Monday, December 17, 2007
We'll probably first see S3200 used with storage devices like external hard disks and optical drives. Eventually, they hope it will be adopted by consumer electronics manufacturers and used with home entertainment products. The new spec will let consumers connect HDTVs, set-top boxes and computers via coax cable with distances more than 100 meters.
Even though many motherboards are designed with a FireWire port, all include several USB 2.0 connections. With the huge success of USB and the expensive FireWire royalties, unless consumers see a big advantage like better audio and video performance, I think FireWire S3200 will have difficulty becoming as common as USB. Maybe people will understand that FireWire was specifically designed to be used for high speed streaming data and is ideal for a hard drive moving large chunks of data, like video. USB was originally designed for low bandwidth, low latency peripherals, like mice and keyboards. It allocates data bandwidth in inverse proportion to demand, so for example, mass storage gets whatever's left after mice, keyboards and tablets have had their share.
Here's a little more technical information on the topic. The USB 3.0 spec claims transfer speeds up to 10 times faster than USB 2.0, but the real world throughput of FireWire S3200 and its peer-to-peer technology might be better because of the overhead caused by USB's host/client technology. FireWire uses a double-simplex architecture, so for example, with the original FireWire speed of 400 Mbps, the actual aggregate speed is 800 Mbps. USB 1.0/2.0 uses a half-duplex architecture and 10% of its bandwidth is reserved for host commands. There are more delays inserted between TX and RX packets while the host and target devices' transceivers switch directions, wasting several microseconds each time. However, FireWire S3200 might become irrelevant because USB 3.0 is suppose to be 4.8 Gbps using double-simplex fibre, which is faster than S3200 on raw speed and finally gets rid of USB1/2's half-duplex overhead.
Thursday, December 13, 2007
- an idea abstract
- executive summary
- final business plans
Product or Service Description:
Amplio Audio is in the Home Theater Personal Computer industry with an exclusive focus on the audio component of the Home Theater experience. Amplio’s product combines the functionality of a soundcard, A/V receiver and amplifier into a single device, providing consumers with an affordable, audiophile quality listening experience.
Customer Definition: Their Needs - Your Solution:
Our target customers are audio/video enthusiasts who use their personal computers (PCs) to play music, watch live TV, movies, and other content as well as to control and manage their media libraries. Amplio’s products provide customers the best possible audio for their media systems through a direct digital interface to their audio data complemented by a world-class amplifier system.
Market Description, Size and Sales Strategy:
The primary market Amplio Audio hopes to attract are relatively young, technically-savvy, Internet connected North American males with some disposable income. Secondary markets will include the same profile except woman and international markets and professional A/V installers and businesses or educational institutions that purchase presentation equipment. Using the market buildup method to analyze our potential market, we determined the size to be approximately $69 million. Customers will be able to purchase our products directly from Amplio Audio’s website. This is the most effective channel based on our customers preferred way to purchase electronics and computer related products.
Competition: In this section identify possible competitors.
Amplio’s products are designed to compete with the high end of their target market while selling for significantly less than current offerings. This market is currently served with a combination of products from several manufacturers, none of which are designed specifically for home theater applications.We have until January 31, 2008 before the judges look at our idea abstract, so we will probably make modifications before that time. Feel free to leave a comment if you have any suggestions on ways we can make improvements.
Tuesday, December 11, 2007
The consumer electronics press likes to make a big deal about the HD format war between HD DVD and Blu-ray. Does anybody really care? Most of my friends don't even seem to know either exists. They seem quite content with their DVDs. I thought their lack of interest was because of the confusion created by the choice of two different systems and apparent changing of alliances from the major movie studios, but most haven't even been paying attention to any of that news.
For those of us that do pay attention, why not just use both formats, especially if you use an HTPC. Back in September I wrote a post about the LG hybrid drive that supports both HD DVD and Blu-ray. Actually, I first wrote about these way back in May, but I was more excited about LG's hybrid drive that could also burn Blu-ray discs. LG also announced that its "Super Blu" BH200 HD DVD / Blu-ray combo player is now available at retailers nationwide for a not so cheap $999.
