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Technology

Making Your Headphones Wireless? 67

Posted by Cliff from the wireless-headphone-kits dept.
Chuck Chunder asks: "I've recently been looking at getting some wireless headphones of the RF rather than infra-red variety. After looking around for a bit it struck me that I don't actually want a whole new set of headphones. I already have a nice pair of headphones as well as earphones. What I really want is an RF transmitter and a small clip on receiver that I can plug my existing headphones/earphones into. The problem is, I can't find anyone selling what I am describing, even geeky places don't quite have what I'm looking for. Does anyone know/have experience of such a product?"

"I see several advantages to this:

  • Adaptability: I can then use earphones/headphones as appropriate for the activity, or possibly use it as an RF link between hardware in different rooms
  • Replacability: If I damage the headphones I only have to replace them, not the whole headphone/receiver unit; this bit will hopefully lead to...
  • Lower costs
Has anyone seen something like this, before?"
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Making Your Headphones Wireless? More

Making Your Headphones Wireless?

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  • This won't work (Score:2, Informative)

    by PhysicsGenius ( 565228 )
    RF devices suffer from a great deal of interference in the high-end band from sources such as sun spots, satellite traffic and meteor showers. Headphones, being small amplifiers, will only make this static louder. I suggest you buy a longer cord.
    • Either make the headphones digital, eliminating all of the static, or use headphones like mine, which don't use RF at all and instead modulate the sound over IR.

      My experience with wireless headphones has been quite good, and there's absolutely no reason why decent quality sound can't be transmitted a short distance. Just look at 802.11b, for example. More than enough bandwidth for full CD-Audio quality. If it comes down to it, why not integrate this into your home theater?
    • Of course it will work. I've done this before. Get yourself one of those cheap FM transmitters that transmits in the normal 88-107Mhz band (it's low power). I think radioshack even carries them (or they used to...) Searching google works too. Then get a cheap AM/FM "walkman". I have a freebee from some tradeshow that's only about 1/2" thick, 1-1/2" square, with a belt clip. Works great.

      Sun spots... Good grief. They guy is going to be a few feet from the transmitter. All sources of interference except from his computer will be a non-issue.
      • Radio shack used to carry only one FM transmitter, and it was the biggest piece of junk ever made, the employees stated 9 out of 10 of them got returned. Some radio shacks now carry a different FM transmitter called the "Irock". I decided to try it, and it works great for short ranges. It takes 2 AAA batteries, and costs about $30. It would probably work well for your purpose provided you don't want to go long range with these headphones. Come to think of it, I may try to do this...
        • I just bought this same transmitter(moving across country, rental truck, want CD's, you get the idea) and it really does work great...as long as it was motionless with respect to the reciever. I stuck it on my Rio mp3 player, and carried it about with my stereo tuned in, and as I moved I heard static. When I stopped, it was fine. It easily worked across the room, but quality declined when too close too the monitor, or behind the computer(was thinkin it might be easy way to get mp3's to stereo without cord). It seems like the old&cheap recharables I threw in it lasted ~8 hours, but I wasn't keeping track. I suppose now I need to figure out how to power it without the batterys, to make it really useful out of the car.
          • This is where itll become offtopic, but if you are still trying to use the irock for stuff:

            1) Use an AC adaptor: I soldered one on, it was a 3v cigarette lighter cord that came from a dead cell phone. Saves loads on batteries.

            2) If you have problems with reception or anything, open the thing up and extend the antenna with a piece of wire. I planned on doing this, but I found that I don't even need to with my setup.
    • 'scuse me?
      I'm using, as I type this, JVC 900Mhz Wireless Headphones. Right this moment, Bon Jovi's "Wild In The Streets" is blasting over them.

      I get mild interferance (that I can fine-tune out usualy) from our 900Mhz cordless phone when it's in use, that's about it.
      There's a couple spots in the house that I get some odd interferance that will clear up just by moving my head, I've been unable to pinpoint what it is, but it doesn't really affect me.

