utility bus, or a telephone bus. Of course, modern consoles-even consoles that are 20 years old oftentimes-program and utility could be selected at the same time, so you could send audio from a given fader to program, and to utility, or audition, if you will.
Some consoles had a built in phone bus, if you will. Even the type of module that it was would decide whether or not it was going to be part of that. But let's say you've got an older console, no possibility to come up with a mix-minus. By the way, remember, why do you want a mix-minus? Well, if you're carrying on conversations with people who are remote, you usually can't send them themselves. So the purpose of mix-minus: if there's somebody on the other end of a phone connection or an audio codec, and IP codec, or whatever it may be, an ISDN connection, you can't send them themselves. You need to send them everything on the console, except themselves and that's mix-minus.
So the fader that's bringing in your guest, your remote person, you want that fader to certainly go to program on the console, like everything else is, buy you don't want that fader to feed into the same bus that's back feeding to this remote person. So, how do you do that, if you have a console that can't do any mix- minus? Well, think about it, does the caller at the other end, do they have to hear absolutely everything or could they get by with just hearing the main mic, or a mix of all of the studio mics?
So at some stations you might go take a field mixer, like Shure mixer, or maybe something from Rane, and you'll put your mics into that, or you'll split your mics. Maybe the mics come in on several faders on the console, you can split those mic feeds, either with the split transformers, and whirlwind device. Or, you could possibly even just do a hard split of the mic and feed it to two places. Feed it to the console and feed it to this mixer.
Then you bring up all of the mics in this mixer and the output of that mixer is all the mics. You could even in other things if you had, but you certainly don't bring in the thing that you want to send the mix-minus, so you don't bring your hybrid or your codec into that, so usually it's just the mics. You take the output of this mixer and your feed that to the caller or the codec send and here you have a hack. You've just made a mix- minus or kind of a mixed-minus. You're sending the audio to the caller that they need to hear without having to have a mix-minus on the console.
I'll bet you've done that before, Chris.
Chris: Oh, yeah, back in the old days, yes. Some of the consoles I had we actually used the audition or sometimes we used to call it a P2 bus, and that would be my mix-minus. I would just tell the jocks, "All these buttons stay in, except that one labeled 'telephone.'" Sometimes I would have to just remove that switch, because some disc jockeys just like to play with things.
Kirk: Now here's a modern take on that hack, though. You just mentioned this key thing, if you set up the audition bus on a console as one mix-minus, but you need another mix-minus. Maybe you've got two hybrids, or maybe you've got a hybrid and you've got a codec and you need to create a mix-minus for each of these things. You've got an audition bus, maybe you can use that. Maybe you've got a utility bus, some consoles had that. Maybe you have a TEL or a telephone bus, some consoles had that that. Maybe you've got a non broadcast console, but got a Behringer or a Makie type of mixer and you have some auxiliary busses, well you can use those.
But the point here is that you the engineer set this up, "Okay, I want to assign this fader, and this fader, and this fader, and this fader into this bus." But if an disc jockey or an operator goes and touches a button, either he moves it from a bus where it should be or adds it to a bus where it shouldn't be, then you're screwed up. Then your mix-minus is no longer proper. Well in modern day electronic consoles, like from Axia or-I don't know, but I'm sure-from Wheatstone, or SAS, or other companies, these bus assignments can be stored.
Then if an operator messes it up you can recall a profile and bam. You're go to go again. You're back to the proper set up. This is a real, real benefit for stations who have operators that don't really know what a mix-minus is. They just know that it needs to work.
Chris, what's been your experience in this modern solution?
Chris: Oh, it works great. We had the Axia consoles in one place I was at and we built several profiles for people, so when they did that exact thing, they played around and made a mistake, they just knew to hit this one button that reset the console. We did the same thing with the VistaMax console system we recently installed in another facility. We also had profiles for that. Yeah, nowadays it's a no-brainer.
Like always say, most jocks, or studio operators, on-air presenters, I don't expect them to know the details about mix-minus or any of the other things we all take for granted, but I do try to offer them tools to find their way back home when they get lost. So it's sort of like a Hansel and Gretel, modern day bread crumbs.