Well, LG started selling these drives in Japan back in September. They finally showed up in North America toward the third week of October. NCIXUS, a Canadian vendor, was the earliest reliable source. They were offering them for around $275 and they were selling faster than they could get them in stock. For some strange reason they weren't available from US online vendors like Newegg.com and PCAlchemy until a few weeks later and they were priced a little higher at around $300.
Now there seem to be a lot of very satisfied owners who no longer have to worry about which format wins. I will probably join them in the near future. Originally, I was waiting for the drive that included the Blu-ray burning capability. Since the Blu-ray blank media prices are probably going to be prohibitively expensive, I'll probably wait to see if the price of the player-only drive goes down when the burner becomes available. I owned a double layer DVD burner for a long time before the media prices were reasonable. At least you didn't have to pay a premium for those DVD-DL drives. The current pricing for a single 25 GB BD-R disc is around $10 - $17.
Monday, December 10, 2007
Troy/pcCinema decided to quit his own project. I don't know exactly what happened. You could try reading the thread to see if you can decipher it, but it looks like pcCinema just couldn't continue the project. Maybe his injuries (I think injured back) were more than he could handle. Or some people accused him of being a scammer and using his plan to get some donations so he could buy some hardware. I think the former is probably the real reason. There were a few people who were suspicious from the start and they questioned his motives. He didn't handle the criticism very well and probably helped fuel the fires of doubt. After quiting, it would have made sense for Troy/pcCinema to either return the donations or pass the hardware on to people who were willing to help out with the project. He did neither and instead probably pissed off everyone who trusted him, especially greeniquana and binary64.
Meanwhile, it looked like greeniguana and binary64 were going to continue on without him. If they could get their software to work with any hardware, they could really help a lot of people. If you are interested in what they are doing, just respond to the original thread. They also meet every so often on the IRC chat line called "HTPC Project." I think the irc address is 220.127.116.11:6667. The hostname is irc.htpcprojectchat.com. If you search the thread you can probably find the information you need to contact them.
There was also a guy named "renethx" who provided a lot of really good information about hardware. Troy/pcCinema basically delegated all hardware choices to him because of his impressive knowledge. As it turns out, renethx created his own thread with detailed hardware recommendations. I even used it to help select a few components to upgrade our demo HTPC.
So maybe there is still hope. Between renethx's hardware recommendations and the other guy's software scripts, people can find some very good information and potential setup tools to help them build and setup advanced and stable HTPCs.
Friday, November 02, 2007
For those of you who have never heard a HD audio track, here's your chance. They let you download a sample track after you register on their website. Their HD audio was actually recorded using HD recording equipment. This isn't previously mastered stuff resampled into HD, like a lot of music currently on SACD or DVD-Audio. It was recorded, processed and mastered in high resolution.
To check this out, go to their website at iTrax.com.
When you register, they will reward you with a sample track that you can download. If you pick 'Login' at the bottom of the webpage, it will take you to another page that will let you register. I think the website is still in beta, so some things may not be working. Unfortunately, they don't let you download both a 16bit/44.1KHz version and a 24bit/96KHz version for comparison purposes, but at least you can try out the 24bit/96KHz track.
BTW, it sounds really good on our demo system. I'm looking forward to purchasing more of their music. I'm not familiar with most of their artists, so I'm open to any recommendations.
Thursday, November 01, 2007
They explain that an amplifier works by applying a voltage of alternating polarity to a loudspeaker, driving it back and forth to move the air that produces the sound. The amp basically has 2 power rails for the + and - polarity voltages.
With a Class A amp, both switches are on simultaneously to create the required voltage, so they're only about 15% efficient. This means that only 15% of the power is used to drive the speakers. The other 85% is lost as heat. That's why the higher power (over 100W) Class A amps are usually pretty large and include massive heat sinks. With Class B amps, only one switch is on at a time, resulting in efficiencies of around 75%. Unfortunately the trade off is poorer sound quality. Class AB is a combination or compromise between A and B with both switches on simultaneously, but the non-load carrying rail was only minimally on. This improved the sound, but only resulted in efficiencies of about 30% due to switching losses. The Class D amp does this by switching these voltages on and off. With the Class D amps, the switching losses are very low resulting in an overall efficiency of more than 90% with very good sound quality.
