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Church and H.O.W. – Forums for HOW Sound and AV - Your Displayed Name Must Be Your Real Full Name To Post In The Church and HOW Forums => Church Sound => Topic started by: Don Sullivan on February 04, 2013, 11:23:00 PM
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I often find myself working with low budget churches, bands, or starving musicians. They want wireless ears but don't have the dime to drop hundreds on that level of pro gear.
While there are wired solutions around that work pretty well, I looked on Amazon and found some low power (100mw-500mw) FM stereo transmitters. I figured I would give one a shot, and it worked very well, though it took some careful setup. Here's what I did - YMMV.
I bought the SainSonic 0.5W Long Range (10km) Dual Mode Stereo Broadcast FM Radio Transmitter (in *Fashion Black*); there are other models but this was the only one that clearly contained all the moving parts. Wall-wart power supply, 1/4 wave antenna, transmitter. There is at least one transmitter on Amazon with switchable 100/500 mw power. This one is fixed at 500 mw (1/2 a watt).
The SainSonic was roughly seventy five dollars. Free shipping with my "prime" account.
I received the transmitter, and just like so many high quality low price items from the far east, - no manual, but it couldn't be easier to operate. Plug in the power cord, 1/4 wave antenna, a line source, select a broadcast frequency adjust the input level and you are on the air.
The line input on the SainSonic is a front panel 1/8 in stereo consumer level (or lower) input and is easy to overload. My first test was to simply play some music from my tablet into the transmitter and listen with an mp3 player which also has an FM tuner (Creative Labs-Zen I had lying around) I walked around the house and this little guy was covering well over a hundred feet very well. I did not try longer distances as I don’t expect to really need more than 200 feet, conveniently the FCC limit for part 15 low power transmitter operation. I checked- The FCC part 15 rule permits low power FM broadcasting (under 200 feet). I'm no lawyer, so don’t take this as legal advice.
But what frequency to use? This thing broadcasts on the standard 88-108 MHz band all our local FM stations occupy. Fortunately radio-locator.com has a vacant frequency finder. Just put in your location and it will list the frequencies nobody in the area is licensed to broadcast on. The bad news here is for people living in highly-populated areas like New-York city. There are NO vacant frequencies there, so if you are considering this approach - check your local listings. You may still be able to over-power local stations within the building you are in, but that doesn’t mean your FM receivers will discern your signal enough to be useable, so be warned. You also don’t want to go around broadcasting on top of licensed stations your neighbors may be enjoying. A 200 foot broadcast can affect a lot of people in a densely populated area, so be considerate.
The other thing I noticed is that if this little guy is close to unbalanced cables it will easily modulate a signal onto the cable or into equipment that may not be well shielded. So much for setting this thing on the FOH console. Still, I was pleasantly surprised with the quality, so I decided to use the transmitter / mp3 player in a live setting.
Without announcing to anyone what I was trying I sent a monitor feed to the transmitter during rehearsal. I should say two monitor feeds as the unit is stereo and I did not have a y cable handy. The transmitter does not have a "mono" only or sum operational mode, as most pro in-ear transmitters do.
Did I mention the unit is easy to overload? You bet. If you try this using an analog mixer you'd better use a compressor between your output and the transmitter input. Fortunately I was using a digital desk with compression available everywhere, so no problem. (Yet another reason to go digital!!) I experimented with various thresholds and ratios and ended up running 2.5:1 ratio with a very low threshold (meaning everything is compressed) zero attack time, and a generously long hold/release. The whole time I was making adjustments I was listening to my Zen MP3 player FM radio receiving the mix I was broadcasting. A limiter may have worked just as well. Again, this adjustment is very subjective but some compression / limiting is absolutely required.
After a few songs I brought the Mp3 player / FM radio with some cheap new skull candy ear buds to the lead singer and asked her to try them. She smiled from ear to ear the rest of the rehearsal, and through the next services. She sang better, kept in pitch, and I was able to drop her from the wedges, significantly reducing stage volume and feedback potential.
The bass player saw what I was doing and pulled out his HTC EVO phone. It has an FM radio. Now he had ears. Cool freebie.
So between the transmitter and receiver I'm in for a hundred bucks. Far less expensive than pro-wireless ears and the cost of adding another listener is minimal, zero for the bass player. Most of the bands I work with can get by on one or two monitor mixes, so I will be picking up another FM transmitter soon for the guitar players.
