Target Curve - New Discovery

[Spridle]

OK guys, since I have been an REW user for almost a year and have experimented quite a bit, I thought I should make this post.

I have always been confused as to what the ideal target curve should look like, but I have found an answer that works extremely well—at least in my case.

I recently received a room correction software upgrade to my sound processor. It's something like a built-in digital parametric EQ that works across the entire frequency spectrum—an REW of sorts. It shipped with a calibrated microphone. Unlike REW, it does not give the user much control over what it does, but I have to say that the results are amazing. I am experiencing the best sound ever. I really have no more complaints about my system and my tweaking days are over.

Similar to Wayne’s "house curve", one of the philosophies behind this room correction is the concept of "room gain" in the low end, which every room has and recording engineers expect when they mix. Also, it corrects for speaker performance and room interactions and creates a flat curve in the mids and highs which make a huge difference in vocals, guitars, cymbals, imaging, soundstage, sparkle, etc.

What I thought would be helpful to REW users is showing you the curve I get when I measure my corrected system with REW using a calibrated microphone. In my attached REW graph (avg. of 5 positions), note the room gain in the low end, the flatness in the mids, and the roll-off in the highs. One thing that was a little different is the software determined a crossover of 120Hz for my subs/mains, instead of 80Hz. But, if you look at my uncorrected curves, 120Hz visually appears to be the most natural choice for the crossover frequency in my case. I tried 80Hz and others but ultimately 120 really was the best sounding. Your room will vary.

Here are the values for my blue target curve in case you want to experiment. The size of the hump apparently varies with room size, so you may need to make the hump smaller or larger:

15 5
20 8
30 11
50 11
70 8
100 2.5
150 1
200 0
2000 0
8000 -1
10000 -2
13000 -4
16000 -10
20000 -20

Of course, you can use the BFD or a Velodyne SMS-1 on your subs. For your mains, tone controls or treatments may do the trick. If you want to take it to the next level, I have previously used Rane PE-17 parametric EQs (bought on EBay) for my mains with no audibly detectable coloration, noise or distortion added. This is a good way to go. I even found a way to precisely set the filters on the Ranes using REW. See a prior post of mine for the technique.

Also attached are the graphs from my processor software that shows my curves before correction (red) and after correction (green).

Hope this info is helpful.

[Wayne A. Pflughaupt]

Interesting post, Spridle!

So the blue line is what the processor generated?

Also, it corrects for speaker performance and room interactions and creates a flat curve in the mids and highs which make a huge difference in vocals, guitars, cymbals, imaging, soundstage, sparkle, etc.

Something to listen for, the fundamentals of mid to upper-mid bass notes reside in the 100-300 Hz range, so this curve might leave them sounding reduced in level. Of course, that’ll be of little consequence for home theater.

If you want to take it to the next level, I have previously used Rane PE-17 parametric EQs (bought on EBay) for my mains with no audibly detectable coloration, noise or distortion added. This is a good way to go. I even found a way to precisely set the filters on the Ranes using REW. See a prior post of mine for the technique.

I’ve regularly been sending people to that thread when they inquire about the benefits full-range equalizing.

Regards,
Wayne

[Spridle]

Wayne A. Pflughaupt wrote:

So the blue line is what the processor generated?

On the REW graph, the blue line is the target curve I created with points to generally follow the red response line that I measured with REW. The red response line was from measurements taken after the processor does its thing and is an average of 5 positions. When I measured with REW then looked at the graphs, I was surprised to see the size of the hump and the narrow range it covers compared to the house curve I was using before which was basically a 4db boost house curve. I was also surprised that the bass does not sound "louder" than before, but rather tighter and more precise. On the graph, the gain at 30-50Hz is a whopping 11dB.

Wayne A. Pflughaupt wrote:

Something to listen for, the fundamentals of mid to upper-mid bass notes reside in the 100-300 Hz range, so this curve might leave them sounding reduced in level. Of course, that’ll be of little consequence for home theater.

I primarily listen to music, so accuracy and realism are most important to me. The sound is very balanced across the spectrum and sounds very much like live music, especially when cranked up. The bass is tight, punchy, and smooth -- much more so than before. The Basia bass line is particularly impressive. Believe it or not, I have been tweak-free for about 2 weeks and haven't heard anything that has caused me to get up and try a new setting.

