Headphones: Quick guide to dB, Ohm and Hz.

What ind of Headphones / Ear Buds should you buy?

Let's simplify all the information related to Ohm (Ohms), dB (Decibels) and Hz (Hertzs). There is a lot of technical information around the Internet trying to explain what they are, but they don't answer the quick, frequent question of what should I take into account when purchasing a new set of headphones?

TrebleClick aims to make your life easier, so we're going to simplify all that, and explain it in an easy-to-understand way:

Ohm, dB and Hz: what they are, what's their purpose, and why are they important?

• Ohm: Ohms are the Impedance of your headphones, or, in plain English: the resistance that your headphones oppose to the flow of an electric current. This determines the amount of power that reaches your headphones, in relation to the amount of power sent. More Ohms will require a higher power input value to work properly. If the resistance value is very high, your system will need an amplifier. You will find the nominal value of resistance in the technical specifications of your headphones. 16, 24 or 32 are usual Ohm values, and they should work for regular purposes.
• dB: The Decibels represent the Sound Pressure Level (SPL), or the audio volume power. Higher dB values will make the sound in your headphones be louder. But higher dB values will also lead to earlier distortion in such sound. The higher this volume value is, the closer to the distortion threshold you'll be.
• Hz: Hertzs are the Audio Frequency, and they actually are the most important parameter to take into account when considering the sound quality of some new headphones. The Hertzs represent the frequency range that your headphones will play back, from the lowest bass to the highest treble. This usually comes specified in minimum and maximum values, so the best headphone sets will have broader ranges, with a lower minimum, and a higher maximum. Human ear can hear sound frequencies ranging between 20 and 20.000 Hz.

Conclusion: what do I need in my headphones?

If you are a professional sound technician, or an expert, and you already have a pretty decent sound system, you won't probably even need to read this, and you may even disagree about some details. But if you are just an average computer user, avid gamer or designer, and the only thing you want is some headphones to use with your computer or laptop, the only things you need to take into account when choosing them are as follows:

• A higher dB value implies higher sound volume. The usual values are set around 112 dB/mW.
• Higher Ohm mean higher resistance values, and this means that you'll need higher input power values - otherwise, you'll experience a lower sound volume. Nominal Ohm values of 16, 24 or 32 are the most frequent ones.
• A higher Hz range will play more sound frequencies, providing higher quality sound playback. This is the other key parameter. 20-20.000 Hz is okay. From that point on, a broader frequency range (like 12-28.000 Hz) should have better sound quality, while a narrower frequency bandwidth (for example, 21-18.000 Hz) would provide lower sound quality.

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iPad for Professional Usages

Professionals using iPad

So far, we all know the iPad. The shiny new tablet from Apple was constantly present in the media. Web browsing and gaming just became a new tactile experience. And the iPad became the brand new toy everybody wanted to have.

But the iPad is more than a toy. It isn't too strange to find that an iPad is used by professionals in their daily jobs.

Examples of iPad professional usages

It's surprising that iPads are becoming popular in conservative businesses as legal practice. In this Apple iPad review for lawyers, an attorney explains how he uses such gadget in his daily job, as a medium between laptops and smartphones.

Some universities are starting to give iPads to their students, like in this new. The idea is that such device would be good to read on screen textbooks in full color.

Professional graphic designers and photographers are using iPads to introduce their works to their customers. The shiny screen of the iPad works pretty well with images and demo reels, being an eye-catching showcase of that visually appealing work.

Even some IT professionals that need to manage simple interfaces just use it whenever a wireless connection is available, for professional applications like managing servers with a remote console on the go.

Another interesting approach used by professional advertisers and publicists consists of displaying videos in several synchronized iPads, having that way a big, array-style screen composed of many iPads - a really eye-catching idea.

Even some professionals use iPads to read scripts in a full color, compact and easy-to-carry way, removing the hurdle of having to print lots of pages, or having to carry a heavier laptop.

