Efficient speakers v. less efficient speakers

You cannot compare efficiency alone without considering speaker/cone size and overall design...it is always a compromise.

The question:

If driven with the appropriate amplifier(s), meaning a higher powered amplifier for a less efficient speaker and a lower powered amplifier for a more efficent speaker, are there any difference?

The speaker design is generally what makes the difference.

An inefficient bookshelf speaker with a big amplifier can be comparable to a full size efficient speaker with a small amplifier when played at acceptable sound levels for both the bookshelf speaker and small amp.

A bigger speaker can ultimately go louder with less distortion particularly when pared with a big amplifier.

On the other hand,

An efficient bookshelf speaker, is rarely comparable to a full size efficient speaker.(Bookshelf being roughly up to 6" woofers, and full size being 12" or larger woofers)

In very general terms:

1) big speakers can be efficient, and play loudest with lowest distortion
2) small speakers tend to be inefficient if they have low distortion.
3) efficient small speakers tend to have the highest distortion even if they can play quite loud with a modest amplifier.

Gs5556,

I agree with you fully. I think you described the differences much better than I tried to explain.

Your point about horn loading is a good one.

A tuned bass reflex port is commonly used to increase a speaker efficiency enormously by adding extra bass response. Unfortunately, most of what comes from a tuned reflex port is resonance and not primary source signal...so that although you get a loud bass response it usually sounds boomy, muddy and warmly resonant => lots of distortion

Audiokinesis,

Very good points about thermal compression issues and how they affect dynamic range and tonal balance. I agree with you fully.

A highly efficient speaker should certainly be better in these regards when listened to at moderate to higher levels.

Do you have a view on how distortion tends to be affected as you increase or decrease efficiency?

Here are a couple of links that clearly explain some of the complexity and compromise involved in speaker design.

http://www.soundonsound.com/sos/oct00/articles/monitor.htm

http://www.soundonsound.com/sos/nov00/articles/ustandingmons.htm

Rlew,

I am only concerned that someone reading this thread will think that a high sensitivity speaker is necessarily better than a low sensitivity speaker.

Unlike the general rule about a bigger box having better bandwidth and therefore being a better speaker.....there is no simple rule of thumb for efficiency.

There are indeed advantages in high sensitiivity speakers, as myself and others have pointed out, such as a better dynamic range (less compression), however speaker design requires a balance of compromises and high sensitivity is not always better.

In very general terms, ultra-efficient speakers should be avoided just as ultra-inefficient speakers should be avoided. Both will have strengths but extremes are generally achieved with large compromises in other areas instead of an overall balance in performance.

Let me give a couple of examples of how a manufacturer can achieve high efficiency at the expense of distortion;

Long coil operating in short magnetic gap gives a low cost and highly efficient driver but it increases harmonic distortion as the voice coil operates outside the linear area of the short magnet gap. Also the heat dissapation is poor in these designs....so while they are highly sensitive they do not dissipate heat as well as a shorter coil in a longer magnet gap.

Very light rigid cone diaphragms made from hard/stiff materials (magnesium,ceramic,polymers). These efficient rigid low mass cones have low internal damping and tend to have high Q resonances. This efficient choice of cone leads to higher harmonic distortion than more critically damped designs.