What is your take on high efficient speakers vs. low efficient speakers?

@larryi wrote: "I sort of think that 95-96 is at the low end of the range. My speakers are 99 db/w efficient, and friend calls that medium efficiency (his speakers are above 112 db/w efficient."

Imo this is something to be aware of:

Very often the limiting factor for high-efficiency systems is the on-axis frequency response at high frequencies. And one way to get very high efficiency numbers is to use a horn whose pattern at high frequencies is very narrow, such that all of the high frequency energy is concentrated in a narrow beam, thereby maximizing the on-axis sound pressure. If the same compression driver were used on a wide-pattern horn, the same amount of acoustic energy would come out, but because it’s spread over a wider angle the on-axis PRESSURE would be less.

By way of analogy, consider a garden hose with an adjustable nozzle. The on-axis PRESSURE is higher when the nozzle is adjusted for the narrowest possible pattern, but the same AMOUNT of water comes out regardless of the pattern width. So too with horn radiation patterns.

Implied by this is the fact that an omnidirectional speaker system is actually putting out a lot more acoustic energy than we would normally infer from its "on-axis" efficiency.  So comparing efficiency (or voltage sensitivity) specs is not necessarily making an "apples to apples" comparison.

Duke

@tannoy56 wrote: "What would you say are the attributes of low efficient speakers? Anyone?"

Low efficiency speakers will give you deeper bass response for a given enclosure size, often dramatically so.

The obvious implication of the above is, low-efficiency speakers tend to have much higher "spouse acceptance factors".

As was mentioned previously, low efficiency speakers tend to have wider dispersion, this because designs which result in high efficiency (such as horns) tend to have deliberately narrowed dispersion. Whether wide or narrow dispersion is better is subject to debate, and imo depends on the room itself and other other considerations.

Some horns have coloration, which imo eliminates them from serious contention. At the risk of over-generalizing, I’d be wary of horns which have sharp-edged internal "kinks" and/or sharp edges around the mouth.

In general smooth frequency response is less expensive to achieve with low-efficiency speakers than with high-efficiency speakers. This is because there are inevitable tradeoffs in driver design, and some of the characteristics which contribute to response smoothness work against high efficiency, and vice-versa.

I’m sure there are other attributes of low-efficiency speakers which I have overlooked.

Imo amplifier + speakers + room = "a system within a system". Typically the room is the most expensive component, and the most difficult to upgrade, implying that the speakers and the amp(s) should be chosen to work well in that particular room as well as with each other.

Imo, ime, ymmv.

Duke

High-efficiency speaker manufacturer

@phusis wrote:

"The EV Constant Directivity horns (HP9040 + DH1A) on my EV main speakers, by virtue of not narrowing the HF response on-axis, should require equalization in its upper band above some 3kHz, at least for their intended cinema use, but surprisingly we’ve only found it necessary and most important to apply some notches and a peak suppression via a Xilica DSP (active config.)... What’s your assessment here?

The short answer is, I don’t know.

Perhaps the crossover filtering is providing the equalization without obviously using a dedicated EQ circuit, by cutting the lows instead of boosting the highs. Perhaps EQ is being applied somewhere without you knowing about it. Perhaps your compression drivers have signifcantly better frequency response than the published curve; I have found that to sometimes be the case, the manufacturer apparently having made unannounced improvements in the frequency response... but usually not to that extent. I don’t see an impedance curve online, perhaps there is an amplifier interaction with the impedance curve which results in a rising top end with your amp, or which resulted in a drooping top-end when the published curve was measured.

That being said, the published unequalized curve for that horn/compression driver combination looks right to me. It looks like the curves I get with large-format compression drivers on constant-directivity horns.

All of the above speculative explanations are unlikely, perhaps even highly unlikely, which brings me back around to "I don’t know".

Sorry about that!

Duke