      These things are not IR, they go through walls, I can walk clear out to our mailbox and still have a signal. Mind you, this is going through a combination of several wooden and concrete walls.

      I see no reason that this "won't work".

      Certainly the sound quality isn't exactly recording-studio-standards, but it's more than enough for any consumer application. And it's far better than what you're going to pull out of an FM *radio*.
  • This is a pretty good project for a beginner geek. Should take a couple hours, including travel time.

    Radio Shack [radioshack.com] carries all of the wires, resistors, transistors, and breadboards that you'll need for this. Basically you're going to build a little repeater/amplifier. Just take the stereo jack (also at Radio Shack) and wire it up to a variable resistor (for tuning the frequency) and a standard transmitter chip.

    Choose a well-known architecture, and you can install Debian Linux [debian.org] on it, good to go.

    Fun little project, and a good way to get your feet wet.

  • You mwan you want this? (Score:5, Informative)

    by hackwrench ( 573697 ) <hackwrench@hotmail.com> on Tuesday May 21, 2002 @09:53AM (#3557900) Homepage Journal
    Here? [bestbuy.com]
    • I wonder if you can recieve your neighbor's cordless 900 MHz phone with this guy. Not a scanner but you can tune it in I bet. Just gota know when to try as in when they are out on their deck with the phone.
    • Having used this quite a bit I can say that even though it is a pretty good deal it is still far from perfect. This Jensen unit works fairly well but as it is analog it is suspect to the limitations of analog technology, ie. you will hear static moving around the house and yard. If they had made this digital it would be near perfect.

      One of my goals was to provide a wireless link for three persons to listen simultaneously up to a distance of about 100-150feet and this did work quite well. Having people be able to use their own headphones was big plus and actually a requirement.

      It did take me quite a few days to find this baby so I would not flame the original poster too much. I just wish that people would just use usenet for things it is best suited for and bother slashdot with something more geeky..(ie. digital spread spectrum version of this would be geeky enough..)

    • He says he wants to use his existing headphones, but you could easily modify this with a 1/8th female headphone jack from rat shack.
    • That looks pretty good. Other peoples comments on digital v analog for reducing static and wireless phones (which I have, as well as living in an apartment building so there could be others near by).

      Looks like I've got a bit more research to do before I stump up the cash but thanks for the pointer.

  • Have you considered a Walkman for receiving? (Score:3, Interesting)

    by Papineau ( 527159 ) on Tuesday May 21, 2002 @09:58AM (#3557936) Homepage
    Building a radio emitter is not very difficult (I remember having an electronic kit when I was young with 60+ different circuits you could build, and one of them was a radio emitter). Ideally you'd choose it not to interfere with your local channels, or some neighbours could become upset if your power is too high.

    Then, on the receiving end, a small walkman is all you need. Plug your headphones or earphones, and there you go!

    Of course, the quality of the transmission will vary depending on the quality of the hardware and which frequency you choose (near or far from some other channel).
  • Firstly, you should be able to buy a pair of cheap RF headphones and rewire them yourself. You can even keep the original RF headphones about your neck, with a jack installed to plug your preferred headphones into. Yes, it will look a bit weird.

    Alternatively, there are all kinds of devices for remote audio that are meant to be hooked to a stereo. Is it really such a big deal to get an RCA to 1/8" phono plug adapter for these and replace the AC adapter with a battery pack?

    Admittedly, either is a little bulky, but certainly not too much to bring about with you in your home or workspace.

  • Here is anouther solution for you. (Score:3, Insightful)

    by Neck_of_the_Woods ( 305788 ) on Tuesday May 21, 2002 @10:11AM (#3558035) Journal
    Turns speak output into FM channel [mp3playerstore.com]

    At which time you just tune it into your walkman, or radio headphones. Simple solution for mp3 players to your car stereo as well.

