Power Rating (1 Viewer)

[Drew_W]

I meant that the SPL meter should be for verifying that the intervals on the receiver volume control are bang on. If they aren't, say that cranking it up from -40 to -35 results in a real 3dB increase, that would mean that 5dB on your receiver is doubling power.

(This is making less and less sense to me the more I think about it, but I think that's what I was thinking)

And doubling power is +3dB and vice versa. Always.

 

[Yogi]

No that would still be +3db. Doubling in perceived loudnesss OTOH is 10 db. Meaning you would need 8 times more power for your receiver to sound twice as loud. So if you needed a receiver that sounded twice as loud as your 100W/ch receiver you would need a receiver that pushes 800W/ch.

Also remember that mostly you only listen to a few watts at most with 90db/w/m (90 db is loud!!! BTW) nominal sensitivity speakers. Its only during the transients (canon shots, explosions etc) that you could need upto as much as 20db headroom (according to Dolby labs) which means in order to reproduce those transients you could need as much as 100 times (=20db) more power. And thats what separates good amps (men with balls) from the wimpy ones (kids). Most people don't listen to those levels and many don't know what compressed and distorted sound sounds like and so most incompetent mass market receivers go un noticed.

 

[ericanthonE]

i'm honestly having a hard time following in some places..


1.What do you mean by DOUBLING POWER?

2.So for every 3db increase NO MATTER WHAT through your volume range, you are doubling the term deemed above?

4. Doubling percieved loudness is 10db. Meaning if you moved your volume range 10db, it would APPEAR but not TRULY, or even NEAR TO truly be twice as loud, is that what your saying?

Even as i reread this, i think i am contradicting what you have just said.

I really would like to know this, and maybe i am difficult, but i'm just maybe missing some of the pieces to the puzzle here.

I hate to ask you this, but could someone(or you) explain it in retards terms.

I do think that i understand the power meter, that is fairly straightforward

I think that the problem is that i am not completely aware of perceived vs. double power.

 

[ChrisWiggles]

Ok, the basic difference between SPL and "loudness" is that SPL is Sound Pressure Level, which is a scientific measure of the intensity of the sound in decibels. What our ears perceive in terms of quiet to loud sounds is INSANELY huge, on the order of many millions of magnitudes between the loudest and softest sounds. We HEAR these sounds logarithmically. Decibels is a logarithmic comparison between sound levels.

What we PERCEIVE in terms of volume or loudness, is much different than measured reality. 3db is twice the intensity of sound, but we hear this as a very small increase in volume. 10db, is usually roughly perceived as being twice as LOUD, but the sound intensity is actually 10times as much.

The equation is this: dB= 10log(base10) I2/I1

Where I2 and I1 are different sound intensities.

Sound intensity is NOT the same as what you *perceive* as loudness. This is why things are a little confusing, because our ears and brain works on a logarithmic scale, rather than a linear one.

 

[Yogi]

Doubling power implies that you are doubling the absolute output power to the speakers. So when your receiver goes from an output of 1W to 2W there is a 3db gain in SPL from your speakers. When it goes from and output of 50W to 100W there is a 3db gain in SPL and when it goes from an output of 10,000W to 20,000W there is a 3db gain in SPL.

The human ear however perceives a doubling of loudness (not power) for every 10db gain in SPL. So if your speaker sounds a certain loudness at 'X' db setting on your volume dial, then at 'X' + 10 db it will sound twice as loud (although it will require your receiver 8 times the power to give you that perceived doubling in loudness). So you see power and loudness are two different concepts.

 

[ericanthonE]

actual power however is exponential(increases compoundingly) through the volume range? correct

i understand this now, i just didn't know where you were calculating from. Makes perfect sense to me now

So if i move my volume range from '-74' - '-64' it will be perceived as 2 times as loud, when in fact it is actually pushin little over 8 times the power, correct. A LITTLE over eight, if i understand correctly now.

I THINK i understand, any comments, thanks for explaining it better

 

[ericanthonE]

so if my speakers are rated at a 92db, what would that mean?
how would that coincide exactly with the ratings i just learned about the amplifiers. thanks. I could start a different post, i don't want to hog this one? I am learning a lot though.

 

[ericanthonE]

sorry guys, but you are obviously right, and that dealer was a little off, that is why i repeated an untruth. A dealer told me that for every 3db increase you were only using 10 more watts. That was the difference.

