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Speaker Impedance

Discussion in 'Home Cinema Speakers' started by tekmonkey, Jul 25, 2003.

  1. tekmonkey

    tekmonkey
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    Speaker Impedance

    Just to aid peoples thoughts when it comes to speaker input impedance, it really isn't as important as many people seem to make out. For instance most modern speakers that quote 8 ohms are usually about 6 ohms. B&W CDM and nautilus both quote 8 ohm yet when bassline gow really low so does the impedance. I used have a pair of B&W CDM 9 s and I reckon they were dropping to between 1.5 and 2 ohms with anything beneath 30 Hz. What I'm trying (and failing) to say is that with satellites (MK in particular) because they are small are really easy to drive, A Denon 1803 is reckoned to be the minimum requirement for MK K series, now it can't do them real justice, but it can drive them.

    This is not the case with all small speakers, just most satellites (and most cheap small bookshelves). There are however exceptions, Acoustic Energy AE1 MK2s, for example, are stupidly hard to drive.

    Would appreciate some feedback on this one!

    Anyone think I'm courting some controversy!!!!!
     
  2. Jase

    Jase
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    Careful what you say as certain M&K satellite speakers are NOT easy to drive for the majority of amps/receivers. The S150 THX/S125, maybe even the S85 range, should be partnered with the Flagship amps at the very least I.M.O. In some cases (Denon excluded) even these are not potent enough to drive them to certain levels.

    To say all M&K speakers are easy to drive because they are satellites is quite frankly wrong.
     
  3. SpiderManPants

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    Hi all,

    I second that Jase, My S85s sounded very thin and weightless when partnered with my 3801. A good power amp like the Rotel 1075 is required to get them singing nicely (at the very least!) IMO.

    I'm no expert, but I would generally tend to follow the manufacturers suggested figures and match them accordingly.

    SMP
     
  4. nathan_silly

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    Second the two previous posters, I've used a Arcam Alpha 8P- 50Wx2 with NHT HDP-2's (6Ohm, but low sensitivity at 86 dB @ 1 W) Not good enough- need more welly.

    M&K are not easy a load! How on earth can you say a 4Ohm speaker can be used with a budget AV amp?

    I would rather use a amp that has plenty of reserve - instead of worrying that I might fry my tweeter (I've done that once with a Yamaha 5xx series and Kef Coda 9)- due to a cheap amp stage no doubt.
     
  5. alexs2

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    Speaker input impedance does become important when a set of speakers with either a very low impedance(esp at low frequencies)and/or a reactive load,is partnered with an amplifier that isn't capable of good current delivery and control into such loads....the AE I mk II's you quoted aren't so much stupidly hard to drive,just a good example of a small speaker using low sensitivity and a very complex crossover to extract unusually good performance from a small and expensive box....the end result is you need to match it with a suitably high quality amp.
    That's one reason for my using Krell KMA 100's with my Nautilus 805's.
     
  6. dts_boy

    dts_boy
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    an interesting way to seel your M&K speakers:D
    are you saying then that a lesser amp WILL drive difficult speakers, just not well enough to warrant buying the better speakers or that by being able to drive these speakers with lesser amps will work and do the job? (did this make sense out loud, it did in my head!) anyway, my view is if your spending that much on speakers you should look at spending that much on ampification to drive them. the wattage output of an amp is not always an accurate figure to help this problem - hifi amps (like the arcam a85) is rated at approx 85w/ch (i think) and av amps of a similar price (say, denon 3803) are quoting a higher output. i would say that the "lower" powered arcam amp would drive a floorstanding speaker better than the av amp, it has a higher current handlng capacity. this is my view, which may well be wrong as i don't have a huge technical background, but htis is interesting none the less
     
  7. nathan_silly

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    I've upgraded my PSU by fitting these into my case. Everyone has been talking about currants= better so I worthwhile upgrade!

    It sounds sweeter!

    Also the current delivery is much better now. I've also placed a paper cup in front of the headphone socket, so when I listen to music current juice comes pouring out!:D
     
  8. tekmonkey

    tekmonkey
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    Ah! Sweet sweet controversy!!!!!!!!!!!!

    I quite agree DTS_BOY. You don't stick a 2 L engine into a BMW 7 Series, but it does work! By the same token, theres no point sticking a V12 in Ford Focus (be a laugh though!!).

    I've seen alot of people worrying about speaker impedance and it's largely unnecessary. What I'm trying to say is it isn't such a big deal. If its an expensive speaker you can bet your bottom dollar it's gonna need a expensive amp.

    Oh and yes S-150s do have some big demands but they are a bloody expensive speaker. And bloody good!!!

    Oh and just for referance I have a pair of AE1s and I use a Naim NAP250 power amp, overkill perhaps but it gets them singing beautifully, and I love it to bits.

    What I mean to say is comparing them to other speakers B&W CDM1NT, Monitor Audio Gold Ref 10, both great speakers, but compared to AE1s very easy to drive. The AE1s are a difficult load for such a small speaker, FACT!

    IMHO - British manufacturers, Naim in particular, rate the wattage much more conservatively than japanese people. Arcam may rate the Denon 3802 at 75w / channel as opposed to 105w. Wattage isn't everything, its current that controls speakers not watts, I mean this in the most technical way! I think!

    I do so enjoy creating chaos!!!!!

    Nathan - I've upgraded to raisans, I think Raisans are much juicier!
     
  9. Reiner

    Reiner
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    I think what's usually forgotten is the sensitivity - the impedance alone is no measure for how hard a speaker is to drive. If both, impedance and sensitivity, are low, the amp will struggle even more and thus a more powerful unit is demanded.

    In general I would be carefull with partnering budget AV amps with high loads, usually the power supply will not be able to cope. It can work, but there are limits and you might not get the best out of the system.
     

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