    • An FM tranmission is at an effective quality of 22kHz. A standard CD/MP3 is encoded at 44kHz. Not only will you lose quality, but FM transponders for home use are too weak to ensure your reception will be static free. This is a Bad Idea (tm).
      • An FM tranmission is at an effective quality of 22kHz

        Not necessarily - the FM broadcast band layout gives each channel 200kHz of bandwidth (which is why all FM broadcast stations have center frequencies ending in an odd digit). Nyquist's theorem says you only need 2x bandwidth to represent a given frequency.

        If you're operating under Part 15, then how much AF spectrum you represent with this is up to you. The more you use, the better the signal/noise ratio you need (Shannon's law), however representing 1kHz of AF with 4.5kHz of RF is already overkill.

        • FM radio stations have a maximum frequency response of 17 KHz. Actually, a carrier signal is transmitted at the base frequency + 19 KHz -- if your receiver detects it, the stereo indicator lights up. The L+R channel is broadcast at the base frequency (so mono receivers get both channels), and the L-R channel is broadcast on a 34 KHz subcarrier.
          • the L-R channel is broadcast on a 34 KHz subcarrier.

            A slight correction: It is 38kHz, see second box down [gsu.edu]. But who is counting. This makes sense as it is pretty easy to frequency double the 19kHz pilot and demodulate the L-R subband.

            The site also claims that the channels are only 15kHz. Elsewhere I have seen claims of 17, 18, and even 19 kHz.
      • You are comparing analog to digital bandwidth. Two different things. As per Nyquist's theorem 44ksamples/sec digital can acurately reproduce a 22kHz analog signal and no more. So in theory a 44kHz mp3 is about equivalent to a 22kHz analog signal. In reality you can't get quite that good, but it dosen't matter as few can hear much past 18kHz anyway.

        As discussed elsewhere an FM transmission has an audio bandwidth of about 17-18kHz, so yes in theory a 44kHz mp3 will be better. Although mp3's sound crappy so you probably won't notice. Nor can most cheap headphones acurately reproduce higher frequencies. So really you have bigger things to worry about then the few kHz of bandwidth you might lose by broadcasting on FM. Things such as the weak transmit power.

        • So in theory a 44kHz mp3 is about equivalent to a 22kHz analog signal. In reality you can't get quite that good, but it dosen't matter as few can hear much past 18kHz anyway.


          You have made a jump from sample rates to sound freqencies here that isn't valid. I can't hear a tone above 20kHz, but I can certanly tell the difference between a track sampled at 22kHz vs. on sampled at 44kHz.

          -Peter
          • There is nothing invalid about my statement. A 44kHz mp3 is an audio signal sampled at 44ksamples/sec. As per Nyquist such an mp3 can (in theory) encode a 22kHz audio signal. My statement regarding 18kHz is refering to 18kHz audio. The dual use of kHz, audio/analog vs digital, is rather confusing.

            Naturally you can hear the difference between a 22kHz digital signal and a 44kHz digital signal. You are looking at analog bandwidths of 11kHz and 22kHz respectively.
  • Link to speak out to FM [mp3playerstore.com]

    This little jewel lets you plug it into your mp3 player and then it tranmits to a FM channel. You could use it in this case to transmit your computer sound out to a small fm headphone set. Or in my case I plug it into my mp3 player and then catch the FM station on my car stereo. Perfect little fix without spending a ton of new money. The kicker at work is you could let everyone with 30 feet of you tune into your custom FM station playing your mp3's.

  • I have four wireless headphones that I use for movie parties in lu of an expensive stereo system. A few things to consider: unless it's in the 900mhz or 2.4ghz range, the static interference will be so annoying that it will defeat the purpose. So, making your own is pretty much out of the question.

    I am not aware of a versitile stereo relay device that is capable of doing what you ask.

    I HIGHLY recommend the Sennheiser products. Don't get the RS-65 though, get the RS-85 from online dealers such as etronics.com ... the units is so damn awesome. The electronics filter out static interference and unlike most wireless headphones, Sennheiser's are capable or reproducing the full 20hz to 22khz spectrum. You won't find that in a Sony product.

