The new THX idea was to ensure that home theater buffs heard the same quality and levels of audio as those sound engineers. Most people now about THX through logos on certified hardware. The implication of buying THX certified gear is that you get that sound mixing room environment. Any home theater enthusiast will know this simply isn’t the case. Simply buying THX certified equipment does not guarantee good sound, there are many other much much more important things that need to be right than the certification on equipment (for example room acoustics). THX certification brings to the table hardware that meets a consistent, minimum set of standards. To get good sound you need to use them in the right way and have good room acoustics.

According to AnandTech article THX Certified HDTVs – Useful or Just Marketing? the THX goal has mutated again. The article tells how the THX certification business works and what it means for TVs. THX tries to define a listening (or, in the case of HDTVs, viewing) experience, rather than just a set of hardware specs. The very act of doing that makes the company somewhat controversial. Since the logo program is a major part of THX’s revenue stream, obvious potential conflicts can occur. What does it mean when THX certifies an HDTV and does it matter anyway? What does the THX mode in an certified HDTV do? Read the article and make your own conclusions. The implications of a THX logo are perhaps stronger than the actual end result.

The theremin is an early electronic musical instrument controlled without contact from the player. It is named after its Russian inventor, Professor Léon Theremin, who patented the device in 1928. Theremins are distinguished by the fact that they are played without the performer touching the instrument. The musician moves his or her hands in proximity to the theremin to control the tone of the sound. I was told that mastering the theremin requires skills and lots of practicing, but only a few instrument provide the unique visual appearance of performance. The sound is quite unique for that instrument. Even if you don’t know theremin by name, you might have heard the sound of it at The beach boys -good vibrations or on the sound offects of some old scifi/horror movies.

The electronics of the theremin consists of two high frequency oscillators connected to antennas. When the player moves hand near the antenna, that changes the frequency of the oscillators, and that changes the sound (frequency or amplitude depending on antenna). Here is a block diagram of theremin from www.thereminworld.com Fred Tells All article.

All DIY persons now interested in theremin instruments can also view Make a Theremin video and check ePanorama.net theremin links.

Many consumer HIFI equipment and other audio signal sources offer only unbalanced outputs. Unbalanced interconnections pick up easily all kinds of noise (especially ground loop noise), so you might want to avoid them everywhere you can.

You can convert the simple unbalanced preamp output to balanced circuit with one of the  following tricks:
- Use a DI box to convert unbalanced signal to balanced microphone level signal
- An audio transformer is a classic way to convert unbalanced to balanced
- Balanced opamp output circuit can convert unbalanced to balanced (more modern approach but more components)

In addition to those there is not so widely mentioned impedance-balanced output option:

1. Figure out the output impedance of your unbalanced signal source. Usually looking at the circuit diagram of the device will tell you that easily. If you don’t have that, you can always measure the output impedance.
2. Pick a resistor that has same resistance as the output impedance of your unbalanced output (as close as possible… preferably within 1% accuracy).
3. Wire the unbalanced output signal to XLR pin 2 (+).
4. Wire ground to XLR pin 1 (ground).
5. Wire that resistor you just selected between XLR pins3 (-) and pin 1 (ground).

Now you have a impedance-balanced output. It is not exactly as good as a real balanced output, but performs pretty close a real balanced output in normal applications. You can use the same idea also with 6.3 mm jacks: signal goes to tip and the resistor to ring. An impedance balanced output with 6.3 mm jacks works as well as an unbalanced output if that is what is needed (just plug in a cable with mono plug).

Impedance-balanced principle has been used some professional electret mics and on outputs of some “budget” mixers! Just by adding one resistor an unbalanced output is converted to impedance balanced output that works very well with all equipment that has balanced inputs.

More information on line balancing and theory can be found at great The Self Site Balanced Line Technology document.

To display manufacturers, this new panel technology is expected to be the next big thing (in addition to 3D). Display manufacturers have been talking about OLED televisions and monitors as “a couple years away” for at least the last half-decade.

Unfortunately, it seems that everything hasn’t worked out too well for OLED. Sony Kills Next-Gen 11″ Display; Manufacturers Hedge on OLED TVs article tells that Sony announced it would halt sales of its 11″ XEL-1 OLED in Japan, where the panel first debuted. Sony’s decision to kill the unit in its home market and reduce the rate at which it’s investing in future OLED TV development has been perceived in some corners as a judgment on the long-term feasibility of OLED technology. In the wake of Sony’s announcement, far too many online pundits have rushed to declare OLED panels dead, dying, moribund, or otherwise abandoned.

