Is DEQX a game changer?

A very interesting summary Al and I sympathise with the challenges you face

At the risk of repeating myself (apologies), are you absolutely sure that there is no chance of taking an outdoor speaker measurement?

I originally made several attempts to achieve a good indoor measurement but none came close to those taken outdoors. Once I saw the cleanness of the resulting plots, any further speakers or subs were always measured this way - including manhandling a huge Miller & Kreisel sub into the garden and then up onto the measuring platform which was a great deal of effort

It does make a significant difference and I believe that is why music created from the resulting calibrations sounds so remarkable. I am rather a 'perfectionist' so I couldn’t have rested knowing that I wasn't getting the maximum performance from DEQX

Yes, this can involve a lot of time and commitment (in my case around three hours from start to finish, moving the gear etc) but provided you use a high number of averaged measurements (I recommend 1.4s/96K x at least 18 sweeps) and the day is completely dry without much wind, the measurements only need to be taken once and are extremely accurate, virtually anechoic if done well. Any random birdsong or other faint wind noises appear to be completely disregarded by the averaging feature of the software

Somewhere I may have photographs of the setup but they are not on this computer so I will have to look for them. If anyone is interested I would try to find them plus some of the resulting measurement plots and post them as images on 'my page'

Thanks Al and Andrew. I guess I'll hold up on buying the panels for a bit. I'll wait for future reports.

Andrew, it may be that I will bite the bullet and schlepp my whole rig outside one day. Gotta tella ya though ... I am concerned about damaging gear by doing this.

As I've already mentioned, my rig is tucked away in my basement/sound-room. At a minimum, I'd have to haul up the steps: two 100 pound speakers; an 80 pound amp; and the DEQX. And what about my 110 pound sub?? I assume I can leave the other gear downstairs.

I have posted a couple of screenshots under 'System' at the foot of my posts for anyone with a DEQX processor to compare the plots

The measurement shows how 'clean' the frequency plot may look relative to an indoor reading that others may have taken and the impulse response illustrates that there is only a tiny reflection from the microphone itself

(The measurement is a raw image from the mid-high range speaker before any correction & at 0% smoothing. Indoor calibrations tend to use up to 100% smoothing and a closer windowing, both of which reduce accuracy and have an impact on the sound in my experience)

Al,

Interesting findings so far.

Sounds like the good news is the unit is providing you the information needed to get it set up optimally as it should, and that you are well versed to interpret and use it.

I wonder what the general recommended apporach from teh vendor is? Is anechoic measurements the norm for geting things calibrated initially? Sounds like it. In which case, there may be no equally effective substitute for some kind of plan for accomplishing measurements outdoors as suggested. Or in some other kind of anechoic environment. How about a recording studio? Maybe there is something like taht nearby at a school or other professional facility that might be accessible. Of course, no way to avoid the pain of having to move heavy and delicate audio gear that way. So it might be a dilemma for which one practically just has to accept some kind of compromise.

I'm sure its going to work out well one way or another in due time.

Andrew (Drewan), thanks very much for providing the info in your system description thread. As I indicated there, it provides a good quantitative perspective for DEQX newbies such as myself on what is possible in the speaker calibration process.

Mapman, thanks also. Regarding DEQX's recommendations for how to approach speaker calibration, on the one hand the manual states:

The microphone should be mounted about 2 ft to 3 ft (or 60 cm to 1 metre) from the speaker and lined up with the tweeter axis. Best results will be obtained if you use a microphone stand with a boom to support the microphone. If larger speakers are used it may be necessary to mount the microphone further from the speaker, in order to reduce the angle between the drivers and the microphone (and any
associated off-axis effects). However, moving the microphone further from the speaker will potentially increase measured room effects and /or reduce the period of the measurement before the first room reflection, hence the reason for the suggested distance of 3 feet. Better results may be obtained by measuring the speaker outside, provided that a quiet location is used. One method, particularly useful for large speakers, is to rest the speaker on the ground, pointing up at a 45 degree angle. The microphone should still be lined up with the speaker's
driver axis, i.e. it will be pointing down at the speaker at a 45 degree angle. When measured with this method, the speaker measurement can be similar to that obtainable in an anechoic chamber.

But on the other hand they state:

The longer the delay for the first room reflection to arrive relative to the time it takes for direct sound to reach the measurement microphone, the more bass information can be gleaned. A minimum target would be 3 milliseconds, which will limit measurement usefulness to frequencies above about 400Hz. Doubling this to 6 milliseconds for example, achieves an additional octave of bass resolution: down to about 200Hz, which is the lower correction limit used for this case. In this example, if you attempt to correct below 200Hz phase distortion will be introduced to the filter, which will make the resulting sound dull and flat - worse than the uncorrected speaker.

The 3 and 6 ms 400Hz/200 Hz guidelines seem very aggressive (optimistic) compared to inputs that were provided to me by Nyal, and that have been cited by others earlier in this thread, and that were used by the DEQXpert people when they set up Bruce's (Bifwynne's) system. (They terminated the "truncation window" about 17 ms after the direct sound arrival in his case, as contrasted with the 3 and 6 ms figures cited in the manual. Also, the corresponding figure in Drewan's case was about 18 ms).

So it seems that given the great number of variables that are obviously involved DEQX is understandably not able to provide a specific quantitative feel for the degree of compromise that will be introduced at various points along the continuum between ideal measurements taken under essentially anechoic conditions, and points that are significantly less than ideal.

06-07-15: Drewan77
At the risk of repeating myself (apologies), are you absolutely sure that there is no chance of taking an outdoor speaker measurement?

Pretty much. Just moving my speakers off and then back onto the bases and footers I have them on, which elevate them less than 5 inches, involved non-trivial effort and careful logistical planning, as they weigh 108 pounds each. To get them to a location outdoors that is both level and not close to reflective surfaces they would have to traverse several steps and approximately 50 feet, and then I would have to provide some non-reflective means of tilting them back, to minimize ground reflections. Also, less significant additional complications would be that I would have to run about 50 feet of speaker cable (my amplifier also weighs more than 100 pounds), and a 40 foot or so XLR extension for the mic.

Well before deciding to purchase the DEQX I had realized from the comments earlier in the thread and from reading the DEQX literature that as a practical matter I would be unlikely to realize its full potential. But as long as it ends up providing me with a substantial improvement over what I had I won't be disappointed. As Mapman aptly said just above, "it might be a dilemma for which one practically just has to accept some kind of compromise."

Best regards,
-- Al