What makes iPad useful for professionals

Since iPad is starting to become useful for professionals, the obvious question would be asking ourselves what gives an edge to the iPad for professional usages as the previously mentioned before. And in fact, there are several advantages for the iPad when compared to other similar gadgets:

• An iPad has a big, full color screen. Typical e-book readers don't have such a big screen, and color e-book readers are just starting to appear (still, e-book ink is rather faded, while the colors on an iPad are quite vivid.)
• An iPad is a quite lightweight, compact and easy to carry device. Some laptops (and even netbooks) are heavier and harder to carry.
• You can read in an iPad even when standing. That's really hard to do with an open netbook. If your professional work consists of reading information while waiting on a queue or moving between areas, the iPad is unmatched.
• The iPad has a tactile integrated keyboard and a big color screen. This is much more comfortable than the keyboard or screen of any small smartphone.
• Some iPads come by default with WiFi and 3G connections. It works with exchange servers too, so it has enough connectivity for professional usages and to keep work synchronized.

iPad professional shortcomings

But iPad has its obvious shortcomings for professionals as well:

• iPad is a rather expensive device. The most basic iPads start from around $600. You could buy a good laptop, or any netbook or advanced smartphone for such price.
• The shiny screen of iPad is not specially optimized for reading texts. The e-ink system of other e-book readers (together with an anti-reflection screen) provides better results for pure document reading.
• The on-screen tactile keyboard of the iPad is not very comfortable. If you are going to write more, then you would need an additional wireless keyboard.
• Some professionals experience synchronization problems with their exchange servers and the iPad, so network compatibility is not fully developed at this point.
• iPad lacks multitasking. If you are that kind of professionals who needs two windows open at the same time while writing on your documents, then forget about using the iPad.
• iPad still lacks good sofware for professional usage. On top of that, some iPad apps aren't specifically designed for the iPad (they are mostly iPhone apps) so their graphic quality would be lacking.

Is the iPad worth buying for professional usages?

It seems that if your work consists of reading documents, showcasing eye-catching images to your customers, browsing and performing quick edits while on the move, then the iPad might be for you, as it is for many system administrators, lawyers and photographers.

On the other hand, if you depend on multitasking capabilities, specific professional apps, and easy synchronization, a smartphone, netbook or laptop might be better for you - and probably, cheaper.

If you want to know more about the topic, you can read / comment the following articles:

• Apple iPad review for lawyers: how iPads are proving useful in legal environments.
• Discusion about iPad professional usages.
• The iPad project: Fraser Speirs' project of installing iPads on school.

       

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iPod voice control commands & headphone shortcuts

Music playback commands in the headphone buttons of iPod touch and iPhone

A little trick to control iPhones and iPods is that they support certain voice control commands as well as some functions or shortcuts in their headphones.

Some models of the iPod Touch and the iPhone have a small control panel in the very cable of their headphones. We can use these headphone buttons to control the music playback in a quick way, with no need of taking out our music player from our pocket.

This control panel in the iPhone / iPod headphones is composed of 3 front buttons and a voice recognition microphone in the back.

With the iPod buttons "+" and "-" we can control the playback volume. And with the central button (pressing the small box in the middle) we can perform the following actions:

• 1 click: Pause / Resume music playback
• 2 clicks in a row: Skip to the next track on our playlist.
• 2 clicks, keeping the button pressed after the second click: Fast forward in the current music track (release to continue at a normal speed from the chosen point in the track).
• 3 clicks in a row: Skip to the previous song in our playlist.
• 3 clicks in a row, keeping the button pressed after the third click: Rewind the current track, (release to resume the playback from the chosen point in the track).
• 1 click, keeping the button pressed: activate the voice recognition mode to use the Voice Control commands on our iPod / iPhone. So we can issue commands to our gadget by speaking to the microphone embedded in the headphones. We could even start phone calls using our iPhone.

The iPod voice control commands to play music are:

• Play
• Play music
• Play (Album) (Album name)
• Play (Artist) (Artist name)
• Play (Playlist) (Playlist name)
• Pause
• Pause music
• Next
• Next track
• Next song
• Previous
• Previous track
• Previous song
• Play more like this
• Play more songs like this
• Shuffle
• Genius

The call comands that we can issue to our iPhone to control it with our voice are as follows:

• Call (name)
• Call (name) (home, mobile, work, etc.)
• Call number (555-555-5555)
• Dial (name)
• Dial (name) (home, mobile, work, etc)
• Dial number (555-555-5555)

Other iPod control information commands, answered by a computer synthesized voice:

• What's Playing
• What song is this?
• What song is playing?
• Who sings this song?
• Who is this song by?
• Who plays this song?

