How do I know my Speaker Coverage angle?

[PandPstudios]

Greetings.

I was designing a control room and while selecting to go with 30 degre soffits or 90 degree sofits, I Looked ad this picture john posted some time ago:


And realized That I needed to know the coverage of the speakers in order to know where exactly to place them in order to get the sweet spot in the 38% area.

Is there some kind of general guide line for this? or do this say in my speaker's manual? I haven't found it there.

Also is in the 30 degree config the listeners head in that position and not right at where the "central lines" intersect (like in the 90 degrees)?

I've read other documents recommended in this same forum, where the listener IS at the intersection point even with the 30 degree config.

Please Help

[carsten_d]

hola,

you don't need to know what the "speaker coverage" (whatever this means) of your speakers are.
in johns drawing the outer dotted lines refer to the sweet spot (the circle around the heads).
it is common use to have the center of the center rays 6-8 inches behind your head so that it
hits your ears and not your nose. the center means: the acoustical center of your speaker. this is
in a two-way-system between tweeter and woofer. closer to the tweeter. to be absoltuley correct
'bout this you should contact your speaker manufacturer and/or search a bit here in the forum.
I'm not sure how this is handled in a 90 degree setup but I guess it might be the same except
that the center could be a bit closer to the head ... maybe john or others chime in to shed some
light on this.

cheers,
carsten

[PandPstudios]

Thanks, But I still don't understand why you have to sit or have your ears placed In a different manner when 90 or 30. I've seen images for example in the grammy Pdf where In a 30 degree config, the "doted lines" resemble more the ones in the 90 degree config.

[Soundman2020]

I still don't understand why you have to sit or have your ears placed In a different manner when 90 or 30.

Ummmm... you don't! You sit exactly the same, and your ears are placed exactly the same, regardless of the speaker geometry. In fact, the entire point of having correct speaker geometry is to ensure that the speakers are pointing at your ears! I'm not sure why you think that you have to sit in different positions, or change the position of your ears. John's diagram does not show that at all.

If it is just you (only one person) at the console, then arrange the speakers such that the acoustic axes of both speakers more or less graze past your ears and meet at a point a few inches behind your head.

- Stuart -

[PandPstudios]

I didn't mean to literally "SIT" in a different spot. what i was saying is that the speakers "see" me in a different position correlative to them.
I post in this thread an "visual" example of what i'm trying to accomplish

http://www.johnlsayers.com/phpBB2/viewt ... =1&t=14828

Please tell me if that config would work, and if I would be able to hear clearly what the speakers are reproducing, (without any loss in high frequencies because in theory they are much more directional tan low ones.)

[Soundman2020]

I agree with Glenn: I would increase the speaker angle a bit there, so that the acoustic axes are aimed more at your ears. Perhaps more like 34 degrees than 30. Once again, assuming that the control room will normally have just one person sitting in the sweet spot.

As it is now, if you lean forward just a bit then your ears are out of the sweet spot. And most engineers do tend to lean forward a bit while they work...

- Stuart -

[PandPstudios]

Thanks

[PandPstudios]

I asked this same question on another threat with no answers. so:

John mentioned that the high end only "projects" in a 30 degree angle (15 degree either side of the center axis). So when calculating your position (sweet spot), you want to place yourself inside that 30 degree angle? a picture to make my question clear.



Does this apply to all/most speakers?

Thanks

[gullfo]

30 degrees, it's probably a very good guess to begin making assumptions with... the best bet is to check the manufacturer site or find product reviews where they have checked the polar dispersion of the speaker - both vertical and horizontal - across the frequency spectrum. in most cases, the output drops dramatically at higher frequencies once you go off-axis.

[PandPstudios]

yes i know but i haven't found anything in the manufacturer site nor the manual, i guess I'll have to mail them thanks anyway.

[PandPstudios]

OK, I contacted them (krk) and told me they didn't had that info. What angle could I use to be perhaps the "worst case scenario", and in this way don't have any issue with any kind of speaker using. Maybe the minimum angle "all" speakers radiate high frequencies.

Thanks

[Soundman2020]

"All" speakers are different, and the angle varies according to frequency. There is also the issue of on-axis vs. off-axis (which is kind of the same thing). So even though your speaker might (for example) radiate 10 KHz really well over 25°, that does not mean that it radiates no 10k at all at 26°: it just means that the level starts to drop around 25°. But there will still be something of 10k at 30°, and also 40°, and also 50°... etc. It will roll off progressively, and probably not evenly. And frequencies above and below 10K will also be rolling off at different rates, and with different evenness....

That's part of the reason why the general recommendation is to have large absorbers at your first reflection points on the side walls, and a large cloud overhead.

If you can't get detailed information for your speakers, then maybe larger, thicker absorption on those points would be better than an angled reflective surfaces.

My $0.02


- Stuart -

[gullfo]

OK, I contacted them (krk) and told me they didn't had that info.

what model do you have? for their vxt4 they have a datasheet with the polar response and acoustic center etc
http://www.krksys.com/manuals/vxt4_datasheet_3_2010.pdf