speaker efficiencey?? Starting point...? 92db??

I recently purchased an spl meter to map out the response on my HT system. The manual for my Yamaha Rx1500(using as pre/pro) says to start at 0 db volume and test each channel from the listening position to 75db. I went through each channel(7.1 sys) and at 0 db i only had to adjust the left front and right surround speakers slightly to hit the 75. All other channels hit 75db at 0db.

Iam guessing that it would be correct to say that my requency response is relatively flat. Forgive my ignorance but i am just starting out in this crazy world of HT. My speakers have an efficiency rating to 92db. what exactly does the efficiency rating mean?>??
A speaker's efficiency rating is customarily the average midrange sound pressure level produced by a 1 watt input measured at 1 meter on the tweeter axis under anechoic conditions.

I say "customarily" because what's actually being measured and claimed varies somewhat from one manufacturer to another, but I figure you weren't looking for a long drawn-out answer. That 92 dB efficiency is considerably higher than average, assuming the numbers aren't somehow inflated.

The 92 dB efficiency rating of your speakers has no bearing in the setting of your channel levels - just follow the Yamaha manual as you have done.

Well average efficiency I would say is somewhere in the 88db to 92-93db,, anything above is just gravy and starts to get into the super speaker range. But with your receiver showing you that you did not have to change anything on a couple channels tells you that from your average listening position those distances just happen to already fall in range of the 75db mark which is fine(as long as you set up your Db meter at ear level of the center seating position in the room)it should be pretty even and flat thru the room. Some might take more some less. But the 92 db absolutly has something to do with your channel levels, cause if they were 89 db vs. 92 db that means they would take 100 watts more of power to reach the same white noise level at 75 db that your 92db speakers do not take, so 89 db would have probably made you boost up the channels 2-3 db on your channel leveler during the test vs. not upping it at all on a few channels. Every 3 db more efficiency the speaker has more or less means the amplifier needs to produce about half the energy to retain the same sound pressure level.. in general from my tinkering and understanding.
Matrix wrote:

"But the 92 db absolutly has something to do with your channel levels, cause if they were 89 db vs. 92 db that means they would take 100 watts more of power to reach the same white noise level at 75 db that your 92db speakers do not take, so 89 db would have probably made you boost up the channels 2-3 db on your channel leveler during the test vs. not upping it at all on a few channels."

Matrix, I think you're making this more complicated than it has to be; I read that sentence several times and I'm still not sure exactly what it's saying. You are correct that an 89 dB speaker would require twice the power of a 92 dB speaker to reach a given sound pressure level, but at 75 dB measured at the listening position we'd be talking about tenths of a watt difference, not 100 watts difference.

All Dzigon has to do is set the levels according to the instructions. He doesn't have to take the speakers' efficiency into account - setting the levels according to the processor's instructions automatically does that and more.

There is nothing complicated about a 92 db speaker possibly falling within perfect range of a basic surround receiver not needing to be adjusted, as he stated a few speakers were dead on without moving channel levels. 92 db happened to make this occur, if they were 88 db, it would guarantee with that speaker the levels would be moved up a bit, and with 96 db speakers probably would have been well over the 75 db benchmark making those levels back off into the negatives on the channel gain levels to match the master volume, thats all I was saying... And I was simply giving a little explanation to his final question SEE above not about the 92 db question, cause yes they will work fine 92 or 102 just trying to build example's to follow, but maybe not the best explanation... first post
" what exactly does the efficiency rating mean?>??"
I see where you are confused, and so am I... I kinda combined the Effectiveness of it Vs. what could happen via difference's in Db ratings, which was part 2 of the first question.. So I did over do it and should have been a little more clear on the basic question and ended up answering as one reasoning behind the theory. Sorry, sometimes I write half and come back while at work on the computer then submit the post, thoughts float around and not always land in the right spot.
Don't get so hung up on the efficiency rating of the speaker...the main thing to look for is it's nominal impedance and is it stable at that number...if the speaker has a higher impedance, low 90's like a Martin Logan but goes down to 2 ohms then you need a high current design amp that doubles down power as the impedance drops.
I would say that the relative levels of the individual channels and how closely they match one another has absolutely nothing to do with the system's ability to provide flat frequency response. That would be a whole different topic and to measure it you'd need test tones recorded at identical volume throughout the audible frequency range, and an SPL meter to chart the results.

Most combinations of rooms and speakers virtually guarantee that the frequency response arriving at your ears will deviate quite a bit from "flat." Then again, if it actually measured flat (nearly impossible without EQ) it would sound way too bright to those with normal high-frequency hearing ability.

