Hahaha! I registered JUST to respond to the comments made by Az.

I've tuned home and car audio systems for many years, by ear and by SPL meters and spectrum analyzers. I understand your point, Az, about the variables. But let's try this example:

Have you ever had your wheels aligned? The adjustments are very simple. You could even do it by eyeballing. And yet any respectable shop will do it by laser and computer. Why? What about the variables of the car, like tire wear and pressure, weight of the driver, full gas tank or half full? How about the rotational mass of the wheels? Road surface imperfections, wind resistance, humidity...it goes on and on. All of which can cause your car to drift after a perfect alignment, so you turn the steering wheel to correct it. Using an SPL meter is no different.

You use the equipment to set the baseline of what a reference point SHOULD be. There may come a time when you change it to what you WANT it to be. Sure, if your car pulls hard to the right you just crank the wheel to the left and it goes straight. But wouldn't it be better if it just went straight to begin with? If you want to align a car by eyeballing, you could do it - it might even go straight, after a few dozen attempts. But it'd be a helluva lot easier just to use the darn equipment!

!
!!!

Now thats some funny !#@$ Sorry !, didn't mean to include you in the expletive! There I go again
DMC

Oh well,
I'll give up. Some of you do at least see my very specific points and their validity as to how they lead to all sorts of diff. end results -though the meter's the same.

This is why my using a meter is irrelevant to my points.

I could go buy a meter today, as post here at least FIVE very diff. surround/sub settings (same meter/same system/all done 'correctly' only variable "choices" would be the diff.) and none could be certified correct.
None could be called wrong either.
No one gets this f-a-c-t?

This is not conjecture.

The variables I pointed out (and others have pointed out unwittingly before me) are real world facts.
Disprove any of them. You've had many days to come up with something.

Matthew, I don't know what you mean about my posts come in pairs? Is that a joke I didn't catch, or what? "Good thing come in pairs?" No, I supose that's not what you meant is it.

Actually I do this to get my post count up. Oh no..., they don't have post counts here!!! I guess this was all a waste of time! -heh

I seen your posts in the past and believe you have a good mind, and I think we often agree (or come close) most of the time.
On this issue, I hope you took the time to think about the almost endless methods you could use to SPL meter your system and wonder how you're sure you choose the right one.
'Cuz the whole point is to be far more accurate than a 'by ear' guess right?

I won't post in this thread again (which will no doubt kill it).

Actually, this is the very definition of conjecture: "I could go buy a meter...." I don't believe your conjecture, and I challenge you to substantiate your claim.



That, by contrast is a fact.

But I think part of the focus of this disagreement hits at the very heart of high-end audio. Do we want something that sounds "pleasant", or do we want something that sounds "accurate"? If the source is of very high quality, then most everyone seems to jump into the accuracy boat. But, as Az points out, esp. in home theater, different mixes have different amounts of bass/surround/etc. which may not be as pleasant as we'd like. And, of course, a meter isn't going to correct for differences in source mixing.

But I think you go too far, Az, when you scream "THERE IS NO TRUE REFERENCE POINT when actually listening to CD's and DVD's." Given a set of listening positions and a weighting of importance among them, you can define a true reference point: maximizing the *accuracy* of your system over those positions in reproducing what's encoded on the disc. Accuracy is a human-independent measure that can be objectively measured (by whatever instrument, human or machine). And that's what an SPL meter is useful for.

If you don't like what's on the disc, and want to tweak it, then, by all means, go ahead. I have no doubt that you can come up with settings for many discs that you would judge to be more pleasant than what an accurate reproduction of the content would require. But many people first want an accurate presentation of what's on the disc before adjusting their controls for the "most pleasant" setting for that disc. And, moreover, many people find the accurately reproduced soundtracks to be very pleasing.

Az:

1) in recording studios for movies, do the mixers/engineers use an audio setup that is
a) calibrated by ear to what 'sounds cool' or
b) calibrated by scientific measuring equipment?

2) You want a specific procedure for how to use a SPL meter? Look on either the Avia DVD or Video Essentials. They provide test signals, and very specific procedures for how to use the RS meter to calibrate accurately to those signals. They aren't ambiguous. They don't offer tons of choices.

3) You claim your room is 'perfectly symmetrical', therefore you don't have to worry about L and R speakers having slightly different SPL levels. Hogwash, I say. Due to many of the same variables you call on to put down meters, your speakers, at the same offset setting, may still be off. Why, you ask?

a) no room is perfectly symmetrical. Is it perfectly square (I do mean perfectly).
-- Are there any windows?
-- Where is the door? Is there an identical door in the same spot on each and every wall? Doors have different resonant and reflective qualities than walls.
-- Any wall art, like movie posters? Are they in identical positions on all walls?
-- What about your big screen TV? Do you have an identical set on the other walls?
-- your bass traps: where are they? Are they symmetrical throughout the room?

b) the electrical paths in your equipment may not be exact for each channel. For example, following L & R channels out of a CD player into a preamp, through the gain and maybe A/D and D/A stages, then out again to an amp, to the gain stages of the amp.... this path (especially amp gain) may cause variances in sound level, regardless of room interactions.