It's also possible to issue voice correction orders to the iPod / iPhone:

• Wrong
• No
• Not that one
• Not that
• Nope

And it is also possible to cancel the iPhone / iPod voice control mode with the simple voice order "Cancel"

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How to buy a flat screen TV

Guide about how to buy a flat screen TV

As a starting point, we have to remember that it isn't possible to pick the best flat TV and the cheapest TV at the same time. The key is to find out which kind is the most important TV feature for us, and then, take into account the quality / price balance. This guide is only orientative so you won't be fooled by biased TV features and data, because while a TV can be very good at some aspects, other TV features might be lacking.

Resolution and screen size

Let's remember that a bigger TV doesn't imply higher resolution. The resolution of a flat screen TV is the number of pixels displayed. While the screen size (in inches) is related to the TV surface where those image pixels are displayed. Having a Full-HD television does no mean that you would be watching all conents in high definition, because you also need a high resolution image source.

• 1080p and 1080i. 1080p is the maximum TV resolution, 1920x1080, also known as Full-HD. means that you have 1080 lines of vertical screen resolution in your TV, progressive and no interlaced. Nevertheless, 1080i means that you have 1080 lines of resolution, but interlaced. At 60Hz, 1080p refreshes all the dots (pixels) on screen 60 times per second, while 1080i alternates even and odd lines in each refresh cycle, refreshing each half set of screen lines with a 30Hz rate, which can lead to the well known effect of "ghosting" or slipstream. In fact, a 1080i HDTV resolution works like a 720p.
• 720p are 720 lines of vertical resolution, 1280x720 is HDTV.
• HDTV stands for High Definition TeleVision, and as a concept, contains every television whose screen resolution is over NTSC resolution of 720x480 (or 720x576 for PAL TVs). So HDTV could be used with a 1080 flat screen TV, but it doesn't have to be this way. HDTV ranges from 720p to 1080i only (1080p is considered Full-HD). So we should pay special attention to the actual resolution of a flat screen TV, because the High Resolution tag could be somehow deceptive.
• HD Ready just means "prepared for High Definition" but, as well as before with the HDTV tag, we have to pay special attention to avoid being fooled by this tag. HD Ready doesn't necessarily mean that a flat screen TV is in Full HD. A 720p TV could also be called an HD Ready TV. Nevertheless, HD Ready 1080p actually means Full HD.

TV Screen Technology: Plasma, LCD and LED

• Plasma was the main technology used in flat screen TVs some years ago. Plasma TVs usually have vivid colors, but that does not last long, as its main drawback is that they need to be recharged after many hours of utilization, as it contains a mixture of noble gases (neon and xenon). Flat plasma TV has also the highest energy consumption, and the lowest image refresh rate.
• LCD stands for Liquid Crystal Display. Flat screen LCD TVs are the most common nowadays. Their underlying technology allow a higher variety of sizes ranging from 15" to 100". LCD screens have a lower energy consumption than plasma TVs, have a longer lifespan, and are a cheaper technology.
• LED means Light Emitting Diodes. Flat screen LED TVs are the latest trend. The whole screen is split into small segments that turn on and off independently. LED flat screens have the lowest energy consumption, and the highest real contrast ratios. On the other hand, it is the newest technology, which makes these TVs expensive, specially at big sizes, having only a few different models available.

Flat screen TV image parameters: contrast, response...

There are many flat screen TVs out there that seem cheap, and that also seem to have great performance in resolution and size. But you must not get fooled by just a couple of TV features. Those parameters aren't everything you need to check when you go to buy a flat screen TV. You need to check other TV features that have probably the same importance, and which could be lacking in cheap TV models.

About TV Contrast, it is necessary to distinguish 2 different kinds of contrast: Static contrast which is the real TV contrast, and Dynamic contrast which could be the difference between a white and dark gray pixels, instead of measuring a color against black, which could bias the result towards a high contrast value, but that is not an actual contrast value.

Most flat screen TVs also have contrast enhancement options called dynamic contrast, which increases the original contrast levels, losing in exchange some tonal image range, with stronger and harder color gradients, higher color saturation, and in overall, sacrificing some image quality.

