Room correction - what device works best?

Well, I read through the DEQX threads - seems intimidating to have to take the speakers (mine about 300 lbs each) into the yard, and then spend month dialing the thing in to get the best from it. But results seem excellent. My speakers are designed for excellent time and phase response across a wide axis. The Lyndorf idea of not changing the character of the speaker and amps etc, assuming people selected them because they liked them, is also logical to me. I am also wondering about waiting for Meridian's MQA to be incorporated into equipment as it sounds like it may be a game changer.

Some clarifications to some of the comments in Gammajo's post just above, for the benefit of others who may read this thread and want to consider DEQX:

Seems intimidating to have to take the speakers (mine about 300 lbs each) into the yard....

While it is theoretically ideal to do this, it is not necessary. That was clearly stated by experienced DEQX users in the "Game-Changer" thread I linked to.

The goal of the DEQX speaker calibration (aka "speaker correction") process is to make the speakers time-coherent (and therefore also phase coherent) at all frequencies above a lower limit falling in the area of roughly 200 to 500 Hz (our hearing mechanisms being most sensitive to phase and timing issues at mid-range and treble frequencies).

If the speaker calibration process is performed outdoors, so that there are no room reflections to degrade the accuracy of the process, that lower limit of the range of frequencies for which the process is effective will be as low as possible, within that area of 200 Hz to 500 Hz or so.

If the speaker calibration process is performed with the speakers moved to the center of the room, as far away from reflective surfaces as possible, that lower limit will be a bit higher than if the process was performed outdoors.

If the speaker calibration process is performed with the speakers in their normal position, that lower limit will be somewhat higher still.

So which of those three alternatives is chosen will simply affect how low in frequency the benefits of the process will extend. The mid-range and treble will benefit regardless of which alternative is chosen.

...and then spend month dialing the thing in to get the best from it.

My understanding is that if the DEQXpert service is used, or the comparable service provided by Acoustic Frontiers, the speaker and room calibration processes can be accomplished in a matter of hours. Or at most perhaps two sessions of a few hours each.

In my own case, I don't plan to use those services. And working at my own deliberate pace, having no previous experience with the product, and with the time I can devote to it limited to some extent by other activities and by the need to not perturb my wife's activities by playing test tones and loud music through the speakers (I use headphones when I want to listen at those times), I envision taking perhaps a month or so to get it fully dialed in. But that's just me.

My speakers are designed for excellent time and phase response across a wide axis.

Regardless of what manufacturer literature may say about time coherence, time alignment, phase response, phase linearity, etc., if the speaker has a crossover and if the crossover is not first order (meaning 6 db/octave), the speaker is not time coherent. If the speaker has a crossover and is not made by Vandersteen, Thiel, Green Mountain Audio, and perhaps one or two others, it is highly probable that its crossover is not first order, and that the speaker is therefore not time coherent.

For background on the benefits of time coherence (which in turn automatically implies phase coherence), see the "Sloped Baffle" thread I linked to earlier.

The Lyndorf idea of not changing the character of the speaker and amps etc, assuming people selected them because they liked them, is also logical to me.

Of course, with DEQX one could choose to simply not do the speaker calibration process, and just use some or all of its other functions (room correction, equalization, DAC, preamp functionality in some models, USB interface in some models, etc). But one would be losing out on what with many speakers in many rooms may be its most important benefit, that is not provided by most competitive products.

Regards,
-- Al

Almarg,

What a great post. Great synthesis of the potential of a DEQX.

Are you planning to go active with your speakers, getting rid of the passive crossovers?

You might recall I thought about the DEQX HDP-4 (at the time) and eventually opted for Acourate. Yet my end destination seems to be very aligned with yours. I opted to build a system around this concept and will build my own speakers, multi-amp, use active digital crossovers and get a time aligned, linearized, room corrected system.

I am technically inclined, but certainly less experienced/knowledgeable than you. It would be great for me to be able to bounce ideas/questions with you as you also go through this process. Such a fun project!

Thanks very much, Lewinski. Yes, I've followed the posts and threads related to your project, and I'm happy to comment whenever I can contribute anything meaningful.

As you realize, the three independently configurable pairs of output channels provided by the HDP-4 and HDP-5 can support active biamping or triamping, but I have no plans to do that. In part because doing so would entail what to me would be desecration of the fine craftsmanship that went into the construction of my speakers; in part because the innards of my speakers are not readily accessible as practical matter; and in part because in the absence of any knowledge of the design of the speaker's internal crossover I would by no means rule out the possibility that the sonic results would end up being a downgrade rather than an upgrade. And of course there would be a lot of expense for additional amplification.

Based in part on listening comparisons with my Stax electrostatic headphones I'm pretty much convinced that the weak link in my system is presently some combination of room effects (which I can't address with conventional room treatments since it is my living room), and speaker time incoherence. So I'm just looking for some modest improvement in those areas, and in the process perhaps I'll also benefit from substitution of the DEQX for my preamp, and from utilization of the DEQX's DAC function in place of the one that's internal to my CDP.

Yes, as you indicated these are fun projects, and also highly educational. Those are the main reasons I am intending to do it all myself rather than utilizing the DEQXpert or equivalent services. And if it takes a month or even two, I'm fine with that.

Best regards, and continued good luck with your project.
-- Al

Using two subs is the best way to get a flat frequency response, unless the room is too small to allow the main speakers to be brought well into the room. DEQX will solve the timing and frequency problems of integrating subs with main speakers.