If your room and equipment do not meet the above criteria (and many others), it is NOT perfectly symmetrical -- and is therefore subject to variations in SPL, even from identical speakers in identical locations. In short, there is no such thing as a truly, perfectly symmetrical room.

Also, I personally disagree with your choice to go without a center channel. While this is more opinion than anything, I feel that a phantom center requires mains that can image very precisely -- which you may very well have. I do as well -- Martin Logan reQuests. With the center off, I also get a very clear, precise phantom center. BUT, move off center, away from the center point, and that strong localization starts to fade. Since you and your wife each sit off center, a center may give a better central image.
Also, phantom centers (and precise imaging in general) work much better with no obstructions between the two mains. Large objects, like your RPTV can degrade imaging focus. I have a FPTV setup, with nothing but open space between the mains.

On another point from one of your posts, you are incorrect about the design decisions behind Martin Logan center channels, like my Cinema center. The cone woofer and tweeter have absolutely NOTHING to do with trying to provide more vertical dispersion. In fact, the speaker is designed to do exactly the OPPOSITE. Ceiling and floor reflections can muddy dialog. The ML centers are designed to provide a narrow vertical dispersion to limit refelections, while providing wide horizontal dispersion to provide a clear center image across the seating stage.

The woofer and tweeter are there simply because of the size of the electrostatic panels. In very large ML speakers, the panel can recreate most of the sound spectrum on its own, negating the need for phase altering crossover networks. However, the panels in the center channels are too small to provide any kind of bass, or very high end. The woofer and tweeter fill in for these areas, while the static panel provides all midrange sound lending ML clarity to dialog (the most important part of a center).

[This message has been edited by bigmac (edited August 10, 2002).]

Ok, I guess I lied. I am posting here again, but only to answer the many questions bigmac asked me. I decided not to ignare him rather than keep my word not to post again. Hope no one flames me for that.

"1) in recording studios for movies, do the mixers/engineers use an audio setup that is
a) calibrated by ear to what 'sounds cool' or
b) calibrated by scientific measuring equipment?"

A). The final recording levels are preference as you hear for yourself in a DD/DTS encoded DVD and the various levels in music CD's. They pobably choose arbitrary 'set' output levels in their playback systems, but what they choose to send to playback play is whatever they feel like. They're mixing the music/soundtrack and decide how loud the surrounds should be or LFE etc...
Like the people who alter-to-taste their home system 'after' SPL calib, which seems like nearly everyone.

"2)-They aren't ambiguous. They don't offer tons of choices."

True, they like most other methods used, chose amongst lots of variables for themselves and tell you 'do this exact method'.
Upon playback of various sources you find a huge range of sub/surround levels -so many teak by ear post SPL meter.

Is it so hard to understand that I go directly to these varied sources and by ear try to find the smoothest average between them. I can only swear to you that my surround set up is very smooth and seemless on avarage.
'Possibly' moreso than someone who chose to calibrate to Avia (etc...) and then listens to all the varried levels of the DVD's/CD's then own, but accepts that this set up's more correct.
I've heard other people's systems. People who have calibrated w/ a meter and have never found them strikingly more seamless or even any more seamless than in my home.

I can adjust my surrounds by ear on any source (as I'm sure anyone else can -I claim no magical gifted ear) so that the surrounds sound too loud AND so they sound too soft. This doesn't take more than a few db (+/-5 at most). If you split the diff. between the two you'll have at the very least -VERY close to perfect surround blending. At most a few db off 'perfect'.
Since diff. DVD's levels vary so much I do this several times and find an average of that. Between them all it doesn't vary too much though really.

Some DVD's will have surrounds too loud, some too quiet, but you all must hear this result too. Some tweak per DVD/CD because you can hear these level diff. for yourself.

"3) You claim your room is 'perfectly symmetrical', therefore you don't have to worry about L and R speakers having slightly different SPL levels. Hogwash, I say.
a) no room is perfectly symmetrical. Is it perfectly square (I do mean perfectly)."

No my room is rectangular. This doesn't bar it from L/R symmetry. Maybe you don't get what the word means?

"-- Are there any windows?"
Yes, two symmetrically set into the far wall behind my mains. They're currently blocked out though to block light and southern heat (damn hot in AZ), not that this is relevent to symmetry issue.

"-- Where is the door?"
It's actually slighlty off center. AH-HAH!! azryan's IS a liar!!! Right?
Well... it's a double door of MDF and is matches the rest of that wall which has additional bracing. It doesn't 'sound' diff. than the wall it's mounted in. At worst I would have to raise of lower my left main speaker one db to counter any diff., and it certainly doesn't sound like I need to, and the rat shack SPL meter couldn't tell me it's one db +/- wrong either.

