Speaker impedence?

[cse]

How important is speaker impedence?

Having recently purchased som Neat Motive SE2's recently I noticed that that my Roksan Caspian MK1 amp needs to be turned up a long way to get the required volume. Doing some research, I see that the Neat's have an impedence of 6 ohms and the Roksan 8 ohms. Could this account for the lack of power. I must stress though, that the Roksan doesn't in any way sound stressed. However, it has made me start thinking about an upgrade, or possibly adding a power amp. Would this make any difference do you think?

 

[Anonymous]

Speaker impedance is very important when it comes to matching to an amp. The six Ohms you quote for the Neats is a nominal impedance and simply gives you a rough idea of the average sort of load they can present to an amp. More important than that is the impedance curve, showing the impedance at each frequency.

If the Neat's impedance drops a lot at any particular frequency area of the graph, then it will be making a heavier current demand of the amp. For example, they might drop to four Ohms in the bass area. If the amp copes with this demand for current at the given voltage (selected by the volume control) then all is well. If it struggles then different things can happen depending on how much it struggles. You may start to find evidence of clipping, with peaks of the music being limited. Yes, this can still happen without destroying your speakers. If it's severe then clipping may destroy the speakers unless the amp shuts down. If this drop in impedance were to happen at a bass frequency where a lot of music is heard, say 100Hz, then it may manifest itself with a slower than desirable bass.

I've tried to find details of your speaker's impedance on the Web with no luck. The Caspian is a pretty good amp and can drive difficult loads so I'm inclined to say that you'll be fine. The mere fact that you turn the volume control around a lot isn't of concern. Start to worry if the amp starts to get unusually hot or shuts down. Worse still is if you start to hear obvious distortion where clipping is likely to fry your speakers.

 

[Richard Allen]

igglebert:Speaker impedance is very important when it comes to matching to an amp. The six Ohms you quote for the Neats is a nominal impedance and simply gives you a rough idea of the average sort of load they can present to an amp. More important than that is the impedance curve, showing the impedance at each frequency. If the Neat's impedance drops a lot at any particular frequency area of the graph, then it will be making a heavier current demand of the amp. For example, they might drop to four Ohms in the bass area. If the amp copes with this demand for current at the given voltage (selected by the volume control) then all is well. If it struggles then different things can happen depending on how much it struggles. You may start to find evidence of clipping, with peaks of the music being limited. Yes, this can still happen without destroying your speakers. If it's severe then clipping may destroy the speakers unless the amp shuts down. If this drop in impedance were to happen at a bass frequency where a lot of music is heard, say 100Hz, then it may manifest itself with a slower than desirable bass. I've tried to find details of your speaker's impedance on the Web with no luck. The Caspian is a pretty good amp and can drive difficult loads so I'm inclined to say that you'll be fine. The mere fact that you turn the volume control around a lot isn't of concern. Start to worry if the amp starts to get unusually hot or shuts down. Worse still is if you start to hear obvious distortion where clipping is likely to fry your speakers.

My Caspian power amp was rated 70 watts into an 8 ohm load and 100 into a 4 ohm load. The Neat's will be relatively inefficient compared to some and a nominal 6 ohms means the swing, knowing Neat, should be in the region of 4.8 to 8 ohms. The Caspian is more than capable of handling this in my opinion.

 

[ID.]

As not having much of an idea has never stopped me giving an opinion before, my guess is that the need to turn the volume dial more is probably due to the speakers being less sensitive than your previous speakers rather than an impedance issue.

 

[Richard Allen]

ID.:As not having much of an idea has never stopped me giving an opinion before, my guess is that the need to turn the volume dial more is probably due to the speakers being less sensitive than your previous speakers rather than an impedance issue.

 

[cse]

Thanks for the information. Would adding a Roksan power amp, make a difference ie at the bottom end? My previous speakers were more sensitive, BW CDM1SE.