Hi Glauf
I may as well just do a quick write up, and you can decide what you want to do with it. My only concern is that I may come across as if I'm some sort of expert, bear in mind I'm not OK?
Also, not sure how much you can do with the eq available to you, but at least you can try it and see.
I would do a bit of a bigger 'how to' if you were going to use something like the DEQ 2496, it can be a bit intimidating at first, it took me a while to work it out. Not sure how much interest something like that would be as a general rule at the shack, most people only want to do their subs. Fir anyone who wants to do their subs AND 'correct' their mains, then go straight to the deq and forget the rest. From what I can gather it is a much higher quality unit anyway, has heaps of processing power to do all the bass as well as eq the mains, and has umpteen presets for varying recording quality, or maybe even for low level listening (ie set your own Fletcher Munson curves if you wish).
this is how (and why) I do it. Like your earlier question above, I hope that the (far) more knowledgable guys will chip in on the 'theory', I certainly don't claim to know it all.
Leaving aside the bass correction, which is admirably covered in detail here, if you wanted to go further the here is my approach.
My aim is to get the speaker itself as flat as possible in it's FR, and so measure the speaker from say one meter (varies according to the speaker, but the main thing is to measure at the point all the drivers gel, if you get me). With the DEQ you can choose to use it's automated FR shaping, and if you do then I go for flat. As this is not a DEQ writeup i won't go into detail on that.
the reason?? Well, as I understand the definition of hi-fi, we want an accurate flat and hence uncoloured speaker that reproduces accurately the signal given to it. It has never made much sense to me that some people spend
oodles of money further back in the chain for accurate source, dacs etc etc and then say 'who cares what the FR is like on the speakers..??' why spend heaps of money for accuracy elsewhere for it to be 'undone' by the speakers?
Your method, depending just how much control you have with yur 3 eq points, would be to do a full range measurement (with something better than the RS meter) and then, trial and error, add the available EQ points and remeasure. Always start with the largest deviations (ie low q on the equaliser) and work your way through as far as you can with the points available to you.
The goal, as accurate a transducer as you can get.
What you get in the room after that is another matter!! But that is the nature of the beast.
In my situation, regarding your question above, is that my speakers ARE flat, very much so ( I use the deqx) and so that is always my first point of call, as accurate a reproduction as possible.
However, as most of us know, not all recordings are good!! With the deqx it is then a trivial matter to 'boost/cut the bass as needed', add or remove treble, or again fiddle with the midrange all from the LP (using the remote) to suit whatever recording I happen to be listening to.
So, I accept your friends argument, but bear in mind I always come from the security of knowing that my speakers ARE flat to start with.
With the DEQ, you can (with a bit of fiddling) have twenty or more different settings stored, covering all those permutations above, and recall the setting depending on the recording.
In addition to having flat speakers, then of course all the bass eq (as outlined on this forum) can be done too.
Regarding EQ
in the room, I personally agree 100% with the comments made earlier, above a couple of hundred hz it's a bad idea. Room acoustic treatments are what is needed.
Here is an article by Rod Elliott covering this
http://sound.westhost.com/articles/dsp.htm , and from memory I think he asks that the whole site gets linked, so here it is too
http://sound.westhost.com/index.html, please take advantage of perusing the whole site, it is a valuable resource.
Funnily enough, in the very long Beyond the Ariel thread on diy, Lynn Olsen said exactly the same thing today
As posted previously, I don't believe in using EQ to correct for room abberations above 300 Hz - above that frequency, I'll only correct for deviations from the drivers themselves, and preferably in the passive domain using the crossover. Below that frequency, though, EQ on a per-channel basis is a good idea, provided boost EQ is kept to a minimum (because it stresses both amplifiers and drivers, and reduces system headroom).
I don't usually go above say two hundred hz myself, but you can always try it and see.
So my 'method' outlined above (which is unashamedly taken straight from the deqx method) bypasses all that, and gets me as accurate a speaker system as possible.
If you are even vaguely contemplating bass eq as well (as all of us here most assuredly strongly recommend) then put a serious thought at getting the DEQ 2496, as you are at least interested in full range eq as well.