"-- Any wall art, like movie posters? Are they in identical positions on all walls?"
No none. I could symmetrically place them in my room though if I chose to retaining L/R symmetry.

"-- What about your big screen TV? Do you have an identical set on the other walls?"

Yes, I do. -heh. Again, you don't understand L/R symmetry. Another RPTV behind me would be front/back symmetry, and certainly no HT incl. yours has this. Just look at your own surrounds. You're confusing the issue here.

"-- your bass traps: where are they? Are they symmetrical throughout the room?"

Yes. Bass traps go in the corners of the room to cut standing waves. I have them in all four corners.

"b) the electrical paths in your equipment may not be exact for each channel.-this path (especially amp gain) may cause variances in sound level, regardless of room interactions."

One, yes my wire lengths are symmetrical.

Two, despite this... they'd have to be tremendously diff. lengths to make even ONE db of volume diff. -which is the smallest I can adjust my system and I'd bet it is in yours too.

I hope you see that I did mean symmetrical. Probably shouldn't 've used the word 'perfectly' but it was more a figure of speech. Compared to most HT's (often living rooms and not dedicated areas) my room/seating/speaker set up is very very symmetrical.

About the phantom center... To clarify... my wife and I sit in on a centered 2-seat love seat, but I calibrate dead center (how I sit when listening to music alone). When I say we sit 'off center', it's certainly ain't by much.

I can sit farther off center and still have a fairly perfect phantom center though. The inevitable angle of the RPTV matches the slight emphasis of the L/R main speaker I'm closer too.

"Also, phantom centers (and precise imaging in general) work much better with no obstructions between the two mains. Large objects, like your RPTV can degrade imaging focus."

Very true. if my RPTV was inbetween my mains the phantom center would not work properly and I'd be a moron for setting my speakers up like that even if I used a center channel.

My RPTV getting in the way is an 'evil' I can't get rid of, BUT... it's 3 feet behind my mains, and I use a dampening cloth over the screen when I listen to music, and have a large sound panel above it on my wall 6' behind my mains to dampen reflections.

"I have a FPTV setup, with nothing but open space between the mains."

As I explained I also have 'nothing but open space between my mains'. But how far away is your wall behind your speakers, and how reflective is it? Almost certainly the area of the FP screen (esp. if attached to the wall) is very reflective, and I'll bet you don't have your mains nearly as far from the wall as I do (6'?). Most people think a few feet is enough, or don't have the room to pull them out as far as they should be even if they want to.

I think I've just shown how you challenging my phantom center based on my having an RPTV (and also compared to your FP set-up) was in error.

"The ML centers are designed to provide a narrow vertical dispersion to limit refelections, while providing wide horizontal dispersion to provide a clear center image across the seating stage."

Yes. You are exactly right. But that 'design' is exactly why they added domes and cones to their stat panel that alone has more vertical output than horizontal.

Ask around about why Martin Logan uses vertially alligned domes and also woofers in thier center. The woofers are to fill out the low end the panel just can't do, but ALSO are there because of the radial pattern of output filling out the horizontal output.
The domes are their to make a slight vertical array adding to this. There's no other reason the Martin Logan stat panel needs to be aided on the high end. Look it up.. their old center speaker didn't use and dome tweeters to aid it.
And that's why M-L curves ALL their stat panels -to aid in horizontal dispertion. Ask around. I'm right on this.

My Newform are very diff. They have a 3/4" x 45" monopole ribbon. They have razor sharp imaging and no strong center 'beaming' so the sweet spot of the phantom center if pretty wide. They also have a much flatter freq. responce than M-L do.

[This message has been edited by azryan (edited August 11, 2002).]

Azryan: yes, they do count posts here. You're at 150.

But I guess it should be 75.

(Sorry. Just had to get that in.)

On another note, I've deliberately avoided posting anything serious here because I know I'm not going to change Azryan's mind, and because I personally don't really care if he uses an SPL meter or not (Sorry, dude, I don't mean to be rude, but it really doesn't affect me in any way that you don't use a meter).

I personally think an SPL meter helped my system. There we go; my opinion is known. But my room is far from symmetrical; I do use a center channel speaker, my six speakers are of four different designs; I have different lengths of speaker wire going everywhere, etc. So maybe my way isn't best for all.

And, BTW, why is a phantom center better (if you can get it to image right) than a real center, other than taking up less space? I've heard lots of reasons why it can work, and I can believe that's true, but why not use one if you can?

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Matthew J. Hill
matt@idsi.net

If you are piloting a land yacht of a rear projection unit, there's no place to put the center speaker. That's why, no matter what Az says, he doesn't use one. (IMO)
And yes, it's Monday after a useless post by the Outlaws.
Mix

OK, wouldn't that be an S - P - L meter? Visions of sunworshipers leap to mind with an SPF meter. ;-)

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"Veni, vidi, vino."
("I came, I saw, I drank wine.")