Read the article if you are interested in more of the details.
Friday, October 19, 2007
“[Faster] Internet access, new content sources, and the evolution of the PC as a multimedia repository promise to change the features and functionality of devices in the home entertainment center,” says Ross Rubin, director of industry analysis for The NPD Group.
Now I need to update my business plan with some of this informtion.
Wednesday, October 17, 2007
Tuesday, October 16, 2007
Since many people (NCIX) have reported seeing $299 prices for the LG GGC-H20L hybrid Blu-ray and HD DVD reader, which is also capable of writing DVD and CD disc formats, I don't think people will get too excited by the Sony price. For $99 more, you get a hybrid drive that reads both of the HD disc formats and can replace your DVD/CD burner.
Sunday, October 14, 2007
'jdyoung75' commented that maybe people aren't even going to get 24bit/96kHz or 24bit/192kHz soundtracks anyhow because the movie studios will probably only provide at best 24bit/48kHz soundtracks. (Actually, I would probably be satisfied with that, but I'd still like to hear 24bit/96kHz surround and/or 24bit/192kHz stereo tracks for concert performances.) His post implies that since the studios aren't going to include anything with a sampling rate higher than 48kHz, then maybe the problem with PowerDVD downrez'g isn't such a big deal. They're still converting the bitdepth from 24bit to 16bit and I'd like to hear them in 24bit. He referenced an article that appeared in EngadgetHD that said the real reason is because of storage space. There isn't enough space to include the uncompressed high resolution audio. But that's why they use lossless compression like Dolby TrueHD and DTS-HD MA to give you the same high quality using less space. These losslessly compressed HD tracks should still maintain the same resolution of 24bit/48kHz or higher (if available).
Just to give you an idea of how much storage space you need for uncompressed HD audio files, take a look at the following chart:
|Bit Depth||Sample Rate||# of channels||Bit Rate (Mbps)||File Size for 1 minute||File Size for 90 minutes|
|16bit||44.1KHz||2 (stereo)||1.411||10 MB||900 MB|
|16bit||48KHz||2 (stereo)||1.46||11 MB||990 MB|
|16bit||48KHz||6 (5.1 surround)||4.6||33 MB||2.9 GB|
|24bit||48KHz||6 (5.1 surround)||6.9||49.5 MB||4.35 GB|
|24bit||48KHz||8 (7.1 surround)||9.2||66 MB||5.8 GB|
|24bit||96KHz||6 (5.1 surround)||13.8||99 MB||8.7 GB|
|24bit||96KHz||8 (7.1 surround)||18.4||132 MB||11.6 GB|
|24bit||192KHz||2 (stereo)||9.2||66 MB||5.8 GB|
As you can see, these HD tracks take up a lot of space. However, those numbers are for uncompressed audio. Don't get confused by the way they measure bit rate and storage size. When calculating the bit rate they refer to million bits per second (divide by 1,000,000) and for storage requirements, they refer to megabytes (divide by 1024 a couple times and also multiply by 8 bits to get a byte).
I don't know exactly how much space we'll save by using the losslessly compressed codecs. The only information I could find regarding the efficiency of these codecs was from this FAQ for Dolby's TrueHD. If I'm interpreting this correctly, with a 24bit recording, they achieve compression ratios of about 2 to 1, for a file size savings of about 50%. So we might be able to store 90 minutes of a 24bit/96Khz 5.1 surround sound track in 4.3 GB of space.
Since HD DVD has a storage capacity of 15 GB for single-layer and 30 GB for dual-layer discs (and 51 GB for single sided triple-layer discs); and, Blu-ray's capacity is 25 GB for single-layer and 50 GB for dual-layer, you'd think they'd have enough space at least for one of the losslessly encoded HD tracks.
