The SWAMP! - Volume One

**lcaillo** · **09-30-07, 10:36 AM**

I recall it being very common to refer to sealed box speakers as infinite baffle in the 1970s and 80s. I always felt it was more of a marketing and sales trend than a technically precise description. Most of the descriptions that I have seen that used the term were actually self contradicting or confusing. Some people still use the term in this manner, though I think it has become uncommon to do so. A google search reveals even recent web publications still referring to sealed boxes as IB.

http://www.soundonsound.com/sos/aug0....htm?print=yes
http://www.soundonsound.com/sos/aug0....htm?print=yes
http://www.echoloft.com/articles/spi...ye-cabinet.htm

**drf** · **09-30-07, 06:27 PM**

I reckon we should go back to using all the old terms for speaker design and construction, Just to confuse all these people who seem to be one eyed about a particular alignment or enclosure type.

I re-read one of my books on re-enforcement enclosures and discovered that it was/is still used to define a sealed box.

I can't see how it is a marketing thing, from a mathematical point of view it seems an accurate description

.

**Chrisbee** · **09-30-07, 06:32 PM**

Quote:

drf wrote:

I re-read one of my books on re-enforcement enclosures and discovered that it was/is still used to define a sealed box.

I can't see how it is a marketing thing, from a mathematical point of view it seems an accurate description

.

Righto then. Define infinite in the context of a shoebox!

**lcaillo** · **09-30-07, 06:59 PM**

I think the idea was that a sealed box simulated an infinite baffle by isolating the front wave from the back. The problem that I have with it is that it creates a whole set of variables that are very different than a true IB design. I think sealed box is the best description.

**drf** · **09-30-07, 07:50 PM**

A circle is an infinite line, a sphere is an infinite shape*, the only difference is that one is 2 dimensional and the other is 3 dimensional. If you were to open the circle up at one point, you then create a line with a start and finnish, therefore it is no longer infinite. If the 3d dimensional shape has a hole in it it also loses its infinite status as any one of its planes or vectors, from that point, now has a start and a finish. There is no difference between this and any other shape/object that is unbroken around all its perimiter. A shoe box, if totaly sealed, has no opening from the inside compartment to the outside space, therefore it is considered to be infinite in exactely the same terms as a circle or sphere or cube, etc.

If there is no way for physical matter to directly transfer from inside a box to outside then the boxes barrier is infinite, in a speaker enclosure the barrier is called a baffle, therefor if there is no way for sound pressure to directly travel from inside to outside then the baffle is infinite.

because the name specifically refers to the baffles mathematical integrity, I cannot see how it has variables. Either it is an infinite baffle or it isn't.

*for the purposes of this discussion.

FOOTNOTE, I am dyslexic and display mildly autistic traits, trying to explain a mathematical fundamental on the text based medium is exhausting and very hard. Can I go lie down now?

**lcaillo** · **09-30-07, 08:03 PM**

The variables that I referred to are the loading effects on the drivers due to the limited volume and the small frontal baffle area of most smaller sealed box speakers. A sealed enclosure is not infinite in terms of volume nor frontal surface area, which are the two major differences in effect with small sealed box designs. This makes the reference inappropriate in my view, and confusing. It is particularly confusing since most of the discussion here regarding IB does not center on sealed enclosures. Sealed (box, encolusre, cabinet) is just much more clear and descriptive than infinite baffle for such designs.

**drf** · **09-30-07, 09:08 PM**

ahhhhh! that explains the confusion then, I see the term "inifinite baffle" as being a description of the baffle in mathematical terms not in terms of its accoustic appplication. Yes you are right about it being deceptive in that context. But most of those variables are still results of what it is, not why its called what it is.

edit: I would argue that the only reason calling it an "infinite baffle" makes it so confusing, is because now people have changed the description of what an infinite baffle is (ie. from a sealed enclosure to an attic installation), not the other way around.

**Chrisbee** · **10-03-07, 05:36 AM**

The "true" IB (which uses an attic or other free volume within the building) is actually a large sealed enclosure. The dimensions of which approach that of a baffle which would be termed infinite with regards to limiting frequency before out of phase cancellation occurs.

**drf** · **10-03-07, 04:34 PM**

Does that mean A "false" IB is one where the baffle is continous from the driver in all directions until it returns on itself, creating an infinite barrier between the front of the driver and the rear, regardless of the fact that it is a very small and frequency limiting enclosure?

