Denon and Yamaha owners with Auto-EQ... your thoughts on this white paper article>>>>

Discussion in 'AV Receivers' started by Sonnie Parker, Jul 30, 2004.

  1. Sonnie Parker

    Sonnie Parker Second Unit

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    I stumbled across a very interesting article today or at least it abruptly caught my interest and attention:

    The Gentle Art of Room Correction


    I'm not trying to sell anyone on Meridian nor do I own any Meridian products... as a matter of fact I just purchased a Denon 2805 to play with.

    One of the several reasons I purchased the Denon was to test the Auto-EQ feature. In this white paper article (above link) it is suggested that equalizing above 250hz is not recommended and might even cause more problems than before auto-eq'ing.

    I've read a couple of reviews on the Auto-EQ feature on the newer Denon and Yamaha receivers but none that really get that technical as to how it's handled. It makes sense that it would only be beneficial for the prime listening position, but the article leads me to question if it can even be done in the right way for the prime listening position.

    It makes me wonder if Denon and Yamaha are just blowing a bunch of smoke to sell a product or is it really a useful feature?


    I do not know anything about the author of the article nor any of his credentials and not being that technical savvy myself wouldn't know if all of what he is saying is correct or not.

    If you have the time to read the article (it's not that long) I would appreciate your thoughts.

    Thanks!
     
  2. Chad B

    Chad B Stunt Coordinator

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    I read that article a while ago. I can't say I follow the same school of thought.
    I do agree that trying to EQ narrow peaks or dips in the response over 250 Hz at the primary listening position isn't a good idea. Sharp or narrow peaks and dips might change just by moving the measuring microphone a few inches. Unless you take a spatially averaged measurement, smoothing them out with EQ can mess up the sound in any other position. For example, those sitting around the listening chair (but not in it) will probably hear poorer sound than before EQ, and even moving your head might mess things up a little.
    On the other hand, if you only conventrate on broad peaks, dips, and slopes, and you do it with moderation, I think EQ can be beneficial above 250 Hz. It can compensate for speaker innacuracies and speaker/room interaction. I know this is a pro audio example, but nearly every good sounding PA system got that way by proper, moderate equalization across most of the audio spectrum.
    My feeling is that many systems, whether HT, 2 channel audio, car audio, or PA, benefit from proper EQ. I'd recommend taking measurements at different listening positions, taking note of the general response shape, and applying moderate EQ to smooth out the shape. Don't go for a perfectly flat response; most experts recommend some sort of slope with a slightly elevated bass (3 to 6 dB), flat midrange, and a gently dropping treble (usually 1 or 2 dB per octave above 1 or 2 KHz).
    I think the auto EQ feature in the new receivers can be of good use if you keep these things in mind. If I had one of these new receivers, I'd try to keep the general shape, but possibly modify parts of what the receiver comes up with. I'd try taking spatially averaged measurements, and see what equalization the receiver applies at each position. See if there's a recurring theme in the EQ, and make sure it's not too narrow frequency wise and too strong EQ wise (6 or 7 dB of correction is getting up there). Then I would go ahead and apply a moderate EQ that would smooth out the response. Don't try too hard to get perfect extention above 10 KHz or below 40 Hz (unless you have a very capable sub or very full range speakers).
    What do you all think?
     
  3. Sonnie Parker

    Sonnie Parker Second Unit

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    I'm thinkin' along the same lines as you as far as placing the mic for these receivers' measurements in a few different locations and see what the Auto-EQ does for each location... then compare the differences. Then use the manual EQ (only a graphic on the 2805 but parametric on the 3805) and make necessary adjustments for a broader equalization in the room.

    However... I'm not so sure that Analog Devices has not created the Sharc-ART (the processor in most of these receivers that does the Auto-EQ'ing) to do something similar to what you and I would suggest.

    I have now been referred to another white paper which explains what Analog Devices is doing:

    Sharc Melody ART White Paper

    Here in this white paper they plainly claim that their Auto-EQ fixes not only the main listening position but also other than primary listening positions.

    As far as equalizing the sub (LFE 120hz down to 16hz) I use the BFD... of course it generally works better for the primary listening position but again you can take measurements for several locations and get a broader correction if you choose to do so. I generally favor a house curve for the bass response. If I notice a huge differential between seating locations I might go back and modify the primary listening position settings and try to find a satisfactory compromise between the two. I'll keep my primary settings on one saved setting for when I'm watching by myself and keep the compromised setting saved on another for when several people are watching.
     