Kirk: Again, I can't speak for other manufacturers, I don't know about their stuff, but a console like an Axia console every fader can create its own mix-minus. You don't actually have to use up a bus to do that, because it's all software. It's all DSP. They designer of the console has the opportunity to do that, say, "Every time this fader is in use, it's turned on, we're going to create a mix of all the other faders minus this fader, and make that available as an output." That works great, especially when you have an audio over IP type of system.
Okay, that was one hack. There's another hack I've got to mention before I have to get out of here.
So, Chris, you're familiar with the good old transmitter, the Harris, maybe it's an, FM5-H, maybe an FM 10-H, the H series.
Chris: Oh, yeah, I had one of those.
Kirk: Yeah. It kind of [inaudible 31:37]
Chris: [inaudible 31:37] 25K.
Kirk: Yeah. Yeah, well the ones that I'm thinking of are the ones that had the blower floor mounted in the bottom of the cabinet.
Kirk: Then the tube cavity started about mid-chest level, so there had to be a tube to get the air from the blower output, which is pointed up, from the bottom of the cabinet. You had to have a big tube to carry that air to the bottom of the tube cavity, where it would go in and hit the base of the tube, then flow past the first deck, and then go past all the tube fins, and then go out the top, a lot hotter than it started. Right?
Chris: Yes, exactly.
Kirk: So this tube, at least on the Harris FM H series, was a, I guess, a custom made canvas tube. Right?
Chris: Oh, yes. In the early days, yes, they were.
Kirk: Three and half feet long, maybe almost four feet long, three and a half feet long certainly.
Chris: That material would deteriorate.
Kirk: About that big around, and made of, I think, white canvas or an off- white canvas.
Chris: It was off-white, yeah.
Kirk: Really heavy duty stuff. Then the clamps, as I recall, the output of the blower was a square output and the input to the bottom of the cavity, wasn't it square as well?
Kirk: And there was some kind of square-ish clamp or was it really round?
Chris: On some models it was round. I think the early versions may have been square and then they found out that in the field it was becoming difficult to maintain. [inaudible 33:15]
Kirk: Well I'll tell you what the square ones did. This is the same reason, by the way, or a similar reason why airplane windows are not rectangular, they're rounded on the corners, because you don't want to present a place where there's extra pressure against the aluminum skin of the fuselage, because they were having tears and breaks on early pressurized airplanes.
So the same thing here, if you have this square output from the blower and you put a round canvas tube on it, and then you clamp the canvas tube with a square clamp, what you end up having is at the corners the points where the canvas is sitting there kind of tugging and pulling, and tugging and pulling, and vibrating all time, with the air going past it. It's putting a little pressure on this point at each of the four corners. So eventually the canvas gets old, it wears out here and it tears. It tears and it starts to tear along the line there. Before you know it your canvas tube is broken. You've got no more good solid connection for air between the blower and the bottom of the tube cavity.
So if you're out at a transmitter site in the middle of a bean field in Mississippi, and your canvas tube is torn up, and your transmitter won't run because you're not getting air to the tube cavity, what do you do? Well, one possibility is you take your pants off. You take your scissors or a knife and you cut a pant leg off and you clamp the pant leg. Now you've got a denim tube. Right? A pant leg, and you clamp it to the bottom and you clamp it to the top hoping that you didn't have the straight leg ones that were too small at one end, or maybe it's the boot cut, but whatever they are. Bellbottoms, those will work.
Chris: A boot cut would be nice and firm, and snug.
Kirk: Yeah, but if it was too snug it may not fit. It's got to be big enough to fit and you can't cut a dart in it to make it bigger, because that'll make it weak there and it won't hold the air anyway you clamp it. I actually never had to do this myself, but I came across it.
Would I have thought of this? Would I have thought to take my pants off and cut a leg off, and make a replacement air tube for the transmitter? I don't know. Would you have thought of that?
Chris: Probably at some point I would have, if I was desperate enough. But I will tell that I did have to use a-I didn't use pants legs, because in this case we had the blower motor itself fail, so it didn't matter what we stuck between the blower motor and the tube cavity-but I had to use the room air conditioner and I fabricated a mount out of, I think I used plastic packing material or was it cardboard cuts, and I'd put it over the louvers on a window air conditioning vents. I built a block and a small little circle and then on that would be-you know those flexible plastic wired accordion vent hose that you use for your dryer at home?
