Is DEQX a game changer?

Thanks very much, Pete, for the nice words and the interesting comments.

An update: I've created and assessed three more speaker calibration profiles, this time based on the measurements I took with no acoustic panels in place. (As I had previously described, the visibly cleanest and most reflection-free measurements had been the ones taken with panels surrounding the measurement microphone, but I found that very early arriving reflections from the panels themselves caused significant differences in the calibration profiles for the two speakers, which worsened in proportion to the duration of the truncation window. The same held true for the measurements taken with panels surrounding the speakers, to a slightly lesser degree but coupled with increased pickup of room reflections. Recall, btw, that I did not have the panels in precisely the same positions when I measured the two speakers, which fortuitously led to me discover the significance of the early arriving panel reflections).

Also, I should mention that when I performed the measurements even though I had pillows and a folded back (double thickness) Persian rug on the floor between the speaker and the mic, the waveforms captured by DEQX for all of the measurements clearly show a significant floor reflection (as can be determined based on its arrival time, beginning a little under 3 ms after the direct sound arrival). There is also evidence of a ceiling reflection arriving a little under 8 ms after the direct sound arrival, although it appears likely to consist mainly of low frequencies that I'm not addressing in the speaker calibrations.

Although all three of the new profiles sounded reasonably good, ultimately I was not satisfied with any of them. Most notably on classical solo piano, where the presentation had a slightly mechanical quality, and a slight loss of definition in the mid-treble, that were not present in bypass mode.

Given all of that, what I've decided to do is to order a third double-section acoustic panel and then re-do the speaker measurements. This time I will place one panel up against the fireplace you can see along the left wall in my system description photos; one panel up against the antique radio/phono console on the right; and one panel on the floor between the mic and the speaker being measured (positioned once again in the center of the room). In my circumstances it is reflections from the sides and the floor, and possibly the ceiling, that appear to be the main concerns. I believe that moving the speaker being measured to the center of the room gets them far enough away from the front and rear walls to allow those reflections to be windowed out without significant compromise to the calibrations.

Apologies for the slow progress to those who may be awaiting the conclusions of this adventure. I haven't even begun to address room correction yet. But from my perspective the slow progress has not been bothersome, as what I have in bypass mode and with one or two of the correction profiles is already better than what I had previously (which in turn I was pretty satisfied with). And it's been an interesting learning experience.

Best regards,
-- Al

Thanks for the update Al. I've been offline since Tuesday/Wednesday and haven't been tracking your progress. I looking forward to reading your future reports.

As you know, I already shared with you via a PM Larry Owen's general philosophical comments about speaker and room correction. I sent a copy to Nyal as well.

Al ... I intend to send you a PM with some room measurements and maybe some pics too if I can figure out to work my cell phone camera. I'm not sure I buy into the point made by Larry and PJ that my speakers and sub are too big for my room. I think my room is so crappy that it could mess up speakers of any size or quality.

BUT, the DEQX tamed my rotten room situation so that is more tolerable. In fact my stepson came in from out of town this weekend to spend father's day with me and played one of his favorite LPs. He was pretty WOW'ed (sp?). He hadn't heard my rig since the first set up attempt.

Cheers,

BIF

Yes, thanks for the updates Al. In your most recent round of speaker calibrations, where did you cut off in the low frequencies?

And in general, I'm curious what cutoff everyone made in the bass and how you arrived at that frequency...

Addendum to my last post ... it occurred to me that there was another factor that may have impressed my stepson other than the DEQX. Namely, since his last visit, I sprung for the SE upgrade to my ARC Ref 150 amp. As many may know, it involved switching out the KT-120 tubes for KT-150 tubes, plus ARC made some proprietary circuit changes. Now I'm not sure.

But what the heck ... my rig sounds better than before and that's what counts.

Bruce, yes, thanks for sharing these things with me. I'll look forward to the measurements and/or pics, in part because I'm curious as to what kind of room configuration they would consider to be too small for your speakers.

Roscoe, so far I've tried 7 different speaker calibrations, based on my initial set of measurements (which I will be re-doing from scratch as described above). The lower frequency limits I've used in those calibrations have ranged from 300 to 600 Hz, depending on where the truncation window was terminated.

Nyal had advised that I start out very conservatively with respect to that parameter, even as high as 900 Hz if the end of the truncation window would have to be as close as 5 ms after the direct sound arrival (with other rule of thumb combinations being suggested such as 600 Hz/10 ms, and 350-400 Hz/15 ms, if the truncation window could be extended to those points without encompassing major reflections). Those are obviously more conservative limits than the ones suggested in the manual, but he also suggested doing additional trials calibrating to progressively lower frequency limits, and trying to identify the point beyond which the sound starts to worsen.

In setting the limits I kept those rule of thumb guidelines in mind, while also, as I created each calibration, going back and forth between the screen on which the truncation window is set, and the following screen which depicts the resulting frequency response. In doing that I tried to set the lower frequency limit of the calibration above the frequency at which significant differences started to become apparent in the frequency response plot as I varied the duration of the truncation window.

Also, at the other end of the spectrum Nyal had advised that I should avoid monkeying very much with the speaker's natural rolloff at high frequencies. And in a separate conversation I recently had with Alan Langford of DEQX, (regarding an unrelated matter involving a very minor quirk I had noticed and reported in the operation of the touchscreen that is provided on the HDP-5, about which they were extremely responsive and will be resolving shortly with a couple of changes the user can easily incorporate, mainly a firmware update), he suggested limiting the high frequency limit of speaker calibration to 10 kHz. Given also that my particular speakers have a rise of a few db between 10 and 20 kHz, according to the DEQX measurements, followed by a rolloff above 20 kHz, I certainly plan to follow their advice on the subsequent calibrations. Although the ones I've done so far have had various limits ranging from 10 to 23 kHz.

As you'll realize from my previous recent posts, I can't really say much at this point from my listening experiences as to which of those limits (both at the low end and at the high end) work best with my speakers, because the anomalies caused by non-optimal placement of the acoustic panels when I did the initial measurements affected the middle frequencies and mid-treble too greatly for those other limits to matter very much.

BTW, during the course of the conversation with Mr. Langford he indicated that as a general rule of thumb outdoor calibration often tends to be less necessary for box-type speakers than for other kinds.

As for my status at this point, I've just received the third acoustic panel I ordered the other day, but most of this week I'll probably be too tied up with various family and other obligations to perform the next set of measurements. Hopefully I'll get them done within about a week.

Best regards,
-- Al