  4. David Judah

    David Judah Screenwriter

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    I've read the article before as well. While it's true that putting the processing power to work below 250 Hz is the most beneficial overall, I would hesitate to say it's absolutely worthless applying EQ higher up in the frequency range.

    I owned a Pioneer 45TX with MCACC and I most definitely preferred the sound with the EQ engaged and it was even more primitive than the Yamahas or Denons that are out now. Call it whatever you want--a more advanced tone control, but in my room, it did help despite the reasons presented in the paper why it shouldn't.

    There have been examples in my HT experience where theory didn't translate as well into the real world and this was one of them for me. The points brought up in the paper, I'm sure, are valid in some situations and should be looked out for, however.

    I wish I could afford Meridian gear, so I could have their more advanced correction system among the other advantadges they offer. In the meantime, hopefully, with DSP processing getting cheaper and cheaper we'll see something similiar at a lower price point.

    For example, I really like the direction NHT is going with their new active, digitally correcting speaker system and I'm sure many other manufacturers will follow suit with the prices coming down to where even I can afford them.[​IMG]

    DJ
     
  5. Chuck Kent

    Chuck Kent Supporting Actor

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    I try to not get into too many of these kinds of discussions anymore because of the valid points that the Meridian paper brings up. The paper's conclusions fly in the face of many Yamaha, Pioneer and Denon receiver owners who hear greatly improved things above 250Hz.

    That said, I do believe that higher frequency eq can work and that Sonnie is on the right track. IMO, if higher frequency eq is to going to consistently deliver good results, it needs to be an entire listening area based approach, not one point in space where current receivers do their work.
     
  6. Wayne A. Pflughaupt

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    I take issue with the article’s stance that equalization issues in the upper-range is intended to address room response.

    Above 200Hz or so, and especially above 500Hz, the source of any needed equalization will generally be the speakers themselves (aside from a necessary room curve, and assuming that needs to be addressed separately).

    I also take issue with the article’s stated presumption that most speakers are “optimized” in the upper frequencies.

    For instance, my speakers had a peak at about 4kHz that sounded much better after equalization.

    A few months ago I took my 1/3-octave RTA to a friend’s home and adjusted his speakers, using only a pink noise source and a few reference CDs I use for this purpose. His speakers had broad, wide-bandwidth problems that could be addressed quite nicely with the on-board quasi-parametric EQs in his Sony receiver. Afterwards both the ears and RTA confirmed a marked improvement in sound quality.

    Bottom line, the Meridian article makes a lot of bad assumptions about EQing the upper frequencies, using worse-case scenarios that would only happen using cheap equalizers and/or using them incorrectly. This is why people like Chad David, and myself, and many others, have experienced good results with upper-range equalization done correctly.

    While broad problems are the easiest to hear and correct, I wouldn’t be adverse to attempting to tweak narrow problems, under a few circumstances.

    First it would have to be audible, and it would have to be confirmed to be consistent in bandwidth and center frequency from multiple locations in the room. If it was a severe or deep problem, the objective would have to be to achieve an improvement, not perfection – just as with all other upper-range equalization, and any “improvement” would have to be confirmed by the ears.

    The thing I like about an auto EQ function is that they perform correction in the digital domain. Assuming the firmware is effective, the result is more precise equalization and less chance for phase errors (which IMO is usually an overblown objection to analog equalization anyway). Narrow peaks and holes can be more effectively addressed digitally as well.

    Still, being the tweaker that I am, I’d prefer to have an auto system that would let me know exactly what equalization had been performed, and I’d like to have the option to override or tweak each adjustment. I guess that at the end of the day I trust my ears more than the computer.

    So Sonnie, IMO the bottom line for the auto EQ functions in your new Denon is, feel free to use it, but let your ears decide if there’s an improvement or not. However, judging from David’s experiences, I’m guessing you’ll be happy with the results.

    Regards,
    Wayne A. Pflughaupt
     
  7. Sonnie Parker

    Sonnie Parker Second Unit

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    Thanks fellows... you know I appreciate your opinions and thoughts.

    I'm certainly feeling less confident about what Meridian is saying and more confident about what Analog Devices is doing with the Sharc-ART. I kinda got the impression that Meridian wasn't necessarily referencing (at least not directly) what the Sharc-ART is doing with equalization after re-reading it.

    Of course as you say Wayne... my ears will be the final judging authority.
     

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