Friday, October 12, 2007
My first click was on Odessa Philharmonic Orchestra. This is really beautiful music. It's a live performance of Tchaikovsky's 5th Symphony at the Musikverein in Vienna from March 25, 2001 by the Odessa Philharmonic Orchestra, Hobart Earle, Conductor. Winner of the "Best Classical Album" Award at the 2002 Just Plain Folks Music Awards. Here's a link to the CD. Hope you enjoy it.
Friday, October 05, 2007
The Teleportation Tweak is the phenomenal new product from Machina Dynamica. The Teleportation Tweak is an advanced communications technique discovered and developed by Machina Dynamica for upgrading audio systems remotely -- even over very long distances. The Teleportation Tweak has a profound effect on the sound and is performed during a phone call to Machina Dynamica; the phone call can be made via landline or cell phone from any room in the house. The tweak itself takes about 30 seconds.
Remarkably, the Teleportation Tweak is independent of distance and signal transmission medium and will work anywhere in the world. The "signals" transmitted over the phone by Machina Dynamica remain robust even over great distances. It is not necessary for the system to be ON at the time of the telephone call; however, if A/B comparison of the Teleportation Tweak before and after the call is desired, the customer's audio system should be turned ON and warmed up prior to the call.
The effects of the Teleportation Tweak are instantaneous and the improvement to sound quality will be audible immediately. The Teleportation Tweak excels in 3-dimensionality, lushness, inner detail and air. Bonus: The picture quality of any video system in the house will also be improved - better color and contrast! Customer should pay via Paypal or check/MO (payable to Geoff Kait) prior to calling Machina Dynamica via landline or cell phone. Machina Dynamica's Teleportation Tweak $60.
Amazing huh! And you probably thought the Bedini Quadra-Beam Ultra Clarifier was the most phenomenal tweak available. This one, which was also from another comment in the Slashdot post, takes the cake so far. I'll let you know if I discover anything that tops this.
Thursday, October 04, 2007
New! Featuring four beams, nearly twice the rotation speed and improved timing processing, the Quadri-Beam is an ultra cool disc treatment. This patented process reduces the noise floor allowing far more information to be retrieved from the disc. It also works great on DVDs, giving you a picture that is brighter, sharper, crisper and cleaner. For those of you who have never experienced the sonic benefits of the Bedini Clarifier, it significantly reduces high frequency glare and increases retrieval of information, enhancing dynamic range. Detail and resolution are improved dramatically.
This is one of the great audiophile tweaks listed on the website that I linked to in my previous post. I also discovered this after reading some of the comments from the Slashdot post. I couldn't resist sharing this.
"…way better than anything I have heard…Simply put these are very danceable cables. Music playing through them results in the proverbial foot-tapping scene with the need or desire to get up and move. Great swing and pace – these cables smack that right on the nose big time."
"…simply way better than anything I have heard prior to their audition."
It looks like he made a similar offer to John Atkinson of Stereophile Magazine, but it was never accepted. Unfortunately I can't find any specific information on that challenge.
I probably shouldn't write anything that either pokes fun of or challenges the credibility of these writers, since who knows, maybe I'd like them to evaluate or review one of our products in the future. Oh well... these outrageous claims drive me nuts and I really enjoy it when someone challenges their credibility.
I first discovered Mr. Randi's offer on Slashdot. I don't know if I've ever made this clear, but I'm not a big fan of some "audiophile" tweaks. Especially since I think a lot of them are just snake oil. Here's a list of some pretty humorous products.
James Randi has an international reputation as a magician and escape artist, but today he is best known as the world's most tireless investigator and demystifier of paranormal and pseudoscientific claims. Randi has pursued "psychic" spoonbenders, exposed the dirty tricks of faith healers, investigated homeopathic water "with a memory," and generally been a thorn in the sides of those who try to pull the wool over the public's eyes in the name of the supernatural.
