Nicolas Levesque said:
MajorFubar said:
As already pointed out, try educating yourself by looking up the equal loudness curve. And yes there is a standard, it's defined by ISO 226:2003.
I have yet to see somthing telling me that companies implement this standard in their loudness control, which would be useless any way. The amplifier not having any way to know the sensitivity of the speakers nor their colorations or even how they react with the room, what room modes you do have etc. Which brings us back to loudness is arbitrary boosting of some frequencies by an approximate amount of Db's that may or may not be variable with volume and in no relation of any kind with how much and how the system need to be compensated.
If we were talking about things like Dynamic EQ by audyssey, at least, we would have a basic of implementing a loudness curve in real life, the speakers have been measured in room by the receiver/processor and I do respect this technology but not loudness on a 300$ amplifier to compensate for something that has not been measured in room and is therefore approximate. And we don't even have a way to make sure the intention was to apply a real correction or to implement a house curve.
McIntosh for exemple have created a product called MEN220 Room Correction System, which use the Room Perfect technology by Lyngdorf to create correction based on real world measurement of your sound system using a prefssional microphone and a 5000USD$ sound processor to compensate for the room, volume, etc. This I respect.
Now if somebody wants to tell themself that approximate loudness compensation done by a 12$ circuit in a 300$ amplifier is HIFI, go ahead. I have said all I'm gonna say in the matter.
My Wife tells me I am a 'know it all', but I have to admit, one of the guilty pleasures I get as an ex engineer is pointing out when a self-appointed expert on a HiFi forum is talking out the hole in his hat.
To slip off topic slightly for a moment, for those of you using vinyl, the implementation of the RIAA equalisation curve filter in your amp is arguably the most important determinant of the tonal balance of your system. It compensates for the pre-mangling of the signal required prior to cutting the disc to compensate for the shortcomings of vinyl as a recording medium.
This crucial aspect of the amp is usually implemented as a couple of RC filters, at a total cost less than £2 per channel - and that is if you use fancy components. A little googling of 'RIAA equalistaion circuit' will give you the idea (the filter is often embedded in a gain stage, so some of the circuits on the web show much more than just the filter).
Now Nicolas seems to have gone off on a tanget, 'loudness' has nothing to do with room correction, speaker performance or sound processors. It is simply a technique to restore the tonal balance of the signal at low volume because your ears don't work very well on quiet music. My point about the RIAA curve above is that if the critical RIAA filter can be implemented for a couple of quid, surely a decent loudness circuit can't be that expensive. The truth is that a loudness circuit can be implemented for far less than Nicolas' $12 hurdle.
A more interesting point is whether a system should or should not try to maintain the perceived tonal balance at differing listening levels - correcting for the poor performance of human hearing. If the director wanted the bass guitar to sound twice as loud as the lead guitar when he mixed it, is it right or wrong to have the bass guitar sound half as loud as the lead guitar when it is played back at a low level. What actually is 'purity' in this case? The point could be argued a number of ways.
My own view is that a loudness button is a useful facility, but make it switchable so that listeners can choose.
I have said all I'm gonna say in the matter.......