Basic question about sensitivity

I think, in general, the way you are looking at things with more sensitivity requiring more power is correct. I think Harbeth are somewhat of an anomaly.

Like all things audio, it depends. Recommended wpc amplification is a very open and unscientific… well recommendation. It can be as much marketing as a real requirment.

The nominal impedance of the Harbeth P3ESR XD is 6 ohms. Which they advertise as “easy to drive”, since many speakers with a sensitivity of 83 are very hard to drive, requiring a lot of power and having impedances dipping down to 2 ohms or lower. The impedance is a measure of easily electrons flow through… and at 2 ohms they flow easily, and if the amp can’t produce tremendous current then it runs out of power.

Also speakers are rated at nominal impedance… because they vary across the audio spectrum. So, some speakers dip to 1 ohm, then go to 8 or more ohms… the nominal impedance could be almost any thing. The electrical characteristics are so much more complicated that these two parameters show, they tell very little with certainty.

A better measure of amps is current… and for speakers the lower the impedance the more current they need to perform properly.

I never look at the power requirements and when purchasing solid state amps I have generally purchased amps of far more than the recommended power rating because they tend to sound better. Tube amps are not nearly as likely to show that they are running low on power.

I choose amps for their character and make sure they have lots of power… regardless of speaker. If you choose Harbeth, you are choosing a specialty speaker and should research amplification carefully.

Higher efficiency = easier to drive.

Higher sensitivity = more output at given voltage.

When the speaker is 8 Ohms, efficiency and sensitivity are the same.

Here’s a common example: Many mid woofers come in 8 ohm and 4 ohm versions. Nearly identical in all other aspects besides the impedance curves. The 8 Ohm version produces 87 dB at 2.83 V. That is, 87 db @ 1 Watt. The 4 ohm speaker produces 90 dB @ 2.83V, but since it has 2x the current it is 90 dB @ 2 Watts.

Generally speaking though, it’s hard to find high sensitivity speakers ( 97 dB or higher) that are not also benign impedance (8 Ohms or better).

To make it easier on you, keep an eye on "minimum impedance" not "nominal impedance."  Higher minimum is (generally) easier to drive, and the sensitifity/efficiency will tell you how loud it will get with your amp.

Higher efficiency = easier to drive.

Higher sensitivity = more output at given voltage.

When the speaker is 8 Ohms, efficiency and sensitivity are the same.

@erik_squires , thank you. The Monitor Audio Gold 300 5G (sensitivity 90) minimum impedance is stated to be 3.5 ohms, which would then explain the need for more power.

@ghdprentice , thank you; I am curious, when you refer to the Harbeth as a "specialty speaker," what do you mean by that.

Thank you for responding @ellajeanelle , no, I wasn’t confusing impedance with sensitivity; however I was not understanding the relationship between the two.

@ditusa , thank you for the link. I read through it quite quickly and it does appear to be quite informative. I am going to give it a careful thorough read.

OP,

You know, that is a great question… since they sit off in a niche to me, they are unique sounding. So, I had to ask that question. So, I did some research. I think in the process… came to the realization that the Harbeth claim of “easy to drive” may be more marketing hype than anything. Bard summarizes:

There are several reasons why Harbeth speakers are considered a niche speaker:

1. Limited Production: Unlike many mainstream speaker brands that mass-produce their products, Harbeth maintains a commitment to small-scale production. Each speaker is hand-assembled and inspected in their UK factory, ensuring high standards of craftsmanship and quality control. This limited production contributes to their exclusivity and appeal among audiophiles who appreciate the difference that handcrafted products can offer.

2. Unique Sound Signature: Harbeth speakers are not designed to cater to the broadest possible audience. Their distinctive "voicing" emphasizes a warm, smooth, and mid-range focused sound, which may not appeal to listeners who prefer a more neutral or analytical sound signature. This specific sonic character attracts a dedicated following among those who appreciate its natural and musical qualities, particularly for listening to acoustic genres and vocals.

3. Focus on Quality Over Technology: While many modern speakers incorporate cutting-edge technology and features,Harbeth prioritizes traditional construction methods and high-quality materials. They remain committed to using thick MDF cabinets, hand-built crossovers, and time-tested driver technologies. This focus on essential elements may not resonate with listeners who prioritize the latest technological advancements, but it appeals to those who value the enduring qualities of craftsmanship and classic design.

4. Specific Amplifier Requirements: Harbeth speakers have a nominal impedance of 6 ohms, which can be a challenge for some mainstream amplifiers. These amplifiers may not deliver enough current to drive the speakers to their full potential, potentially resulting in a less dynamic and detailed sound. This requirement for specific amplification options limits their accessibility to a broader audience, but it also attracts audiophiles who enjoy the challenge of pairing their speakers with compatible equipment to achieve the best possible sound.

5. Price and Value: Harbeth speakers are not inexpensive, and their pricing can be considered high compared to mass-produced speakers with similar features. This can be a barrier for entry for many potential buyers. However, for audiophiles who value exceptional build quality, unique sound character, and long-lasting value, Harbeth speakers offer a worthwhile investment. Their focus on quality over quantity ensures a superior listening experience that justifies their higher price point for dedicated music lovers.

Overall, Harbeth speakers occupy a niche within the speaker market due to their unique combination of traditional design,specific sonic character, high-quality materials, and limited production. They cater to a select group of audiophiles who appreciate the craftsmanship, musicality, and long-term value that they offer. This niche positioning allows them to focus on their core strengths and continue producing exceptional speakers for discerning listeners who value a truly special audio experience.

A singular focus on a particularly poorly crafted specification, in this case one that includes trash aka distortion as output, is not a wise pursuit. Easy load with low distortion ( breakup, frequency response, impulse, time and phase ) would be laudable.