Wednesday, October 03, 2007
What's interesting to me is they are releasing this album with no record label backing. In this Audioholics article, they mention "As one of the few innovative music acts with any significant degree of mainstream popularity, Radiohead has apparently decided on an equally innovative approach to music sales: boot their recording label, give the music away, ask only for a donation, and only ask a fixed price for value added content." They go on to explain how this differs from other artists who create their own independent labels, but still use the same basic business model. By providing the album as a download, not only do they avoid the recording industry's unfavorable contract terms, they also avoid all the middle men like iTunes and other online music retailers. And since they are offering the downloads without DRM and almost for free, they eliminate any of the incentives that contribute to online piracy. The Audioholics article is really about how Radiohead and other artists are leaving the traditional recording industry. They include a copyright statement from Robert Fripp to explain what they mean by the industry's unfavorable terms.
I still don't know if they will offer the tracks in a lossless format. I doubt it, but that would be really great. Especially if they could somehow show that the lossless tracks generated more income than MP3s. This would encourage other artists to also offer lossless as an option. Since they are appealing to "audiophiles" by offering their music on vinyl, they should consider offering lossless tracks for download and maybe even 24bit/96kHz for download or on a disc format. Someone on this AVS Forum thread mentioned when they emailed the support contact listed on the Radiohead website and asked what format and bitrate they planned to provide, the response was 'MP3'. This makes sense, since they are letting us name our own price. I'd love to pay $15 or $20 for the album download in a lossless format especially if it was available as 24bit/96kHz tracks.
Wednesday, September 19, 2007
More from the press release: "USB (Universal Serial Bus) 3.0 will create a backward-compatible standard with the same ease-of-use and plug and play capabilities of previous USB technologies. Targeting over 10x performance increase, the technology will draw from the same architecture of wired USB. In addition, the USB 3.0 specification will be optimized for low power and improved protocol efficiency. USB 3.0 ports and cabling will be designed to enable backward compatibility as well as future-proofing for optical capabilities."
Some people are saying USB 3.0 will finally supplant FireWire. If it really delivers the 300 Mbytes/second or 4 Gbits/second theoretical speeds it obviously leapfrogs the 400 Mbit/second performance of FireWire 1394a and the 800 Mbit/sec for 1394b and 1394c. If the "Quality of Service" support for HD video also results in a very low jitter interface for audio, USB 3.0 is definitely the way to go. The only advantage for FireWire is cable distance. FireWire's 1394c can work over ethernet cable with speeds of 800 Mbit/second up to 100 meters and USB 3.0 may be limited to only 2 meters. However, it might be a long time before we see any audio interfaces that support 1394c. I've also read that the 1394 Trade Association is reading proposals for a 10 Gbit/second FireWire spec. For more detailed information on this, read this article in EETimes.
It will be awhile before we see any USB 3.0 chipsets and drivers for USB Audio, so this probably won't have any impact on our current development efforts. It would be nice if we finally had an interconnect that was very high performance (meaning it could handle up to 24 or more channels of 24bit/192kHz audio with extremely low jitter) and was available on all shipping PCs.
Tuesday, September 18, 2007
Oh, and you gotta love the models. Kind of reminds me of an American trade show from the '70s.
Monday, September 17, 2007
Open architecture or modularity might work for an audio system similar to the way it has for PCs. Standard components could be available for the power supply(s), PC audio interface, preamp, amp modules and chassis. The preamp would be similar to a PC's motherboard. This is where the source devices would be selected and routed to the amp modules, plus it could include circuitry for analog volume control. The PC audio interface would have all the functionality of the PC's sound system. It would include the interface to the PC using USB or FireWire, along with the DSP, ADC and DAC chips. An amp module would provide the power for one channel or speaker output. Or maybe some manufacturers could design modules that provide stereo pairs at less cost. Amp modules of different power ratings, like 100W, 200W, 400W, etc. could be available, just like we currently can choose hard drives with different storage capacities. These amp modules could also come with integrated power supplies like the ASP Series from IcePower shown on the left. The chassis could be designed with standard layouts and connectors similar to what is currently available for today's PCs. There might be small cases for 2 channel stereo systems, larger 5.1 or 7.1 surround or even huge tower systems that could house enough channels for a sizable whole house audio system. Someone could choose a very basic chassis with a plastic or painted sheet metal skin and save some money, while others could purchase an expensive thick gauge aluminum chassis with a polished finish.
