YEAAAAAH reading with an actual decibel meter.

With a cold, Eli registers at 121. World record is 128. We're presuming that with full health Eli "YEAH SUGARLAND" Pete is now the loudest human being alive.

Which is the Best - Portable Table Saw Or Contractor Table Saw?

Choosing a table saw for your business is very important. For anything related with the woodworking business, an individual must know the pros and cons of table saws. So, if you have finally decided to open a shop, then you should understand the difference between portable saws and contractor saws.

These both types vary dramatically and here, we will find what makes them different. After reading this, you would be able to understand what you are looking for and what suits the best and if you are a beginner where you should go and if you are an expert and want to open a woodworking shop what are the requirements.

Portable Table Saw: portable saws or bench top table saws are light in weight. Contractors often use portable saws or these bench top saws. These saws are really very easy to use and are easy for transportation too. These portable saws are easy to use and can be used anywhere. You just have to start using these and you will find the comfort and difference. What else do you need when you get everything in one go?

Portable table saws are the best if you are looking forward to start your woodworking shop for the first time and if you are a beginner. You do not have to worry about anything. In terms of weight and size, bench top saws generally weigh less than 65 pounds. They come up with the universal motors attached with brushes. They also have direct drive with louder decibels greater than other table saws.

Contractor table saws: contractor saws are heavier than other saws and they have a lot of weight. This is ideal for woodworkers who are experienced. These saws generally have larger tables and the cutting is smooth and precise. A typical contractor saw comes with 115v amp draw which ranges from 11-18. Generally, contract saws weigh about 220 pounds.

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Some Basic Concepts of Fiber Optic Loss Testing

When testing loss in a fiber optic link, some basic principles must be kept in mind all the time.

1.The testing wavelength should always be the same as the working wavelength. Because optical fiber loss varies with light wavelength, you will get incorrect result if your measuring wavelength is different from the actual working wavelength. For example, if a system is designed for 1550nm but you test it with 1310nm light source and power meter, the result will not be correct.

2.The testing light source should be the same as the intended working lightwave equipment light source. If the system is designed for a LED source, you should test it with a LED source. If the system is designed for multimode laser light, you should use a multimode laser light source for testing. This is also true for single mode laser light source.

Fiber optic equipment used in a loss testing

In a basic loss testing setup, four types of test equipment are needed. They are the light source, the power meter, the reference patch cables and the adapter (mating sleeve).

Here are some considerations when choosing your equipment.

The light source should have the same wavelength as the operating equipment, proper mode (multimode or single mode, should be same as the operating equipment), type (LED or laser, same as the operating equipment) and proper connector.

The power meter should have the same wavelength as the light source, proper connector and calibrated.

The reference patch cables should be high quality with know loss, proper connectors and be the same type as the fiber plant being tested.

The adapter (mating sleeve) should be with high quality ceramic sleeves and be proper type (FC, SC, LC, etc).

Understanding dB (decibel) in fiber optic loss testing

As in any power measurement, fiber optic light power measurement unit can be expressed in milliwatt (mW), but a more convenient unit is dB(decibel).

Decibel (dB) is most often used in electronics testing. It is the ratio between two levels. One level is the input and the other level is the output. The ratio is calculated in logarithmic as explained below.

For power measurement, dB is defined as: dB = 10 x log(output power/input power)

So for example, after a fiber link, the output light power level becomes 50% of its input, the loss of the link will be 10log(0.5)= -3 dB.

Since dB is actually a ratio, it has no absolute units. So from above measurement sample, we have no idea of the actual power, may it be 0.1 mW or 1 mW.

That is why we have another unit dBm. It is the ratio of the measured power to 1mW of reference power. It is defined as: dBm = 10xlog(measured power/1mW)

So for example, a 0.1mW light power expressed in dBm will be 10xlog(0.1mW/1mW)=-10 dBm.

From above we know that dBm is a absolute unit, we know exactly how many mW it is.

