At risk of opening up a hornets nest of comment, I have just read through all of the posts on this quite lengthy and interesting thread and feel I have to add something
I do not consider myself particularly technically minded but I am first and foremost a music lover and have spent a lifetime regularly listening to live, mostly amplified music (aren't we all MUSIC lovers and hi-fi gear is just a means to an end?). Sorry about this but I get frustrated with lengthy academic debates about theory whereas surely the acid test is actually listening to MUSIC at home and referencing that to a live performance. I rarely see that word mentioned in many posts on forums like this and I post quite rarely because I enjoy listening to it too much
On that basis, I discovered DEQX back in 2012 and it has totally transformed the realism of my system. You may well judge my response as some type of placebo effect, however I know what I hear and it is like nothing else I have experienced in many years of seeking hi-fi nirvana
I am quite an experienced DEQX user and would like to comment on one or two things I have read here and maybe clarify any misconceptions (from the viewpoint of a user)
Here is a pretty basic description of the process. It can be as simple or as complex as you choose. I started off quite simply... with surprisingly good results. Now I understand the many complexities and interactions, the final result can only be described as stunning (whilst listening to music)
Firstly (actually... first check the weather forecast!) - measurement and automatic timing/phase correction of each speaker should be ideally performed outdoors in a large open space. The speakers in my case were raised around 1 metre above grass and the microphone positioned at tweeter/normal listening height at 1 metre distance away. A calibrated microphone is used of course
For subwoofers I also measure at 1m height above ground but in this case the mic is centred 150mm in front of the single driver centre
DEQX produces a lengthy rising frequency tone (for each speaker or sub, not by means of music as I had read in one of the posts) which repeats multiple times to average out other noises (ie birdsong etc...be aware that any neighbours may believe that aliens have landed nearby as this should be at around 90db which is pretty loud, with subs it is best to remove false teeth or limbs first)
This tone can be extended over many minutes if required and there is also a facility to repeat the exercise after DEQX has made the corrections and see the original frequency or phase/timing/group delay plots adjusted. At this point the frequency response is automatically corrected to 'flat' within the parameters of the drivers in that speaker. DEQX claim this correction is carried out thousands of times within the frequency response. From the finished result (see end) I can see no reason to disagree
Then repeat for the matching stereo paired speaker
All drivers in both main speakers are then calibrated by yourself as a stereo group using the frequency plot produced together with your chosen type and slope of crossover - at a point on the plot before the first reflection (using the method I describe, there is hardly any apparent reflection but easy to see it when it eventually appears)
Then, choose the type of setup you will be using, up to 6 channels in total from a single speaker, bi-amp, tri-amp or with up to 2 separate subs. Then 'create' virtual speakers on the PC with appropriate crossovers and load these into the DEQX processor in 4 separate switchable (on-the-fly) filters
Finally, at the listening position, place the mic at head position and re measure using the same rising frequency tones. The subsequent plots show firstly the damage any room will do to your once 'perfect' and flat corrected frequency response and allows subtle equalisation (I have no need for anything more than +/- 2db and only below 250hz)
Secondly, you are able to see the time response of each speaker and sub and slow the main speakers (either the whole speaker or separate driver sets) to align exactly with the subs. This makes an incredible difference to the final result once you hit the spot. Using the four presets or even changing the timing in real-time listening to MUSIC (that word again) allows you to get this spot on and you know when you are there. It just sounds holographically real
As I said, I do not go into any of the theory of sloped baffle or other means to achieve time alignment but if you take the time to fully appreciate what something like DEQX can do it, the final results certainly bear out the claims made. In fact, reading the multiple reviews replicated on their website this former cynic has to agree wholeheartedly
Now back to the real reason I did all this, but I won't annoy you all with that word again....
