Give me an Amp Crash Course

[herbu]

I have a feeling it's difficult for you to put yourself in the shoes of someone who knows far less and then explain something to that person so that he gets it. You know, like good professors do.

Sorry you feel that way. I thought I was pretty good at it.

You said turn volume up and down, but in relation to what? What is the reference point?

The reference point is any volume at which you're listening. Your question was, "I must admit I don’t know what this i.e. -6dB means in reality… Is it audible or not?" My answer was listen to something... turn the volume up/down 6dB and you will actually hear how "audible" a 6dB change is.

killdozer, your last post made it clear you came to class without completing the reading assignment, (your Yamaha Owner's Manual), or even the CliffsNotes. So I will speak to you appropriately.

Your volume control has an assignable scale. You can choose a pedestrian numeric scale of 0-100, or a dB scale. The numeric scale may be roughly interpolated to a dB equivalence by a knowledgeable user, (which you are not).

On the dB scale, "0" indicates THX Reference Level... http://www.thx.com/consumer/thx-technology/thx-reference-level/
It does not represent silence. Quite the opposite.
Changing your volume control up or down 6dB is an actual 6dB change. Thus my answer to your question, "Is it audible or not", was the only correct answer for you and your unique ears.

I'm a literature/theory of cinema professor.

I applaud and encourage your entrance into the field of audio. Your presentation of theory can only be enhanced by an understanding of at least a modicum of reality as audio has played an integral part in the evolution of cinema. Of course there is much more detail and some exceptions to the information above. But until you pass 101, no good professor would waste time trying to explain it to you.

 

[killdozzer]

Sorry you feel that way. I thought I was pretty good at it.

The numeric scale may be roughly interpolated to a dB equivalence by a knowledgeable user, (which you are not).

Nope! You’re not good at it. Sorry to have to break it to you. What you wrote in last couple of posts in this thread was useless and condescending.

Here; a table Audioholics web site links to. It says 0dB is “threshold of hearing”. You know how I reached this table? By not only reading the articles on Audioholics web site, but opening and reading everything those articles link to (this particular one stemming from “The Decibel (dB) Scale & Audio Rules 101” and that one stemming from: “Subwoofer Integration: Bass Management and Distance Settings Explained”). So will you cut the c… with:

came to class without completing the reading assignment

When, after someone admits to not understand something and asks for explanation, a person comes to underline the fact that said someone doesn’t understand and dances over that fact a couple of times, combining that with insults directed at said someone’s profession, you know how that person looks like. Like an asshole.

But the rule of instant karma, or irony if you prefer Yale’s school of New Criticism (read “Irony as a Principle of Structure”), comes to our aid when you went and did something as stupid as writing:

Your presentation of theory can only be enhanced by an understanding of at least a modicum of reality as audio has played an integral part in the evolution of cinema.

False! I could try to explain that to you, but I think of myself as a good professor and even my students do, so, as you said, I won’t waste my time on you as good professors don't.

Sorry, I get offended easily. There, you can base your next argument on that fact, underline it a couple of times and dance all over it with a couple of insults like you did the first time. But let me tell you, I know exactly as little as before these few posts, so where did you come up with this:

Sorry you feel that way. I thought I was pretty good at it.

beats the hell out of me. Couldn’t you simply avoid my thread if you don’t like it?

kd

 

[lovinthehd]

0dB as an absolute value of 0 to represent no sound is different than the use in avrs of the relative volume scale, maybe this will help http://denon.custhelp.com/app/answers/detail/a_id/136/~/relative-and-absolute-volume-ranges

 

[herbu]

I know exactly as little as before these few posts

If you could put aside your indignation a moment and actually read/comprehend what I wrote, perhaps your state would not be so stagnant.

I'll copy it for you here, so you don't have to go look for it:

"Your volume control has an assignable scale. You can choose a pedestrian numeric scale of 0-100, or a dB scale. On the dB scale, "0" indicates THX Reference Level... http://www.thx.com/consumer/thx-technology/thx-reference-level/"

And one word of advice. If you are easily offended, perhaps you should not be so quick to offer offense... "I have a feeling it's difficult for you to put yourself in the shoes of someone who knows far less and then explain something to that person so that he gets it. You know, like good professors do."

 

[KenM10759]

Calm down killdozer. This "dB" thing isn't really complicated, it's just shifted in audio specs since the introduction of THX's "reference level." My take on it is something like this:

As the chart you posted shows, total silence is 0dB. Standing next to a locomotive engine at top rpm might be 100dB.

Now what THX has done is establish that for movies a level of 85dB is their new "zero point." What I mean is that the overall sound pressure level of a movie soundtrack should be 85db, and some scenes could go as high as 105db. (THX specifies there be 20dB of headroom.)

So now the manufacturers of many audio-video receivers have taken to setting the "zero" of their unit's volume dial up at what should be 85dB when connected to the average speaker at the average impedence and average sensitivity. So now a setting of 0dB on the amp isn't dead quiet, it's quite the opposite. Turning it down from there results in a -xxdB value.

Trouble is, speakers are really all over the map on those things. Your LS50's are not as sensitive as some others, so wouldn't go as loud as a more sensitive speaker with the same setting on the amp/receiver. So in summary it's doubtful that any amp or receiver and speaker combination is actually putting out an 85dB sound pressure level when set at "0dB" unless it's in THX's lab with a bunch of white coats running around.

 

[ski2xblack]

I really like that ELAC piece. It checks all the right boxes, and only slightly more expensive than a late model Denon AVR (cursory googling revealed $599 here in the US). Maybe someone is listening.

 

[lovinthehd]

Trouble is, speakers are really all over the map on those things. Your LS50's are not as sensitive as some others, so wouldn't go as loud as a more sensitive speaker with the same setting on the amp/receiver. So in summary it's doubtful that any amp or receiver and speaker combination is actually putting out an 85dB sound pressure level when set at "0dB" unless it's in THX's lab with a bunch of white coats running around.

Well, ideally if using an avr calibrated to the standard, then two different speakers of different sensitivity would actually play at the same volume at the same setting....theoretically. Non calibrated volume dials would be in line with the different speaker sensitivities....