For fiber optic loss testing, decibel is the most often used unit since it is much easier to work with. Why? Because two dB values can be simply added or subtracted. For example, a total fiber link may have three sections, each has loss of 0.5dB, 5dB and 0.5dB. The total loss can then be easily concluded as 0.5dB + 5dB + 0.5dB = 6 dB. You can try to convert it to actual milliwatt and you will see that I am right!

Colin Yao is an expert on fiber optic communication technologies and products. Learn more about innerduct coupler, innerduct for fiber, plenum inner duct on Fiber Optics For Sale Co. web site.

teamSPB Project DFN U Mike gets a demo!...now running 25kwrms!!!! 4 Ascendant SMD 18s!

Mike from CCUK feels the MIGHT from Project DFN U!!! Needs some more tweeking yet me thinks!!

2 Walled Off DC 18's Hitting 159.8db w/ Hasebien's Dual Stetsom 14k2d Amps - Team USA Audio LOUD

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Coaxial Cable For Non-Geeks

Coaxial cable is used for transmitting high frequency signals for communications (i.e. video or satellite signals). Electrical interconnect is not glamorous, but it's an important detail that is often overlooked. Have you ever heard someone say, this "worked a lot better in the store"? There are reasons.

A coaxial cable has two conductors, which share a single common axis. A coaxial cable has a solid copper (SC) or copper plated conductor (CCS) surrounded by dielectric insulating material. This dielectric is surrounded by foil and/or braid shielding which forms the outer conductor. This outer conductor also shields against electromagnetic interference (EMI) from external noise sources. Some coaxial cables are identified with an "RG" designation. RG stands for "Radio Government". The number following is a specification identification. The number value is arbitrary.

High quality coax cable is used for High definition TV (HDTV), Satellite TV (SATV), Broadband, Cable TV (CATV), VSAT (very small aperture terminal, satellite communications including broadband), TV Antenna, and Satellite Master Antenna Television (SMATV). The three most common coax cable types used for these applications are RG59 (low grade), RG6 (medium grade), and RG11 (high grade). Coaxial cable for these applications has an impedance of 75 ohms.

RG59 cables use a 20 or 22 AWG center conductor, RG6 cables have an 18 AWG center conductor, and RG11 cables use a 14 AWG center conductor (the smaller the AWG number, the larger the diameter of the center conductor). There is much variance in the cable specification within each class. An economy RG6 might have a thin aluminum braid and a copper plated steel center conductor, as opposed to a high performance RG6 cable with quad-shield shielding and a sophisticated dielectric.

Video/HDTV

Most analog video cables are coaxial. For example, an "S Video" cable is two mini-coaxial 75 ohm cables combined in a common outer jacket. S video keeps the luminance and chrominance signals separated. One line carries the luminance signals, one carries the chrominance signals, and the other two lines are ground wires.

Component Video Cables use three separate 75 ohm coaxial cables with connectors at each end. The three cables are in a single jacket or three separate cables. This allows for separate transmission for the red, green, and blue signals (RGB).

Serial Digital Interface (SDI) is the standard for digital video transmission over coaxial cable. The SMPTE 295M standard provides a maximum distance of 300 meters (about 1000 feet) for standard definition TV and 140 meters (about 500 feet) for HDTV. SDI provides a method for transmitting uncompressed digital video, audio and other data between video devices. SDI is currently only available in professional video equipment. Licensing agreements, restricting the use of unencrypted digital interfaces, prohibits its use in consumer equipment.

Signal Loss (Attenuation)

One of the main factors when choosing a cable is a calculation of signal loss (attenuation). Attenuation is often expressed as in decibels (db) per distance. This ratio is expressed as log ratio of input: output.

A high performance RG6 cable at 100 megahertz could have a signal loss of 6.4 db per hundred meters. Since the decibel scale is logarithmic, this means that the signal in this cable will have been reduced in signal strength by about 75% over a distance of 100 meters.

If the run is short, this may be a minor consideration. Often, however, signal loss will be of paramount importance. RG11 cable will typically exhibit a signal loss of about 4.5 db per hundred meters at 100 megahertz (loss of about 65%). RG59 cable will typically exhibit a signal loss of about 7.5 db per hundred meters at 100 megahertz (loss of about 82%).