Chris: Well, we had a couple of those for something, I'm not sure why we had them, but we did. I said, "Okay." We took that and then stretched that out and put it to the back of transmitter, removed the blower motor, popped this bellows in its place and began to use the cold air from there to run it in.
So I was like, "Wow, this is pretty cool." Then I started to realize, "Wait a minute, if I remember my fluid dynamics and temperature differentials required for cooling a tube, I Mac Class 101, we are going to run into a problem in about an hour. Why? Because back in the day it was very popular to vent the hot air into the run, because you wanted to keep a closed system in you r transmitter building, so you'd minimize bringing in the dirt and dust by having negative pressure in the building. So negative pressure brings dirt in, positive pressure pushes it out; however, that's based on a certain dynamic, heat load versus cooling.
So now I've got an air conditioner that was not meant to cool a tube that's running at about-Well, it was 3 kilowatts. I think the temperature of the stack typically on a normal day was around 110 degrees-so yeah, the air conditioner wasn't meant to do that. So we then had to be then had to take the same bellows material, vent the tube heat out of the room. So we created sort of like, in the air conditioning world it's what you call a circulation through plenum. The supply comes into the room and the plenum draws it out. You create a high and low pressure environment.
It didn't happen in minutes. It took us a while to figure this out. I had to do a lot of reading books, the Internet didn't exist at the time, and it made it work. We were able to get by for about four days before the new blower motor arrived. The guys at the transmitter-it was a Rockwell Collins transmitter, now, at the time it was Continental Electronics managing all of that stuff- and the guys at Continental were like, "Wow, we would have thought be the second day the tube would have melted, but I guess you got the right differential between the in and out and was enough to maintain it." So, it worked.
So that's a hack and I'll never forget that one. That was a classic.
By the way, I just started working at this radio station out of college. I was there for six months and I was the young guy always coming up with these wacky things. I did some stuff with audio matrixing. I did some stuff in the studios. The engineer I was working with, the guy was 65 years old, and he's looking at me like, "You young kids think you can do anything." I was like, "No, I'm just having fun. Tell me what I should do better, because I'm learning under you tutelage."
Then he went on vacation, the blower motor dies. I had to come up with something crazy. He shows up at the transmitter site the next week, read the email-well the mail that we had. Yeah, we had email at the time, but just barely-and he was like, "Okay, I read this and I had to come see it for myself." He went out to the transmitter site on a Sunday, went into the room and saw this wacky contraption. He goes, "Wow. I never thought that would work, but that was pretty good." So it's just one of those things, those many hacks I've done, and stuff like that in the past. It's kind of wacky.
Kirk: Hey, we've got to take a quick break here. We're going to talk about our sponsor for just a minute and we're going to come back with some more engineering hacks. We've had a couple of good ideas here from Bob Halawanko [SP] in the chat room. If you want to join us in the chat room, do so. Go to GFQlive.tv, maybe you're already there watching live, and jump in the chat room. Talk about your favorite engineering hack or something that you think could be done, or that you have done to get around a problem. By the way, I'm sure there's been a few Western Electric 111c repeat coils that have been used as hacks to solve a problem.
Chris: Oh, yeah.
Kirk: Consider that. Our show is brought to you by-By the way, you are watching This Week in Radio Tech Episode Number 202. It's a Kirk and Chris show today. Andrew Zarian is going to be joining us in a few minutes, because I've got to jet out of here. I'm on a trip out of town, and I can't change the time, so I've got to go. Andrew Zarian and Chris Tobin will continue on with a few hacks.
Andrew, he's probably figured out a few hacks himself in the studio environment, so I wish I could hear the end of the show. I'll try to listen in the car. Oh, that might be dangerous.
So, our show's brought to you by the folks at the Telos Alliance. I want to tell you something that's kind of cool. Usually you wouldn't just advertise a website, but I want to have you go to the new Telos Alliance website, it is gorgeous and better than gorgeous, we're just filling it with lots of information. So if you go there at Telosalliance.com you'll see some big pictures at the top with a few of our favorite users: Tom Nelson, for example, at Minnesota Public Radio, one of the first people to put in a huge AoIP system; Dave Anderson of the Joy FM, he's been a guest on our show, using audio over IP, audio over the public Internet to feed his transmitter sites; Andrew Jefferies with Clear Channel Media in Los Angeles, a big fan of the Omnia 11 audio processor.
