Room correction - what device works best?

To the question of time alignment for speakers with passive crossovers, these quotes from the PreMate review should clarify things. From the Positive Feedback review:

... it corrects for …."the distortion that all speakers make—electro-mechanical devices that they are—and offer room compensation as an added extra. While righting frequency-response errors as other units do, they also uniquely correct critical timing errors by adjusting thousands of frequency groups so that they arrive on time.

"In correcting the speakers—before the room—our comprehensive DEQX-Cal™ software generates correction filters for phase, timing coherence and frequency-response. Only then does DEQX-Cal measure from the listening area for room correction.

"It corrects speaker frequency-response and timing errors by adjusting thousands of frequency groups, depending on your speakers' measure­ments, so that they arrive at the correct time."

Doesn't get much clearer than that.

It appears as though unlike DEQX, DIRAC does not offer cross-over features.

Currently, DIRAC does not offer cross-overs or bass management, both of which must be implemented prior to DIRAC processing.

Its still too bad the DEQX requires the movement of the speakers and consultation to obtain best results.

My current speakers weigh 215lb each and have spiked feet.

Perhaps sometime in the not too distant future there will be a more user friendlier version.

In the meantime, I'll stay on the sidelines awaiting Almarg's adventure.

Kal, or anyone else who may know, how does the speaker correction of Dirac compare to DEQX?

There's a subtle difference between room and speaker correction.

Room correction you put the mic at the listening seat and you measure speaker and room combined.

Dirac only offers room correction (though a very good algorithm, and one I really like).

The DEQX separates out speaker and room correction into separate processes.

The speaker correction is done by measuring the speaker nearfield and windowing out the room response (or measuring outside). Then you take the mic and put it in the listening position like you would do with Dirac.

Not sure when people refer to Dirac if they are referring to the software package or a hardware unit with Dirac inside? Either way I understand it can't do crossovers. In case someone meant software, then Acourate can do digital crossovers, driver linearization, time alignment and room correction.

There was a comment above indicating frustration that DEQX could only handle 96kHz, and a great reply by Almarg. I completely agree with Al. To add my experience from another angle: at some point I was considering the 8-channel DAC e28 from exaSound, which can play 24/192 & DSD256 natively on 8-channels. It looked ideal for my needs. Discussing this with Uli Brueggemann from Acourate, he explained he tried it at 24/96 and a powerfull computer was running out of steam, suggesting 24/192 would be very very hard. So I dropped the idea, despite my computer being very powerful (server motherboard with Xeon processor, etc).

Acousticfrontiers,

Can you explain what the benefits are from separating room and speakers into 2 distinct steps? From what I can tell from the Dirac website, they are also doing some speaker correction, which appears to be from the listening position in the listening room.

Thanks for your helpful clarifications.

Simplistically speaking above 250Hz (room's transition frequency - look that term up) the frequency response at the listening position is dominated by the speaker. Below 250Hz it is dominated by the room.

The idea behind speaker correction is that you are measuring and correcting for the on axis speaker anomalies only. The correction applied can be higher resolution than room correction, which necessarily must use multi-point measurements and time domain smoothing to prevent over correction.

Room correction you cannot separate speaker from room, so if you apply "full range room correction" like Dirac then you are correcting the combined response. The best full range algorithms are very gentle in how they correct above the transition frequency. I only like Trinnov and Dirac at the moment.

Like Kal from Stereophile found in his review, the best results would be combining DEQX speaker correction with Dirac room correction. However parametric EQ, when applied in the bass as DEQX intended will get you just as good results as Dirac, it just takes a lot more time and expertise to get it dialed in.

I don't have the luxury of a dedicated listening room and, therefore, have significant challenges dealing with a well furnished living room. I use the Behringer DEQ2496 with the microphone to balance for my listening position. I've tried other methods but this approach allowed an improvement that even I was able to hear and I'm not very good at detecting subtle changes. I can't comment on phase issues associated with its installation but assume that it will cause some shifting. The bottom line is, save for well chosen upgrades of other components in the audio stream, that it may be the best choice I've made to improve listening enjoyment.

Thank you for that excellent clarification.

As many of you already know, I own the DEQX PreMATE. It took a couple of sessions with Larry, the DEQXPert, to dialed in my rig and I am quite satisfied.

No need for me to repeat what Al (Almarg), Drewan and other believers have already said. Suffice to say, I give the DEQX a Thumbs Up.

Update: I received my new DEQX HDP-5 from Acoustic Frontiers a few days ago. See my post dated today in the ”Is DEQX A Game-Changer?” thread for a detailed update, which is all good at this early stage (I have not yet attempted any measurements or calibrations). Further updates will follow in that thread in the next few weeks.

Regards,
-- Al

The Rives PARC has been a nice addition to my system, as I have a large peak node at 90 Hz and a broad hump of excess energy between 160 and 400 Hz at my listening spot, without flexiblity in changing loudspeaker or listening positions. I also prefer not to run my vinyl through AD-DA (or add it to the DA already done to cds upstream). Its limited functionality in the analog domain has improved my system significantly.

My new Emotiva XMC-1 has Dirac. I think it sounds better than my TacT 2.2x with Maui mods. My Tact does a fantastic job on sub integration that Dirac doesn't do. I haven't tried integrating my sub yet, but I understand I will have to do a little bit of manual adjustment to complete the integration. I am very impressed with the XMC-1.

Bob

The version that comes with the XMC-1 is Dirac Live LE for Emotiva is a limited(!) version. The full(er) version is well worth the extra $100.