Is DEQX a game changer?

Well, hearing one vote in favor and none opposed I've decided to order the large acoustic panels I referenced in my previous post, for purposes of shielding the mic from reflections during the speaker calibration measurements.

The one slight concern I've had about doing that is the possibility that the panels might in themselves cause some low level reflections, that would arrive at the mic a millisecond or two after the direct sound. But hopefully not, and even if that were to occur to some small degree I'm thinking it could probably be minimized by some re-positioning of the panels. And although I would normally be hesitant to spend $340 on something that may end up being used only once, I'm guessing that the investment will provide benefits that are essentially permanent.

Andrew (Drewan77), thanks again for your always valuable perspectives. I find it interesting and somewhat surprising that they extended the window of Bruce's speaker calibration as far out as 24 ms (about 17 or 18 ms after the direct arrival), given that significant reflections occurred earlier. Makes me a bit less worried about the reflections I may end up with.

Best regards,
-- Al

Andrew (Drewan) and Al ... do you think the reason that Larry, the DEQXPert, used such a "heavy hand" with corrections to my rig had more to do with the speakers or the room?? For example, any thoughts if I were to invest in a pair of Vandies which start out time aligned?

Andrew ...going back to your point about doing time alignment corrections outside, how much improvement do you think I would achieve if my speakers were aligned that way?

Bifwynne,
Vandersteens are not only time-aligned, they are time-coherent which is the superset & what you want in the 1st place.
If you decide to pull the trigger on Vandys, get the 5A or higher. They are expensive but the sonics will surpass your present-day speaker & more & make you forget about upgrading for a (long?) while. Do audition them in your home, if possible, before buying. I've heard the 5A at a dealer's & I was not disappointed. thanks.

This reply is to Bruces' questions - From your measurements I would say you are already using very good speakers as the response is better than I managed to achieve in-room with my original Shahinians. I guess you used quite a lot of sound absorbtion material

Investing in time aligned speakers is not really the issue as the DEQX algorythm has already time aligned all frequencies that the mic picked up from your exiting pair (including the reflections of course!)

I think the 'heavy hand' probably results from a combination of:

- In-room measurement reflections which are included in the subsequent calibration
- A poor room or placement
- Your inexperience with the room equalisation and reliance on either the auto-eq or Larry trying to set this, based on your comments over the 'phone

I sent you a couple of emails with screenshots & a suggestion to experiment by starting with less room equalisation based on the lower frequency peaks you can see on the software, playing music which tends to excite room bass nodes and adjusting or adding further points on-the-fly. You won't do any harm and you will also learn a lot!

The amount of equalisation Larry has used suggests either that your room is really challenging or that he was being guided by you by telephone & couldn't hear what was happening to adjust himself

I actually found that once the speakers are properly time aligned and using a second sub in a different position then the need for room eq becomes almost irrelevant (but setup and time alignment using step responses with the second sub etc becomes more complex). Believe me, my room created all sorts of issues back in 2011 before I started out with this. There really are none now.... so it can be done

Time Alignment outside - Looking at the screenshot of my speakers, you can see how the main impulse is sharp and fades away clearly and very fast to a flat line until the first tiny reflection at 26.2ms. The speakers are at the extreme front edge of a narrow platform, DEQX and amps are on another table many feet away to the side and the ground, 3' below the speakers is soft grass. I believe the tiny reflections are actually caused by the mic & stand because when I measured one of the subs at 3' and then 6", the same reflection appears much sooner on the closer measurement

Andrew

(note: when I say 3', I really mean 3.28 feet, ie 1 metre but as I am an older Brit, my generation is still a bit more American than European !)

Bruce, the only thing I can add at this point to the good responses that have been provided to your questions is to mention that in contrast to speaker correction, DEQX allows you to perform room correction adjustments on the fly, in real time, by inserting and/or dragging adjustment points on the computer screen while you are looking at the measured frequency response plots on that screen and while you are listening. Which is a neat and I believe pretty much unique feature.

You can also click a button which inverts the room correction curve, then insert and/or drag correction points so that the inverted curve lines up with the most significant peaks and dips in the measured frequency response ("most significant" based on the combination of magnitude and width), then re-invert the correction curve and assess it sonically. Also a neat feature.

In doing that you would of course not want to risk messing up the real .mzd file that is in use. The manual describes a procedure for creating a duplicate file that can be played with, but it seems unnecessarily roundabout. I've found that a simpler procedure is to copy the .mzd file to a different folder, then change its name and copy it back to the original folder. Then double-click its icon to open it with the DEQX software, or else open the DEQX software first and use "file/open."

When you're done you can then re-upload the original file to the DEQX, if you want to.

Best,
-- Al