Okay, but more than advertizing, if you scroll down a bit over to the Tech Talk area and click on "Read More," it's going to take you to the opening page of our blog. This is our tech blog, so we give you a lot of great ideas. More are being added every week.
Here at the top of the blog, here, is an article posted by Clark Novak. It's about setting up Axia GPIO connections for AC and DC. It's an interview or some ideas from Laura Gutnecht the technical director at WUSM at the University of Wisconsin. She needed to get some GPIO connections going and figured out some good things there.
There's also how to direct dial your Z/IP One IP audio codec. How to get GPIO to run your one-air lights in an Axia system. There's an article and an accompanying video by me about doing easy Smartphone remotes with a Telos Z/IP One and the Luci Live software. Question too, like what's the maximum cable length between Axia components and an Ethernet switch.
So there's lots and lots of articles here and many, many more as well if you click on some stuff at the bottom. I also want you to take notice, though, of the signup sheet on the left, "Subscribe to Direct Current."
Now Direct Current is the new name for our newsletter. We used to call it E-News, and it was about once a month. Now we're sending out Direct Current about once a week. I don't want you to feel like you're going to feel like you're getting spammed, because Direct Current is not a bunch of advertising about Telos products. It links to this kind of blog articles and what other people are doing to solve problems in their studios and at their transmitter sites. So, if you'll check that out and subscribe to the Direct Current. It's easy to do, just fill out your name, and email address, and what company you're with, and what country that you're in, and Bam. We'll get Direct Current off to you. The phone number is optional; you don't have to fill that out if you don't want to.
Also there are lots of links for more of these articles that in this technical blog. Lots to see and lots to learn here at this Tech Talk Blog.
Oh, wow. If you've got a tip to share, let us know. If we use your tip we'll send you a license for Omnia A/XE Streaming Audio, valued at $395, so there's even some financial incentive to share your story with the Telos Alliance and maybe a hack that you're doing, or someway that you're putting our gear or our software to use.
All right, check it out. It's at Telosalliance.com. I appreciate them for sponsoring the show.
Oh, and all of our manuals are always available online, you don't have to signup, they're just there. You don't have to sign your life away and tell us everything like that, just download them.
All right, we are talking about engineering hacks on this episode of This Week in Radio Tech. It's worthwhile to point out that there's a guy who actually puts engineering hacks together every month-is it once a month or twice a month? At least every month- in Radio World magazine and that's John Bisset. John, now, actually works for Telos full time, but he's still doing-as far as I know, I've seen them-he's still doing his Workbench article. There's a lot of cool hacks, tips, and tricks, and ideas.
I was just looking through one, getting myself reminded about the DOS command, "ARP -A". This will show you all the other devices that have IP addresses that are on the same switch. Now it may not show you stuff that are being separated through a managed switch, but at least on a hub environment you can see other things that are using it. So, that's a real quick kind of IP scan, is the ARP command.
There's an article that John has about how to turn old iPhones- if you have an old iPhone, you might-how to turn old iPhones into security cameras. That's kind of an interesting hack. Actually I've done that with an iPad.
If you need an emergency replacement for a porcelain insulator standoff; well, your hardware store may have some PVC supplies that will help you with that. John wrote an article about doing exactly that.
There's an article about how to build a low-power dummy load that keeps the impedance right. It may be the equivalent of the old cantenna that Heath Kit [SP] used to have. Putting a scrape satellite dish to good.
So, I just did a Google search for John Bisset. I searched for John Bisset and Workbench and found a link to it, just a whole bunch of John's Workbench articles, great hacks.
All right, Chris, what else have you got for us? Do you have any more hacks that we can talk about, idea starters?
