USB Sound Card

In this article I will discuss my own experiences about designing a USB sound card, which is the USBDAC. DAC is an acronym for Digital-to-Analog Converter because in a sound card, digital data representing the sound is converted into analog voltage that moves the speaker cone.

My device is loosely based on the PCM2706 reference design. I will not go through the tecnical details but instead concentrate on my own experiences in the design of the device. This is to keep people not familiar with electronics, as well as newcomers to electronics design, interested. You will see that one working product is the result of many failed prototypes. 

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Valve Sound Converter

‘Valve sound’ is not just an anachronism: there are those who remain ardent lovers of the quality of sound produced by a valve amplifier. However, not everyone is inclined to splash out on an expensive valve output stage or complete amplifier with a comparatively low power output. Also, for all their aesthetic qualities, modern valve amplifiers burn up (in the full sense of the word!) quite a few watts even at normal listening volume, and so are not exactly environmentally harmless. This valve sound converter offers a cunning way out of this dilemma. It is a low cost unit that can be easily slipped into the audio chain at a suitable point and it only consumes a modest amount of energy.

A valve sound converter can be constructed using a common-or-garden small-signal amplifier using a readily-available triode. Compared to using a pentode, this simplifies the circuit and, thanks to its less linear characteristic, offers even more valve sound. For stereo use a double triode is ideal. Because only a low gain is required, a type ECC82 (12AU7) is a better choice than alternatives such as the ECC81 (12AT7) or ECC83 (12AX7). This also makes things easier for home brewers only used to working with semiconductors, since we can avoid any difficulties with high voltages, obscure transformers and the like:the amplifier stage uses an anode voltage of only 60 V, which is generated using a small 24 V transformer and a voltage doubler (D3, D4, C4 and C5).

Since the double triode only draws about 2mA at this voltage, a 1 VA or 2 VA transformer will do the job. To avoid ripple on the power supply and hence the generation of hum in the converter, the anode voltage is regulated using Zener diodes D1 and D2, and T1. The same goes for the heater supply: rather than using AC, here we use a DC supply, regulated by IC1. The 9 V transformer needs to be rated at at least 3 VA. As you will see, the actual amplifier circuit is shown only once. Components C1 to C3, R1 to R4, and P1 need to be duplicated for the second channel.

The inset valve symbol in the circuit diagram and the base pinout diagram show how the anode, cathode and grid of the other half of the double triode (V1.B) are connected. Construction should not present any great difficulties. Pay particular attention to screening and cable routing, and to the placing of the transformers to minimise the hum induced by their magnetic fields. Adjust P1 to set the overall gain to 1 (0 dB). The output impedance of 47 kΩ is relatively high, but should be compatible with the inputs of most power amplifiers and preamplifiers.

For a good valve sound, the operating point of the circuit should be set so that the audio output voltage is in the region of a few hundred millivolts up to around 1.5 V. If the valve sound converter is inserted between a preamplifier and the power amplifier, it should be before the volume control potentiometer as otherwise the sound will change significantly depending on the volume. As an example, no modifications are needed to an existing power amplifier if the converter is inserted between the output of a CD player and the input to the amplifier.

http://www.ecircuitslab.com/2012/04/valve-sound-converter.html

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XM Satellite Radio Vs Sirius for your Auto Sound System Selection

If youre in the market for a new auto sound system you might want to seriously take a moment and consider whether or not you would be benefited by subscribing to either Sirius or XM Satellite Radio. Both of these subscription-based services have something wonderful to offer their subscribers and both of them require specialized equipment in order to operate. This means if you are going to wish to use either service, you will need to have decided which service before you have your auto sound system installed.

It really doesnt matter which of these you choose they each have different features that will appeal to a wide variety of audiences. You will find some wonderful competition among the two not only by way of music radio but also talk radio. If you really love talk radio you really need to subscribe to one of these in order to find a treasure chest of talk radio gems. You will find everything from the mundane to the controversial. From Oprah to Howard Stern exist in the realm of satellite radio, which seems to not only be catching on but also here to stay.

It has been commented on many times that XM Satellite Radio has a strong lead when it comes to subscriptions. This is very true but you should also keep in mind that the new subscribers seem to be leaning more towards Sirius for their satellite radio rather than going with the traditional favorite. Ive checked out the line up and cant see that one has much of a clearly defined lead over the other so I cant give a definitive reason for the massive new subscribers to Sirius or even the phenomenal lead that XM Satellite radio is currently enjoying. Regardless if this is something that might interest you, you really should check out each website and decide for yourself which, if either, is more appealing to you as well as whether that appeal is worth the investment and the monthly subscription fee.

I will say this however: XM Satellite Radio for the moment seems to have much better toys to offer consumers. That being said, Im actually quite surprised that the vast number of new subscribers are going with Sirius rather than XM. Of course, being the gadget geek that I am, I am basing that surprise solely on the fact that XM seems to have much better toys. At the moment XM is offering some really cool gadgets that double not only as XM Satellite Radio receivers but also offer GPS functionality and navigation assistance and controls. Some of these devices even go one step further and play DVDs, CDs, MP3s, among other things.