But now i know that a 3db increase is doubling the power that the amplifier is working on putting out(it is working twice as hard), but you would not even hold close to seeing that the amplifier is working twice as hard till it is actually working 8(almost a little more than i think) times as hard.

Sorry, but that is how i pound this into my brain, by typing it out to understand better.

 

[ericanthonE]

could someone explain to me why the volume range? as that would be called would say start out at -74db and work it's way to say a +12db. I don't understand why it is like that? It's not like it is putting out negative(-) sound pressure, is it?

Eric

 

[Yogi]

Usually the 'zero' on the volume scale of your receiver corresponds to reference level which is what it should sound like when you are in theaters. This however depends on a lot of other parameters like your speaker sensitivity, room volume, room treatments etc etc. That's why you have to calibrate your receiver with an SPL meter to determine your system/room reference levels (@85db). My reference level is at -8db on my receiver. Your's might be something else, but the idea is that you are either listening at a certain db below reference or at a certain db above reference with reference being '0' (not necessarily the zero on your receivers scale)

Hope that makes some sense.

 

[ChrisWiggles]

Also see the Beginner's Primer and FAQ, it answers these and many other questions quite well.

http://www.hometheaterforum.com/htfo...hreadid=120328

 

[ericanthonE]

that would explain why i need to turn my dvd player up for it to become louder(farther toward o for it to sound right) whereas the CD player would only have to be at say 30 to sound very loud? I thought that it maybe had to do with the fact that i had an older cheaper DVD player, with worse processing, than say my CD player had. I have a recent post on this called 'analog vs. digital' if you could care to enlighten me.

I got cha' about the speaker at 92db, being half the power of 89.

Thanks soo much, for it is important to me to know this stuff!

 

[ChrisWiggles]

eric, that you have to turn up your DVD player is because of the increased dynamic range used in most DVDs. Many CDs are relatively compressed dynamically, i.e they are roughly the same volume the whole time. Many cds aren't like this, especially well-done classical cds, and you'll find you'll have to turn them up more for most of the passages to be at a good volume, but then there are large dynamic swings, and loud passages can get REALLY loud. Whereas most rock is just the same, loud, all the time.

DVDs have huge swings in dynamic range as well usually, from just dialog, to loud action scenes.

 

[ericanthonE]

can one of you guys reply to my post 'analog vs. digital' in the tweaks, and connections thread. I would appreciate it!

I would like to open up an audio shop in about 10 years for a hobby, for i really get into this stuff, so i will hopefully know my stuff well by then. Thanks to all your posts.

 

[Yogi]

I dont know if that would be such a good idea esp. 10 yrs from now. I have seen a number of speciality audio stores close down because a best buy or a tweeter has opened in the area. Most consumers (not the ones in this forum) these days are into mass produced HT gear and dont know what a good two channel (or HT) system sounds like. And making a profit selling those mass produced speakers/gear where economies of scale rule is getting harder and harder to do in a small outfit. Wait till Walmart seriously gets into the game.

OTOH this is a fun hobby and one should know as much as possible about it.

 

[ericanthonE]

well i will be a medical doctor, and i would just love to do it for a hobby. people would be robbing me blind.haha But it is hard to still get quality audio gear.

You think that things like rotel, anthem, mark levinson, krell, def tech, B & W, paradigm, Lexicon. etc will be available at wal-mart? that is what i would like to sell. Stuff that noone else wants to sell

a high end audio shop. and no i probably wouldn't make any money, but a fun outlet!

 

[ericanthonE]

i was talking to a guy at the high end audio store that mistold me about the watts. more like i might have misunderstood him. Anyway, he was saying how this caters to 1 in every 1000 people, and how he wouldn't get involved with it.

Eric

 

[Yogi]

No, but how many people buy Levinson, Krell and Tag gear? You wouldn't be able to justify carrying all that inventory even for a hobby, IMHO, and who knows how many of them will be in business ten years from now. Its good that you don't plan on quitting your day job for this hobby

 

[ericanthonE]

yeah, that's the way that the world is though. It will be run by a few really rich people.

I would do it on the weekends. Oh man, it was a nice dream, and you go and burn the reality straight into it!

Thanks for all the input. i appreciate it.

 

[ericanthonE]

oh, i didn't know that the smiley blinked, i certainly didn't want to make it look like i was hitting on you or anything. yikes.

what kind of amplification do you have? I need to do something about that. I have 7 def tech's that i need to amplify.