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Headsets for cordless phones

Discussion in 'Electronic Repair' started by Lloyd Randall, Nov 18, 2003.

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  1. A week ago I received a GE cordless phone and a Plantronics M110 headset
    which I had ordered by the internet.

    The phone has better range and clarity than my old one, and the headset
    sounded great on my first conversation. Since then, I have discovered
    that for most conversations the headset is not as good as listening to
    the phone itself.

    It sounds like an impedance mismatch. The input impedance for the M110
    is 32 ohms, but GE doesn't seem to publish the output impedance for the
    phone.

    The Plantronics box says the headset is for mobile and cordless phones
    and will provide crystal clear conversations for most headset-ready
    phones. When I contacted them, they said the M series is not
    recommended for 2.4GHz or DSS phones. Doesn't at least one of these
    apply to most headset-ready cordless phones?

    They recommend their H51N with an adaptor cord. I paid $20 for My M110,
    while the H51N lists for $100, and I'd still have to find an adaptor.

    I wanted a headset to make calls when I'm likely to be put on hold and
    for incoming calls when I'd like to continue manual tasks. It would be
    worth $20 to me but not $120. It would have saved me some trouble if
    their advertising hadn't led me to believe they recommended the M110 for
    my phone.

    Besides price, the difference between the two headsets seems to be
    impedance or the earphone. I think the H51N is 150 to 300 ohms, but I
    haven't seen it published.

    There's probably a suitable headset available for less than the H51N,
    but vendors of cordless phones and vendors of headsets tend not to
    mention impedance. How can a consumer match the two without knowing
    impedance?

    If I can't get specs for headsets, I might get specs for microspeakers,
    to replace the one that came in the M110. For example, I've seen a
    100-ohm microspeaker advertised for $2.

    What should I do?
     
  2. The last GE phone I bought came with its own headset; it was 150 ohms.
    I suspect your phone might be as well. Natch, no headset worked with my
    phone when the supplied headset broke; VERY low earpiece volume.
     
  3. If a earphone were a resistive load, it would simply be too soft if the
    source impedance were too high. In fact, earphones have mechanical
    resonance at various frequencies. The higher the source impedance, the
    louder these frequencies will sound, relative to other frequencies. The
    output will wound harsh and distorted, and it will sound unclear because
    some frequencies will be very soft.

    With the GE phone, my M110 is harsh and unclear with some voices. I
    think those are the voices that are strong in the frequencies where the
    earphone resonates.

    Telephone-line impedance is nominally 600 ohms. That would explain why
    telephone headphones use to be at least 150 ohms. Earphones for
    lightweight aviation headsets are nominally 600 ohms.

    I think the walkman was responsible for the popularity of 32-ohm
    earphones; with two penlight cells for a power supply, you couldn't get
    loud music if the earphone impedance were much higher.

    Is 32 ohms standard for cellphone headphones? If so, it may be because
    walkman earphone elements were readily avialable. If cordless phones
    don't use the same headphone impedance, could it be because
    manufacturers don't want customers buying cheap cellphone headphones for
    their cordless phones?

    There must be inexpensive 150-ohm headsets or earphone elements
    available. If only specs were easier to find!
     
  4. I have loud tinnitus; the volume was too low for me to detect distortion.
    It was low enough that I could barely detect speech, and too low to hear
    what was being said.
    That argues in favor of yours being high-impedance as mine was.
    But that doesn't say a thing about why GE picked a nonstandard speaker
    impedance for installation in their entirely electronic cordless phone.
    All the other cordless phones I've had worked fine with a 32-ohm headset,
    even one 8-ohm headset.
    Simpler is to get another phone. I'm so spoiled by the headset that I
    can't hold an earpiece any more.

    I bought a V-tech branded Radio Shack because it showed up $100 off and
    was nice and small. Dropped it once too often, replaced it with another
    RS unit made by Uniden that's both inexpensive and really nice, still
    on sale at RS.
     
  5. I hear you! The phone I replaced was another GE cordless. It had
    become so faint that I'd shut off all noise sources and jam the phone
    hard against my ear, but I'd still have trouble understanding what was
    said. Even if all phones had microphones with the same gain, some
    voices would be faint because people let the mike get too far from their
    mouth. Some of the faintest are in customer service.

    The first time I tried my headset, I walked around outdoors to see the
    range of the cordless phone. The man I was talking to said he knew I
    was near the limit of the phone's range because he kept hearing pulses
    of hissing as I moved around. I never heard them until I tried the
    phone without the headset. I guess the impedance mismatch made those
    frequencies too faint to hear in the headset.

    Overall, my headset sounded reasonably loud (but not clear and pleasant)
    because resonance made the impedance high at some frequencies.
    Hmmmm... how long have headset-ready cordless phones been available?
    Did any of your phones operate at 2.4 GHz or have DSS? Plantronics says
    they don't recommend their 32-ohm headsets for any of these phones. It
    sounds as if a lot of manufacturers are using higher impedances.
    According to Plantronics, buying another phone may not solve the problem.
    My cordless phone/answering machine cost $30. GE has a headset for $35,
    but I'd rather do without than buy theirs, under the circumstances.
    When they said "headset ready," didn't they imply that a standard mobile
    headset would work?

