What's so special about speakers in phones?

Discussion in 'General Electronics Chat' started by MikeA, Jan 24, 2015.

  1. MikeA

    Thread Starter Member

    Jan 20, 2013
    125
    17
    Pulled apart a headset from a fairly modern land line phone, and was surprised by the ear speaker. The thing is huge, and weighs quite a bit. Feels like at least half the volume inside is a magnet.

    Hooked it up to an amp, and the frequency response is just horrendous. Analog phone quality band-pass.

    What's the reason behind this monstrosity? Is it designed to take a direct lighting strike while someone has it up to the ear?

    20150124_182849.jpg 20150124_182828.jpg
     
  2. #12

    Expert

    Nov 30, 2010
    16,284
    6,797
    I think the manufacturer would be the best place to research motives.
     
  3. AnalogKid

    Distinguished Member

    Aug 1, 2013
    4,535
    1,251
    The acoustics of a phone speaker measure badly on a bench, but sound surprisingly good when pressed up against a human ear. They are not free field devices.

    Also, they have that big magnet and voice coil so they are hearing aid compatible. Many modern hearing aids are designed to pick up the speaker's radiated magnetic field on purpose.

    ak
     
  4. takao21203

    Distinguished Member

    Apr 28, 2012
    3,577
    463
    High impedance telephone sets use high voltage

    Its maybe just the way they are made for decades.
     
  5. MikeA

    Thread Starter Member

    Jan 20, 2013
    125
    17
    Like headphones?:D I put it on a scale, it's almost 2oz. More than a complete set of full frequency headphones might weight. The radiated field for hearing aid is an interesting idea.
     
  6. crutschow

    Expert

    Mar 14, 2008
    13,009
    3,233
    What high voltage?
     
  7. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,346
    Hello,

    As far as I know the impedance of those speakers is about 600 Ohms.
    When you drive them with the wrong amplifier, it will not sound that well.
    Also in the phones a frequency range of only 300 - 3000 Hz is used.

    Bertus
     
    absf likes this.
  8. takao21203

    Distinguished Member

    Apr 28, 2012
    3,577
    463
    60 volts
     
Loading...