How much amplifier power do you really need?

[David A]

Agreed.  I did a little bit of reading up re the dBA scale and it appears to only be relevant to "relatively quiet" SPL's.  There might be some debate about how loud the music was playing in the video, but I suspect we can all agree that it was most likely not "relatively quiet".  Fletcher Munson might be more relevant I think, but maybe drifting off topic here.

(Some kind of Fletcher Munson widget might be a nice use for all this new Devialet DSP power that is going spare in the CI Board? - but that's definitely off topic here)

Actually, when it comes to hearing protection concerns which is what the dBA scale was designed to be used for, it's high volume situations that it's relevant to. "Relatively quiet" SPLs aren't going to damage your hearing but high SPLs will. Our hearing is most sensitive in the mid-range frequencies (that's what the Fletcher Munson curves show) and that's where noise related hearing damage occurs first, not in the bass and high frequency regions. The dBA scale gives a measurement which is dominated by the loudness in the frequencies where the ear is more sensitive and therefore more easily damaged and gives progressively less emphasis to those low frequencies which present a lower risk to hearing.

Normal hearing protection recommendations tend to take effect at levels equivalent to an 85 dBA average for a continuous 8 hour period. If you have an environment in which the sound reaches that level and you measure the SPL using the dBC scale you'll get a higher reading, and if you measure it using a flat scale (no weighting) you'll get an even higher reading. If you use the dBC or flat measurement as a measure of the risk of hearing damage you'll overestimate the risk. The dBA scale gives a more accurate idea of what the risk of hearing damage will be.

Re your idea of a "Fletcher Munson widget" to make use of the DSP power in the CI board, it's not necessary. What the Fletcher Munson curves show us is that you have to play notes in the bass range louder than notes in the mid range if you want them to sound as loud as the notes in the mid range. If the bass player plays his notes at the same SPL as the singer/guitarist/pianist is playing their notes, the bass player will sound softer than those other musicians and you'd need to either turn the bass up, or raise the level of the music overall, or a bit of both in order to make the bass player sound as loud as the other musicians. In practice you don't have to do that because the bass player knows how loud he/she wants to sound relative to the other musicians so he/she plays at a level that produces the level balance the musicians want you to hear. Basically all musical groups are effectively delivering EQ to compensate for the frequency differences in our hearing sensitivity when they play because each of them plays loud enough to proceed the balance of sound they want the listener to hear. We want our amps and speakers to have a flat frequency response so they don't exaggerate one part of the frequency band and minimise other parts. The music being played doesn't have a flat response, it has a response with some notes louder than others at a given moment so that the balance of those notes "sounds right" for what they're trying to do, and they determine what "sounds right" based on how loud each musician's notes sound. They're automatically compensating for the hearing behaviour the Fletcher Munson curves show as they play and equipment with a flat response ensures we hear music as the musicians intended us to do.

That's why when it comes to any of the concerns about sound pressure levels we have when assessing equipment, we need to use a flat measurement rather than a measurement made using a weighting scale like the dBA and dBC scales. Flat measurements tell us what we need to know when it comes to assessing power requirements because they tell us how loud the sound being produced is and that allows us to calculate how much power we need in order to get the levels we want.

Actually, if I'm correctly guessing what you would want your widget to do, your Devialet already has 2 widgets that do what you want, the bass tone control and SAM. If you can't get loud enough sound overall with the amount of bass you want when you have your volume set to 0 dB and your bass tone contol and SAM, you need a bigger amp. If the bass doesn't go low enough at peaks with your bass tone control and SAM adjusted then you need speakers with more bass extension.