Power and sensitivity

If it really matters to you, its a case of simple arithmatic:

Doubling your wpc power will give you an additional 3dB in terms of SPL.

My speakers are 92 dB/W/m, and I use a Densen power amp rated at 100 wpc/8 ohms which goes f****** loud in my small room.

That's 6 dB more than average speakers at 87 dB/W/m which is the equivalent in the speakers of going from a 30 wpc amp (Nap 90) to a 120 wpc amp (Nap 500 ish...)

Living Voice Auditoriums have a sensitivity of 94 dB/W/m, so they will go as loud off a DNM power amp @ 23 wpc as you would get using a 200 wpc amp into any average speaker in terms of sensitivity.

A Nap 250 will thus only give you about 4 dB increase in SPL, and the Nap 135s only a fraction above that.

Never mind the figures, a Nap 140 goes louder @45 wpc than a Nap 150 at 5 wpc more. My old Densen B100 integrated amp went much louder than my previous Rotel RA 971 MKII measured at 100 wpc by Paul Miller at HFC, iirc.

Wpc is nothing in comparison with current capability for transient attack; the Nait 5 @ 30 wpc goes much louder than, say a Yamaha amp rated at 100wpc.


Regards,

Steve.

[This message was edited by Steven Toy on WEDNESDAY 18 December 2002 at 02:28.]

I have always wondered if higher sensitivity speakers might be more sensitive to microdynamics. When I have read reviews of high sensitivity speakers this does seem to be a common characteristic. This seems to make intuitive sense to me.

I have friends who are die hard fans of Dynaudio speakers and it seems that they are a monster to drive. They would then have to search high and low on getting an amp that is powerful enough and given the fact that most of us have limited finances, they would have to compromise on their source.

I wonder, is there something that Dynaudio speakers can do that no other speakers can, to justify spending an obscene amount of money just to find an amp powerful enough to drive it. Or are there some characteristics that low sensitivity speakers can achieve that none of the higher sensitivity speakers will ever achieve. Something to do with physics?

Consulted SWMBO. Tells me that it's not how big it is, it's what you do with it that matters......

Girl at work told me "if a girl ever says that to you, she thinks you're tiny!!"

Anyway, it's the quality of the first watt that counts

Simple math does not begin to approach a comprehensive illustration. Although it does tell, in vague and general terms, how an amplifier reacts.

Mr. Toy's comments are about as useful in describing the complex relationship as a schematic would be at telling you what an amplifier would sound like.

Leaves out a lot of variables, not the least of which is how far is the listener sitting from the speakers.

Dynamics, impedance at given frequencies, etc. are all environmental factors that come to bear on the working relationship.

It would seem logical that larger amplifiers,(ie. massive output stages) may be better suited to lower sensitivity speakers, and yet many lower powered, simpler circuit designs drive low sensitivity speakers with more aplomb.

I've used ES 14's with great sucess on a Nait 5, and later on a 112/150.

My experience driving speakers shows that it is how low the impedance drops, particularly at lower frequencies, that dictates suitability in the amplifier v speaker match up, not wpc of the amp or the sensitivity of the speaker.

On a good day, my 250 case gets quite warm driving a 4 ohm 90 db sensitivity speaker when playing a Bach Cello Concerto at tactile volumes

Hi,

Had ES 14 for many years myself. First with Nait 2, then 72/140, then 82/140 and finally 82/250.

They are imho very good speakers and you will really need something much more expensive to justify changing them.

However, they seem to really like power. Going from 140 to 250 made a huge difference. This is not to say that I didn't like what they did with the smaller amps. Not at all. But with a 250 (or perhaps 180 - I never tried this) they are simply much better.

Claus

On paper my DNM amp shouldn't be able to drive the rather inefficient Neat Petite IIIs - 86db, 4 ohms - but it does. So power isn't the key. It must be something else - quality of PSU, perhaps?

TC '..'
"Girl, you thought he was a man, but he was a Muffin..."

If a speaker has a high sensitivity it normally also has a low impedance, which might upset some poweramps, as low impedance means the speaker is "pulling" more current from the amp. This is why an easy impedance is more important than high sensitivity if you use a low powered amp or an amp with limited current delivery.

A speaker with lower sensitivity is also easier to manufacture with a more even frequencyresponse.

High sensitivity speakers tend to sound more dynamic, but might also suffer from colourations.

Some manufacturers build their speakers these days with a high sensitivity, in a quick a-b demo they can sound louder and more impressive, but remember that high sensitivity does not mean that the speker is easy to drive. The impedance tells more about that.