Chris: Yes, actually this is going back to the old school stuff again. Well, actually you can do it today, because it's probably out there. If you recall, there was a transition time period between the old dedicated copper loops, dedicated lines between transmitters, studio to studio that you get from the phone company, 15-kilohertz loops. Then they migrated to something called digital technology, which allowed to take the same wide- band uncompressed audio you'd normally put into a phone line, but digitize it and put it across a single pair of wires to the central office, and then pass it on the other [end], the studio or transmitter link, or wherever you're going. Those products were made by a company EXEL and they used to call them "Program Channel System Units."
Now, I had come across these units, we used them in many places over the years, and I wound up collecting some of them, because the phone company would leave them behind we would abandon sites. One day I got a hold of the paperwork for it. If you can see this-I don't know if it comes out okay. It probably won't.
Kirk: Yeah, it's all right.
Chris: Yeah, I've got to get the right angle. In any case, I started reading the little spec sheet that came with them and realized that these units can be setup in a master/slave arrangement over a pair of wires, so I said, "Wow. I'm doing some remotes in a music arena and I need to get some audio from backstage out to our front of house console and the place says we can use their in-house wiring." We tried to use them and the buzzes, and noise, and clicks and we were like, "Oh, boy."
So I had a pair of these units and I was like, "Ah, give it a try." I took out a Beldon roll of cable, spun out the 8451 from the back of stage out the front where we were, through the cable tray, put the slave unit at the stage side, put the master at my end, and guess what I got? 15 kilohertz uncompressed stereo back to me. I'm like, "This is pretty cool."
Fast forward a few years and Pulse Com comes out with the APTX version of this same thing, which means you can do compressed audio over longer distances, because it was designed that way, because it uses 2B1Q modulation.
I did the same thing for a news event. We were doing a press conference, couldn't get the audio where we needed to because of the location, roll out some cable, pop these guys on, and we had it. So, it's a hack, but it's something you may not come across often, but I bet you a good percentage of people in the audience have these units sitting on wall in a phone closet doing nothing. If you have a pair of them you can actually make little umbilicals. Granted today you could buy all the things that do the same thing in IP, but it was just something we did. I carried them in little road case and kept them for remotes. They came in very handy on many occasions.
Kirk: I love it. I love it.
Hey, Chris, I'm going to give you one-or you may have your own-I've got to leave right now, but I want you to wrap the show up in the next five, ten minutes or so, but I want to give you this notion. Remember the days when we used those 111C repeat coils, to use an unloaded dry telephone pair from a studio to the transmitter, right?
Kirk: Then we came up with doing this in stereo, so we had a 111C repeat coil for the left and for the right. At the other end we may have had an equalizer, probably did, but you could also run it through a transformer first. The point is these 111C repeat coils had just the most perfect center tap on them, on both the input side and the output side.
Now, with a stereo pair of these, so you've got four wires from here to there, terminated at each end, each pair terminated by a transformer that had a center tap on it. Add another pair of transformers, so now you have a total of six transformers. What was the hack that you could do to get some free audio from here to there?
Chris: That's interesting. I'm trying to remember that. I used to do DC between the coils to do [inaudible 50:03]
Kirk: Oh, DC from the center taps, but you could . . .
Chris: I did that for a couple of things.
Kirk: Granted you might hear some crosstalk way down, 60, 70, 80dB down, but you could take the center tap of the left transformer, take the center tap of the right transformer-now this is on the phone company side-take the center taps there, bring those taps, one from the left channel one from the right channel, brings those taps to a third transformer. Then on the other side of that transformer apply you audio.
At the transmitter site do the same thing, center tap, center tap of the telco side, go to another transformer. Basically you're sending audio in the common mode on the left channel, and the common mode on the right channel. As long as there's nothing stupid in the way, between the two sites, this would work fine. You could get a free audio channel. You could send audio in either direction with this thing. Right?
Kirk: So I used to it bring-we had a Marty [SP] receiver at the transmitter site, because it was up high on a hill and great reception from there, so we had a Marty receiver in the transmitter shack, and antenna way up on the tower. We had this Marty audio, but how do you get it back to the studio? Well, you could inject it in the subcarrier of the FM, and some people did that, but there was a real audio quality limitation there, about 6 kilohertz or something like that.
So we built up this phantom audio circuit from the existing left and right center taps, and got audio back to the studio. We did have a little tiny bit of crosstalk. If you were using the Marty for a remote on the AM station you could hear little bit of crosstalk on the FM, but if you're using for a remote on the FM you never noticed it, because was almost in phase and it just worked fine.
