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Terminology: "Difficult to drive"

Discussion in 'Home Cinema Speakers' started by Serpico, Jan 16, 2004.

  1. Serpico

    Serpico
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    I've seen some speakers being described as difficult to drive. Could someone tell me what that means, in words of one syllable if possible?

    Thanks!
     
  2. munkay

    munkay
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    low impedance can be hard to drive - that is you will need a powerful amp say 100wpc for instance to drive them well (get good / sustained sound when needed)

    Bear in mind, just because an amp is quoted at say 100wpc does not mean it will give 100pwc - it will be usually be less, especialyl when using 5/6/7.1 channels
     
  3. hornydragon

    hornydragon
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    Lower impeadance means more current for same volume, Current is key and so is a little thing called THD sony and other large brands quote power at 10% THD (total harmonic Distortion) sounds horrible! Hi Fi manufactures quote it at below 0.1% THD and ratings at 8 and 4 ohm impeadance the most common, some speakers rated a 4 ohm impeadance can drop to 2.6 (B&W are buggers for this) meaning at volume they draw huge current and will trip out lesser amp current overload ciruits.

    Hope this helps.
     
  4. Serpico

    Serpico
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    I was with you all the way up to "Low/Lower". Ah well, I'll listen and tell you what I fancy and you can give me the yay or nay. Otherwise I'll have to start Electronics 101 at night class.
     
  5. munkay

    munkay
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    http://www.whathifi.com/newsMainTemplate.asp?storyID=34&newssectionID=3

    Impedance
    The resistance, measured in Ohms, offered to AC (alternating current) signals by a component. In loudspeaker specifications 8-ohms is the norm, 6-ohms is becoming more popular, but be careful with low-impedance 4-ohm speakers because not all power amplifiers are happy driving them.


    read and learn young jedi :lesson:
     
  6. Reiner

    Reiner
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    "Difficult to drive" is influenced by two things mainly: the impedance (Ohm) and the sensitivity (dB) of the speaker.
    In both cases the rule of thumb says 'the higher, the better'.

    A speaker with low impedance or low sensitivity is harder too drive, i.e. it needs more power to reach the same volume levels than a speaker with high impedance or high sensitivity. This put's more stress on the amp and leaves less headroom.

    And that WHF writes a lot of rubbish is just proven by the above, most speakers aren't 8 Ohm.
    Not to mention that 4, 6 or 8 Ohm usually has not much to do with the impedance since impedance is a variable (frequency dependend), not a constant.
    As such the rating is more likely to be the (DC) resistance, i.e. just some reference value for matching amps and speakers.
    And in particular power amps are more likely to cope with low loads (like 4 Ohm speakers) than integrated / budget amps.
     
  7. alexs2

    alexs2
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    Reiner's points are very true,and another worth taking into account is that many speakers which are labelled as difficult to drive have relatively low impedances in the bass regions(B&W Nautilus speakers being a good current example,and the best example of all being the Apogee Scintilla,no longer made,which had swings down to approx 1ohm in various areas,and obviously only a very few amps would drive this thing without catching fire!).

    This draws a very large amount of current from the amp in an area where many are least able to cope.

    Ideally,an amplifier should not only sound good,but also be able to double it's output as the impedance halves,and continue to do this....again,very few amps will actually manage this,as the power supply requirements are both large,and expensive.
     
  8. bobgriffiths

    bobgriffiths
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    Reiner i couldnt have put it better!
    people often forget about the sensitivity of the speaker and prattle on and on about impedence.
    In the same way as they go on about wattage of amps and dont mention the current capability of an amp.

    I completely agree with you that WHF writes aload of rubbish its The Sun of hi fi journalism and has far too much influence on the general public in terms of educating them and sales of products
     

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