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.

 

[highfigh]

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.

Lower sensitivity speakers can be rated at the same impedance as higher sensitivity varieties- sensitivity & impedance are determined by the voice coil's wire gauge, magnetic strength, distance from the coil to the magnet, diameter, number of layers....lots of variables. As long as the impedance doesn't dip too far and the voice coil's inductance isn't too high, it won't be difficult to drive. 4 Ohm speakers are harder to drive because the Current is higher and that creates more heat in the output devices, as well as taxing the power supply more than an 8 Ohm speaker.

Definitions and descriptions matter- ask some people a question and the answer is clear & concise, ask others and it's overly-technical and harder to understand- the problem is that when people are put in support positions, the ones hiring them don't ask the right questions and don't necessarily know what to ask in order to find the best communicators.

I would like to go back in time to the point where the idiot from Associated Press was about to release the personal info for the technical trainer from a major electronics manufacturer, grab them by the neck and say "Don't even think about it!".

 

[highfigh]

That's not how he explained it to me -- he DEFINITELY used the term "engineer" -- but you could be right.

And he may be an engineer, but if you read my previous post, not everyone is a great communicator and not everyone understands what they hear in the same way. If you can call back and find the same person, maybe you can ask them to explain why it's harder to drive, assuming the impedance of both is basically the same. Or, you may speak with a different person who explains it differently.

 

[highfigh]

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.

One thing that can create problems in understanding this whole issue is that the commonly used test voltage is 2.83V, which calculates to 1 Watt ONLY at 8 Ohms. Using that voltage with a 4 Ohm speaker calculates to 2 Watts and amplifier output is in Watts, not Current.

A 4 Ohm speaker with 84dB@1 meter sensitivity using 2.83V input is a poor choice when someone wants to peel the paint in a large room when 100W results in ~104dB @ 1 meter.

 

[PENG]

amplifier output is in Watts, not Current.

Obviously that is the case based on the conventional ways of how manufacturers specified amplifier output from day 1 (I assume). Unfortunately, it would have been better if they use rated voltage and current with specified load conditions (among other metrics, such as 20-20kHz, THD+N<0.1% etc.etc.) instead of watts. Amplifiers are used with loudspeakers, not resistors.