Chris: That's great. I actually worked at a station and we did have that kind of a setup. I totally forgot about that.
Kirk: There you go.
Chris: That was a long time ago, but we did the exact same thing. It was for the Marty it was for the [inaudible 51:58]. I remember there was a note on the receiver-I think this is how we got by the crosstalk to some degree-I do remember between the phone points, it's 150 ohms, and the customer side is 600, and there was a note on the receiver that said, "When the phone line is connected, do not exceed -10 DbM, or something, on the output of the receiver." I was like, "What the heck is this about?" Then at the other end we have a preamp that would bring it back up to get into the console.
Now that you mention the crosstalk, that's probably what it was. I'd never even thought about, because at the time we were just doing things that make things happen, but that would make total sense.
Kirk: Yeah, I know.
Chris: I used to do DC between the coils and do relay controls for transmitter stuff.
Kirk: That's a good idea, yeah.
Chris: Of course, the phone company's going and doing testing and their going, "Beep," of course with the [inaudible 52:52], and they're like, "What the heck was that?"
Kirk: But you were using common mode of each side, but you were making another pair from . . .
Kirk: Yeah, yeah, by doing common mode.
Chris: Oh, yeah, yeah. A couple of times the guys at the phone company would call up and say, "Hey, we think we have a leaky cables situation. You've got DC on your pairs. We're going to have to take it offline to fix it."
Kirk: "No, no, it's okay."
Chris: I'd have to quickly call them back, "No, no, I think the problem's solved. There was a guy the other day." I did it with the voltage off the line.
Kirk: Problem solved.
Chris: And they'd call back, "Hey, you're right, it's gone." "Okay, thanks." And we're like, "Oh, there's goes that little freebee."
Kirk: Hey, audience, thanks for being with us. Stay with us, Chris Tobin and Andrew Zarian are going to you out of here. I've got to run. You guys have a great week. We'll see you next week on This Week in Radio Tech.
Chris, if you'd wrap it up at your conveniences, whenever you want to. I've got to go. See you guys later.
Chris: All right, Kirk, safe travels.
Chris: All right, audience, now we're going to go to the chat room and see what we have. We were talking earlier about antennas. Andrew, are you going to come in on the voice only side of this?
Andrew: I'm here on the voice only
Chris: This is a voice-only operation, okay.
Andrew: But I do have a couple of questions for you, Chris.
Andrew: Some podcasting hacks, if you want to talk about that.
Chris: Sure, why not.
Andrew: There's a lot of corners that a lot of podcasters need to cut due to financial reasons, or at the last second something breaks. Something that I had to do once, I had a problem with my main mixer. It totally went bad. It was a Mackie mixer. It just died right before I was supposed to go on the air, so I had a smaller mixer. I hooked it up, but the problem was I didn't have enough outputs out of that mixer. I had a main out and I had a tape out, and that was it, nothing else.
So what I ended up doing was, I took the main out and I got a distribution amp, a RCA distribution amp, plugged it in there, and then I distributed the audio to all of the devices that needed to hear the audio. Not the best way to do it, but it worked.
Chris: Well, actually no, that's a good way to do it, because the key with distributing audio is to keep the impedance or the levels between devices equal, so the distribution amp actually provides that buffer. If you just did a hardwire, like I've walked into a couple places that called me up and they said, "I'm having issues with my levels on my devices. I don't know why." I walk in and they've taken their RCA output and just spliced more RCA connectors on to the one output and plugged it in to all of the devices. It's like, "Well, there is a certain amount of electronics mathematics that goes into this, and once you start doing that it creates havoc." So using a distribution amp, though it may appear to be a hack, is actually the proper way.
Now, using RCA jacks, which is unbalanced audio, is not a bad thing as long you properly terminate, and connect, and do the right things and then you're off to the races.
There also a hack that used to be in one of those trade magazines. I don't know whether you can see this. I've got to change my lighting here.
But in any case this allows you to take a balanced connection and make it unbalanced. So for a cheap little schematic like this, you can still use your unbalanced mixers with the professional equipment if you happen to be receiving donations from, let's say, a radio station somewhere. It's just one of those things. So that's a hack that you can do that's really cool.
