I have a few comments:
@Sean Olive
- If I am not mistaken, Harman used "Virtual Headphones" in one of their experiments to remove some of the biases i.e. touch information, comfort, weight etc. that could easily be detected by the user when blind but in direct contact with the DUT.
How many EQ points were used? Harman might have been using a FIR (which is even more complex), to simulate a number of headphones through a single one.
How close to the actual headphone *curve* or "representation" (whatever that may be through averaging smoothing etc.) of the performance of the real device did it need to be for the virtual headphone to be statistically indistinguishable from the real thing?
This should give a good indicator for the EQ complexity, parameters and tolerance we should be aiming for and probably a way to get a better representation of the performance of the DUT.
- If the Harman curve it to be trusted and we can characterize the performance of the device adequately,
there is no point EQing to anything else for a general EQ. I might restate what is already known there...
No matter what efforts you put in designing your EQ it will have your own subjectivity (taste) signature built in.
You are your own data point, it is the most important for you, I do realize that, but this is it, no more, no less.
Even trained listeners must be averaged.
Your EQ may work for some but it may not for others then we are back arguing on what sounds "good" to each subjectivity i.e. taste.
It is interesting in itself but not that fruitful, "y" prefer Bordeaux wine "x" prefers Burgundy wine Ok, then what?
Why should be argue that one is better than the other? Give AI a few years, and maybe we may see something coming from it...
The default Harman curve on the other hand is speaking for a much larger portion of the population (circa 64%) so statically if the population is large and representative enough we have a far greater chance that it will provide the user with something that hits the spot.
Nothing prevents the user from adding its subjective preference which will always be the case anyway but most of the leg work is done upfront.
I would argue that if someone is interested in using any of the published EQs that person will most probably deviate form the default settings and invariably add that person's subjectivity into the mix; if it is not just to compensate for perceived unit to unit variations.
- With regards to the "0.71 vs 0.7" comment I am not arguing that it may or may not be audible in fine however I believe this has more to do with the representation of the filter than its audibility. To me this is a different problem, not related to any EQ or designer in particular.
This is probably pedantic but let's take the following example:
BQ1 PEQ Freq = 1000.0, Gain = 3.00, Q = 3.00,...
BQ2 PEQ Freq = 1000.0, Gain = 4.00, Q = 1.00,...
If I were to express the biquads in their direct form :
bb1 =
1.003749261367279 -1.977580181386317 0.978074156083333
aa1=
1.000000000000000 -1.977580181386317 0.981823417450612
bb2 =
1.014808395051763 -1.945190025905157 0.934555368306628
aa2 =
1.000000000000000 -1.945190025905157 0.949363763358392
Your argument would be: why do you need so many digits, you can't hear the difference between
-1.945190025905157 0.934555368306628 and
-1.977580181386317 0.981823417450612, well you might.
This is equivalent to the spelling for written languages, the more correct it is the more precisely the meaning is conveyed, nothing else.
You are right when using computer generated EQ we tend to over do things, I try not to (and probably fail) but you need precision to convey the design.