This open architecture approach has a few serious challenges. To be successful, the components have to be designed with standard connectors and form factors. Just like the hard drive's enclosure is designed with a 3.5" form factor and standard connectors for data and power or a PCI card that fits into the connector on the motherboard, has standard heights and widths and includes the backplate to attach to the back of the chassis. It will probably be difficult to get the component manufacturers to agree on standard connectors and form factors unless they are confident there is a large market for these standardized products. In the early PC days, the IBM architecture was very popular because IBM was a well established, respected company. I don't know of any other manufacturer that could have accomplished this level of standardization and there really isn't anybody in the audio industry with that type of clout today. Besides, most of the manufactures prefer to offer their mostly proprietary solutions.
In addition to the open architecture with standard components, there's also modular design. By this, I mean providing specific components for certain tasks. Separate components for the PC interface, the preamp, amp modules, power supplies, chassis, etc. There's also the separate components you can purchase for your home theaters and sound systems. For example, you can buy a CD and/or DVD transport, D/A processor, preamp, and amplifiers. The specialized components usually sound better, look better and cost a lot more than an integrated solution. Amplio's prototypes have been integrated solutions that include the PC interface, DAC/processor, power supplies, and amp modules all in the same chassis. However, some customers might prefer the flexibility of separate modules. We could provide different products like a preamp that combined the PC interface, DAC, volume control, etc., and amps that can be purchased in mono, stereo or multichannel configurations. Two flavors of preamps might let you choose between a 2 channel or 8 channel solution. The combination of an 8 channel preamp and 3 - 2 channel amp modules plus 1 mono amp module would result in a good 7.1 system. Here's an example of an interesting modular design for PCs called the UNI Computer. Maybe we could do something similar for the preamp and amp modules.
If you have any thoughts or questions about modular and/or open architecture design, I'd love to hear from you. Please feel free to post a comment!
Wednesday, September 12, 2007
Tuesday, September 11, 2007
My response just touched on the issue of how the resolution of the audio data is related to dynamic range. There are other factors that come into play, like the tonal effects of high frequency harmonics and phase accuracy. There's also the argument that when an analog waveform is converted into digital data, the higher the sampling rate and resolution of the data, the representation of the original analog signal will be much more accurate. There are also concerns about the quality of the resampling algorithm, etc., etc.
Let me get back to the subject of this post - dynamic range. Dynamic range, when used in audio measurements, refers to the difference between the loudest undistorted sound and the quietest passages. In digital audio, the maximum possible dynamic range depends on the bit depth of the audio data.
To calculate the maximum theoretical dynamic range based on a digital audio bit depth, you multiply the log of the total bit depth by 20.
Dynamic Range = 20 * log(bit depth)
For example, CD audio has a bit depth of 16 bits. A bit is a binary unit, so they are actually referring to 2 to the power of 16, which comes to 65536 decimal units. To be more accurate, we would use 65535 because they use values from 0 to 65535.
When we apply this to the formula above, we get:
DR (16 bit CD) = 20 * log(65535) = 96dB
The maximum theoretical dynamic range for 24 bit audio comes to:
DR (24 bit) = 20 * log(16777215) = 144dB
If it is true that some classical music performances can have a dynamic range of over 110 dB, then it's also possible that an HD movie could also have this large of a dynamic range. Hopefully, there will also be some other musical performances (live or studio) that were recorded in HD and become available in HD DVD or Blu-ray that will also have this high of a dynamic range.
My point is, if the audio data is always converted down to 16 bits, we won't be able to enjoy the full dynamic range available from a high definition audio performance.
Have you ever wondered how a musician can pick out a single wrong note in a complex piece of music? Has anyone told you that you are tone-deaf or have a tin ear? These all relate to a sense of pitch—roughly speaking, the highness or lowness of a sound. It's what distinguishes a soprano from a bass singer and gives each piano key a distinct identity.
Our ability to distinguish pitch is not fully understood, but we do know that it involves some processing by the brain after a sound is perceived. This means tone deafness is not necessarily linked to any hearing disorder. An individual with perfect hearing may still have trouble distinguishing pitch because of how the brain interprets the sounds.