Signal "leakage" occurs when the coaxial cable allows some of the signal to be radiated. All coaxial cables have a certain amount of dielectric and resistance loss. Resistance loss is the largest contributor to signal loss in coaxial cable. Losses caused by the resistance of the inner conductor vary with the diameter of the conductor.

The more significant loss is frequency related. As the frequency of the signal increases, the signal is carried through the conductor closer to the perimeter of the cable. This is called "skin effect". The same RG6 cable that has an attenuation of 6.4 db per hundred meters at 100 megahertz might have an attenuation of 23 db per hundred meters at 1000 megahertz (loss of more than 99%).

Cable Sub-Classifications for Application and Safety

CATVX is the lowest grade of cable. It is suitable only for limited use in residential buildings.

CATV has a higher-grade jacket, but this cable should not be used in risers or air handling ducts. Riser spaces are cavities or openings that penetrate more than two floors. Commercial buildings often use the same space to install cables as air handling ducts.

CATVR (Riser cable) has a slow vertical burn rate and is suitable for any application other than air handling (plenum) ducts.

CATVP (Plenum cable) is the highest rated cable jacket type. Plenum cables can be used anywhere within a building. It has a slow burn rate and emits lower toxic fumes when burning. Plenum cable is typically color coded white, and costs about 75% more than standard cable for similar electrical performance. Plenum cable will often not withstand outdoor conditions as well as standard cable.

"Flooded cable" is designed for burial underground. Flooded cable has a more robust jacket to withstand the compression of being buried, and also contains a gel substance within the outer most braided shield. The gel compound prevents water migration along the braid when the jacket is damaged. This cable is unsuitable for above ground applications.

Coaxial Cable Connectors

Coaxial connectors are available for communication applications such as audio, video, HDTV, digital applications, and satellite communications. Impedance, frequency range, power capabilities, and physical size are important considerations when selecting a coaxial connector.

BNC connectors are bayonet type connectors, commonly used in CCTV systems. They are the most suitable connector for use with RG59 cable. The BNC connector has gained wide acceptance in video and RF applications for frequencies up to 2 GHz. The BNC connector uses a plastic dielectric. This dielectric causes increasing losses at higher frequencies. BNC connectors are specified by IEC standard IEC60169-8.

F-Type connectors are used for Cable TV, Satellite TV, and Digital TV (HDTV) in conjunction with either RG6 or RG11 cables. Usually the inner conductor of the cable forms the inner "pin" of the connector. Although "twist-on" type connectors are available, they do not produce a reliable connection in comparison to a connector that has been terminated with a ratchet-crimping tool. F-type connectors are specified by IEC standard IEC60169-24.

N-Type: A 75 ohm version of the N Type connector is widely used by the CATV industry. The N-type connector has an air gap between center and outer conductor. Better N-type connectors can be used at frequencies up to about 18 GHz.

UHF-Type: UHF connectors have an impedance which tend to vary, and are unsuitable for use at frequencies above 300 MHz.

Summary

High performance communications requires sophisticated interconnect technology. As the environment continues to evolve, the system may need to support voice, data, video, and more recently, HDTV. The growing size of networks and the introduction of high-speed access create a critical need for reliable, high performance cabling systems.

About the Author: Brian Bradshaw is a Certified Technical Specialist (InfoComm CTS). Areas of expertise include Video, Audio, Computation, WiFi, HDTV, Satellite Systems, and Communications. He has a communications technology business that serves the Southwestern United States with offices in Plano, Texas (Dallas) and an office in Peoria, Arizona (Phoenix), managed by his brother, Keller Bradshaw.

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Honda Generator EX1000 Reviewed, Truly Small But Terribly Dependable

Honda generator EX1000 is noted for its compact size and great reliability. This handy machine can easily be transported from place to place; so wherever you have to go, it will make the transfer stress-free.

Honda generator EX1000 produces 1000 watts of power supply output. It also has a fuel meter, as well as a frequency meter. This model also comes with a four-stoke side valve for an unequalled torque and fuel effectiveness. It is designed with top quality circuit breakers and a switch for engine and fuel.

