Home power (deep cycle) batteries are generally measured in "amp-hour" capacity. One amp-hour is equal to one amp of current drawn for one hour of time. Amp-hour capacity is generally given as the "20 hour rate" of the battery. Therefore, the number given as the amp-hour capacity for a deep cycle battery will be the number of amp-hours the battery can deliver over a 20 hour period at a constant draw. A 105 amp-hour battery can deliver 5.25 amps constantly over a 20 hour period before it's voltage drops below 10.5 volts, at which point the battery is discharged.

We are often asked if a particular driver is suitable for using in a down-firing configuration. Below is a formula that takes into consideration the effects gravity will have on the "sag" of the cone structure of any woofer. You will need the Fs, Vas, Sd (surface area of the cone), and the Xmax to determine the relative long term usefulness of up or down-firing any woofer.

You can calculate the sag of a driver from:

Percentage of Sag = 24,849 / ( Xmax * Fs²)
where

- 24,849 is a constant value based on the relationship of acceleration due to gravity and Pi.
- Xmax is the maximum linear excursion of a loudspeaker voice coil while remaining within the magnetic flux field (mm).
- Fs is the free-air resonant frequency of the woofer (Hz).

The following is the same formula, including the relationship of acceleration and Pi in this case:

Percentage of Sag = 981,000 / (Xmax * (2 * Pi * Fs)²)
where

- 981,000 is acceleration due to gravity (mm/S²) * 100 (for the percentage).
- Xmax is the maximum linear excursion of a loudspeaker voice coil while remaining within the magnetic flux field (mm). - Fs is the free-air resonant frequency of the woofer (Hz)
- Pi is the ratio of a circle's circumference and diameter, usually rounded to 3.14.

As a general rule of thumb, any time the sag exceeds 5% of the driver's Xmax, it's not recommended for a down-firing subwoofer application.

Providing subwoofer design software programs for solving the required calculations for custom bandpass, sealed and vented box cabinet designs. Can be used for car, truck, sport utility vehicle (SUV), jeep automotive, guitar and home theater applications and projects. This site provides the instructions and "how to" information to successfully plan, design, construct, build and setup subwoofer enclosure systems using AJ Bandpass Designer, Sealed Designer and Vented Designer. Works with any type and size of driver (8, 10, 12, 15 inch). The Subwoofer Designer Series is intended for the hobbyist, audio / acoustic enthusiast and Do It Yourself (DIY) speaker builder.

This calculator will tell you:
Whether the speaker is better suited for a sealed or ported enclosure
The 3dB down point of the speaker in either enclosure
The recommended volume for sealed and ported enclosures
The resonant frequency of both enclosures
The port length for ported enclosures
The reference efficiency in both % and decibels at one watt
If any of the fields return 'NAN' or 'infinity', you did not fill one of the fields required to make the calculations.

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Let's talk time scales real quick. Your computer's CPU lives by the nanosecond: most CPUs can get a few things done in each nanosecond – mostly simple math and comparisons. To make this easier to grasp, suppose you're the CPU and instead of nanoseconds, you live and work second by second. For clarity I'll keep this metaphor to a single-core of a single processor.

You can hold a few things in your head (register). Not more than a dozen or two in your active memory, but you can recall any of them pretty much instantly. Information that's important to you you'll often keep close by, either on sheets of loose-leaf paper on your working desk (L1 cache) a couple seconds away, or in a one of a handfull of books in your place (L2 and up cache) which is so well organized that no individual piece of information is more than a dozen or so seconds away.

If you can't find what you're looking for there, you'll have to make a quick stop at the library down the street (RAM, i.e. main memory). Fortunately, it's close enough that you can go down and grab a book and get back to work in only ~8 and a half minutes, and it's enormous, some are thousands of times the size of a typical strip-mall book store. A little inconvenient, until you remember that this library has a free delivery service, so it's really no bother at all so long as you can still find things to work on while you wait.

But the local library mostly just stocks things on demand (which is fair, your bookcases, worksheets, and even the dozen or two facts you hold in your head are mostly the same way). The problem is that when you need something that's not there, it can take a while to get it. How long? Think Amazon.com in the age of exploration. They send out an old wooden boat and it could be a week, could a month, and it's not unusual to wait 3 years before you hear a response.

Welcome to the world of hard disk storage, where your information is retrieved by making plates of metal spin really fast. Many metric tons of sweat have been spent making this as fast as possible, but it's hard to keep up with electrons flowing through wires.

So when someone says that Solid State Disks are awesome, it's because they're able to turn that slow, unpredictable old sailing ship into a streamlined steam-powered vessel. A good SSD can often make the voyage in less than a week, sometimes in little more than a day. It can also make many thousands more quests for information per year.

