What Causes Glare?

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John151

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What Causes Glare?
« on: 24 Feb 2010, 03:22 am »
I have been tweaking my system to get more detail and reveal.  Several changes that I have made take the sound from warm to neutral, which provides more reveal/detail, but also at times brings "glare".  I want to know what causes glare so I can avoid/prevent/fix it in the future.  Any input is greatly appreciated.


Wayne1

Re: What Causes Glare?
« Reply #1 on: 24 Feb 2010, 03:59 am »
There is no one thing that causes glare.

As you improve your system, it's faults become more obvious.

What you are calling glare could be caused by RFI/EMI.

Noise being carried through your AC might also be a cause.

AmpDesigner333

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Re: What Causes Glare?
« Reply #2 on: 24 Feb 2010, 04:16 am »
First, what one listener perceives as glare is not the same for another listener.

Second, what I personally perceive as glare is simply distortion.  Of course, distortion comes in so many forms that nailing it down to even a small group of distortion mechanisms is pretty much impossible.  However, strain at high frequencies is perceived as glare by most listeners.  Notice that I use the word "perceived".  Next, try to define strain.  Same issue.

Third, if you are hearing what you personally perceive as glare, you are probably clenching your fists or experiencing some other physical symptom while listening.  My father (unfortunately no longer with us) had a great way to test a listeners "happiness level" with an audio system...  Have someone else play the music, which was necessary back in the day, listen to some of your favorite tracks, and start out with your hands flat on the arms of a recliner or similar chair.  If your hands are not flat after half an hour, you aren't liking what you hear!

rockadanny

Re: What Causes Glare?
« Reply #3 on: 24 Feb 2010, 12:56 pm »
Yeah, glare sucks!
If by glare you might also mean glassy ...  For me, once it was a tube choice in a power amp but only in the high freqs., and the other time it was a set of speaker wires. Much more so on the speaker wires as they were glassy in the high and mid freqs.

John151

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Re: What Causes Glare?
« Reply #4 on: 24 Feb 2010, 01:55 pm »
What I am calling glare is phenomenon that occurs briefly at higher frequencies, is fatiguing, uncomfortable, and short in duration.  Most often occurs on certain piano keys or female vocals, as if a certain note is simply not played well by the system.  I was expecting that the cause might be room acoustics, and the solution to be room treatments.   I have noticed that when I am playing through warmer gear, I don't get glare, but as I swap in neutral gear, the glare returns.  The glare is the worst with my SWL pre-amp, which is the most revealing of my components.  The glare got worse when I added the new EE DAC to the mix.  When I swap in my Candela for the SWL, the glare is almost gone, and when I run the old DAC thru the Candela, the glare is completely gone.  However, with the glare, I get greater detail and imaging.  Is this a trade off I have to live with? 

JackD201

Re: What Causes Glare?
« Reply #5 on: 24 Feb 2010, 02:54 pm »
What I am calling glare is phenomenon that occurs briefly at higher frequencies, is fatiguing, uncomfortable, and short in duration.  Most often occurs on certain piano keys or female vocals, as if a certain note is simply not played well by the system.  I was expecting that the cause might be room acoustics, and the solution to be room treatments.   I have noticed that when I am playing through warmer gear, I don't get glare, but as I swap in neutral gear, the glare returns.  The glare is the worst with my SWL pre-amp, which is the most revealing of my components.  The glare got worse when I added the new EE DAC to the mix.  When I swap in my Candela for the SWL, the glare is almost gone, and when I run the old DAC thru the Candela, the glare is completely gone.  However, with the glare, I get greater detail and imaging.  Is this a trade off I have to live with?

It seems to me you have good instincts so I say run with your first read on your situation. I'll wager you'll be right.

