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MetropolisLakeOutfitters

the X-curve

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Curious as to if anybody here employs any EQ to mimic the X-curve found in theaters.  With Klipsch in particular, it would be easy for us to blow the doors off the upper end of the typical response.  Everybody always says they want cinema sound, but most likely your upper highs and lower lows are killing what you'd find in a commercial theater, at least in terms of response curve and not necessarily raw decibels. One big thing I like about the cinema line like the 904's that Scrappy has is that for whatever reason they seem to roll off naturally so all the ear piercing fatiguing crap gets filtered out.  Really really enjoyed that.  It seems that everybody plus their cousin Mr. Audessey wants it to be flat though.  So, does anybody here override that and follow the X-curve even though their highs could be flat as a pancake or even sharply spiked?  

Edited by MetropolisLakeOutfitters
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The Pioneer avrs come with an X-curve setting.  What it will due is attenuate the highs in the1-3 kHz and higher to tame the highs.  I use this sometimes but, most of the time I don't bother.

Edited by derrickdj1
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Curious as to if anybody here employs any EQ to mimic the X-curve found in theaters.

 

Just for the record, considering that both music and movie soundtracks are mixed in control rooms of about the same internal volume of your listening space, it would be double dipping to apply a large-room X-curve on at HT setup.  X-curves arise solely due to issues related to loudspeaker directivity and power response issues, as well as large-space air absorption and perceptual changes in the human hearing system in large venues.

 

I've got some JAES articles on the subject--they all say the same thing as above.  If you have Toole's book, you can read all about it on pages 385-389.  The bottom line on this discussion is that Dr. John Eargle (the same guy that once worked for PWK as the recording engineer of Klipsch recordings and went on to become VP of engineering at Harman Kardon/JBL as well as a Grammy-award-winning recording engineer for Delos) wrote:

 

"...a loudspeaker with 'flat power response, in conjunction with constant directivity-frequency characteristics, will yield the desired results with no further adjustments required, other than compensation for through-screen losses...'"

 

I think the "X" curve usage in home theaters today arises mostly from misunderstanding of the above, and from the fact that most HT loudspeakers aren't constant directivity (i.e., they're direct radiating loudspeakers with constantly changing directivity vs. frequency) which will cause issues in-room when placed in real rooms, even though they may have been EQed flat on-axis anechoically.

 

Chris

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Jeff Meier from accucal eq'ed mine to look like the x curve with the receivers eq. I've since changed it but that was the first time I had even heard of doing such. I am not sure it could be accurate with what, 2-3 bands in the treble section but he seemed to think it could be.

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Curious as to if anybody here employs any EQ to mimic the X-curve found in theaters.

 

Just for the record, considering that both music and movie soundtracks are mixed in control rooms of about the same internal volume of your listening space, it would be double dipping to apply a large-room X-curve on at HT setup.  X-curves arise solely due to issues related to loudspeaker directivity and power response issues, as well as large-space air absorption and perceptual changes in the human hearing system in large venues.

 

I've got some JAES articles on the subject--they all say the same thing as above.  If you have Toole's book, you can read all about it on pages 385-389.  The bottom line on this discussion is that Dr. John Eargle (the same guy that once worked for PWK as the recording engineer of Klipsch recordings and went on to become VP of engineering at Harman Kardon/JBL as well as a Grammy-award-winning recording engineer for Delos) wrote:

 

"...a loudspeaker with 'flat power response, in conjunction with constant directivity-frequency characteristics, will yield the desired results with no further adjustments required, other than compensation for through-screen losses...'"

 

I think the "X" curve usage in home theaters today arises mostly from misunderstanding of the above, and from the fact that most HT loudspeakers aren't constant directivity (i.e., they're direct radiating loudspeakers with constantly changing directivity vs. frequency) which will cause issues in-room when placed in real rooms, even though they may have been EQed flat on-axis anechoically.

 

Chris

 

 

... and Audyssey Reference provides a gentle roll-off of the highs that Chris K and team think is appropriate for Home Theater size rooms.  It is something like -2 dB at 10K, rolling down to -6 dB at 20K.  Some Audyssey Reference configurations also incorporate the "BBC dip" which cuts a few dB at about 2K.  I have found all of the above useful with magnetic era movies, and movies or CDs that tend toward harshness.  Audyssey FLAT, on the other hand, attempts to provide flat room/speaker response, 20 to 20K (with some subs, there is comp as low as 10 Hz).  With GOOD movie soundtracks, and GOOD CDs, SACDs, DVD-As, etc., I find Audyssey FLAT to be better.  Audyssey recommends FLAT only for a few highly treated rooms.