**Chrisbee** · **10-03-07, 05:42 PM**

Quote:

drf wrote:

Does that mean A "false" IB is one where the baffle is continous from the driver in all directions until it returns on itself, creating an infinite barrier between the front of the driver and the rear, regardless of the fact that it is a very small and frequency limiting enclosure?

I'm not going to rise to your barbs!

Let's try and get away from this infinite barrier.

By no stretch of the imagination is the barrier infinite in any sense.

It is not infinite in size.

It is not infinitely resistant to air pressure.

It is not infinitely dense.

It is not infinitely anything!

By default it must be finite!.

**drf** · **10-03-07, 06:24 PM**

Oh oh!

So what you said would apply to a set of drivers mounted in the ceiling with an attic for a rear chamber also. it's no more/less infinite than a circle. Like this:

hehehehehehehe!!!

**Chrisbee** · **10-03-07, 06:31 PM**

Is it just me going round in circles?

Goodnight!

**Sonnie** · **10-03-07, 06:33 PM**

Is it infinite circles or finite circle?

**drf** · **10-04-07, 03:01 AM**

A circles perimeter is infinite but its area is finite. Which is where most of the confusion probably is.
As a finite object it has a value for its diameter, radius, area and position. Yet it has no begining or end therefore cannot be considered a finite object. I don't want to go into pi right now, I am not hungry.

**Ayreonaut** · **10-04-07, 08:34 AM**

They're called "infinite baffle" because the owners are infinitely baffled. It's as simple as that.

**Sonnie** · **10-05-07, 03:01 AM**

There ya go Naut... that's good reasoning ...

So what do you guys think about the new banner ads we have now... instead of those ugly adsense ad.

They are javascript and flash ads, so I'm wondering how fast the site is loading for others. Not sure if those type ads migh be slowing things down some.

**Mike P.** · **10-05-07, 09:15 AM**

The loading time for the ads is about the same as before. Not much difference in load time as far as I can tell.

**Chrisbee** · **10-05-07, 01:18 PM**

My computer totally locked up on the forum this morning.
It keeps being dropped from the server and then can't find it again.
It sometimes takes four attempts to preview my posts.
The same to post them.
Lucky I don't have much to say, isn't it?

**Sonnie** · **10-05-07, 01:27 PM**

We were having serious problems with Firefox and those Sony flash banners that our ad partner loaded late yesterday evening. It was locking up, hanging, freezing... very sluggish. IE7 was fine, but FF couldn't handle it. I think their may have been some bad javascript coding in that ad banner. Anyway... I had them take it off and all seems wonderfully fine now. We still have flash ads running, but they are not a problem, hence my reasoning for bad code.

**Chrisbee** · **10-05-07, 01:33 PM**

I am running FF so that may explain my problems.

**Sonnie** · **10-05-07, 04:50 PM**

The latest version of FF does not have an updated ActiveX version and this is supposedly the problem. Not a good thing for FF users and ads with rich media. FF usually stays ahead of the game on things like this, but seem to have dropped the ball on this one.

**drf** · **10-06-07, 07:29 PM**

All seems to be running fine at my end, yesterday I didn't log on, so I couldn't say if there were problems then.

**Sonnie** · **10-06-07, 10:34 PM**

I've been optimizing a good bit, so things should be okay. If anyone notices any persistent problems... be sure to let me know.

**Chrisbee** · **10-07-07, 05:26 AM**

I've changed my security software in the hope of fewer problems than an all-in-one solution.

Grey and misty here today after glorious autumn sunshine yesterday. We drove along the coast enjoying the quiet lanes.

Here's a picture my wife managed to capture despite a high hedge on the roadside.

**Chrisbee** · **10-07-07, 05:41 AM**

And here's a very large erratic boulder from the íce age. Difficult to judge the size from the image but it's probably 60 feet long 30 feet high x 30 feet wide. There are some nice legends about a giantess throwing it from a nearby island. She was aiming for a high church steeple but missed. The stone is supposed to have kept growing until it was fully exposed by excavations when it stopped growing. Denmark has very little exposed rock. This huge boulder lies out in the middle of the fields with a narrow lane leading down to it and a ring around the stone itself. After I had practised my rock climbing to reach the top we enjoyed a picnic of tea and Danish pastries in the warm sunshine.

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