Near Field Height

Cujo · Post by **Cujo** » Tue May 03, 2005 12:55 pm

Where should the near fiell monitor most idealy sit? The Reveal notes say ear level should be right between the tweeter and woofer, Is this good advice? Should Dyanaudios be set the same?
All those years monitors sat on top of the console often woofer above ear level (NEVE) and nice mixes happened. Should I measure an old neve and put them at that height?

knightfly · Post by **knightfly** » Wed May 04, 2005 9:23 am

That advice is fine as far as it goes; there's more to it though (big surprise) - depending on your ceiling height that position might cause problems by placiing the woofer in a null, making the speakers work really hard and STILL not put out the bass they were designed for. If the height choice were to place the woofer in a PEAK relative to the vertical modes of the room, then you would have EXCESS bass in the room at that modal frequency, which means uneven response and bad mix choices down the road.

There is also the problem of early reflections off desk surfaces, console, etc, which can be worse if the speakers sit on the bridge - this is a main reason for separate stands BEHIND the bridge.

Also, if speakers are resting (without decoupling) directly on a surface that can conduct sound structurally, there is the possibility that lower frequencies can travel through this material FASTER than through air (wood, in some axes of travel, can conduct sound 12-15 TIMES as fast as air) so the speakers need to be decoupled from structure. Otherwise, your desk might be sending you the LF information sooner than your speakers, and phase cancellation can result.

For a more involved look, you might check out this thread

http://www.johnlsayers.com/phpBB2/viewtopic.php?p=18059

Places to AVOID putting your speakers (specifically the woofers) - half of ANY dimension of the room, 1/3 of any dimension, 1/4, 2/3, etc -

This also applies to your head, BTW - although for stereo you DO need to be centered left-to-right. You do NOT want your head within 5-6 inches of centered between floor and ceiling, same as your speakers. STandard 8 foot ceilings make this an important thing to remember; it's 'way too easy to sit so your head is equidistant from floor and ceiling, guaranteeing that you will be in nulls for first and third harmonics, and the peak for the second harmonic. See the Harmon calculator in the above link for more on that... STeve

Cujo · Post by **Cujo** » Fri May 06, 2005 1:21 pm

All good advice, I was thining of rubber stoppers under the speaker stand tops then my mopads. What is a good fraction to sit the woofers at if not 1/2, 1.3 or 1/4? is say 5/8ths from floor ok? I'll remeasure my room hight tomorrow.
me thinx it is in the 8" range.

knightfly · Post by **knightfly** » Fri May 06, 2005 8:05 pm

Rubber stoppers? Is this to adjust the height? If so, you'd be better off with something more solid, and just use the MOpads for decoupling. Otherwise, you may get your speakers rocking which can cause phasing between woof and tweet to shift due to varying distance from the listener.

Heightwise, 42-46% of the distance from floor to ceiling is good; depending on your ceiling height, this can be measured either from the floor OR from the ceiling... Steve

Cujo · Post by **Cujo** » Fri May 06, 2005 10:45 pm

Now would this 42-46 % be to the center of the woofer or bottom or bottom of speaker?

The rubber pads I am talking about are super hard dampers fpr HVAC use. They wont rock in that way. I was thinking of sandwiching those between a first self and then a primary shelf that the monitrs rest on secured by may be an anchor bolt in the middle of the shelf, Could be over kill since I have the MoPads though.

knightfly · Post by **knightfly** » Sat May 07, 2005 4:58 am

That's to the center of the woofer; the bottom of the box is supposedly stiff enough NOT to be the main radiator of sound so wouldn't matter nearly as much.

I would not set up a mass-air-mass double shelf for speakers just on the outside chance that its resonance could interfere with normal speaker/room dynamics. The mopads will decouple so you don't get induced sound thru structure before the airborne sound reaches you, and that's all that's necessary... Steve

Cujo · Post by **Cujo** » Sat May 07, 2005 9:44 am

Well, using just MoPads will save some work for sure!
I have on last 703 panel (2x4) am intend to hang over mix postion.
Should I suspend it with the width ways going speaker to speaker or longways down the middle to allow more fornt and back movement from my chair?
My guess is the former to cover the width of the speaker spread.
I saw a post about some 703 alternatives, I'd like to add some other things to even out the absorption. I have 3 panels I made a while back with regular owenes corning r15 or something covered in batting and then burlap. I recently saw a 2x4 sheets of a styro insulation type panel (white) would this stuff do to fill in spots I find with the mirror test?