    I'll watch for a suitable headset or microspeaker.
     
  6. sg

    sg Guest

    Did your GE phone list which headsets would work with it? If not, you
    might try posting your question on a newsgroup slanted toward cordless
    phones or electronics, asking if anyone has the model phone you have
    and is using a headset. You might get some good replies.

    Good luck.
     
  7. Andrew White

    Andrew White Guest

    You're getting very technical, but I doubt you found the right reason.
    The headset might just be junky. I tried a whole bunch of different
    ones until I found a perfect one that sounded great: Panasonic
    KX-TCA88. They are cheap too, under $25.
     
  8. I looked first for telephone newsgroups. I found three for cell phones
    and none for cordless.

    I crossposted. I figured somebody at electronics.repair might have
    technical information.

    It also seems to be a consumer issue. Cordless phones are very popular,
    and many are headset ready these days. The phone box said it was
    headset-ready, and the headset box said it was for most headset-ready
    phones.

    Only when I opened the phone box and read the manual did I learn that GE
    recommended only their headset accessory, which would cost me twice what
    I paid for the Plantronics headset. After I found that the Plantronics
    headset did not work satisfactorily with this phone, Plantronics told me
    they in fact do not recommend this headset for two categories which
    probably comprise most headset-ready cordless phones sold today.

    The same pitfall awaits any consumer in the market for a headset for a
    cordless phone.

    Instead of spending over $100 for the headset Plantronics recommends, I
    can buy hundred-ohm cellphone speakers for 50 cents. One of those would
    be small enough to replace the speaker in my headset.

    I think I see why many new cordless phones seem to be designed for
    higher-impedance headsets than used to be standard. It probably
    increases the amount of time a consumer can talk between charges. I
    just wish manufacturers would put impedance requirements on their
    packages.
     
  9. The V-tech and the current RS/Uniden were both 2.4GHz and DSS. Plantronics'
    headset gives *me* good volume with them, but their boom mike gives low
    outgoing volume on those two and two other phones I tried it on. (Works
    fine with the cell phone, though.) I currently use a $30 RS binaural
    headset with the RS/Uniden phones and like it.
     
  10. Oh no! I have to worry about the mike, too? Plantronics gave the M110
    a three-position switch so the user could choose -45, -50, or -55 db.
    You can't please everyone. One caller preferred -45 and another -55, so
    I leave the switch at -50.

    Any equipment you plug into the line input of a stereo amplifier should
    work because it's all supposed to have a signal of 1 volt and an
    impedance of 600 ohms. Phonograph signals also have electrical
    specifications, allowing one to use different turntables or cartridges.

    Telephone equipment used to adhere to electrical specifications. Aren't
    there electrical standards for the signals at the headset jack of a
    phone? What a mess!

    You've gotten me curious about Uniden/RS.
     
  11. I don't think my Plantronics is junky, but it could be that Panasonic
    has done a better job designing a headset to work with a phone like mine.

    The KX-TCA88 doesn't seem to be available any longer, and I don't know
    if newer models are as cheap. Panasonic headsets have pleased owners of
    some 2.4 GHz phones. I wish I knew if that means they would excel on
    all 2.4 GHz phones.
     
  12. killme

    killme Guest

    I've been trying to find a headset to work with my Uniden phone. I've
    tried 4 headsets. On 3 of them the caller can barely hear me. All of
    them had the mic positioned some distance from my mouth. The one that
    worked had the mic positioned very close to my mouth, but it was over
    the head design and I can't stand wearing it.

    The first two I tried worked great on my friend's cell phone and were
    designed for his headphone. The third was designed for cordless phones
    according to the package. I just don't get it.
     
  13. Guest

    The only one I've found that works was ~$20 from Radio Shack, but it's
    an over the head design, too. We tried those relatively expensive tiny
    headsets but callers just couldn't hear us, no matter how we positioned
    the short microphone. Even the one that works must be adjusted so that
    the foam-covered boom mike is nearly directly in front of the mouth.

    The headset hassle got to the point where we just talk on the phone
    without it most of the time.
     
  14. Andrew White

    Andrew White Guest

    The best headset I've found after trying maybe as many as 7-8 headsets
    from various companies was Panasonic KX-TCA88. The sound quality is
    amazing, comfort is great and it's only $20. It's been replaced by
    other models, but you can still find it on the Web, for example:
    http://www.xkms.org/Etronics-35/Pan...eight-Headset-for-2.4-GHz-Cordless-Phones.htm

    Here's the place that sells other, current Panasonic models. The TCA86
    and TCA92 look similar, the latter has its own volume control:

    http://www.101phones.com/browse/1d2710dd65d5039a1a04bf6ec85aacbd
     
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