Please Read and express your feelings and opinions....

Regarding the debate about the relation between SPL and speaker input power, I found the following sub-page at the site which provided the calculators that were referred to earlier:

http://www.sengpielaudio.com/calculator-efficiency.htm

Entering various parameters into either of the two calculators closest to the bottom of that page (one entitled "Sound Pressure Level and Amplifier Power" and the other in the section entitled "Electro-Acoustic Sensitivity") clearly confirms what Atmasphere, Erik_Squires and I have all said on this subject. Namely that if the input power to a speaker is changed by a given number of db, SPL at a given listening distance will change by the same number of db. (As previously stated, this of course assumes that the speaker is not being driven hard enough to cause thermal compression in the drivers to become significant).

I also found the following writeup at PSB’s site, which provides additional confirmation. About 2/3 of the way down the page a table is provided showing power vs. volume for an unnamed 87 db speaker used as an example. Note that 40 watts results in a volume of 103 db, while a 6 db reduction in that power level (to 10 watts) results in a volume that is 6 db less (97 db). While a 3 db change in power, from 1 watt to 2 watts, changes the volume by 3 db, from 87 db to 90 db. And a 20 db change in power, from 1 watt to 100 watts, changes the volume by 20 db, from 87 db to 107 db.

http://www.psbspeakers.com/articles/Guide-to-Speaker-Specifications

On another note, Erik, thanks for injecting some sorely needed humor into this thread, with the donuts post :-)

Regards,
-- Al

@fleschler 
I think negative feedback is one of those very misunderstood things. Not to say that I understand it. For my purposes, it's a good thing. The F5 I built uses a generous amount of it, and yes, it does complicate the distortion spectrum, but the artifacts are down below -120dB. That seems like a good trade off for lowering the overall distortion a good bit for the power I'm demanding of that thing. On top of that, the amp is completely stable into loads well below what any normal speaker will exhibit. 
I always keep an eye out for amp descriptions that suggest "no feedback", "no loop feedback", or "no global feedback". I assume that if they're qualifying the type of feedback, then they're using some kind of negative feedback such as degeneration. 

Like a few of us or the many of us who buy/sell/trade here on A’gon I have endeavored since my start on the site to maintain a degree of civility in the forums I participate in not only because most of them manage to be civil anyway, but also to complement my feedback score.  I find that such goes pretty much hand in hand.  

When arguments/dialogues/exchanges here become less than civil it can become tiresome to say the least. However I have witnessed some incredibly funny, witty, and intelligent back and forths between and amongst members that are highly entertaining for me - and very possibly for them too.

Are many audiophiles too serious?  Indeedily.  Personally, I’m an “audiot”,  I don’t know a mosfet from a misfit but I have learned, and occasionally retained, some of the information I’ve read and received here, and all for the betterment of my enjoyment.  When a forum becomes a contest with name calling and insults I simply scroll past them or abandon it for awhile. I don’t believe censoring posts that I may find offensive will correct such behavior. 

Free speech is free, intelligent speech costs none the more, it all depends what’s in yer moral wallet to begin with.  

oblgny - ...However I have witnessed some incredibly funny, witty, and intelligent back and forths between and amongst members that are highly entertaining for me - and very possibly for them too...

+1

I very rarely or if ever have posted here. But I have seen it also.  The anonymity on the internet sometimes brings out the worst in us. We can say things and do things that we might now otherwise do or say if we were all in the same room.

What is a wonder to me is are we not all here for almost the same reason.  We have more in common than not when it comes to audio. We like music, we like good audio.

Many times it's not that we express our opinion it is how we express our opinion.  I tell my kids. "It's not what you said. It is how you said it.". 

We really all don't know each other, so it is hard to read audiogon posts where people assume other audiogon members are lying or not telling the truth.

I can't remember in my life when arguing ended up with a good result.  A good discussion yes, but arguing brings up bad feelings.  

Well that is my rant.