Is this for everybody? Absolutely not. Is this as good as pro wireless in-ear monitors? No way. FM transmitters do not have the dynamic range the pro units deliver. If your artists are very discerning, they may not like the sound. Then again, for a low budget solution this has real promise.
This unit also has potential as a hearing-impaired broadcaster, and a parking-lot FM transmitter. Some progressive churches have members who don’t want the loud music (like anything with a guitar) but want to hear the message. With one of these units members can tune in before coming into the building.
Again your mileage may vary, but this is pretty cool. :)
Don--
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Nice info, I'd been thinking about trying something like this so it's good to know it works. The band I work with changes instruments regularly(sometimes multiple times per show) and my initial idea of using wired IEMs for some of them hasn't been working very well... That and the drummer didn't like them because they were mono and he sounded like he was in a can.
Sent from my iPad using Tapatalk HD
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I walked around the house and this little guy was covering well over a hundred feet very well. I did not try longer distances as I don’t expect to really need more than 200 feet, conveniently the FCC limit for part 15 low power transmitter operation. I checked- The FCC part 15 rule permits low power FM broadcasting (under 200 feet). I'm no lawyer, so don’t take this as legal advice.
The actual rule for Part 15 transmitters operating in the FM broadcast band states the field strength can not exceed 250 microvolts/ meter at 3 meters. This translates to approximately 200 feet of usable signal strength given unobstructed propagation path; it is not the absolute. This extrapolates out to a transmitter with about .1mW RF power. I guarantee you your 100mW-500mW does not meet Part 15 Subpart C technical requirements. Further, if it doesn't have an FCC ID number, it's not legal to sell or use [with an appropriate license] in the US.
How did it sound?
Edited .1W to .1mW
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The actual rule for Part 15 transmitters operating in the FM broadcast band states the field strength can not exceed 250 microvolts/ meter at 3 meters. This translates to approximately 200 feet of usable signal strength given unobstructed propagation path; it is not the absolute. This extrapolates out to a transmitter with about .1W RF power. I guarantee you your 100mW-500mW does not meet Part 15 Subpart C technical requirements. Further, if it doesn't have an FCC ID number, it's not legal to sell or use [with an appropriate license] in the US.
How did it sound?
Like I said - I'm not an attorney but it sounded great. I'm buying another one. I wonder how powerful those ipod-fm transmitters are? :)
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Like I said - I'm not an attorney but it sounded great. I'm buying another one. I wonder how powerful those ipod-fm transmitters are? :)
Be careful; you're operating a transmitter illegally.
Those iPod FM transmitters that meet FCC technical specifications and have FCC ID numbers are generally a couple of microwatts.
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Be careful; you're operating a transmitter illegally.
Those iPod FM transmitters that meet FCC technical specifications and have FCC ID numbers are generally a couple of microwatts.
Don,
I would listen to Henry. He knows what he is talking about. Your doing something illegal! Your also doing it at a church. Please stop.
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Don,
I would listen to Henry. He knows what he is talking about. Your doing something illegal! Your also doing it at a church. Please stop.
Not only that, but you're now permanently "on record" as having been informed of the problems. You can no longer claim "ignorance of the law" though, as they say, that's no excuse.
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Ok I'll stop with this transmitter. Perhaps I can make the micro-watt transmitters work over 60 feet?
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Ok I'll stop with this transmitter. Perhaps I can make the micro-watt transmitters work over 60 feet?
Sounds like you have a decent, cost effective, solution for your musicians.
It should not be difficult to find a transmitter that meets the legal requirements.
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Ok I'll stop with this transmitter. Perhaps I can make the micro-watt transmitters work over 60 feet?
FCC Part 15 Compliant - We meet FCC Part 15 rules so you don't need a license to broadcast.(FCC ID: 2ABT5AX05B7C)
http://www.radioddity.com/us/czh-05b-0-5w-fm-transmitter.html?kpid=142_us&gclid=CMDIydz40MMCFe_m7AodihMA0w
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FCC Part 15 Compliant - We meet FCC Part 15 rules so you don't need a license to broadcast.(FCC ID: 2ABT5AX05B7C)
http://www.radioddity.com/us/czh-05b-0-5w-fm-transmitter.html?kpid=142_us&gclid=CMDIydz40MMCFe_m7AodihMA0w
Yes truth in advertising. Hmmm? So for the people that are not technicians and are church musicians and volunteers this is a problem because we trust the adds.