A gradual rolloff in the lower high frequencies (probably with some degree of boost in the upper highs) sounds "natural" to most people. And that's a whole different topic unto itself, as well. :)
Plato is right.We may be onverge where even HT recievers have room correction to flatenntheings out buit that is now perveiw of #,600 DEQX (great pre/pro),$10K TACT.Some speakers like Infinity have RABOS to take out upper bass "hump" and produce flatter response.But this strays from the question path.
92 db may mean in say 12x14 room you could get into esoteric SET (single ended triode)amps that put out 6 watts as long as you didn't want to blow walls down.But this is another application that you are not into.This efficincy means you will be happy with your 75 watts while another person with 87db speakers would crave more current.As far as what audiokenisis and Matrix were saying I have also heard room of thumb is that-every increase of 3db is like doubling power.But as Laryken points out this is speakers that are 92db with an easy load.I sold B&W for a time and even though 803Nautilus was rated at 90db effcinecy 100 quality watts (an amp stable to say 2 or 1.5 ohms).I thought 200 watts was what folks needed and if in a big room maybe 300 wats so they got CURRENT whose amps may be important than wats.The reason for this even though the speaker was rated at 90db (should be easy to drive right?) it had a nasty impedance dip down into that 2ohm or so range.I do not think that the current delivery from 75 yamaha Watts is at all close to beter made (read more expensive amp) from another company.Even when selling HT I noticed that Harmon Kardon might be rated 65 watts but was louder than a 100 watt reciver (stereo or HT ) from another mid fi brand.Not knocking Yamaha at all they introduced a lot of HT invotaions in HT reciver market and are a good choice at the asking price (which can go to $3K for a top of the line unit),But don't expect it to run like a Krell set up or any other with 200 rms and high curent delivery all around.In sum I don't think if you hear it breaking up where it shoudn't (don't expect the reciver to not distort say the cannon fire in "Last Of The Mohicans".Almost all gear will.Be reasonable).The thing is in Hifi one spec is realtive to another.Things in 70's got so bad the goverment imposed certain standards because companies were coming out with "1000 watt" audio and car gear that would play no louder than one that rated for 60 watts that kept it's ratings to an industry norm and folks complained to FTC.An easy to see example of this is speaker measurement.Measuring speaker you get much better idea on paper of what you will hear if spec is for say low freqency say 60 Hrz. is Plus or minus 2db not plus or minus 6db.Both might be "true" but you'd much rather the bass within the 2 db measurement.The goverment standards were just to keep things from getting into total BS/deceptive advertising but as wuith my comparrison of HK verus Yamaha I sold the goverment standards did not ame evryuthing "absolute" just from getting out of hand.Still you can find those 1000 watt monster amps at Costco for $89.99 so againn by empahsizing one spec while deviating from accepted norm still happens.Not sure why your meter readings trouble you(or if they do) is importanty to you as to paraphrase Duke Ellington "if it sounds good it is good"
Ah, um, I think i was less confused when i initiated the thread. Maybe my question was incorrectly phrased do to my ignorance. Basically, since being on the gon I have learned that your "system" is only going to sound as good as your equiptment and "set up"(bass mgt, speaker distance, etc, etc.) is. I know my Yamaha, Adcom, Def tech system is, well, some sort of "fi", call it what you will, and i am not even sure i will get any benefit out of mapping out the frequency response from my speakers. I just figured it couldnt hurt. I guess i may be confusing the terms themselves at this point.

As per the manual on my Yamaha i set the main volume to 0db and sent test tones to each speaker. Now, the Yamaha does have this Ypao(mic that you put in your main listening position and it calibrates speaker distance, level, "small/large", eq, etc. I have done the set up numerous times and after each set up i always find that the overall sound can best be described as sort of "meak". I have to turn the volume up much further. When i manually check the speaker settings the fronts and center are set from (1db)left to 0 center and .5db right. Usually i end up setting them to 4 db, 3db and 3.5 respectively to get some more "oomph". This is why i puchased an spl to compare what the YPAO settings were to a handheld spl. NOW, i am clueless!! When i manually adjust the speaker levels am i screwing up the soundstaging, etc.?

Is there a site for maybe "midfigon for newbies".
Audiokinesis, dude what are heck are ANECHOIC CONDITIONS anyways, better yet maybe i dont want to know. I am just looking for inexpensive tweaks here and there to get the maximum out of the equiptment i have well basically because, well how my wife phrased it " this stuff needs to last you for the rest of your natural born days". I think that means she wont even let me by a dictionary to look up anechoic.
Don't worry about getting "flat" in-room response. This is what makes audiophiles wear tinfoil hats and wait for "them" to come.

The numbers in the on-screen display of your Yamaha are relative volume levels. THe numbers themselves mean nothing. Your turning them all up about equaly simply means that you don't have to turn the main volume up as high to acheive the same volume level. The ideal is to simply have all of your speakers playing at the same volume level when you run the receivers test tone. That way when you are listening to multi channel recordings you hear the whiz-bang effects at the volume level the recording engenier intended.

The SPL meter will get you close to the right relative volume levels. From there close your eyes and adjust according to what YOU hear. If your rear right speaker sounds muted turn it up. You will be listening to the sound coming from your speakrs... not your SPL meter.

Good luck!

Sorry didn't realize I was making things more confusing. "Anechoic" means "without echo", and in this context refers to measuring only the direct sound coming straight from the speaker to the microphone, without any reflected sound reaching the microphone and being included in the measurement. Don't worry - it's not on the final exam, but that is the condition normally used when a loudspeaker's efficiency is measured.

I have no familiarity with the Yamaha YPAO system, so can't comment on it.

Can you turn your system up so that it no longer sounds "meek", but sounds right to you? If so, then you're in good shape. If not, is it because you're running out of volume control adjustment range, or is it because the sound starts to distort?

As far as soundstaging goes, so long as you have your speakers at the correct loudness relative to one another your soundstaging should be fine.

I suspect that the slight imbalance in perceived loudness that causes you to set the levels differently for your front 3 channels is related to room acoustics. The ears don't perceive loudness exactly the same way that an SPL meter measures SPL (let me know if you want more details on this phenomenon). Since ultimately it's your ears that you listen through, I'd say give them the final say as you fine-tune the relative channel levels. You're doing great if you can tell that one channel is .5 dB too loud or too soft!