Unfortunately, most data displayed when you need to pick the right flat screen TV are about dynamic contrast, because using such data the TV specifications look better, but that isn't a completely reliable information. Before buying a new flat screen TV you should search for specific technical information in detail, and for product reviews through Internet.

TV screen refresh rate. Another important feature that should be taken into account is that your flat screen TV should have a good refresh rate, also called response time or Hz, which cause seamless image transitions. With a 50Hz refresh rate a screen can convey a sensation of flickering, specially in very high screens. These are often overlooked data in the flat screen TV advertisements (except in those models that have very good values, because they take special care to highlight these data well for these TVs), as response time is usually an unknown factor by people, and so they don't recognize its real importance. A good refresh rate value is 100Hz. There are some models that feature up to 200Hz, and obviously, this good performance highly increases their price tag.

Some models include a special mode called Motion Plus / Fast Motion, which calculates when extra frames are needed. Depending on the effect level in which you configure this feature, you could either achieve an even more seamless image transition, or in too high values you could experience some image "travelling effect", like a blurred screen image feeling.

Pick the right flat screen TV according to its usage

You have to take also into account the main usage an purpose of your new TV, as that can really help you to identify the most meaningful features of your target TV.

• If you are wanting to buy a flat screen TV to watch blu ray discs, then you really need a Full-HD TV, as it is the only way to appreciate all the details include in such high quality video.
• Nevertheless, if you are going to use your new TV to watch regular TV, resolution is not very important, as HD TV broadcasts are just starting, and the source image is not in very high resolution - you could en up watching a blurred TV image in very big screens.
• Finally, if you are wanting to play HD videogames take into account that most of them won't run at native 1080 lines, so an HD ready TV would suffice for most videogames. Nevertheless, the trend is to create full HD games, and that's why a Full-HD TV is your best option - even lower resolution HD games are scaled pretty nicely in Full-HD screens. Videogames have also quickly moving images, so a good refresh rate becomes specially important for this purpose.
• According to the TV size, the rule of thumb is to pick a flat screen that is completely covered by your vision angle, which is around 30º, so you would be appreciating small details while achieving an immersive TV experience. That means that a widescreen TV of 40 inches will look good at a distance of around 1.7 meters.

Other flat screen TV details

According to the color, as well as to the smooth flowing of the image (the refresh rate, Hz, previously mentioned) the best we can do is to see a TV in real life and check it by ourselves. We have to take special care to identify whether the flat TV that we are currently watching is with the dynamic contrast option enabled or not, because that could highly affect the original color.

Another fact to take into account when picking a new flat screen TV is that most TV shops feature their products under strong lights. That's why the usually pick the higher contrast settings in all the exhibited TV screens. But such high contrast would be really extreme in a normal TV environment at your house. So take that into account when buying your new TV, as you could not be needing such high amounts of contrast ratio, and even those flat TV screens that seemed somehow dull under strong lights could look great at your home. Usually color accuracy is a more important factor than just color contrast.

Flat TV screens have what is called a vision angle. That means that the screen is not seen the same way straight from the front or a little bit from its side, so it is another fact worth checking. As well as the type of screen, gloss or matt (non reflective) finish. At first sight, and specially at a shopping center, the glossy TV screen could look more vivid, specially if the flat TV is displaying very colorful images in its screen. But watch out, as this supposed image improvement doesn't need to be necessarily real. It is worth taking into account when buying a new flat screen TV that glossy finish could also reflect objects and light sources, specially when displaying dark images or black areas.

All the information in this guide is focused in flat screen TV features, given as technical data. But according to the underlying technology of the TV (plasma, LCD or LED) and its specific manufacturing, it could display the final images better or worse. So at the end, our best suggestion is to check the TV with your very own eyes. From trebleclick.blogspot.com we only expect to assist you about how to buy a flat screen TV checking which kind of TVs should be taken into account, what does each TV feature mean and how to prevent being fooled by deceptive TV specifications.

From the original guide to buy an HD TV at Triple Clic

Some examples of good flat screen TVs to buy

Samsung LN32B360 32-Inch 720p LCD HDTV is probably one of most competitive TV options, specially taking into account its cheap price tag. It isn't full HD, and 8ms of response time might be rather slow, but nevertheless, you are getting a 32 inches flat screen TV with great colors with a low cost - perfect for watching regular TV and even HDTV programs (thanks to its built-in HD digital tuner) without eating all the empty space of your home.