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I have tested this myself, on a 2006 Mac Pro. You can upgrade or downgrade at will. If you have a CPU or CPUs in a 2007 Mac Pro that isn't supported in the 2006 Mac Pro, the system will not boot after the update until a compatible CPU or CPUs are installed. The program checks the Mac Pro model and will only install the 2007 Mac Pro firmware on a 2006, or the 2006 Mac Pro firmware on a 2007, whichever is appropriate. If you have a 2007 Mac Pro, the program will warn you about downgrading, but will still allow the firmware update. The download does not contain any firmware updater files or image files. The program creates a small RAM disk, downloads the needed files, copies all of the scripts to the RAM disk, and then runs the scripts. Everything is left on the RAM disk for you to look at and study, if needed.

The SMC version will stay at whatever version it was at before the update, and I'm looking into a SMC firmware tool, as it is also an EFI program that runs during the boot process. If I'm successful with that I will post a utility for that, although many people have upgraded the dual core Xeons in the 2006 to quad core Xeons without any ill effects, so I don't know how important this really is.

I'm also going to work on a utility for the iMac4,1 and iMac5,1, as there is a RAM limit that can broken if the firmware is updated. There have also been requests for a MacMini1,1 and MacMini2,1 utility, but the installer file from Apple has only one firmware image in it, so this one I don't understand.

I hope you enjoy the benefits of extending the value of your 2006 Mac Pro, or being able to change your system back and forth for development purposes.

2) Upgrade utility to upgrade 2006 MacPro1,1 with firmware of MacPro2,1, this brings support for some CPUs to MP1,1
3) Tutorial for installing Chameleon on a Mac, so you can boot 64-bit kernel on a Mac with 32-bit efi and 64-bit cpu.

Using Chameleon to boot the 64-bit kernel on the early Mac Pro

UEFI 2.0

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When labor is free and time is plentiful, a damping glue may be an excellent choice for soundproofing. Through the application of clearly defined research and test methods made available on our website, Serious Energy believes it obtained an accurate comparison of Green Glue and QuietGlue Pro. Based on 3rd party back to back laboratory testing contracted by Serious Energy, we find that QuietGlue Pro performs equal to or better than Green Glue, and at 30% lower cost.

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Issues Fixed in this method which did not work in earlier method.
1) Third party boot loaders not required. This goes with VirtualBox built in EFI boot loader.
2) Shut down and restart of virtual machine works.
3) ‘About this Mac’ information works.
4) Screen resolution can be set to 5 options.

First of all, it's dead animal skin, which means that animal has to be raised: fed, watered, pastured, and eventually slaughtered. Most leather (about 66% of it) comes from cows, and it takes 8 acres of land, 12,000 pounds of forage, 125 gallons of gasoline & other petroleum derivatives for fertilizer, 2,500 pounds of corn, 350 pounds of soybeans, 1.2 million gallons of water & 1.5 acres of farmland (to grow the crops for feed), plus various insecticides, herbicides, antibiotics & hormones to grow one cow from an 80 pound calf to its full size, when it can be slaughtered and the hide harvested. Something like bison, on the other hand, takes less land and less water, and they're primarily pasture-raised, meaning they aren't stuck in feedlots getting fat for half their natural lives. Since they're on the pasture, and their hooves are smaller and sharper, they help till and fertilize the soil (with their waste as fertilizer), and though they require more feed per pound, they aren't picky about where the food comes from; it can be prairie grass or whatever they happen across. Regardless, the point remains: it takes a ton of resources to grow cows.Once the animal skin becomes available (usually as a byproduct of the beef industry), it doesn't get much prettier. Before tanning, the skins are unhaired, degreased, desalted and soaked in water over a period of 6 hours to 2 days. To prevent damage of the skin by bacterial growth during the soaking period, biocides, such as pentachlorophenol (a synthetic fungicide that is toxic to humans), are used. Hides are then either vegetable tanned or mineral tanned. Vegetable tanning employs tannin, from which tanning gets it name, which occurs naturally in tree bark; the primary barks used these days are chestnut, oak, tanoak, hemlock, quebracho, mangrove, wattle, and myrobalan. Hides are stretched on frames and immersed for several weeks in vats of increasing concentrations of tannin. Vegetable tanned hide is flexible and is used for luggage and furniture; Q Collection, one of TreeHugger's favorite sustainable designers, uses vegetable-tanned leathers in their furniture (this gorgeous chair is an example).

Mineral tanning, on the other hand, usually uses chromium and is a fairly chemistry-intensive process. The hides are "pickled," raising the pH to a high acidity level (about 3) and enabling chromium tannins to enter the hide. For preservation purposes, fungicides and bactericides are also applied (yum). After pickling, when the pH is low, chromium salts are added. To fixate the chromium, the pH is slowly increased through addition of a base of magnesium oxide and more fungicide -- sounds like something you'd really want to snuggle up against, no? Chrome tanning is faster than vegetable tanning -- less than a day for this part of the process -- and produces a stretchable leather which is preferred for use in handbags and garments.

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