Edited by garyrc

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Look at the typical loudspeakers that Audyssey is trying to EQ - and I think that you might have an answer to why there is HF roll off, due to the "collapsing polars" in both axes of direct radiating HT loudspeakers in the midrange, but not so much in the tweeters.  That extra tweeter off-axis energy becomes a problem relative to the midrange, just like the collapsing vertical polars of Klipsch Heritage (particularly Khorns, which are higher off the floor in the midrange and HF)  in rooms without carpet or high ceilings.

 

Chris

Edited by Chris A
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All this is to say: the term "x-curve" is not appropriate for HT...and roll-offs of HF in HT-sized rooms has probably got a lot more to do with badly mastered music and perhaps even too-hot movie soundtrack than it does in terms of psychoacoustics, as Toole and Eargle have pointed out.

 

The BBC curve is another issue that I'll leave alone here, other to say that it was tied to a "boo-boo" in a certain BBC monitor design in terms of polar control and vertical separation of the midrange vs. tweeter.

 

Chris

Edited by Chris A
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The BBC curve is another issue that I'll leave alone here, other to say that it was tied to a "boo-boo" in a certain BBC monitor design in terms of polar control and vertical separation of the midrange vs. tweeter.

 

  • Chris K's view: he says he never heard a speaker that couldn't be improved by the slight dip at about 2K ("midrange compensation") in Audyssey Reference.
  • My view: the 2K dip, and the HF roll off in AR, together improve the sound of some movies, but very few, if any, ones made in the last few years.  Seemingly, the less distortion on the soundtrack, the less the dip helps.

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Curious as to if anybody here employs any EQ to mimic the X-curve found in theaters.  With Klipsch in particular, it would be easy for us to blow the doors off the upper end of the typical response.  Everybody always says they want cinema sound, but most likely your upper highs and lower lows are killing what you'd find in a commercial theater, at least in terms of response curve and not necessarily raw decibels. One big thing I like about the cinema line like the 904's that Scrappy has is that for whatever reason they seem to roll off naturally so all the ear piercing fatiguing crap gets filtered out.  Really really enjoyed that.  It seems that everybody plus their cousin Mr. Audessey wants it to be flat though.  So, does anybody here override that and follow the X-curve even though their highs could be flat as a pancake or even sharply spiked?  

"the X-curve found in theaters" ?

Next time im in the Bay area, ill ask my Nacamichi guy about this "X-Crrve" thingy.

Another reason iv zero interest in HT. i do not know chit, as long as you people keep going to the "Real Movies",

Im happy as a clam.

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The Pioneer X-curve function can attenuate the 2 kHz to 20 kHz from 0-3 db/oct.  This can help with some harness that people find with their Klipsch speakers.  Chris is correct that the home HT is not like the cinema and has it's own challenges.

Edited by derrickdj1

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I dont bother with it even though pioneers usage is very easy to employ.

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Jeff Meier from accucal eq'ed mine to look like the x curve with the receivers eq. I've since changed it but that was the first time I had even heard of doing such. I am not sure it could be accurate with what, 2-3 bands in the treble section but he seemed to think it could be.

 

 

He's been to my house a couple times as well for panel calibration.  He does a great job.  Nice guy as well.

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I'm curious about the Pioneer now, all the charts I've seen on the X-curve was a lot more aggressive than 2-3 db on the treble.  We're talking about something like 8-10 db down at 10-12 kHz, nearly a 45 degree angle if you chart it out past like 2 khz.  

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We need to figure out how to defeat the X Curve in the new KPT Surrounds...

 

Unfortunately, I know nothing about crossovers. However, I'm very willing to provide pictures and such of my crossover to anyone who thinks they can defeat it.

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We need to figure out how to defeat the X Curve in the new KPT Surrounds...