Research shows that several percent of the U.S. population has problems with pitch perception. Studies in twins also indicates that the role of inheritance in deficits in pitch recognition is extremely high, with little effect of environmental experience. Tone deafness appears to stem from nature, not nurture.
Want to test your own sense of pitch? We've developed an online version of the Distorted Tunes Test, a standardized survey in use for over 50 years. In it, you'll listen to a series of snippets from well-known tunes—some of which have been distorted by changing various notes' pitch. Your task is to pick out the incorrectly played tunes.
Give it a shot. I picked 26 out of the 26 snippets correctly, so I must have a fairly good sense of pitch. Most of the tunes were pretty familiar to me, so it was easy to hear mistakes. The test may not be so easy if you are not familiar with the songs.
Monday, September 10, 2007
OK, so maybe this isn't really a prototype sketch, but I thought it was a pretty cool illustration and that readers of the blog might appreciate it. I came across the drawing on Audio DesignLines article "Amazing Hi-Fi' cartoon/illustration from 1950s". It was drawn by Roy Doty for the April 15th, 1958 issue of Look Magazine. Click on the Audio DesignLine article link to download a copy of the original image.
Wednesday, August 29, 2007
Maybe this information will help you figure this out.
Amplifier power is usually given in watts, which is the amount of energy expended in one second (1 joule per second). In electrical terms 1 watt is equal to 1 volt multiplied times 1 ampere. Not sure if that helps here, because this doesn't seem to directly relate to how much sound you can generate with an amplifier. We usually measure the loudness of something using decibels or dB. The dB uses the logarithmic (base 10) scale because that is how our ear/brain perceives sound changes. Theoretically, the smallest change in sound level the human ear can perceive is 1 dB.
The following chart shows the amount of dB per watts ((dBW), which will make it a little easier to relate the amplifier's power rating to the amount of sound it can provide:
As you can see from this chart, an increase of 3 dB results in a doubling of power. So to handle an increase in dB from 23 to 26dB, you will need to double the power from 200 to 400 watts. To be able to notice the next incremental increase in loudness, you would need to go up to 500 watts.
Another factor that we need to consider is -- How loud do you need to go? That depends on your listening preferences. If you normally listen at fairly quiet levels, you don't need a lot of power, but if you like listening to rock music at live concert levels, then you may need a lot. Here's another chart (I love charts) to show how the dB relates to different sound levels:
|Decibel (dB) level||Cause or Effect|
|-80 (p)||Underwater nuclear submarine microphones listening to shrimp chewing on food at 100 meters distance|
|-30 (n)||One human talking 20 miles away (60 db / meter at a distance of 20 miles)|
|-4 to +4 (n)||The ticking of an ordinary wristwatch at 1 meter|
|0 (n)||Beginning of hearing, a mosquito 10 feet away, the ear drum moves less than 1/100 the length of an air molecule|
|10 (p)||Absolute silence, AT&T - Bell Labs "Quiet Room"|
|13 (p)||Ordinary light bulb hum|
|15 (n)||A pin drop from a height of 1 centimeter at a distance of 1 meter|
|30 (p)||Totally quiet nighttime in desert - impossible anywhere near city|
|35 (p)||Anechoic hearing test room|
|50-65||A normal conversation|
|80||Average city traffic noise|
|85||Beginning of hearing damage (8 hrs), earplugs should be worn|
|85-90||Lawnmower, food blender|
|100||Normal average car or house stereo at maximum volume|
|104-107 (p)||The beginning of pain at the most sensitive frequency of 2750 hertz|
|116||Human body begins to perceive vibration in the low frequencies|
|117-123||Home stereo system, a very loud and powerful 200-2000 watts|
|120-130||front row at a rock concert - up to 200 refrigerator size speakers and 50000-300000 watts of clean, full frequency sound|
|125||Drum set - only at the moment of striking, continous level 115|
