Connect hi-fi repro boxes with PC?

By Klohgloh ยท 12 replies
Aug 12, 2009
  1. Hello,
    My problem I want to help with is this: I have these speakers and I want to connect them with my computer. Problem is that the speakers have this "wire and clips" connection.
    In the computer there is 3,5 jack... so what would be your ideas how to connect these together?
    Now im using a mp3 cassette but the quality is quite bad and im hearing the turning wheels all the time :/

    Attached Files:

  2. Ididmyc600

    Ididmyc600 TechSpot Chancellor Posts: 1,415


    you need a soldering iron some solder, a stereo 3.5mm jack plug and then you connect the 2 reds to 2 points on the jack and the 2 blacks to 1 point on the jack....problem is, is the output on the computer gonna have enough power to power the speakers, chances are it need to have powered speakers,,, unless you put the output through an amplifier, that would work...but its a lot of messing about when PC speakers can be bought for as little as a tenner.
  3. turbo1

    turbo1 TS Maniac Posts: 353

    why not use the whole set (amplifier and speakers as the image shows ).all you have to do
    is look at the back of your amplifier and check the audio inputs like
    line-in,CD-in or AUX.

    if you have figured out what type of input connections you have,just
    buy a set of cables called RCA to 3.5 mm stereo the link
    below to view the image.
  4. Klohgloh

    Klohgloh TS Rookie Topic Starter Posts: 32

    If so, how do I find that out? What are the decisive parameters of speakers/sound card?

    turbo1: Oh, sry, forgot to mention that the amplifier (audio system or whatever it is called) doesn't have an input :/
  5. turbo1

    turbo1 TS Maniac Posts: 353

    you need audio inputs in your amplifier to throw sound into your speakers.

    you cannot directly plug-in a speaker into your pc's audio output.

    unless your speakers have a built-in amplifier or amplified.

    i cant believe that your audio system doesnt have any audio input.
    can you pleasae check at the front panel if you have a switch button
    or rotary switch that says cd-in or AUX? or it might have a cover over
    the audio inputs or something (front and back).
  6. Klohgloh

    Klohgloh TS Rookie Topic Starter Posts: 32

    No, it really doesn't have one, i looked all over it again :) But I found that out some time ago, with an input, it would be all too easy.

    I tried to plug a couple of cheap little speakers in the pc (which don't have an amplifier either) and I could hear them quite OK on PC's max volume. I don't know though if it will be the same with those bigger ones... guess not.
  7. turbo1

    turbo1 TS Maniac Posts: 353

    oh boy,the thing is that does it match the impedance?
    for now its ok,after a period of time...if the speakers clipped,
    your sound card will be damaged.
  8. Klohgloh

    Klohgloh TS Rookie Topic Starter Posts: 32

    How do I get to know the impedance of the PC audio? (mb)

    *So it's just a matter of impedances how loud the speakers will be?

    *What do you mean by "speakers clipped" ?
  9. turbo1

    turbo1 TS Maniac Posts: 353

    alright,i'll explain this the best way that i can.

    Your soundcard is made for you to plug-in either headphones or
    amplified speakers.Its output is made to handle 4-32 ohm loads.

    Sound cards are not really intended for driving out a lot of power.

    A typical card is intended to drive a 32 ohm load (headphones) on the
    green LineOut jack. The signal level is "line level", which might be
    1 volt AC RMS or so of signal. The headphone jack on the front of the
    computer, may be tied into that as well, or the front headphone jack
    may have its own 32 ohm drive.

    if you have a 5.1 or 7.1 sound card,the actual output impedance
    of some of them, is around 1 ohm.But that doesn't mean you can
    use the chip to go further than that.the chip might go into current limiting,
    if you attempt to abuse it, and the result would be a heavy dose of
    distortion. The 1 ohm output impedance is a small signal
    kind of rating, more of academic interest than anything
    else. The 32 ohm rating is the one to pay attention to,
    as that one is a "full power" rating.

    if you're using your speakers directly plugged into your PC audio ouput,
    without using any amplifier,then you are using it as "speaker line level"
    which is not good.indication is that you're going have some distortion,
    noise,HUM and leads to a clipped speaker.

    This is when a speaker has reached its maximum output capacity yet tries
    to keep up with the input signal gain ratio between the signal source.

    runs out of voltage from the supply rails and we get a flat spot at the
    upper and lower peaks of the wave form. In an extreme case,
    "severe clipping", there is so much additional energy buildup (heat)
    into the voice coil(s), but the cone does not move (motivate) enough to
    cool the voice coil and former adequately. Hense, the voice coil over
    heats and either seizes in the gap or burns the voice coil windings.
    RESULT: OPEN CIRCUIT and a blown speaker!

    inside a blown speaker,normally,the magnet wires are burnt and the windings
    are crumpled and tangled.if it does stay that way while playing music and
    your speakers start to clip without noticing,instead of impedance,it will
    create voltage (speakers hate this) that will backfire to your sound chip
    and your sound card is done.
  10. Klohgloh

    Klohgloh TS Rookie Topic Starter Posts: 32

    Thank you for explaining, so if those speakers have 8ohm it wouldn't "hurt" anything (as it's between 4 and 32 ohm) but the sound won't be too good (it should be (only) like 4x louder than it's in the headphones, which is not enough, plus the impedance difference is too big so the quality of sound will be poor too.) Do i get it, more or less, right?
  11. turbo1

    turbo1 TS Maniac Posts: 353

    yes,but you are still using the "speaker line-level" kind of process.and you
    can never know when your speakers can stand the distortion.i can tell its totally

    i suggest you get a simple 2.1 amplified speakers so your speakers and sound chip
    will both have protections.not so expensive nowadays.:)
  12. Klohgloh

    Klohgloh TS Rookie Topic Starter Posts: 32

    Ok, thanks much for your time and help.
  13. turbo1

    turbo1 TS Maniac Posts: 353

    you're welcome :)
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