ASi_TEK

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Re: What Causes Glare?
« Reply #6 on: 24 Feb 2010, 03:41 pm »
Many things can cause glare. I find they are mostly due to AC mains distortions/harmonics, digital source issues with jitter issues and with mediorce or less quality parts (ie: esp subpar coupling capacitors smearing and pinching the sound) used and in the signal path. Skin effect and eddy current issues can contribute. There just really isnt one direct answer to this and can be caused my many different factors as previously discussed.

woodsyi

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Re: What Causes Glare?
« Reply #7 on: 24 Feb 2010, 04:01 pm »
You get glare from too much light bouncing off irregular reflecting surfaces.  The same applies to sound.  That would be the acoustic portion.  You also get that from jitter on digital source.  I hear it when signal is over-processed within the bandwidth, especially at 16 bit depth.  It's like the sharpness adjust on your TV -- there is an optimal point and then the picture gets glary and jagged when you apply more "sharpness."  This gets much better at 24 bit (and higher I assume). 

richidoo

Re: What Causes Glare?
« Reply #8 on: 24 Feb 2010, 04:03 pm »
It is acoustic distortion. I have the same problem. The more resolution I add the more obvious it is. Midrange damping (1") on the walls and corner damping will cure it.

I used to have 8th nerve corner treatments, but low WAF was their end. With many of the tricorners and seam corners treated, the overall sound was much more pure and beautiful. Bass response was smoothed out too, as measured by my computer. They had a reflective surface which I prefer over an absorptive surface on the front wall. These are the only people I know who make triangles now, but there may be others.
http://michaelgreenaudio.mybigcommerce.com/products/MiniCornerTune.html
http://www.realtraps.com/p_tri-corner.htm

As a diagnostic you can hang some comforters on opposing walls to see how much slap echo is contributing. Treat with 1" FG panels if you find an improvement. Don't forget the ceiling/floor if you don't have a carpet.   You can use a piano to find the frequency of the offending notes, then use modecalc.exe from realtraps.com to see if your room dimensions are the cause of acoustic node at that freq. You can also see if the problem is lessened as you stand in different locations in the room.

The frequencies you're describing from piano flute, etc are about 1k-2k, so they are easily absorbed with 1" FG. They can be diffused if you don't like the sound of absorbtion. But quality diffusion that will work at those relatively low frequencies is more expensive than absorbtion.
http://www.gikacoustics.com/gik_d1_diffusor.html
http://www.realtraps.com/diffusor.htm

Less effective diffusion, but better WAF. This one absorbs the freqs of concern but also diffuses higher freqs so it doesn't sound as dead as pure absorbtion.
http://www.rpginc.com/products/badpanel/index.htm

Congrats on your acoustic awakening! The room is the final frontier.
Good luck!
Rich

BobM

Re: What Causes Glare?
« Reply #9 on: 24 Feb 2010, 04:07 pm »
Polarized sunglasses sure help eliminate glare. Hey, does anyone make polarized glass for a tube?

Mike B.

Re: What Causes Glare?
« Reply #10 on: 24 Feb 2010, 04:44 pm »
other posters have pegged the areas of concern. AC noise can do it. First reflection points as well. Some older or cheaper designed tweeters can create this.

Wayne1

Re: What Causes Glare?
« Reply #11 on: 24 Feb 2010, 04:57 pm »
Some simple things you can do to isolate your glare.

Unplug your sources from the wall. Plug one back in and play it. Is it glarey? Plug the other one in. Does the glare increase. Play the second and unplug the first. Any changes?

Both you sources use switching power supplies. These can add noise into the AC line and be picked up by your other components. If this is happening, you might want to look into linear power supplies or AC isolation transformers.

Computers, cell phone chargers, etc also contribute to the noise running around you AC lines

If you are using unshielded interconnects, they may pick up some of the RFI from cell phone towers or even you microwave and wi-fi.

mfsoa

Re: What Causes Glare?
« Reply #12 on: 24 Feb 2010, 05:23 pm »
Sometimes it's just the software I think.

Even if you brough your system to where you feel it's perfect, that would be only for a small number of recordings. All the rest have to be either a bit too much of one thing, a bit too little of something else.

I see the sonics of the software on a bell-curve where only a tiny portion lives at the top, and all else has to diverge from the top in one way or another.


-Mike

DTB300

Re: What Causes Glare?
« Reply #13 on: 24 Feb 2010, 06:00 pm »
You get glare from too much light bouncing off irregular reflecting surfaces.  The same applies to sound.  That would be the acoustic portion.  You also get that from jitter on digital source.  I hear it when signal is over-processed within the bandwidth, especially at 16 bit depth.  It's like the sharpness adjust on your TV -- there is an optimal point and then the picture gets glary and jagged when you apply more "sharpness."  This gets much better at 24 bit (and higher I assume).
I agree on the room acoustics and reflections - comb filtering. 

