Image height question

BrunoB · « **on:** 2 Sep 2005, 05:17 pm »

On my system, the speakers produces an image that is very high, sometimes close to the ceiling. The height increases from the left speaker to the center and thereafter decreases, like a half circle.

I like this effect but I wonder why this happens?

Thanks,

Bruno

ScottMayo · « **Reply #1 on:** 2 Sep 2005, 05:40 pm »

Quote from: BrunoB

On my system, the speakers produces an image that is very high, sometimes close to the ceiling. The height increases from the left speaker to the center and thereafter decreases, like a half circle.

I like this effect but I wonder why this happens?

Thanks,

Bruno

That's, um... abnormal. Without knowing about your speakers and your room layout I don't know what's going on, but reflections off of the ceiling have to be thought about. If you move around in your room, the effect should vanish or change a great deal, so if you decide you want to get rid of it, just moving your seating might do the trick. So would adding some room treatments.

_scotty_ · « **Reply #2 on:** 2 Sep 2005, 09:41 pm »

BrunoB, This effect is caused by HRTF interacting with room related comb-filter effects. It is usually a quite symetrical phenomenon and is dependent on precise amplitude and phase matching between the left and right speakers. If your room has very different sound absorption characteristics on the side that is lower or there is a level mismatch from one speaker to another due the your pots being adjusted differently on right speaker vs. the left this might explain the asymetery you are hearing. If your ears response do not track one another you will also experience asymetry or not hear this sort of effect at all.
When everything is perfectly matched you should have images that are on the floor or on the ceiling as well as running down the sides of the listening room. You will also experience images over your head and behind you. These effects should be independent of speaker height.
I hear these effects almost exclusively on studio recordings. I think that most of these effects are intentional and are part the studios special effects arsenal. Chesky issued a CD that intentionally demonstrated these effects with a this is what you should hear explanation a few years ago and I didn't buy it. Oops.
If everything is stuck on the wall in front of you at the same height and never images in the way you are describing on studio recordings you may have a problem.
Scotty

BrunoB · « **Reply #3 on:** 3 Sep 2005, 06:49 am »

Scotty, thank you for your expalnation.

Quote from: _scotty_

BrunoB, This effect is caused by HRTF interacting with room related comb-filter effects. It is usually a quite symetrical phenomenon and is dependent on precise amplitude and phase matching between the left and right speakers. If your room has very different sound absorption characteristics on the side that is lower or there is a level mismatch from one speaker to another due the your pots being adjusted differently on right speaker vs. the left this might explain the asymetery you are hearing. If your ea ...

I am afraid I was not clear: the effect is symmetrical. The images closer to the center are higher than left or right images. I have noticed this effect with three different sets of speakers. I don't think it is due to ceiling reflections because I have sound adsorbing foam on the ceiling. My speakers are about 5.5 feet from the listening position and 7 feet apart. I am using a near field listening position and foam to decrease room interaction.

What I am going to do is the try a pure mono signal sent to both speakers to see if the center image is higher than the speakers.

Bruno

_scotty_ · « **Reply #4 on:** 3 Sep 2005, 07:22 am »

You might try raising the front of your speakers an inch or two and changing the toe-in and see if this changes the the image height or makes the images higher directly above the speakers. My system will put images at ceiling height clear across the front of the soundstage starting at about 6ft. outside the edges of the speakers.
Spacemusic frequently images in this fashion as well as my Isao Tomita vinyl records.
The effect is unreal but it definitely suits some styles of music and I enjoy
the 3D soundscape. Movies like Independence Day are also a lot of fun,especially when the fighters fly over your head and you have to dodge missiles and disruptor fire.
Scotty

hifitommy · « **Reply #5 on:** 5 Sep 2005, 11:35 pm »

how your speakers do it depends on the speakers and their surroundings. when i had sequrerra met7s, there was little in image height. but even my dyna a25s exhibited appropriate height.

an organ recording had the high pipes up above the rest of the image and i thought it was bs. later i read about height in tas and realized it was a real effect of the recording. the in the minnie ripperton disc-perfect angel-the effect showed itself again. a bird in the tree above the singing voice and alone in space was there.

that tomitas recordings do this isnt surprising, his discs do VERY well in surround, even passive surround like dynaquad.

_scotty_ · « **Reply #6 on:** 6 Sep 2005, 01:44 am »

Unfortunately when BMG reissued Tomita's back catalogue on CD they remastered with Dolby Surround and destroyed the original phase relationships which produced the effects found on the vinyl and earlier CDs
This is yet another act of vandalism I will never forgive BMG for.
End of rant. Scotty

hifitommy · « **Reply #7 on:** 6 Sep 2005, 02:46 am »

listen in DPL and you will get back the surround feel. it just cant be lifted out of the disc. its all in the stereo tracks.

_scotty_ · « **Reply #8 on:** 6 Sep 2005, 04:23 am »

hifitommy, I am a 2ch kind of listener at the moment and don't recognize the DPL reference. What is it? Also, are you a related to Perfect Tommy of the Hong Kong Cavaliers?
Scotty

hifitommy · « **Reply #9 on:** 6 Sep 2005, 04:29 am »

no cavaliers.

dolby pro logic is a surround progaram found on most older surround receivers.