It is guaranteed by the United States Department of Agriculture to contain qualified spark arrestors to prevent incidents of fires. Also, it is manufactured with a fully-enclosed built to run without generating too much noise. In addition, because it is lightweight, it can be carried by one hand to facilitate convenient carrying.

Honda has made a name in the line of generators. Its products market in the area of commercial to household consumers. Generally, generators from this maker produce between 1,000 to 10,000 watts of power that can ideally be consumed for construction, recreation, rental and emergency use. Surely, consumers are ensured of reliable good turns with Honda.

At the present time, almost everything depends on electric power. And for that, we have too much to lose if we don't expect things to fail - especially electricity. This is why generators are here. It is a shrewd move if you get your unit now. You don't have to be troubled of the stresses brought about by power interruptions and outage. Just make sure you get your generator from Honda.

Other reliable Honda generators include the 10kw portable Honda generator and the Honda em4000 generator. Also should you buy a used Honda eu2000i for sale or a new one.

What is a "Silent" Computer?

Some years ago, Intel and Microsoft laid down noise guidelines for computers in certain applications, using the term "silent" as one of the descriptors. The response from acoustics engineers in the industry was swift and merciless. The critics argued correctly that "silent" is not possible to define in any meaningful way, at least from an engineering perspective. It is also a challenge to define legally, an issue whenever there are corporate legal teams that routinely consider worse-case-scenarios. The term has more or less disappeared from Intel and Microsoft's official vocabulary, and now it is impossible to find well defined recommendations or guidelines about low-noise PCs on either company's web site.

Yet, there is a growing need to define "silent" components and computers in a way that is possible for engineers to agree upon, and more importantly, for consumers to understand and trust. As media PC popularity grows, so does the awareness among consumers that the typical computer is not the ideal silent servant. Instead, there is dismaying realization in many households that that a media PC must be relegated to a closet, a spare room - anywhere but out in the open due to its intrusive noise. There are quiet computers on the market, but with the co-opting of the terms "silent" and "quiet" by marketing teams in the computer world, it's impossible to tell whether one is really quiet until it is brought home, plugged in and turned on. This is not a good state of affairs for consumers or for the PC industry, which looks to the media PC as a major source of new sales.

Why is "silence" such a difficult term for the engineers? Simply defined, silence is the absence of sound. There are two aspects to sound: Its generation, and its perception. Yes, the age-old question, "If a tree falls in a forest with no one to hear it, then does it make a sound?"

Physical Sound and Psychoacoustics

The engineers who criticized the use of the term "silent" were concerned with the physical phenomenon, the generation of sound. Except in deep space, where there is no air to transmit vibration, which we define as sound, there is no silence. Everywhere on earth, there is always some level of acoustic energy in the air. Even a computer with no moving parts still generates sound from its transformers and other electronics parts, it cannot be silent like a rock.

Sound is also the human perception of acoustic energy. From a psychoacoustic perspective, silence is achieved when a human being perceives no sound. (Of course, one can argue that even in the most advanced anechoic chamber, a human being can always hear his own breathing or the sound of his own internal organs.) The key here is human perception.

A PC acoustics white paper from a major system brand stated: "The human ear is not a reliable instrument with which to measure sound levels because its sensitivity varies with the frequency of a sound." What this statement reveals is that for the writer, sound level - or more precisely, sound pressure level - is the reference. From the point of view of designing products for people, this is backwards. It is human perception that must be the reference, not SPL, which describes the way a machine "perceives" sound. It is human aural perception that we need to begin with in order to design a computer that sounds quiet to people.

Acoustics engineering in the PC industry is mostly dominated by sound pressure level and sound power. They are single number metrics that are extremely difficult to correlate to human perceptions of sound. Is a 2.8 bel sound power measurement quiet? Is it noisy? How about 25 decibels, A-weighted from a meter away? No one can say for sure from just looking at the numbers. Why? Because quiet and noisy are qualitative terms that refer to human perception, not the physical phenomenon. The sound power and SPL numbers refer to the physical phenomenon. An experienced acoustic engineer would ask to look at the waveforms, study the spatial, temporal and time structure of the sound, and perhaps ask for a listening jury to work with. And then, and only then, could he say with scientific certainty whether it is quiet or noisy. We are now speaking not just of sound level or loudness, but sound quality, which is a growing sector in acoustic engineering.