I don't fully understand this. At its core, is the X-curve a byproduct of crapola commercial theater acoustics, a byproduct of speakers that can handle the kind of sustained SPL that is necessary, or do they do it on purpose because that's just how it's supposed to sound? It seems that cinema speakers have a natural rolloff and possibly are purposely designed to do so which makes me think it's done on purpose in all scenarios.

Edited by MetropolisLakeOutfitters

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I'm curious about the Pioneer now, all the charts I've seen on the X-curve was a lot more aggressive than 2-3 db on the treble.  We're talking about something like 8-10 db down at 10-12 kHz, nearly a 45 degree angle if you chart it out past like 2 khz.  

 

The real X-curve is too aggressive for a well treated HT with modern movies, at least in most cases.

 

Edit:  Even the SMPTE guest experts can't agree on the benefits v.s. downsides of the X-curve.  If I understand correctly -- and there's no guarantee of that(!) -- the build up of reverberation the X-curve it is partly meant to correct is not near as much of a problem in most HTs, because they are much smaller than a commercial cinema, are generally treated, and we can use "pings" as with Audyssey, rather than the steady pink noise that was used for testing in cinemas back when they X-curve was developed.  As the article below points out, the curve was also handy in hiding high frequency distortion in some commercial cinema speakers, to say nothing of damaged or bad-to-begin-with soundtracks.  I believe, but cannot prove, that there has somehow been a distortion build-up over the years in some of the soundtracks of the great magnetic era (a long discussion for esewhere).  Nonetheless, I wouldn't use the X-curve in the home.  I like Audyssey with some subwoofer boost, and I choose between Audyssey Flat and Audyssey Reference (moderate roll-off) depending entirely on the soundtrack. 

 

Scroll down past the many, many author's credits

SMPTE Meeting Presentation
Is the X Curve Damaging Our Enjoyment of Cinema?

http://www.aes.org/technical/documentDownloads.cfm?docID=391

Edited by garyrc
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I should correct what I said about the Pioneer X-curve, it is 0 to -3 db/oct.  So, up to -3 db attenuation at around 2 kHz and -10 db at 20 kHz.  This is an aggressive function.  Correction made to previous post. :)

Edited by derrickdj1
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The X-Curve FR shelving feature of the Pioneer Elite is nice to have. It's easy enough to enable/defeat (particularly through the AV5 app), and with the amount of DSP power on tap, I'd rather have it available than not. It does make certain soundtracks more palatable.

 

In addition, I'd like to see more shelving filter options available for AVRs. Out of all the "whiz-bang" features they pack into these things, shelving has a huge impact on the overall sound. :emotion-21:

 

As far as X-curve in regards to cinema, we get what we get. It's not like we're free to root around in their equipment racks if we hear something we don't agree with.  :ph34r:

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As far as X-curve in regards to cinema, we get what we get. It's not like we're free to root around in their equipment racks if we hear something we don't agree with. :ph34r:

 

True.

 

Movie sound in commercial cinemas has had its ups and downs.  Magnetic soundtracks in 70mm films were (usually) marvelously warm sounding, and they truly sounded like there was a (big) orchestra present.  Unfortunately, they aren't always that way on BD (another long discussion for later).

 

IMHO, a rank order from best to worst, in commercial cinemas, is as follows:

 

Best to Worst, starting with the best:

 

6 track magnetic sound on 70mm prints (1955, gradually phased out in the '80s)

 

4 track magnetic sound on 35 mm prints

 

Modern digital sound in cinemas.  Now, usually, very good with bass that extends as much as 2 octaves deeper than the above, but tends to lack the warmth.

 

The transitional Dolby analog formats

 

Fantasound (see Scientific American, Peck, 1941  or 1940)

 

Pre-Dolby Opitcal sound on movies that were meant to have optical sound ... mostly pre-1953 ... varied ... the best may have been called "silver" soundtracks.  Still, no highs, no lows, and fair amount of distortion.

 

Optical soundtracks that were of lower quality yet, including many of those poorly transfered from good sounding magnetic masters after 1953

 

A great example of the contrast was the magnetic stereo v.s. mono optical versions of The Unsinkable Molly Brown (1964).  The mag was dynamic, warm, thrilling; the optical was dull and even made the dancing look bad.

 

Ironically (?) BDs made in the last few years from newer movies, as heard in our HT, are just about as good as the best in the cinema, ever.

Edited by garyrc
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