I would advise that a letter to the FCC with a description of the usage and the item (transmitter with the ID number). If a response comes back from the FCC than one would keep that on file to show you had asked and received permission and approval. Adding in the rough frequency to be used on the routine basis and the time of the services would show your not for profit home radio DJ.
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FCC Part 15 Compliant
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Mac
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Ok I'll stop with this transmitter. Perhaps I can make the micro-watt transmitters work over 60 feet?
I only scanned the report, it's a little noisy but not bad. Certainly within limits of the device. It is also the type certificate for the listed device. Certainly looks legal to me.
https://apps.fcc.gov/eas/GetApplicationAttachment.html?id=2216822
All documents on device in FCC records:
https://apps.fcc.gov/oetcf/eas/reports/ViewExhibitReport.cfm?mode=Exhibits&RequestTimeout=500&calledFromFrame=N&application_id=686762&fcc_id=2ABT5AX05B7C
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Ok I'll stop with this transmitter. Perhaps I can make the micro-watt transmitters work over 60 feet?
Nice write up - though the legality seems to be an issue. I'm surprised latency is not an issue with them. But if the singers and players are happy...
And of course, the others are right - get legal/permission. You really don't want to expose your church, with admittedly limited funds, to a hefty fine from the FCC.
Micro-watt transmitters going 60' - An option is to place the micro-watt transmitters on or close to the stage so the 60' distance problem goes away. The transmitters don't really have to live at FOH - they could just as easily live at the end of the return snake.
frank
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Hi Don,
The concerns stated here regarding the (il)legality of using this gear for IEM use are accurate and valid. One more thing to consider is that the purpose of the transmission, modulation scheme, transmission frequency, and transmission bandwidth are all relevant parameters for the legality of Part 15 transmissions. For example, open mics transmitted via IEM is a completely different application than transmitting your MP3 player to your car stereo, and the FCC does recognize the difference.
For a more concrete example, consider that language translation systems and hearing-impaired assistance systems are strictly regulated to the VHF bands, regardless of the technical feasibility of using UHF IEM systems to accomplish the same objective.
It's important to know the rules as they apply to you, and to be a good citizen by doing your best to comply. Especially in the service of your congregation. After all, He did say, "Render unto Caesar the things that are Caesar's, and unto God the things that are God's." I'm in the camp that translates "Caesar" into "Uncle Sam". :-)
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Hi Don,
The concerns stated here regarding the (il)legality of using this gear for IEM use are accurate and valid. One more thing to consider is that the purpose of the transmission, modulation scheme, transmission frequency, and transmission bandwidth are all relevant parameters for the legality of Part 15 transmissions. For example, open mics transmitted via IEM is a completely different application than transmitting your MP3 player to your car stereo, and the FCC does recognize the difference.
For a more concrete example, consider that language translation systems and hearing-impaired assistance systems are strictly regulated to the VHF bands, regardless of the technical feasibility of using UHF IEM systems to accomplish the same objective.
It's important to know the rules as they apply to you, and to be a good citizen by doing your best to comply. Especially in the service of your congregation. After all, He did say, "Render unto Caesar the things that are Caesar's, and unto God the things that are God's." I'm in the camp that translates "Caesar" into "Uncle Sam". :-)
It's a type accepted device. FM Radio is 15Khz of bandwidth, it deviates 7.5Khhz either way if modulator is fully driven,
The type acceptance testing was conducted with several different AF frequency and both IF and spurious emissions were within limits.
Not sure what is making you think Jason that the use is contrary to Part 15
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It's a type accepted device. FM Radio is 15Khz of bandwidth, it deviates 7.5Khhz either way if modulator is fully driven,
The type acceptance testing was conducted with several different AF frequency and both IF and spurious emissions were within limits.
Not sure what is making you think Jason that the use is contrary to Part 15
Hi Scott,
I wholly agree that the type certification is a hugely valuable resource, and I thank you for the link. It reveals much about the equipment's capabilities, limits, and intended purpose. I also agree that the application does not directly violate Part 15, but it is notable that the manufacturer's Declaration Letter For FM specifically states, "This product is designed to transmits audio signal from mp3 player or MIC, etc," I honestly don't know what they intend "MIC" to mean. If they meant microphone, an abbreviation would not be suitable for this document. Its 7.5 KHz deviation indicates, to me, that it is not intended to be a high fidelity system suitable for professional use (which HOW applications certainly are), and the commission enacted authorization based on this declaration.