Human Perceptions of Computer Noise

This brings us back to the main concern of a noise-conscious computer consumer: "Can I hear it and is it a nasty noise?" The terms I like to use are "inaudible" and "benign", so that the question can be changed to, "Is it inaudible? If it is audible, is it a benign sound?" Again, these are simple questions, but scientific answers to these questions are not easy to get.

Let's examine what I mean by each of these terms and what is required to achieve what they describe.

By inaudible I mean we don't hear it. What qualities must a sound have in order that we don't hear it?

* It must be at a very low "loudness" level, lower than the ambient background noise level in its operating environment.

* It must be constant, or almost constant, so that people's attention is not drawn by changes in noise characteristics.

A constant sound, even a fairly loud one, is something most people can tune out with a little acclimatization. Not so with irregular sound. People, like animals, have high built-in sensitivity to any sudden change in our environment, which seems directly linked to survival instincts; in nature, it often means imminent attack by a predator. A movement in the scene in front of our eyes draws our attention instantly, as does any kind of change in noise - even when it is much lower in level than the ambient. This happens because once we adapt ourselves to the ambient noise as being normal, it ceases to be consciously perceived, even when it's pretty loud. The human mind/hearing is capable of incredibly sophisticated filtering.

By audible and benign, I refer to a gentle and unobtrusive sound that we can hear. This means that...

* It must be smooth, lacking in "sharpness".

* Again, it must be constant, or almost constant. This is even more important for benign than for inaudible.

From a design point of view, making an inaudible computer is a tough challenge, but it is possible to do, unlike a silent computer. There are two basic approaches which can be taken:

1. Fan less, with costly, custom enclosures for passive cooling of components. Most often modest heat producing components are used, but some ambitious products allow the use of very hot components and near-cutting-edge performance.

2. Fan-cooled, with careful optimization of heat generation and performance in a more conventional enclosure. High performance heat sinks and high quality fans are musts. The ability to run multiple fans at slow speed without risk of overheating is critical.

With each approach, care in component choices are critical. Cooler components make lower noise easier to achieve, but hotter, higher performance components can also be used successfully.

Fanless System Design

Key computer components today generate enough heat that cooling fans are almost inevitable for stable operation and to avoid jeopardizing product reliability or longevity with high temperatures. The handful of commercial computers with a serious claim to be "silent" are mostly fan less, with custom cases that are in part massive external heat sinks to allow passive cooling of the hot components. This means there is no fan noise, which is a big part of typical computer noise. However, this does not eliminate all sources of audible noise.

There is the hard drive, an electro-mechanical device spinning at high speed, often more than one in many systems. Hard drives have a wide range of acoustic output and also add vibration to the case, which usually causes a host of other audible effects, including harmonics and inter modulation. They also make quite different noises when seeking compared to when they're idle, and the change is very noticeable for anyone who listens. The acoustic effects of the hard drive must be neutralized if the costly removal of cooling fans is to be effective in achieving inaudibility.

There are still other noise sources: electronic parts such as capacitors and inductors can emit mid/high frequency noises, especially of a tonal nature, and often intermittent. These parts are found mostly on power circuitry and they can be truly annoying even when at very low measured loudness. With conventional computers, such tonal noises are often not heard directly because they are masked by the roar of fans and hard drives. In a fan less system, this noise is plain to hear. It is far more common than you'd think. It can sound like CRT monitor high frequency whine, which most people have heard. It can also sound like a buzz or hum. Often this noise is too low in loudness to appreciably affect any conventional SPL or sound power measurements. But they are perfectly audible for users with normal hearing, as many a frustrated user can attest. Only careful selection of parts and good circuit design can ensure that such noise problems don't arise.

What all this means is that in designing a fan less system for low noise, any one of many factors can lead to failure, to nasty noise, unless the primary design target is kept firmly in mind: Human perception.

