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Thread: How to install new pc speaker for 486?

  1. #1

    Default How to install new pc speaker for 486?

    I already thought I had perfect 486 computer until I realized that instead of magnetic pc speaker there's only dreadful piezo integrated into motherboard. Unfortunately there are still speaker-only games that I want to play but are too slow in 286 hence the need for 486. Listen the difference between piezo and 286's "real speaker":

    https://www.dropbox.com/s/9hayugbxhm...M0001.mp3?dl=0

    https://www.dropbox.com/s/0bqgfrnnne...M0004.mp3?dl=0


    The computer is AST Bravo LC 4/25S. I found other bravo's motherboard details and many of them contained external speaker connector... but of course mine doesn't. Is the only way to add new speaker is to remove the piezo and solder new into same spot? Or is there alternatives, like multicontroller cards with external speaker connector? Does any ISA sound cards contain external speaker connector?

  2. #2
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    The PAS16 uses some black magic to monitor the ISA BUS, highjack the PC speaker signal, and send it to your external speakers - might be a good option? The PAS16 happens to be a cracking card for a 486 too.

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    You can use a speaker (8 ohm or higher) in place of the piezo speaker if you take the precaution of putting a 100-150 ohm resistor in series with it. There are also piezo speakers that plug into the normal speaker header on a PC.

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    I think those older boards had speaker connection built in that might just need pins soldered to them to connect a real speaker to.
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    My Packard Bell's motherboard has the PC speaker header that either uses the piezo squeaker, or the real speaker. I salvaged a speaker from an old walkie-talkie and installed it in my Packard Bell later on (hooked up to the Lo-Tech Tandy 3-Voice compatible sound card, and I also took out the speaker from the busted PowerMac G3/400 and hooked that up to the motherboard itself.

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    Quote Originally Posted by Chuck(G) View Post
    You can use a speaker (8 ohm or higher) in place of the piezo speaker if you take the precaution of putting a 100-150 ohm resistor in series with it.
    Why is the resistor necessary, and why such a difference from the speaker? (150 ohm vs. 8 ohm)

    There are also piezo speakers that plug into the normal speaker header on a PC.
    Agreed, and they're cheap in bulk.
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    The 150 ohm resistor is a precaution. The circuit driving the piezo might actually be designed that way--i.e. provide a high-voltage/low current drive. The resistor serves as a current limiter, since the speaker presents a resistive/inductive load rather than the purely capacitive load of a piezo transducer. Yes, it's likely that the circuit design is either-or, but caution at the price of pennies is not ordinarily a bad thing. Alternatively, load resistor with capacitive coupling to the speaker would be another way to ensure that no DC current flows through the speaker coil.

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