Is Denon Correct About This?

[John Lohmann]

"engineer" of what?

You'd have to ask him; I was told he was a Denon/Marantz "Tier 2 Engineer."

 

[Verdinut]

what is a Tier 2 engineer - Google Search

Tier 2: This tier handles more advanced troubleshooting, working on issues that require deeper technical knowledge than Tier 1 can provide. Tier 3: Tier 3 consists of highly specialized technicians or engineers who manage complex, system-level issues that may involve advanced configurations or development.

 

[John Lohmann]

Who cares at this point what the meaning is behind this guy's moniker? The underlying query was about if the things being said about ohms and sensitivity were true or not, and it seems that's been answered, essentially by way of a "it depends" conclusion (taking the sensitivity element out of the equation).

Here's the thing, in a proverbial nutshell:

Because you so often read about how a speaker ohm selection in a piece of electronics should always be set to 8, regardless of scenario (otherwise, the story goes, you're severely limiting power of the amplification device), I was wondering if what I was being told regarding that was accurate.

Also, it didn't seem to make sense to me what was being said regarding lower sensitivity speakers -- I was always told these are harder to drive than higher sensitivity variants.

 

[Verdinut]

Who cares at this point what the meaning is behind this guy's moniker? The underlying query was about if the things being said about ohms and sensitivity were true or not, and it seems that's been answered, essentially by way of a "it depends" conclusion (taking the sensitivity element out of the equation).

Here's the thing, in a proverbial nutshell:

Because you so often read about how a speaker ohm selection in a piece of electronics should always be set to 8, regardless of scenario (otherwise, the story goes, you're severely limiting power of the amplification device), I was wondering if what I was being told regarding that was accurate.

Also, it didn't seem to make sense to me what was being said regarding lower sensitivity speakers -- I was always told these are harder to drive than higher sensitivity variants.

No, lower sensitivity speakers require more amp power than the one with a higher sensitivity to output same SPL. But nowadays with amplifiers having more power than 75 years ago, they are rather easy to drive.

With regard to the AVR Speaker Impedance switch, I think you should read again the info in the link at post #2.

 

[John Lohmann]

No, lower sensitivity speakers require more amp power than the one with a higher sensitivity to output same SPL

So that's what I thought...

 

[dolynick]

I'm not an engineer so someone can feel free to correct me if I misspeak here.

As Peng said, Impedance is basically resistance at a given frequency. So less resistance can be interpreted as easier flow of electrons. So correct in that interpretation I guess.

When dealing with speakers, amps and volume though, sensitivity is a rating of SPL (loudness) at 1W and 1 meter away. As you increase loudness, you require more power. Power is I^2 * R (current squared times resistance). So current might flow easier through that lower impedance, but more of it is required to achieve the same power (and thus SPL/loudness) at the lower resistance.

If you're trying to put out 100W into 8 Ohms, you require ~3.5A of current from the amplifier.
If you're trying to put out 100W into 4 Ohms, you require ~5A of current from the amplifier.

Most people will interpret that behavior as being "harder" on the amplifier. Which is where the disconnect from the Denon rep's statement is.

As far as sensitivity goes, it takes double the power to increase output (SPL) by 3db. So in order to get an 83db sensitivity speaker to be the same perceived volume as an 86db speaker, you automatically need twice as much power. Perceived "twice as loud" is an increase of 10db or 10 times the power, so you can see how power/current can quickly ramp up when sensitivity is considerably lower. SPL also drops off 6db (x4 power) every time you double distance (remember speakers are rated at 1m), so by the time you're 10 feet away, you're requiring x16 as much power to get that same SPL level from the speaker.

 

[John Lohmann]

Thanks for your input, Nick.