I think this case does not yer prove that. Sony OLED case was just proven that people currently don’t want to spend kilobucks on technology that’s not even ready from prime time because LCD LED and Plasma TVs are “good enough” for everyone. Sony XEL-1 is a sub-HD resolution small 11 inch (28 cm) television that cost thousands of dollars and looked pretty ugly, no wonder that it failed. If you are into electronics and want to see what electronics is inside that display, take a look at inside XEL-1 OLED TV display picture.

After this incident we’ll probably see development focus shift at least in short term from large panel sizes to smaller ones, particularly since the smartphone/handheld OLED market. OLED technology will evolve there and maybe some day it will be more ready for the prime time in larger displays. After smartphones the next step would be netbooks/notebook, then laptops and then computer monitors.

Image source:

http://www.logitechsqueezebox.com/product_matrix.html

The first video and the picture below (from that video) shows a downward-propagating negatively charged, stepped leader. The lightning branches out in many different directions, causing one leader to make a connection with the ground, creating a bright return stroke.

After watching the videos it is a good idea to also read how to protect buildings and electronics against lightning damages. K1TTT on grounding and lightning protection highlights the need for single point grounding system. Check also surge suppression links and documents on ePanorama.net.

Earlier some hifi people have built hi-fi stand made out of IKEA Lack side tables, but now the world is ready for 19″ networking equipment racks. Check LackRack home page for more information on how to build your own very cheap 19″ rack system. The page also tells that also Ikea LACK coffee table and Ikea ODDA night table have right dimensions and can be easily converted to cheap 19″ racks.

Image source: http://wiki.eth-0.nl/index.php/LackRack

In earlier blog post there was information that Ayre DX-5 bluray player was a modified Oppo BDP-83 blueray player. The repackaged device with new power supply changed the price from $500 to $10000.

Now there is another similar case. Now it looks there is even less modifications.

AV Rant #163: Bacon Wrapped Vegan blog posting says that Lexicon BD-30 looks like Oppo. Audioholics article Oppo on the Inside, Lexicon on the Outside shows that inside Lexicon BD-30’s beautiful chassis there is Oppo BDP-83. The article says that according to the reps at the show, Lexicon had merely taken components of that player and tweaked them to make it their own – adding technology and making improvements to what was a good basic building block. What a load of hogwash. The article claims that Lexicon actually put a full Oppo BDP-83 INSIDE of a chassis, slapped a label on it and is shipping it for $3000 more. Don’t take our word for it, however, check out these pics. Where they went wrong, however, was when they simply lifted the Oppo BDP-83 player and threw it into their own chassis without making any performance enhancing modifications – despite claims to have done just that. What they’ve done doesn’t seem to even begin to justify the exorbitant price markup

We live in a world where everyone is building products with other peoples parts. It is just not possible to design and manufacture many electronics devices (even very possible) from “ground up”.
For most companies it’s simply not cost effective to produce their own DVD / BD players or other very complicated digital audio/video device. So the high-end manufacturers that make this kind of devices need to take some shortcuts and use ready made components. What they are now doing on those examples doesn’t seem to even begin to justify the exorbitant price markup. Has high end industry become to state where High End is just repackaged consumer electronics with huge price markup?

Differential video amplifiers have a limitation on their input voltage range which gives some limitations how much common mode signal those circuits can tolerate. If the ground potential difference is more than few volts, then operational amplifier based isolators don’t work effectively. Too high voltage difference can cause problems from very distorted video signal to damaged differential video amplifier. If the voltage difference is a substantial proportion of the DC supply voltage of the amplifier, you will probably have trouble using an amplifier alone.

It is a good idea to measure the voltage difference before using differential video amplifiers to be sure not to damage them. Measuring can be done using a multi-meter (check using both AC and DC ranges) or better using a scope earthed to the mains supply, and put the probe on the earth connection of the incoming video cable. If you many potential difference which are many volts, then you have quite probably something wrong in the grounding of the building and you should consult a qualified electrician to check and correct this potentially a dangerous problem

Image source: http://www.edn.com/archives/1997/050897/10di_06.htm#Figure%201

Look also: http://pdf1.alldatasheet.co.kr/datasheet-pdf/view/136144/MAXIM/MAX9546.html