Samsung LN40B530 40-Inch 1080p LCD HDTV goes a step beyond than the previous model. With its 40 inches flat screen and an improved response time of 6ms, this TV delivers rich colors, big images and quick response. So this is a very good choice for watching full-HD blu ray discs and playing videogames, still with a very competitive price tag.

Finally, if you buy a Samsung LN52B750 52-Inch 1080p 240 Hz LCD HDTV, you will be getting it all. It is an expensive TV, but if you can afford it, you will realize that it is worth it. With a huge screen of 52 inches, a quick response time of 5ms, a dynamic contrast of 150,000:1, and a refresh rate of 250 Hz, this TV is perfect for just everything.

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Image inputs port list

List of image input ports sorted by image quality

Many people gets confused about which are the best image inputs to plug your gaming console to a High Definition (HD) TV. Even I was confused about the tv input ports not so long ago.

For all these people I'm listing all the TV image input formats sorted from the better input format to the worst (some of the input ports are of the same quality, but we need to list them).

HDMI > VGA > COMPONENTS > SCART > S-VIDEO > COMPOSITE > RHF

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An open controller: inside a gamepad

How to extend the life of a N64 gamepad

The texture of the Nintendo 64 joystick didn't degrade over time: it wasn't made of soft plastic, as the PS2 joystick. But, as all of the N64 controller users know, the joystick becomes somehow loose after repeated usage.

Nevertheless, N64 gamepad owners are lucky to extend the life of N64 controllers, because spare parts are sold to replace the complete Nintendo 64 joystick (not just the stick, but the whole inner mechanism too), at a lower cost than a new N64 gamepad.

(click to enlarge)

You can purchase a Nintendo 64 joystick online. Each N64 joystick costs around 5 or 6 euros at ebay. You can even get some discount purchasing a pack of some N64 joysticks. The keywords to find these articles through ebay are "N64 thumbstick" (and be sure to perform a worldwide search). How to open a Nintendo 64 controller and replace the joystick is pretty simple. Just remove the screws of the N64 gamepad, remove the old joystick, and put the new thumbstick in its place. And that's it: your gamepad now feels like a new one.

Curiosity: inside the N64 joystick

The installation of a new joystick in a N64 controller does not require to dismantle a gamepad as much as is shown in the following image. On the other hand, I always felt curious about how a Nintendo 64 joystick works and what's inside a gamepad. Will there be springs? Elastic rubber bands? ... Why do joysticks feel loose after some usage?

(click to enlarge)

So I opened the Nintendo 64 controller. The joystick itself just rotates 2 pieces that move 2 gears. The displacement of the stick from the central point is calculated according to the position of these 2 gears. There is just 1 spring that makes the joystick come back to the central point (so the N64 gamepad does not have a spring for each direction, as some pads or buttons do). Such single spring is placed in the middle of the mechanism (so you cannot see it in the image), but it really pulls both gears towards the center.

Video in!

How to repair a PS2 controller

How to open a PS controller is really a quite simple task. But we tend not to open PS controllers because we don't know how, or because we fear breaking the gamepad if we open it. We fear that the pieces inside the controller could be dismantled and be hard to place again in their original positions (which really happens with many other things).

(click to enlarge)

This isn't just a tutorial. It states that you can open a PS controller, without fearing the feelings of "What if I open the controller and leave it worse? Now it's so-so, but not bad after all". So I have attached the photographs that I have taken of my own open controller.

As they don't sell spare joysticks for PlayStation controllers, we can just swap the PS left joystick and the PS right joystick, because the right stick is less used, and it's often in a better condition (while the left stick usually loses the bump texture, which enhances the grip of your thumb).

(click to enlarge)

(click to enlarge)

To open the PlayStation controller just remove 5 simple screws with a Phillips screwdriver (a cross-point screwdriver). The PS joysticks are attached without any weird system or screw: the sticks just fit like Lego blocks. This can also be useful to replace worn out buttons by the buttons of a broken irreparable controller that we could have laying out there.

Nevertheless, there is just only a situation in which we won't be able to mount again the open controller, as it happened to me: if your housemate (a member of this blog too) sits on the bed where you put the screws, spreading them through the floor and losing them...

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