Computer Speaker Impedance

Discussion in 'Microphones, Speakers & Audio Processing' started by WQ4G, Nov 7, 2019 at 4:18 PM.

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  1. WQ4G

    WQ4G Ham Member QRZ Page

    Greetings:

    I am curious about the impedance of amplified computer speakers and whether they can be used on other devices.

    I've seen some videos on Youtube of people plugging amplified computer speakers into the audio output (headphone) socket of their Smart Phones. Is that safe? Can amplified computer speakers be directly used in place of 8 ohm speakers? What is the impedance of amplified computer speakers?

    I am also curious about the use of amplified computer speakers with chips such as the CD7613. The speakers would be connected directly to pin #12 of the chip (through a cap) which, according to the datasheet, is expecting 8 ohms.

    Here is a link to the chip's datasheet:

    https://www.datasheet4u.com/datasheet-pdf/ShaoxingSilicoreTechnology/CD7613/pdf.php?id=522067

    Any information would be greatly appreciated...

    Thanks

    Dan WQ4G
     
  2. VA3VF

    VA3VF Ham Member QRZ Page

    Computer headsets are 32 Ohms in some cases. Not sure about speakers. There will be mismatches, but I never had any 'catastrophic' failure by mixing and matching them.
     
  3. K7JEM

    K7JEM Ham Member QRZ Page

    OTL type chip amplifiers, which are the most common for many decades, don't really care if anything is attached to them or not, assuming you don't go to less impedance than it is rated for. For example, you can attach a 32 ohm speaker to one of these amps and it will work fine, you will just get much less maximum power output. You can attach them to a high impedance load, like an amplified computer speaker, with no detrimental effects.

    BTW, your link goes to a yagi antenna, not a data sheet. But the data sheet for that chip indicates it has an audio amp on board similar to an LM386.
     
  4. KA9JLM

    KA9JLM Ham Member QRZ Page

    The input is low level (1V P-P is a norm) , The output to the speaker is high level (Several volts).

    You can drive a high impedance with a low impedance , But you can not drive a low impedance with a high impedance. Without a amp, to get levels correct.

    You need to lower the level if you plan on feeding the amplified speaker with a 8 ohm driver. A simple pad can be built.
     
  5. K7MEM

    K7MEM Ham Member QRZ Page

    That's odd. For me, the link goes directly to the spec for the "AM/FM 1 CHIP RADIO CD7613".
     
  6. VA3VF

    VA3VF Ham Member QRZ Page

    Same here, and I'm using a #$@% Chromebook.:)
     
  7. WQ4G

    WQ4G Ham Member QRZ Page

    Ooops! I thought I fixed that....

    Dan WQ4G
     
  8. K7JEM

    K7JEM Ham Member QRZ Page

    Yes, you probably fixed that right after I posted, is working ok now.
     
  9. WB8NQW

    WB8NQW Ham Member QRZ Page

    Amplified computer speakers expect a line level input which is up to 1 volt AC peak to peak.
     
  10. WA7ARK

    WA7ARK Ham Member QRZ Page

    ... and they have a fairly high input impedance, (wag: >1k Ohms). Common sources with an 1/8" line-out jack, like sound cards, CD players, MP3 players, and phones will drive them just fine...
     

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