Bottom line is that it is highly unlikely that anyone would be cited or fined for using this extremely low-power equipment in the OP's application, and your excellent research supports this. I just hope to spread the word about the intricacies of the FCC's rules and the importance of studying and understanding them before we step way outside of the norm to achieve our objectives.
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Hi Scott,
I wholly agree that the type certification is a hugely valuable resource, and I thank you for the link. It reveals much about the equipment's capabilities, limits, and intended purpose. I also agree that the application does not directly violate Part 15, but it is notable that the manufacturer's Declaration Letter For FM specifically states, "This product is designed to transmits audio signal from mp3 player or MIC, etc," I honestly don't know what they intend "MIC" to mean. If they meant microphone, an abbreviation would not be suitable for this document. Its 7.5 KHz deviation indicates, to me, that it is not intended to be a high fidelity system suitable for professional use (which HOW applications certainly are), and the commission enacted authorization based on this declaration.
Bottom line is that it is highly unlikely that anyone would be cited or fined for using this extremely low-power equipment in the OP's application, and your excellent research supports this. I just hope to spread the word about the intricacies of the FCC's rules and the importance of studying and understanding them before we step way outside of the norm to achieve our objectives.
Thanks Jason, wasn't much research, I just entered the type acceptance number into the FCC's DB and breezed the document to see if they had used a pro forma application that didn't match the gear.
I think the key is that if the article is type accepted an end user has done their due diligence and can operate the device in any commercial or residential setting.
The reason I posted was beating the OP with the regulatory hammer was the wrong tack. Clearly the OP understood the limitation, utilized some compression and EQ to get where he need to be and saw an improvement in the overall production. He shared his success in the hope in would benefit others. Pointing out technical limitation is great, scaring people away that the radio cops will haul them away to the S&M chamber was a bit much.
I usually simply list my day gig as IT, but I am actually now a network engineer and have 30 years of telecom. After a brief stint with the LEC I worked for a paging carrier for many years that later was the non-wireline cellular company. I have quite a bit of self taught RF engineering knowledge from the experience. I stayed in telecom until 1999 when I was the lead Switching Engineer for Sprint's Motorola CDMA FoA application, it's how I ended up in Cleveland. Being around the CDMA braniac's and the drive test team I absorbed quite a bit via pure osmosis.
Operating a non type accepted device and causing interference by modifying a type accepted device (IE: wifi hi gain antenna and amplifier) is very serious. If the users of the spectrum are savvy you will have an enforcement action on your hand. This is especially true with wireless MIC's that operate in the PCS spectrum. These can wipe out several cell sites in a dense urban area. The cellular carriers have their own cops and you will get a visit. If you don't cooperate they will file a complaint with the FCC and sit outside your door collecting emissions history with a spectrum analyzer.
The FM radio spectrum, unless you put this thing on the rooftop of a high rise with a 9db antenna and launch a pirate radio station you will not catch the attention of the enforcement folks.
Keep up the good work Jason.
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As everyone responds… keep in mind that the OP is from 2013……….. :D
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As everyone responds… keep in mind that the OP is from 2013……….. :D
Ray, wow, major attention to detail failure.
This revival occurred because the vendor posted to this thread. Must have come up on a Google search of their product. Interesting.
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Ray, wow, major attention to detail failure.
This revival occurred because the vendor posted to this thread. Must have come up on a Google search of their product. Interesting.
Oh yeah, I figured that's why it came up again. At the same time, since it was originally posted Feb/2013, same month, year looks almost the same at a glance… I wanted to heads-up people so we don't spend a lot of time helping an OP that… has… probably… resolved… their… concerns… in the last 24 months. Heh.
Still good reading, though, don't get me wrong! :)
-r
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FCC Part 15 Compliant - We meet FCC Part 15 rules so you don't need a license to broadcast.(FCC ID: 2ABT5AX05B7C)
http://www.radioddity.com/us/czh-05b-0-5w-fm-transmitter.html?kpid=142_us&gclid=CMDIydz40MMCFe_m7AodihMA0w (http://www.radioddity.com/us/czh-05b-0-5w-fm-transmitter.html?kpid=142_us&gclid=CMDIydz40MMCFe_m7AodihMA0w)
Resurrected by a newbe who didn't use their real name. Missed all of that (blush)
frank