Believe me, Sirius has a lot to offer its customers as well, Im simply thrilled over select items that can be found at XM that I really havent seen adequate competition for elsewhere. On the level of music, both seem to carry similar genres, lineups, etc. The same holds true for the Talk radio line up. The only major difference I am finding between the two are the gadgets. Even the prices are rather competitive with one another. I see only one other major difference and that is the fact that Sirius offers a lifetime membership that cost about the same as the five-year plan from XM Satellite Radio. The thing to remember however is that the lifetime membership is for the lifetime of the device not the subscriber.

I should also point out that opting for satellite radio more than likely will not eliminate your need for a new auto sound system it may however pose certain requirements for the type of sound system you will be able to choose. One thing I have noticed with both companies is that there are plenty of devices from which to choose. You will have your hands full selecting the right equipment for your auto sound system upon which to enjoy the wonderful sounds that satellite radio will bring to your ears each and every day.

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Top 5 Reasons for a New Auto Sound System

If you are a fan of David Letterman, Im sure youve seen and heard his nutty and often hilarious top 10 lists. He has become famous for them and they have been often imitated but never quite aptly duplicated by many around the world. I have no intentions of trying to claim or ever hope to be as funny as Letterman but I would love to create a top 5 list of why you need a new auto sound system. The sad part is that some of this may ring true for many, if not, I bet it will at least make you smile.

5) You really hate your neighbors and secretly hope that enough loud, late night thumping from your car will convince them to move. Admittedly not the kindest reason for the need of a new auto sound system but if youve had some of my previous neighbors I am fairly certain that it isnt too bad of an idea. Just be careful not to shake too much or they may be leaving part of their automobiles behind.

4) Because you saw it on Ebay and like Weird Al Yankovich you just cant seem to refuse when it comes to last minute bargains in the worlds largest garage sale. The truth of the matter is that Ebay can be an excellent resource as far as auto sound systems go. It is important however, to remember that you really need to hear the system before you spend your hard earned money buying it and a lot of time and/or money on the installation of the sound system you select. For that reason Ebay may not be the best choice for your particular needs.

3) Because youre tired of crummy speakers that seem to play static more than music and make more popping and snapping sounds than your old fashioned popcorn popper. Speakers are often only a small part of how your sound system runs. Chances are if you are currently having speaker problems an entirely new auto sound system is going to be in order to insure that all the problems are fixed and solved to your complete satisfaction.

2) Because your Aunt Ethel who has cataracts has a better auto sound system than you. Believe me I know this one stings a little, especially when it hits home. We all hate to think that someone that is older has a more technologically hip and sound product than we do. We often like to kid ourselves into thinking that we live on the cutting edge of technology when that is probably far from the case. Aunt Ethel probably has the kicking sound system she does so that it can be heard without the assistance of miracle ear so keep that in mind before you pull all of your hair out.

And the number 1 reason you should get a new auto sound system is that the 8-trac went out of fashion long before your first child was born. Even though youve clung to the past, it has finally met its limitations of usefulness and it is time to move along and embrace the wonderful world of modern technology and what it can mean to you and the time you and your family spend riding in your vehicle. Hope you had a great smile for the day!

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Auto Sound Systems for the Budget Minded

Despite popular belief, it is quite possible to get a great quality auto sound system even if you are operating on a limited budget. I completely understand your skeptical glances and the comments and grumbles that being on a budget means different things to different people. I can tell you without a doubt that you can get a really nice sound system for your car, truck, or SUV even if your budget is less then $300.

There are several things you can do as a savvy consumer that will help drive the price of the wonderful sound you seek to a bare minimum if you use a few tips, tricks, and techniques, in order to do so. First of all, the competition in this market is fairly fierce. As a result of that you will find that prices tend to be pretty competitive from one shop to another and that your best bargains are usually going to be found online. Search around online and find the absolute best bargain you can find on the auto sound system of your dreams.

Once youve found the lowest online price, get on the phone with local retailers. Many local stores understand the need to compete on a much larger scale. As a result they are often willing to match prices and even through in perks such as installation or freebie upgrades in order to sweeten the deal. Once youve gotten a few upgrades from local markets, continue calling around and let them compete with one another for your business. Take into account the value of the freebies and upgrades to you. If you really have no use for the bobble head hula girl then skip that offer and go for the one that offers an upgrade on speakers or an extended warranty thrown in for free. Make sure that the upgrades are really worth something to you. Also consider the value of the upgrade verses the price and go with the best bargain.

Another truth when it comes to purchasing an auto sound system is that you do not have to buy the best known or biggest name brand in order to get a great sound and excellent quality. Spend your money where it matters most to you. Sometimes you are paying for nothing more than the name attached to a product. Im a huge fan of Bose. I love the sound and have yet to find a product that can offer the quality of sound at a lower price. That does not mean I would not jump at the chance to buy an untried brand if the sound in the display equaled the quality of sound I can get with a Bose sound system. In fact, I have held onto an SUV for 10 years because Im not ready to give up my sound system and my truck still runs. A Bose system is not a budget investment, but you can find bargains that are similar and sound wonderful. In other words, dont become a name brand snob if you dont have to.

In reality, there are many discount dealers you can find both online and off that will be more than happy to hook you up with a great set of sound for your car, truck, or SUV at a really great price. It simply takes a little leg and phone work on occasion to find them.

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