Understanding Loudspeaker Sensitivity Specifications & Measurements

[admin]

Loudspeaker manufacturers sometimes exaggerate the specifications of their products to make them look better than they really are. Some are more honest than others in this regard. The focus of this article is on loudspeaker sensitivity and what to look for in this rating so the consumer can make a more educated purchasing decision when comparing products. We propose an ideal solution every speaker company every loudspeaker company can easily follow, giving all of us one very specific, agreed-upon, universally-recognized way of measuring and stating sensitivity. If all speaker companies did this, then consumers would have a reliable, transparent way to compare sensitivity ratings from different manufacturers, and reviewers would have a concrete benchmark against which to verify their test result findings against the manufacturer's claims. But, alas, not everyone does, so caveat emptor!




Discuss "Understanding Loudspeaker Sensitivity Specifications & Measurements" here. Read the article.

[GO-NAD!]

I really don't understand this view:

The other viewpoint is that in the real world, a speaker’s impedance is what it is, and the amplifier puts out its voltage as it does. Assuming the amp is muscular enough to drive low impedances, then if a speaker has a lower impedance, it will play louder for the same voltage input from the amp and this is information the consumer should have. In other words, the speaker’s sensitivity rating should not be “penalized” because it’s a 4-ohm instead of an 8-ohm speaker.

We can't just assume an amp is muscular enough to drive low impedances, rendering the speaker's impedance unimportant. I would say that if one has such an amp, he won't be all that concerned about speaker sensitivity to begin with. If one is concerned with his amp's ability to drive low impedance loads, and is only going to be purchasing speakers, he will have to "penalize" the 4-ohm speaker. Unless, of course, the 4-ohm speaker's sensitivity is high enough to compensate. Is there something I'm missing here, that makes the viewpoint valid?

[JerryLove]

I agree with you. Both my 801's taught me that, while sufficient amps sound the same, I cannot determine sufficiency just by looking at sensitivity of the speaker.

[Steve81]

We can't just assume an amp is muscular enough to drive low impedances

I don't believe anyone is suggesting you can.

I would say that if one has such an amp, he won't be all that concerned about speaker sensitivity to begin with.

You'd still need to be concerned; an amplifier can run out of voltage before it runs out of current, especially at higher impedance levels (ie 8 ohms and up).

If one is concerned with his amp's ability to drive low impedance loads, and is only going to be purchasing speakers, he will have to "penalize" the 4-ohm speaker.

This would be an odd way to go about things in my book. I buy speakers based on their sound, and correspondingly will buy amplification based on what speakers I end up with. Limiting yourself to what speakers can be driven by some weak kneed amp seems a bit counterproductive, especially considering how many relatively low priced amplifiers are available that are competent into difficult loads.

[GO-NAD!]

I don't believe anyone is suggesting you can.

From the article:

Assuming the amp is muscular enough to drive low impedances...

Looks that way to me.

You'd still need to be concerned; an amplifier can run out of voltage before it runs out of current, especially at higher impedance levels (ie 8 ohms and up).

I'm not even going to pretend to understand that.

This would be an odd way to go about things in my book. I buy speakers based on their sound, and correspondingly will buy amplification based on what speakers I end up with. Limiting yourself to what speakers can be driven by some weak kneed amp seems a bit counterproductive, especially considering how many relatively low priced amplifiers are available that are competent into difficult loads.

I'm just looking at a scenario where someone may be in the market to upgrade and can only budget for speakers. If he can't pony up for a powerful new amp, then he has to keep that in mind when he is shopping for those new speakers. You may not think in those terms, but someone else might. And there's nothing wrong with that.

[Steve81]

Looks that way to me.

Depends on how you want to read it I suppose. I don't think Gene is trying to imply that any old amplifier will handle a difficult load, simply that an amplifier with a stout power supply will hold voltage steady regardless of impedance.

I'm not even going to pretend to understand that.

Lets put it this way: suppose an amplifier can "double down" into a 4 ohm load from an 8 ohm load. That means into a 4 ohm load it is delivering doubling the current for the same amount of voltage relative to the 8 ohm load. Therefore at the 8 ohm load, the speaker isn't current limited, but voltage limited.

You may not think in those terms, but someone else might. And there's nothing wrong with that.

Depends on the level of price and performance we're talking about to some degree I suppose. On the mid to higher end of the scale the price of high performance amplification will tend to be dwarfed by the price of a high performance speaker. An Emo XPA-5 for example can deliver solid output into 5 channels for $180 a channel (and less on sale). A pair of Ascend Sierra Towers OTOH will run $950+ a pop. In the grand scheme of things here, the amplification is a pittance, and limiting yourself wouldn't be advisable IMO.

Of course, if we're talking about lower end gear, yeah someone whose got $200 to spend on speakers and not a dime more with a lower end receiver should probably avoid a 4 ohm rated model with dips down to 2 ohms.

[BoredSysAdmin]

Thanks Gene.
This is a great read and most of it over my head , but if you copy an image from xkcd at-least a mention of source is needed I imagine.
xkcd: Spinal Tap Amps

[j_garcia]

Thank you for writing this up!! Could we PLEASE add a statement about speaker "wattage" ratings to this article?

[GO-NAD!]

Depends on how you want to read it I suppose. I don't think Gene is trying to imply that any old amplifier will handle a difficult load, simply that an amplifier with a stout power supply will hold voltage steady regardless of impedance.


Lets put it this way: suppose an amplifier can "double down" into a 4 ohm load from an 8 ohm load. That means into a 4 ohm load it is delivering doubling the current for the same amount of voltage relative to the 8 ohm load. Therefore at the 8 ohm load, the speaker isn't current limited, but voltage limited.

OK, this hypothetical amp can deliver the required current to drive a low-impedance speaker. I understand that part. But, what's telling us that it is voltage limited?

Of course, if we're talking about lower end gear, yeah someone whose got $200 to spend on speakers and not a dime more with a lower end receiver should probably avoid a 4 ohm rated model with dips down to 2 ohms.

This is the kind of person I had in mind. We should keep such people in mind when we discuss these topics.

[Steve81]

OK, this hypothetical amp can deliver the required current to drive a low-impedance speaker. I understand that part. But, what's telling us that it is voltage limited?

In a purely resistive circuit, Power = Voltage x Amperage. If the amplifier is not limited by amperage (which is pretty clear if its doubling down), then the amplifiers ability to cleanly swing more voltage is the limiting factor.

This is the kind of person I had in mind. We should keep such people in mind when we discuss these topics.

Ultimately I would hope the market keeps them in mind. Presumably Andrew Jones for example has designed his entry level line such that they won't explode on contact with Pioneer's entry level receivers