Wayne A. Pflughaupt wrote:

I’ve regularly been sending people to that thread when they inquire about the benefits full-range equalizing.

It would be interesting to hear about the results with the Ranes and what target curves are used. I'll search the thread to see if anything has been posted.

[Wayne A. Pflughaupt]

On the REW graph, the blue line is the target curve I created with points to generally follow the red response line that I measured with REW. The red response line was from measurements taken after the processor does its thing and is an average of 5 positions.

Ah. Well then, I can't help but notice that the red-line response the processor generated has the house curve shelving at ~30 Hz, a figure I mentioned in my house curve article.

Are you still using the Ranes, or did the processor have EQ to replace them?

Regards,
Wayne

[Spridle]

I have removed the Ranes. I have the processor room correction set to work up to 15K Hz.

[tnargs]

This looks like the RoomPerfect curve. I am using a similar (slightly different) target for my DEQ2496.

The RoomPerfect people claim that it is based on the principle that we are used to hearing room gain when we are in a room. I think this is a weak rationale.

However, much more important to me, is that most final mastering of recordings is done in a studio, which will have room gain. The mastering EQ is therefore based on sounding right in a room with room gain. In these (dare I say normal) cases, it would result in too little bass in our rooms if we EQ flat in the bass.

You would be making a mistake to say your search for a target curve is over. Some recordings are mastered with headphones (shudder). And some are so-called 'direct to disc', which can mean what it says, but more generically means recordings that are effectively unmastered, e.g. some of the Water Lily Acoustics recordings of live classical work captured direct to two microphones and not further equalised, or recordings like Marcus Miller's Ozell Tapes that are mastered direct from the mixing desk. Such 'unmastered' recordings will sound too bass heavy (I can vouch for it) because your target curve needs to be flat in the bass for them.

So you need to have a few target curves on hand. But the one you are using is a better default setting than flat (eech) or X-curve (misapplied in the home living room), which I have used over the years.

[thewire]

tnargs wrote:

This looks like the RoomPerfect curve. I am using a similar (slightly different) target for my DEQ2496.

The RoomPerfect people claim that it is based on the principle that we are used to hearing room gain when we are in a room. I think this is a weak rationale.

However, much more important to me, is that most final mastering of recordings is done in a studio, which will have room gain. The mastering EQ is therefore based on sounding right in a room with room gain. In these (dare I say normal) cases, it would result in too little bass in our rooms if we EQ flat in the bass.

You would be making a mistake to say your search for a target curve is over. Some recordings are mastered with headphones (shudder). And some are so-called 'direct to disc', which can mean what it says, but more generically means recordings that are effectively unmastered, e.g. some of the Water Lily Acoustics recordings of live classical work captured direct to two microphones and not further equalised, or recordings like Marcus Miller's Ozell Tapes that are mastered direct from the mixing desk. Such 'unmastered' recordings will sound too bass heavy (I can vouch for it) because your target curve needs to be flat in the bass for them.

So you need to have a few target curves on hand. But the one you are using is a better default setting than flat (eech) or X-curve (misapplied in the home living room), which I have used over the years.

I think that most mixing studios are checked out by Dolby Digital and they mix the master using an X-Curve. When they go back an recode for the format DVD, Blu-Ray, Digital Copy , they are mixing for an enviornment that is entended to be flat, unless they expect you to do the curve yourself. How to know which is right can be impossible. I wish that I knew a way of extracting these metatags or downloading them that are intended for the THX Media Director. Better yet they should just make it all public so we can know how the mixes were done. That is probobly asking too much but it would be nice. Even then we would have to rely on the people releasing the media to tell us, and they already don't as it is most of the time.

[tnargs]

I agree it would be sooo pleasing if people in the industry (the big players) would join the internet discussions and make interested audiophiles aware of the room acoustic they would recommend for the recordings. Then we could aim for that. At the moment it feels like groping in the dark!

[tnargs]

thewire wrote:

I think that most mixing studios are checked out by Dolby Digital and they mix the master using an X-Curve....

If so, they would be doing the consumers no favour.

In the bass, it means anyone with room gain will hear excess bass. Since every room has room gain, only the very few consumers with equalised flat bass will hear bass at the right level. OTOH it is good news for those of us who do equalise.