Fan Cooled Quiet System Design

A different approach to low noise computers using carefully selected, high quality, low noise fans in more conventional cases is usually cheaper to implement. Although the absolute measured "loudness" of such fan-cooled systems might come in a bit higher than for completely fanless systems, the perceived audibility may be just as low. In many conditions, the residual broadband airflow noise of the fans can provide a smooth masking effect over tonal aspects of the acoustics that can lie at very low loudness levels. Keep in mind that serious tonal or intermittent noise factors will still be easily heard by noise-conscious users, and hard drive noise still has to be well managed.

Furthermore, the issue of fan speed changes in response to rises in component temperature (due to high load or hot weather) also must be managed well. Too much of a speed up (or even down), especially in a short period, is heard as an annoyance by most users. Lower power components, especially those meant for mobile computing where the drive to maximize run time on batteries has created highly power-efficient parts, can make noise optimized fan cooling a practical and viable way of building inaudible computers.

Carefully designed fan cooling can also be used to create high power computers that are audible but have a benign acoustic signature that makes them unobtrusive in most environments, for most people. A broadband random sound like softly falling rain can actually measure fairly high, yet rank very low in perceived "loudness". Combined with care around the other noise factors above, such a computer can have excellent acceptance among noise conscious consumers.

Undesirable Qualities

Despite the name of our web site, a silent computer may be scientifically impossible... but "inaudible" or "audible but benign" computers are well within reach. Careful system design is necessary to ensure that all the potential pitfalls are avoided, not just "low measured loudness":

* sharp tonal aspects

* intermittent sounds

* rapid changes in noise

* harshness (caused by intermodulation and harmonics)

* vibration induced noise

Keep in mind that all of these various aspects of noises can be identified using sophisticated audio measuring equipment, the same equipment need to test for sound power.

A Need for People-centric Metrics

In light of these various factors, the long upheld ISO 7779 standard for measuring computer acoustics is clearly lacking. By focusing only on sound power and a single half meter SPL measurement, ISO 7779 manages to ignore the sound quality aspects so important to human perception, leaving only a machine-language definition of overall noise. The fact that so few companies actually use this standard and its results for promotion is actually something of a relief. It would only lead to greater confusion and consumer dismay.

For complete, up-to-date information about silent computing, visit Silent PC Review , the world authority and primary discussion forum on every aspect of acoustic around computing devices.

Cicadas Seek Mates at 98 dB!

2011 Middle Tennessee Cicada emergence. Noise level is a stunning 98 dB peak as displayed on the sound level meter. Prolonged exposure at anything over 90 dB can cause hearing damage. Rock concerts, trains, heavy traffic inhabit this realm of noise. Fortunately, these critters aren't around long -- 6 weeks in May and June and only every 13 years. Cicada's mate and die, eggs hatch, fall and live underground for 13 years then emerge to repeat the same cycle.

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Playing around w/my 1999 Toyota 4Runner's Audio system w/music www.cardomain.com Big Three, KINETIK HC1400, KICKER 1/0 Gauge, STINGER/KINETIK Terminals, TECHFLEX Sleeving, KENWOOD Head, KNUKONCEPTZ Connects, RE Audio RE6.5FR Co-Ax Fronts, RE Audio RE5.25FR Co-Ax Rears, RE Audio TW-1 Tweets Front Factory Sail/Rear C-Pillar, AUDIO CONTROL EPIC 150(Volt Meter/DB Meter), Sub Enclosure(MDF/Fiberglass,5 Cubes,33Hz)Amp Rack, 18 Gauge Co-Ax/Tweet Wire, HIFONICS XX-JUPITER 4 Ch Sub Amp(325x2@2), HIFONICS 4 Ch Mids/Highs Amp(110x4@2), KICKER Power/Ground Dist Blocks, 2 RE AUDIO SRX15D4 15" Subs, 8 Gauge Sub Wire, TView 9" Fold Down TV/DVD Player/Headliner(USB/SD Card)

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Hitting a 152 db with my 2 12"s. Meter used is an EPIC 160.