    They have velvet ear cushions, lithum ion batteries, strong bass synthesis, excellent range, and you can buy additional receiver units so you and your friends can all watch a movie at your own personal viewing volume. It's amazing the things you never hear in a movie with traditional stereo systems. At $185, they are a bit pricey but I think it's one of the best entertainment investments I've made.
  • Well, ignoring cost, maybe you should look at pro audio in-ear wireless monitor systems. They typically operate over VHF or even UHF frequencies, are channel selectable, and the receiver consists of a walkman-sized beltpack. Too bad they run $400-$1000 new from Nady [nadywireless.com], Samson [samsontech.com] or Shure [shure.com] but who knows what you can drum up on Ebay! Yes, this is professional audio gear, and it LOOKS expensive. As long as you take care of it, it should last you the rest of your life, or 2 road tours, whichever comes first.
  • you could try a very cheap guitar wireless unit. It'd be quite the hack, with a lot of 1/4"-1/8" adapters (and vice versa), but it'd work. My cheap wireless (a Nady Wireless One) has a range of about 1500 feet via a 235-ish mHz transmitter/receiver combo.

    There's one here [ebay.com] on eBay right now for $25.

  • FM Broadcast transmitter (Score:2, Informative)

    by smurd ( 48976 )
    I went through a bunch of "propriatary" headphones for watching tv. After problems with batteries, interference and the expense (if you step on the headphone, you need to buy a new transmitter). I decided to go with a real FM Broadcast band transmitter. I got me a Ramsey [ramseyelectronics.com]
    FM 25 kit (it has to be a kit, FCC rules)
    and have been loving life since. Some of the bennifits include:
    • You can use any headphones that receive FM
    • I can use a little pocket radio around the yard playing CNN
    • Much more development effort and cost reduction goes into a mass market item than the big clunky "wireless" headphones
    • It's "open source" (grin)

    It took about 4 hours to build the kit and was not difficult (all components are through hole).
    At $130, it''s not cheap initally, but you will wind up saving money in the long run.
    • This is definately the way to go. Alternatively, you might get away with some low power VHF ham gear if there's nobody in the area to hunt you down and yell at you - but at 30mW, your broadcast range won't be very high either. The kit is going to be much cheaper than that anyhow, unless you have the gear already. You WILL lose some fidelity over the wired headphones though, don't kid yourself. Most people will never notice the difference.

      Mildly off topic, don't ever read anything on how to detect errors in compression. I used to work with MPEG codecs and I can't watch most of the movies on the net.. I can imagine what learning to detect mp3 artifacts does :).

      The only thing that would be better is if you designed or bought a small digital transmitter and decoder with a 16bit x 44.1kHz bandwidth. These units might exist out there if you look, but every single one of the stand-alone FM units (aside from quality kit like the Ramsey unit) blow chunks because of frequency drift or intermittant static. The other problem is batteries go dead, I listen to music all day when I'm at work.

      FWIW my solution at work is to stream to my notebook and then listen off it.
  • You could try this [techtv.com]...I'm not sure about its range, but it will probably work in an average sized room. Just get a walkman and use one of these thingamajigs to play your music on a standard FM Walkman. You could even save batteries and get a crystal radio (just pump up the volume on your PC).
  • Put on your headphones without plugging them in and turn your speakers up really loud.

  • It's something like $80 at Best Buy. It can use standard earphones, but comes with it's own. Works fairly well, but the incoming signal strength needs to be set right so it doesn't clip the audio. It's not particularly strong - it won't penetrate the steel subflooring where I work so I have to turn it off when I change floors and I sometimes have to "reorient the antenna" when there is a lot of metal between me and the transmitter. :( It uses rechargable batteries (included) and has a built in recharger. Charges usually last 10-12 hours. In Wired parlance, it delivers economy level performance, but I've yet to find a product one functional tier higher. Perhaps one of the other responses might enlighten.
  • 1. Buy a pair of headphones
    2. Buy a laptop
    3. Build a 802.11b wireless net for your apartment/home/domicile
    4. Share/nfs/serve your mp3's from your desktop.
    5. Retrieve/mount/client your desktop's mp3s from your notebook.
    6. Enjoy music
  • I had a great idea: Wireless earpieces for cellphones. That wire is a pain to deal with. Of course, it almost feels like a similar idea to a remote controlled remote [theonion.com].