In the treble, an average-sized listening room has no X-curve, i.e the pink noise treble does not fall off in the treble. So, again, no one will hear the treble at the right level at home.

OTOH if it is true, we home EQ guys have something to work with....

[Wayne A. Pflughaupt]

From Part Three of my house curve article:

As industry pro Tomlinson Holman explains in this article, the X curve is used in both theaters and dubbing soundstages. He readily acknowledges the problem most of us are aware of with home movie releases, that “when heard over a modern flat loudspeaker in a small room, program material balanced on an X curve monitor sounds overly bright.” Mr. Holman adds, “This is not too important because, so long as everyone [in the industry] agrees to use the same curve, then the response sounds the same to the mixer on the dubbing stage as to the audience member in any auditorium. Interchangeability of X curve material with home video can be handled with a simple re-equalization.”

tnargs wrote:

The RoomPerfect people claim that it is based on the principle that we are used to hearing room gain when we are in a room. I think this is a weak rationale.

Try taking your speakers outside and the first thing you’ll notice is the bass is gone.

So you need to have a few target curves on hand. But the one you are using is a better default setting than flat (eech) or X-curve (misapplied in the home living room), which I have used over the years.

I’ve had satisfactory results merely adjusting the system for a house curve appropriate for the room, and then adjusting the overall sub level up or down as (occasionally) needed (which is easy since I have remote control for my subs).

Regards,
Wayne

[tnargs]

Wayne A. Pflughaupt wrote:

From Part Three of my house curve article:

As industry pro Tomlinson Holman explains in this article, the X curve is used in both theaters and dubbing soundstages. He readily acknowledges the problem most of us are aware of with home movie releases, that “when heard over a modern flat loudspeaker in a small room, program material balanced on an X curve monitor sounds overly bright.” Mr. Holman adds, “This is not too important because, so long as everyone [in the industry] agrees to use the same curve, then the response sounds the same to the mixer on the dubbing stage as to the audience member in any auditorium. Interchangeability of X curve material with home video can be handled with a simple re-equalization.”

To which I responded here (over a year ago):
http://www.hometheatershack.com/foru...html#post68712

Try taking your speakers outside and the first thing you’ll notice is the bass is gone.

Supporting my point that I disagree with the RoomPerfect people’s notion that we are “used to” hearing room gain in our homes (and by extension “used to” the lack of bass outdoors). If that were true, we would not notice the change indoors vs out.

I’ve had satisfactory results merely adjusting the system for a house curve appropriate for the room, and then adjusting the overall sub level up or down as (occasionally) needed (which is easy since I have remote control for my subs).

I am interested in what you think is a house curve “appropriate to the room”. I may be wrong but I think for a home-sized listening room, the appropriate house curve is zero. The need for X-curve EQ gradually diminishes with room size from 100% for an auditorium or theatre, to zero for typical lounge or listening rooms. For example, there is a Small-Room X Curve, designed to be used in rooms with less than 150 cubic meters, or 5,300 cubic feet. This standard specifies flat response to 2 kHz, and then rolling off at a 1.5 dB/octave above 2 kHz.

Somewhere on the "Secrets of Home Theater and High Fidelity" there is an article on the topic which says:

"Since the advent of Dolby Stereo though, the soundtrack of virtually every movie (be it Analog or Digital) is crafted for playback over a system equalized to the XCurve and set at the reference playback level. Unfortunately there is no entry in the X-Curve table for rooms as small as most home theaters, and even if there were, like theaters and studios, you'd need 1/3 octave equalization on each channel to conform. Don't worry. Read on.

"If you could get your hand on the X-Curve table, one corollary would stick out for you: As the rooms get smaller, less and less of a roll-off is defined, because as we said, smaller rooms have less of the reverb which the X-Curve addresses.

"By the time we shrink a room down to typical home theater size, we can say that no X-Curve compensation is needed, much to the contrary of popular opinion. There is not an inherent overabundance of treble in motion picture soundtracks, at least not due to the X-Curve."

Makes sense to me.