Now I have panels of 70s (4" thick in corners) and the some panels on the walls at 1")

Also hsould I keep the panels up above knee hieght? is there any thing helpfull by having any on the floor, say 2 feet tall and 4feet long or am I wasting those panels?

Thank you agian

Cujo · Post by **Cujo** » Sat May 07, 2005 10:27 am

Wow, sorry about the incoherent English. I was in too much of a hurry.
I mean, I had a last 703 board after making my panels that I would like to hang over head.

Cujo · Post by **Cujo** » Mon May 09, 2005 12:22 am

Heightwise, 42-46% of the distance from floor to ceiling is good; depending on your ceiling height, this can be measured either from the floor OR from the ceiling... Steve[/quote]

I did this, however it seems very low. at 43.7" (46% of 95") does this seem right ot you?

knightfly · Post by **knightfly** » Mon May 09, 2005 10:01 pm

Yeah, unfortunately an 8 foot ceiling tends to put you and your speakers right at the 50% mark, which is the LAST place (acoustically) you'd want to be.

To get around this, you either have to play "low rider" or sit higher than seems natural.

On the panels - I'm not sure only one 2x4 foot panel will be enough for a "cloud" you need enough so that it covers any areas close to reflection points from either speaker.

I wouldn't waste panels on areas near floor or ceiling, except at early reflection points (or straddling wall-ceiling corners)... Steve

Cujo · Post by **Cujo** » Mon May 09, 2005 11:15 pm

Good words.
Could I go 43-46% height of ceiling with the same good results?
And to pick your brain even further, should I use absorption on the wall behind the speakers and comp monitors? Or shall I just worry about the mirror test? I seem to find conflicting opinons on this.

You've been a big help,
thank you.

knightfly · Post by **knightfly** » Tue May 10, 2005 6:37 pm

Sure, that height would be fine; and I'm not sure it's even possible to get TOO much absorption on the front wall when using free-standing speakers; the more absorption, the smoother the response. In a smaller room (less than about 10-12 feet from your head to the rear wall) the same applies to that rear wall. Philip Newell uses rear traps that are several FEET deep, in varying densities/absorptions/stiffnesses when building his "non-environment" rooms... Steve

Cujo · Post by **Cujo** » Tue May 10, 2005 10:28 pm

All great stuff. SHould I vary the materials on the wall behind the speakers?

next up, re work the recording rooms!

Thanks again.

Cujo · Post by **Cujo** » Tue May 10, 2005 10:44 pm

Oh one last question. (ya right)
Is it ok to take the rug up. The ceiling is untreated. I have concerns about marking the plaster ceiling up with holes for hanging panels. So would hard wood and hard ceiling be a problem as I have long assumed? right now the rug is wall to wall with rug pad under.
the cluster over mix positon is still in the plans, but I'll never be able to treat the whole
ceiling.

knightfly · Post by **knightfly** » Wed May 11, 2005 7:51 am

For front walls (behind your speakers) I wouldn't vary materials so much as just get enough absorption to treat SBIR problems; I'd use a minimum of 4" material, 3PCF preferably, and place it at least 4" away from the wall - more wouldn't hurt, less won't usually be enough to do the job.

Rugs don't have nearly as wide an absorption range, so tend to make the room sound dry and "boxy" - but if you remove it, you now have two hard surfaces facing each other; more flutter echo in ranges that weren't a problem before.

If you can build a "cloud" for over the mix area that's at least 4' x 6', maybe larger, then the rest of the room won't cause problems as long as you have the corners absorbed, plus the treatments we've already discussed. But I don't think I'd take out the carpet until the cloud is ready to go up, and you may want to keep carpeting in parts of the room AWAY from the mix area - since all rooms respond somewhat differently, having the option of carpet/no carpet makes the most sense so you can "dial it in" based on listening and ETF tests later... Steve