    Somone's going to make a pile of cash off this idea, aren't they?
  • Actually, I've also been thinking of doing something similar. The trick is, I want to make a baby transmitter on a belt clip that can plug into a Discman/Walkman/Mp3 player/radio. This would transmit to earbuds powered by a watch battery with only a tiny antennae sticking out. This is the beauty: no wires, and completely concealable (think toque).

    Does anyone think this is possible? Have any advice? So far the only thing keeping me from building it is the smallness required to effectively work inside an earbud.
    • A bunch of companies make full AM/FM radios in an earbud. Had one a few years ago, cost me a whopping $14, with digital tuning and a L/R/Mono switch. Set one to right, one to left, and use one of those $40 AAA powered FM transmitters.

  • Here's the tools you'll need to build it (Score:1, Funny)

    by Anonymous Coward
    To build the wireless headset you will need the following:

    - big 50's style TV rabbit ears
    - magnetic induction core
    - 5 pounds of cobalt 60
    - chin strap
    - 8 track player
    - car battery
    - lots of velcro

    Once you get this stuff it practically builds itself.
  • Check out Amphony.com.

    For around $150, you get a couple of megabits/sec
    streamed to your ears.

    Unfortunately I don't know how quality the
    supplied headphones are, although it might not
    be too hard to hack up your headphones by ripping
    the receiver out of the Amphony headset and
    warming up the soldering iron.

    Of course for much more cash, buy an iPAQ and
    plug in an 802.11b card :)
  • I got one of these for Christmas a few years ago. It's from Radio Shack, model no. 33-1165. I couldn't find it on radioshack.com [radioshack.com], so perhaps it is discontinued. The receiver is about the size of a deck of cards, and the sound quality is average for wireless, which means fairly bad.
  • Ok I've seen way to many of these posts dogging anything less that 900MHz or 2.4GHz. First to clarify why we like higher frequencies better. High Q circuits or the relationship between the cuttoff and ideal resonance gives us less interference with larger bandwidths at higher frequencies with less power lost. This is great for the ever shrinking world of electronics were we want less power loss cause we like batteries to last longer, smaller wavelengths shorter antennas/permeates through more structures easier... This however does not mean that circuits with a lower Q value like those you would find with the same bandwidth at a lower frequency lack any ability to reproduce the audible spectrum. Granted it does require more electronics to filter out things like harmonics and possible outside interference but that doesn't mean it will sound any worse that a 2.4GHz products. It is simply cheaper to make consumer goods like this and assume it is of a quality that is acceptable enough to be sold at a particular price point.

    What I would recommend is you find a product that you can test out before purchasing or has a liberal enough return policy that you could use the product and decide if it works for you because a poorly designed 2.4GH product could sound far worse that a well designed 87-108MH product.

    To examine what I'm talking about here further just search for resonant circuits on google.
    • The 900M / 2.4G freqs have too much crap on them now. I can't even use
      all the equpment I have now due to one interfering with another. Yah, digital, spread rectum and all, doesn't matter. Sometimes, simple tech is better. This is one of those times. Go FM 87-108.
  • I just bought a kit for one of these and put it together. Works great for my iPod, except you have to shield the thing with some copper wire (if you're buying a kit). I find that everything causes the frequency to vary, from looking at it, to sometimes driving in the wrong direction (power lines I guess). They're great if you can contain them properly. And what beats soldering up something yourself?

    Mmmm. Rosin Core...*drool*

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