[thewire]

Your not taking into account how close one is to the speaker. The speaker will sound harsh at times depending on the mix unless it is factored into the remix and encoding proccess to disc. I hear it sometimes but other times it is not as bad. It is dependent on what the film maker wants to do mostly. If they are listening to speakers that are not going to sound harsh while they mix, it isn't going to sound that way. Here is a quote directly from the THX website about their version of Re-Eq.

THX Re-EQ is a compensation technology taking soundtracks that are mixed for large cinemas, where speakers are placed farther away from you, and re-establishes the accurate tonal balance for your close range home theater speakers. Without THX Re-EQ, higher frequencies sound excessively “edgy” or “bright.” With THX Re-EQ, the movie soundtrack is true to the original immersive cinematic experience.

Example: The THX Certified DVD classic action film Aliens is loaded with audio and visual effects. When watching this film with THX Re-EQ activated in your THX Certified receiver or pre-amplifier, the technology adjusts and reproduces the high frequencies to play at the appropriate audio level in your home. Otherwise these frequencies would sound overbearing and distracting.

My pre/pro calls this theater mode.

[tnargs]

thewire wrote:

Your not taking into account how close one is to the speaker.

Sure I am (or did, in Dec 07):
http://www.hometheatershack.com/foru...html#post68712

The speaker will sound harsh at times depending on the mix unless it is factored into the remix and encoding proccess to disc. I hear it sometimes but other times it is not as bad. It is dependent on what the film maker wants to do mostly. If they are listening to speakers that are not going to sound harsh while they mix, it isn't going to sound that way.

No argument.

I still reckon the X-curve for a small (home) room is zero.

In saying the X-curve is zero, I am not saying there is no need for EQ in the home. I am only saying that the reasons EQ is needed are not founded in the X-curve rationale. Therefore the shape of EQ that is needed in the home is not based on the X-curve's shape.

[Wayne A. Pflughaupt]

tnargs wrote:

To which I responded here (over a year ago):
http://www.hometheatershack.com/foru...html#post68712

Hmm... not sure how that one got past me, but IIR, I was working long hours at the time.

Wow – where to begin?

The point of the quote I italicized in my previous post was to show that the movie industry utilizes the X curve for both production (soundstages) and playback (movie theaters), which was in keeping with the discussion (please review the posts above it). And no, that was not something you addressed or even mentioned in your Dec. 2007 thread.

Reviewing both your 2007 thread and your comments above in Post #11, it looks like you’ve been confusing a house curve with the X curve:

I may be wrong but I think for a home-sized listening room, the appropriate house curve is zero. The need for X-curve EQ gradually diminishes with room size from...

I also cannot leave be the stated notion that the house curve is one where the listener hears all notes or tones at the same loudness…

My conclusions? Yes, most recordings sound too sharp with flat EQ’d pink noise at the listener’s seat. No, it is not due to the X curve effect...

The X curve is specific to the film industry (not pro audio as you surmised – that’s PA systems used in all sorts of public venues). It’s something they came up decades ago to address the deficiencies in optical soundtracks and old-school speakers.

Best as I can tell by wading through the article I linked above and Dolby Lab’s History of the X Curve, Ioan Allen of Dolby Labs and other movie industry types came up with the X curve back in the early 70s by comparing hi-fi KEF speakers located near-field with old-school film monitors located far-field, equalizing the latter until they felt they timbre-matched the former (which strikes me as a futile exercise going in). After this exercise the film monitors' “new” response was electroacoustically measured. All parties in attendance where surprised to find that the film monitors exhibited not the KEF’s verified flat response, but a roll out of the high frequencies above 2 kHz. They couldn’t readily explain the discrepancy, but nevertheless the curve they’d measured was later adapted as the X curve. Never mind that the ancient film monitors were dead in the water above ~8kHz to begin with, or perhaps their prehistoric compression drivers just sounded nasty with their highs suitably elevated so maybe they instinctively kept them rolled back. Or maybe their primitive equalizers were doing the film monitor no favors. Who knows? They sure didn't, and they made no attempt to get to the bottom of it.

Subsequent testing took reverberation in movie theaters into account and further validated the X curve as suitable for maximizing speech intelligibility in movie soundtracks. The curve’s low-end roll off was implemented to minimize distortion from overloading the speakers of the day.