For Jitter, the new clocks out by VSE really address this issue and the results are significant in sound quality improvements for all formats.

For 16bit and 24bit discs the format does not necessarily mean it will sound a certain way.  I have heard really good and really bad with both formats.  We are all still at the mercy of how the original recording was done.

rollo

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Re: What Causes Glare?
« Reply #14 on: 24 Feb 2010, 06:22 pm »
  It is realy simple. The tweaks you made take them out. No glare before no glare now. as one tweaks or changes gear, tubes etc sometimes it brings out faults in the gear which you did not notice befor you gained more resolution.
   One change usually promotes another and so on. It can be neverending and frustrating to boot. So what to do. Get better gear and stop tweaking.  :thumb: Did I really say that "Stop", yes I did  :duh:


charles

Prosoundman1000

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Re: What Causes Glare?
« Reply #15 on: 24 Feb 2010, 07:05 pm »

   I have read all the other postings and the probable cause is in there somewhere.  I wouldn't start pointing my finger at any one component as the culprit until all the acoustic possibilities
have been visited.
   I suspect you are experiencing too much upper-mid/lower high reflection from hard, flat surfaces.  The frequency band within the eighth octave (2048-4096 hz.) can be brutal if there is too much from the music source or worse from excessive reflection, especially if focused toward the listening position.
   A low cost experiment/quick fix is to employ a laser pointer, a small, flat mirror and an assistant.
   Seat your assistant in the sweet spot of your listening position and have he or she hold the pointer in front of their nose; send a beam to the centre of the mirror which is flat against the wall, ceiling or other flat surface.  When the beam is reflected onto the tweeter, you have your point of reflection.  Replace the mirror (still held in position with a self-adhesive felt pad (4x6 inches)
length-wise toward the back wall.  Physics tells us that the angle of incidence is equal to the angle of reflection so roughly halfway between the tweeter and the listing chair is a good starting point for looking for your mark with the mirror.
   There may well be several of these 'hot' reflection points so this procedure may take a while.
Be patient and as precise as possible. You should be rewarded for your efforts. Don't forget to do left and right sides of the room.

   What this experiment/tweak does is eliminate strong secondary waves from reaching your ear slightly behind the direct wave from your tweeter.  We are talking about a few dozen micro-seconds here but it is enough to cause blurring of your image and the glare you speak of.
    This phenomenon is exacerbated with digital sources and it certainly doesn't help that human hearing is most acute within this octave.
    If your analog source produces the same amount of glare as your digital then you could very well have electronic issues or even damaged tweeters.

               Best of luck on your quest.  Regards,
                                                                      Jon 

rockadanny

Re: What Causes Glare?
« Reply #16 on: 24 Feb 2010, 09:56 pm »
4" x 6" pad? Really? That small? I always see devices about 2' x 4'. Will 4" x 6" really work?

rockadanny

Re: What Causes Glare?
« Reply #17 on: 24 Feb 2010, 10:27 pm »
Ahh ... 2048Hz = 6.5" ... I see. But still, adequate size in general for reflection?

*Scotty*

Re: What Causes Glare?
« Reply #18 on: 25 Feb 2010, 12:41 am »
You could do it this way. I would go to the Linen closet and get a couple of blankets and hang them in the same place as 4"x6" piece
of felt. The high frequency radiation from the tweeter is not emitted in a focused laser beam fashion but in a forward hemisphere of radiation not counting diffraction effects to the sides and rear of the loudspeaker. The vertical and horizontal lobing errors the speaker may have also modify the polar radiation pattern as well and may substantially contribute to the perceived "glare" that may be present.
The other unfortunate possibility is that some of your equipment doesn't try to achieve High Fidelity reproduction and has poorer imaging and detail and some of your equipment attempts High Fidelity reproduction of the signal and fails, which results in the glare you hear. 
Scotty

jimdgoulding

Re: What Causes Glare?
« Reply #19 on: 25 Feb 2010, 02:55 am »
Sometimes glare or sheen can ride along high pitched instruments and female vocals if a CD player or DAC isn't up to snuff.  This is more generic to older units.  I suppose that would have to include some digital interconnects, too.