Andrew: It's interesting, now that we have the Axia gear in the studio, I've kind of forgotten a lot of the crazy, weird ways we used to do things. And every now and then, I'll be cleaning up the studio or something and I'll be like, "Wow. I can't believe we did it that way. I don't even know how it worked, but it did."
Chris: But see, that's how you get to the places we're at today. Okay, GFQ starts out in the infancy of an idea, it's migrates to or evolves to another idea. Then as you go along that path you do all these little hacks and that's what gets you farther along. Then the day comes when you're able to graduate, if you will, to the higher level and now you don't have to worry about hacking anymore.
But you wouldn't have gotten to the higher level if you hadn't done the learning process, because if you did, somebody just walked up to you five years ago, "Here you go, guys. Here's a brand new IP distributed audio system for you to play with," and then go off. You would have no idea what it would take to do it right. You'd do stuff and it'd be like, "This thing sucks." But, because you went through a graduated evolution you learned the principals, the foundation, and you say, "Hey. I can appreciate what I've got now, because of where I came from."
That's what podcasters need to remember, those of us who are doing stuff at home or a home office, it's not a bad thing, just learn from what you're dealing with. It's like Andrew pointed out, "I had a distribution amp. I had the RCA. I only had this one way to do it." That's right. That's the proper to do it and you happened to stumble across the proper way. No one told you that, but you just assumed it was bad.
Andrew: Sure, some of the other things we do wrong is-it's not necessarily a hack, but more like a tip-a lot of people are not doing Tip, Ring, Sleeve, they're not using TRS cables. A thing that plagues a lot of podcasters is an awful ground loop.
Chris: Well, that's because most folks today, unlike many, many years ago, which was a do-it-yourself environment, if those of you who are in the audience remember, there was Radio Shack where you could buy parts to build things. There was Lafayette Radio Electronics and many other places, and you would build stuff. So you knew the difference between a Tip, Ring, Sleeve, TRS cable and a tip, ring only cable, like a RCA jack. You understood what the difference is and why you need to do so. Today, we're so accustomed to being able to buy something off the shelf, you plug it in and it works. In the computer world it just happens to work most of the time, so we don't even bother to learn the foundation. This goes back to what I was saying earlier with the evolutionary steps that GFQ took to learn what they have today.
So learn those basics and then tip, ring, sleeve is easy to use, and you'll be like, "Oh, now I understand why I'm not having any more problems. This is great."
I hope that helps.
Andrew: But that RCA distribution amp really went a long way for me, for a while, until I got my mixer back.
Chris: Yeah, but that's what they do. That's what you use them for. Trust me, I've built many a facility where we had 15, 20 distribution amps in a rack, and we were distributing audio to a plant with 27 studios, 56 channels of satellite up linking audio, and that's the way we did it. But every one of them, when you put a tone in, let's say zero dB on the meter, they can't [balance] zero dB everywhere else in the plant, because that's what you needed to have. If we had just done it the old fashion way, which some people used to do, which was just to split the wires, at some point we would probably have some places where it just didn't work right.
So that's how it goes. It's not a bad thing. What else have you got?
Andrew: You've been in the studio and we've discussed this a bunch of times. I mean, most of the time when we grab a drink we're talking shop, and we're talking about ways to kind of get things to work properly. In the podcasting world, I think, cutting corners is very common. I kind of encourage it. Learn how to do it on the cheap and learn how to it properly, like with sound proofing, for example.
None of us a broadcasting in great sound-proofed studios or rooms. A lot of times you hear a lot of room noise. Something that I did, I got these curtains from, I think it was Target, and they're supposed to be sound-dampening curtains. They're not any special, nothing that you pick up in a music store, they're just regular curtains and it says "Sound Dampening," on them. They're a thicker material. I'll tell you, Chris, it really changed the sound of the studio.
Chris: It will. Well, there's two things to remember, sound proofing and sound treatment are two different terms and two different applications of the technology.
