TuneLand :: View topic - Chipdivot's Home Theater and Listening room

Michael Green · Founder of MGA Joined: 16 Jan 2004 Posts: 4208

Hi Guys,

Can't beat that!!! Thanks GARP Cool

Here is a simple drawing of a pressure box

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Michael Green
MGA
Las Vegas,NV
702 368 7550
info@michaelgreenaudio.com

chipdivot · Posted: Thu Aug 13, 2009 2:41 pm Post subject: Pressure box

Hi Michael,

Can I use a uhaul moving box? I still have a bunch. Do I tape the ends, or fold them,??? then do I cut a hole and put a TP roll in it like the drawing?

I never saw this before...then how do I use it?

Thanks,
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Chipdivot

Michael Green · Founder of MGA Joined: 16 Jan 2004 Posts: 4208

Hi Chip,

We'll make this (your thread) the temporary stumping ground for this adventure.

The Pressure Box is a cool DIY trick. I've made these on the spur of the moment when I would be on tour. I also use them to help me with speaker designing. (another story) The pressure box acts like a PZ (pressure zone) finder. Depending on your listening skills you can use almost any size.

Pressure zones can be found in a lot of different places in or out of a persons room. For example: ever been listening and need to use the little boys room? Well your sitting (or standing lol) there and all of a sudden you hear that note that was missing in your system. How can this be? Well most of your sound is made up of a good things call sympethetic (got to get that spell check on the downstairs computer) harmonics or vibrations. These vibrations hunt for the easiest places to survive. one pressure zone can make or break a system. A lot of people blame things on their systems that have nothing to do with the equipment at all. Good sound has every thing to do with tuning in the energy.

Once you find a box that you think will work, tape the seams closed as straight as you can. If the box sounds like a drum when you turn it on corner than this is a good start. Next cut a hole about 4.5 inches away from the corner to edge of the roll as a rule. Cut the box and glue the tube in as a port. Now your ready to start experimenting.

Don't start stuffing the box until you understand it or you'll start losing notes right and left like when people use traps. nono

At the same time these Pressure Boxes will blow away a trap if you are good at studying the scale of your room. Do not use RTA's when listening.

ready Idea

set

begin

Make it fun and put on some music with a nice bass line. Q why do I like music instead of a tone? A a tone will never fix a musical problem. A tone is only a limited fraction of a musical note, let alone notes. Never in our lives do we listen to a tone (unless your ears are being tested). We hear tonality, but not a tone.

next we'll talk about finding and shaping the zones

Are you with me thus far?

Wink

_________________
Michael Green
MGA
Las Vegas,NV
702 368 7550
info@michaelgreenaudio.com

chipdivot · Posted: Fri Aug 14, 2009 2:49 pm Post subject: Are you with me thus far?

Hi Michael,

yes I am...I'll make one this weekend and get back here!
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Chipdivot

Michael Green · Founder of MGA Joined: 16 Jan 2004 Posts: 4208

Within pressure zones are the balance of music. We listen to air pressure, and these zones of air pressure contain the upper side (db) of the musical content, meaing this is where you will find the bulk of the music in your room.

The pressure box acts like a valve when set in a zone. It also acts like a magnet for sound waves when place in dead areas. Energy (sound) is vibration and is attracted to conduits of lower mass when settling and attracted to conduits of higher mass when transfering. A pressure box is like a natural equalizer exchanging vibration with the other furnishings of the room or structure. It attracks vibration because of its low mass light weight.

Get familar with the Boxes abilities by placing it in an active area of your room then an inactive area to get use to what it does. Keep notes on the direction that the port faces as a reference.

Wink

let me know how you are doing
_________________
Michael Green
MGA
Las Vegas,NV
702 368 7550
info@michaelgreenaudio.com

Sonic_Beaver · Posted: Mon Aug 17, 2009 2:54 pm Post subject:

Hi Michael and Chip

Michael, you are absolutely right in saying the box acts like a magnet for soundwaves when placed in dead areas (see my thread for what I heard).

My cardboard box is 67 ins (W), 21 ins (H), 11.5 in cm (D). The port is a toilet paper roll about 1.4 ins diameter. The edge of the port is 4.5 ins from the nearest corner. All seams are taped and the thing sounds like a boxdrum.

As Sonic understands it, the box is a Helmholtz Resonator and this cavity volume and port diameter and length gives an absorption of 15 hz according to an online calculator for room and speaker acoustics. Dunno the Q though. To some extent, the box may act like a capacitor, charging up when air pressure rises and releasing/equalising pressure when the pressure in the box's Zone goes down. This may explain why it can improve a pressure-dead zone and improve the sound-fill like in my room.

It sure made an audible difference in the right spots in the room. The difference vs cost ratio is over-the-top. Give it a try, friends of the Tune Very Happy

Sonic

Michael Green · Founder of MGA Joined: 16 Jan 2004 Posts: 4208

Hi Chip,

Time for you to join us in the "techno-zone" http://tuneland.techno-zone.net/forum.htm . I was going to wait to put the zone on line but I like the technology of the advanced phpbb so much that I wanted to build the zone instead of continuing to post on TuneLand's archive.

Wink

_________________
Michael Green
MGA
Las Vegas,NV
702 368 7550
info@michaelgreenaudio.com