Target Curve - New Discovery - Home Theater Forum and Systems - HomeTheaterShack.com
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post #1 of 43 Old 08-25-08, 12:02 AM Thread Starter
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Target Curve - New Discovery

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.

Target Curve - New Discovery-final-rew.jpg

Target Curve - New Discovery-arc-final-1-8-22-08.jpg

Target Curve - New Discovery-arc-final-2-8-22-08.jpg
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post #2 of 43 Old 08-26-08, 09:46 PM
 
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Re: Target Curve - New Discovery


Interesting post, Spridle!

So the blue line is what the processor generated?

Quote:
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.

Quote:
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



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post #3 of 43 Old 08-27-08, 12:51 AM Thread Starter
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Re: Target Curve - New Discovery

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Wayne A. Pflughaupt wrote: View Post

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.

Quote:
Wayne A. Pflughaupt wrote: View Post

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.

Quote:
Wayne A. Pflughaupt wrote: View Post

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.
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post #4 of 43 Old 08-28-08, 07:17 PM
 
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Re: Target Curve - New Discovery


Quote:
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



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post #5 of 43 Old 08-30-08, 05:38 PM Thread Starter
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Re: Target Curve - New Discovery

I have removed the Ranes. I have the processor room correction set to work up to 15K Hz.
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post #6 of 43 Old 02-20-09, 08:17 AM
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Re: Target Curve - New Discovery

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.

Last edited by tnargs; 02-20-09 at 08:36 AM. Reason: expanded
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post #7 of 43 Old 02-20-09, 11:30 AM
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Re: Target Curve - New Discovery

Quote:
tnargs wrote: View Post
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.
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post #8 of 43 Old 02-20-09, 09:41 PM
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Re: Target Curve - New Discovery

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!
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post #9 of 43 Old 02-21-09, 09:31 AM
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Re: Target Curve - New Discovery

Quote:
thewire wrote: View Post
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....
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post #10 of 43 Old 02-21-09, 11:30 PM
 
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Re: Target Curve - New Discovery


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.”

Quote:
tnargs wrote: View Post
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.

Quote:
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



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