So, here's how it goes. What you did was sound treatment, so the room itself needed treatment, because the four wall-or three depending on where the room is-needed to be treated, because they were reflective. [inaudible 01:00:46] the room's liveliness, which remember in audio we're so accustomed to hearing things in the stereo mode, two ears, or what they call binaural. So our brains automatically adjust for things, so when we walk into a room that's very loud and echo-y, I'll call it that, your brain automatically knows how to compensate for those echoes and sort of subdues them, or subtracts the enough so that you can hear what's important. Microphones, radio equipment, podcasting encoders do not do that. They will take whatever they hear and pass it on.
So in the case of GFQ's studio, which was very lively, if you walk into a room, snap your fingers just above your head, and if you hear it reflecting back and forth, bouncing back, and listen to how long it takes to bounce back, that's the degree of the liveliness of the room. So the sound treatment is used to reduce those echoes. So by you using the curtains, the fabric that you got, hanging it up on the walls, and depending on where you place it in relation to the microphone, helps to reduce the reflections.
Now, you don't want zero reflections. Zero reflections makes a dead room and it becomes very uneasy to talk in. Your ears need to have a little bit of noise in order to understand balance. Trust me, if you've ever walked into a studio that was totally sound proofed and isolated from the building itself to create completely isolated environment, you walk in and you suddenly stop and you sort or lose you balance. You body says like, "Whoa, what happened?"
So this is just the background. I'm not expecting people to understand the full physics involved, but that's the difference between sound treatment and sound proofing. So I'm in a room that is not sound proofed, but I've treated two of the three walls so that the amount of echo that I have is minimal. If I stay close to the microphone, where I'm at, which is a typical distance, you know the old thumb and a pinky, it should be reasonably acceptable to use. If I step back, like this, you should start to hear a little bit of the room, because I have the ceiling above me and a wall to the side that's not treated, so that's what you're going to hear. That's how you learn to balance what you have.
Sound treatment is the easiest way to go. Think of it as light. You speak into a microphone, the sound goes into the microphone, goes past the microphone to whatever object's beyond you. So if that object is reflective, like an LCD screen of a computer, the odds are you're going to get something reflected back. Now when it reflects back, it doesn't only come back to you straight it may come back to you at an angle to the tabletop, so now the table top becomes a reflector. So now you have two reflections and if those reflections come back in the wrong way, guess what? It sounds "phase-y," and you don't know why it doesn't sound right. That's what they call comb filtering.
So the trick is, sound treat the walls. Try and uses a sound treatment on the tabletop if you can. So if you have a glass tabletop, that's very reflective. Get like a rubber mat, a nice little rubber mat and that will help reduce the reflections. So now the microphone is strictly hearing mostly audio reflections from your voice and maybe what's behind it. Because the odds are you have to have a LCD computer screen, so were' not going to make that work, but if you minimize the other surfaces, now you've created a much cleaner sound. Then you can also turn the gain up on the microphone, you can do things. You don't have all the room noise coming in your way.
Did that help to understand things?
Andrew: Very cool. Very cool. I think we're at the end of the show.
Chris: Is it that time?
Andrew: It is that time.
Chris: No show coming up?
Andrew: No other show coming up.
Chris: All right it's-oh yes, that's right, was it Mat Men?
Andrew: Mat Men.
Chris: Yes, excellent. [inaudible 01:04:12] studio today?
Chris: Excellent, that's the way to do it. Okay, I think you need to get a mat in that studio and start doing some live demonstrations.
Andrew: I don't know if that will work.
Chris: Oh, come on. Well, you can do it in that other area that you cordoned off, just roll up the carpet, that's all.
Andrew: That's it, that's what I'm going to do.
Chris: All right.
Well, this is going to be the conclusion of our great Episode of 202- Two hundred and two, wow. That's wild-of This Week in Radio Technology. I'm Chris Tobin along with Andrew Zaria, who's our producer, board operator, and gracious host of the GFQ Network.
Kirk Harnack had to leave early. He's hopping a flight to Haiti. He's also gotten his shots, those of you who may be concerned. He's feeling good about it. Of course, once you take those shots of Hepatitis and other things you're never the same for 24 hours, but then again that's just Kirk.
Anyway, that's where we're at and we're going to be on our way. For now, Mat Men comes up after us. Well, that's for this one. I shouldn't say that now.
This concludes Episode 202 of This Week in Radio Tech. Goodbye.
Topics: Radio Engineering
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