Over the decades as advancements in professional loudspeaker design have improved both low- and high-end extension, the film industry has rigidly adhered to the X curve, essentially keeping movie theater sound “dumbed down” to the level of the inferior stuff that was used “back in the day.” Adding insult to injury, modern theaters are much more- and better-dampened than they were in the past, diminishing the effect of reverberation on both measured response and speech intelligibility; yet the X curve remains.

Small wonder that movie theaters today sound dull and lifeless, and small wonder that an X curve didn’t sound good in your home theater. Bottom line, whoever told you it was the gold standard for a domestic audio system should be severely beaten.

If you review the house curve article, you’ll find that I never claimed that the X curve was intended for use in a home theater, or any domestic system. Indeed, I thoroughly refuted the notion of applying any kind of rigid-value slope (which is what the X curve is) that purported to be the reference standard for any and every room (which again, is what the X curve is). As such, I fully agree with the quotation you presented from Secrets of Home Theater and High Fidelity, as well as your own personal conclusions: The X curve was never intended for our tiny rooms and should not be used.

Likewise, I never claimed that dialing in a proper house curve (which is not the same thing as an X curve) would result in every recording magically sounding perfect. That’s an impossible goal. The whole point of the article was to show that a house curve is needed in order for a system to sound natural and balanced. I offered a few tips on how to accomplish that goal. This is what audio professionals call “calibrating” or “setting up” a system. It is accomplished with various response-measuring tools, and confirmed afterwards with program material that the calibrator has found to be a good representation of an accurate recording, making further adjustments at that point as needed, irrespective of what the measurements may indicate. It should be noted that global calibration of the system is not the same thing as compensating for deficient program material.

However, in the world of home theater, rife with untrained, amateur system “calibrators,” the house curve will naturally reflect the owner’s personal tastes and expectations. For instance, we can anticipate that a basshead fresh from the world of car audio, or someone who’s used to the “boom-sizzle” generated by a smiley-face EQ curve, will expect that their home theater should sound the same.

That’s not really a problem. Once the system is calibrated, even if it’s intentionally “miscalibrated” to accommodate the owner’s taste and expectations, it becomes their personal point of reference. The notion of calling up a different house curve for every DVD or CD that’s loaded up – or as I’d characterize it, deliberately un-calibrating the system - is not the proper way to do things.

Basically, IMO you’re making all of this much more difficult than it should be. Just calibrate the system to sound as accurate as possible in your room and call it a day. At that point, whatever you put in your DVD or CD player - “it is what it is.” If a certain CD or DVD has, for example, bloated midbass – fine, I assume that’s the way the director or producer wanted it to sound, right or wrong. I’m not interested in re-equalizing my whole system to “unbloat” their idea of “correct.” As I noted, addressing problems in program material is a whole ‘nother cantaloupe from proper system calibration, and should be only general, not wholesale, temporary adjustments. As such, the most I will do is a broad, overall adjustment to the treble or (bloated-sounding) bass if it is excessive or deficient. If you find yourself making the same adjustments on a regular basis – e.g. always dialing the treble up a few notches – then tweaking the system a bit further is in order.

Regards,
Wayne

[thewire]

tnargs wrote:

Sure I am (or did, in Dec 07):
http://www.hometheatershack.com/foru...html#post68712



No argument.

I still reckon the X-curve for a small (home) room is zero.

In saying the X-curve is zero, I am not saying there is no need for EQ in the home. I am only saying that the reasons EQ is needed are not founded in the X-curve rationale. Therefore the shape of EQ that is needed in the home is not based on the X-curve's shape.

It's going to not resemble an X-Curve in a home if the mix was not redone for home. It is going to exagerate bass, not be flat. The purpose of Re-Eq is to make it flat, not like an X-Curve, because the mix was not remixed for a home theater.

A mix itself has zero X-curve most of the time because it has been remixed for home but it is not related in any way to a home theater enviornment. What you have instead is a mix where it sounds correct to a mixing room enviornment. If the room is overly dampened your going to hear bass that is muffled, distorted, perhaps even way too loud. It has been tried to match mixing studios to sound the same, but it has failed to have worked. The idea of mixing with an X-Curve, then correcting that is to take the sound in the cenema, and bring that to the home enviornment so you hear how the mix was intended originally instead of hearing what someone thought it sounded right in the mix room. Why you would be against ones choice of using Re-Eq to correct for a theater X-Curve whether left intinitally or not, I am not clear on. It sounds like you would prefer to listen to the way it would be mixed for the theater in a home enviorment.

As Wayne explained, an X-Curve and a shelving filter are not related. The purpose of one is using the same standard for older theaters, and the purpose of the other is what a person prefers.

[JimP]

Wayne A. Pflughaupt wrote:

...snip...

Basically, IMO you’re making all of this much more difficult than it should be. Just calibrate the system to sound as accurate as possible in your room and call it a day. At that point, whatever you put in your DVD or CD player - “it is what it is.” If a certain CD or DVD has, for example, bloated midbass – fine, I assume that’s the way the director or producer wanted it do sound, right or wrong. I’m not interested in re-equalizing my whole system to “unbloat” their idea of “correct.” As I noted, addressing problems in program material is a whole ‘nother cantaloupe from proper system calibration, and should be only general, not wholesale, temporary adjustments. As such, the most I will do is a broad, overall adjustment to the treble or (bloated-sounding) bass if it is excessive or deficient. If you find yourself making the same adjustments on a regular basis – e.g. always dialing the treble up a few notches – then tweaking the system a bit further is in order.

Regards,
Wayne

Wayne,

I agree with what you say but only up to a point. Consider that TNT and certain shows on SciFi have something major wrong with their bass, I don't think you have much a choice but to have a different setting (or memory) in your Sub EQ setup. Coming up with a compromise setting that you can use for everything is most likely to result in settings that don't sound good for anything. I'm not sure exactly what TNT is doing, but for the time being I'm just lowering my Sub EQ by 6dbs. There may be more adjustments needed, but this at least gets it into the ball park.

[thewire]

JimP wrote:

Wayne,

I agree with what you say but only up to a point. Consider that TNT and certain shows on SciFi have something major wrong with their bass, I don't think you have much a choice but to have a different setting (or memory) in your Sub EQ setup. Coming up with a compromise setting that you can use for everything is most likely to result in settings that don't sound good for anything. I'm not sure exactly what TNT is doing, but for the time being I'm just lowering my Sub EQ by 6dbs. There may be more adjustments needed, but this at least gets it into the ball park.

A format your watching on your DVD or Blu-Ray is broadcast. This is a different type of mix. It is done with the intential expectations that the mix is compressed, and adjustments are done according to what it supposed to sound like however... The equipment that is envolved in the playback of these broadcast will vary and a service provider is not going to use the same compression from one to the next. What you have instead is a problem where someone has not checked the quality of the boadcast, or they did a poor job at it. It is much more simple to simply turn down the level. Dialing in a curve isn't going to correct something like this, as it will also not specifically address tonal balance or impact in a specific recording on Blu-Ray or DVD, which is going to be alot more consistant from one player to the next. Contrary to common beleif, we are not all watching the same episode on local channels as well. What is on air is up to your local broadcast provider. Thought I might mention that also..

[thewire]

I'm sorry. I confussed a statement I made earlier in this thread. Most movies that are mixed for the cemema will benifit with RE-EQ. The majority of material we may be expossed to however such as games or broadcast will not benifit from RE-EQ.

[wackii]

I've stumbled to this thread the other day and decided to give this target curve a try. I've recently bought a Marantz SR8001 and real happy on the SQ. Anyway, this receiver has the MultEQ Audyssey calibration built in. I was trying to tweak the manually calibration to my best to get it closer to this target curve. I'm really like how it sounds especially on the vocals, but it seems to lack on the bass department though. I like how the Audyssey setting sounds more with the bass. So I combined this target curve with the lower freqs Audyssey target curve and got what I want. It sounds great with music and movie now. I really like how it sounds now, even GF give a thumb up on the newer EQ system.

Here is my curve.

15 15
20 15
30 15
50 11
70 7.5
100 2.5
150 1
200 0
2000 0
8000 -1
10000 -2
13000 -4
16000 -10
20000 -20

My measurements with Target Curve


Before and After graph.
Green = Audyssey OFF; Yellow = Audyssey ON; Blue = EQ FLAT; Red = Preset - manual calibration (volume was 1 db higher by accident)


Thanks Spridle and everyone else for the target curve.

Al,