|127||Human tinnitus (ringing in the ears) begins|
|128 (p)||Human, loudest scream measured at a distance of 8 feet 2 inches, head hair begins to detect vibration, can begin to detect very slow “blast wind” of 0.124 meters/second|
|130 (n)||Marching band - overall level at a distance, 100-200 members|
|132||Eardrum “flex” totally noticeable|
|133 (n)||Gunshot- ear level, may vary greatly to size and type of gun, duration converted to one second, peak level may reach 140-160|
|130-135 (n)||Large train horn|
|135||Human, a slight cooling effect begins to be noticed, from air expansion|
|137||Human body vibration is strong|
|137-140||Human ear all frequencies are painful|
|140||Extremely damaging to hearing no matter how short the time exposure, human throat and vocal cord vibration begins|
|141||Human body begins to feel nausea after a few minutes|
|142||Human body chest pounding is intense|
|143||Human body feels as if someone just football tackled your chest|
|144||Human nose itches|
|145||Human vision begins to vibrate making it slightly blurry, 1-3 degrees|
|148||Human vibration very uncomfortable and slightly painful|
|149||Human lungs and breathing begins vibrating to the sound|
|150 (n)||Rock concert “The Who” two 10 story stacks = 144 double refrigerator sized speakers, actual level reached 120 db at a distance of 32 meters for this normalized reading of 150 db. Continuous level 114-118db (p) at 32 meters|
|158||Human body vibration is violent, nausea becomes more intense|
|153-163||N.H.R.A. Dragsters- 5000 to 7000 horsepower, liquid nitroglycerin fuel, earthshaking at 50 feet, humans find it hard to see, and breathe 140db (p)|
|163 (p)||Glass breaking level, minimum, it is very hard to break glass windows. Many stories come from breaking glass but it is highly variable: it is easier to break if the window already has a crack, is very large or old and brittle and not car safety glass which can flex massively before breaking. An opera singer at 110 db may break a wineglass but it is an example of frequency resonance, and not high sound db level|
|145-165 (np)||Common type of fireworks at professional pyrotechnic shows|
|172 (n)||Boeing 727, 737, 747, 757, 767 cruising at 6 miles high mach 0.84, at the ground (sea level) loses an additional 6 db because air density is only half sea level at a height of 6 miles|
|180.5||Alan Dante reportedly set a new record in the world of in-car bass output by using four Stetsom 7KD amplifiers, 15 Power Master batteries, and a single Digital Designs 9918Z subwoofer.|
|183 (p)||6 p.s.i. Total destruction of all structures, particle velocity (blast wind) is 180 miles per hour. 0.9 miles from Hiroshima atomic bomb and 3.3 miles from 1 megaton nuclear bomb, less 0.1 % object survival|
|190.6 (np)||Richter scale 0 (zero) earthquake|
|190-195 (p)||Human eardrums rupture 50% of time|
|210 (np)||Richter scale 2.0 earthquake|
|215 (n)||Thunder, the largest positive giants. Ordinary thunder 165-180 db. Lightning strike on ocean surface 234db (p) at 2exp-5 newtons per square meter|
|240 (n)||Tornado, Fujitsu 5, energy guess based on 300 mile per hour wind, 1 mile wide|
|257 (n)||Nuclear bomb, 1 megaton (1 million tons of t.n.t.)|
|300 (n)||Hurricane – average, extreme energy is “diluted” by covering 500,000 square miles. Energy = approx. 1000 nuclear bombs a second.|
|320 (n)||Volcano eruption, Tambora Indonesia, 1815, ejected 36 cubic miles. Approximately equal to 14,000 megaton nuclear bombs or a 14 gigaton bomb based on ejected volume, change in megatons times 1.345 equals volume ejected change. If was a nuclear bomb it would create a crater about 12.4 miles wide and 1.33 miles deep. Internal pressure is believed to be about 47 million p.s.i. = 347 db (p)|
(p) = actual Peak pressure meter readings i.e. a force per unit area
(np) = Normalized Pressure used in explosive measurements, blast wind is not included
sources: Ultimate Sound Pressure Level Decibel Table, COPYWRITE WILLIAM HAMBY 2004, National Institute on Deafness and Other Communication Disorders.
Update 9/11/07: new entry for 180.5dB from Engadget post.
So, if you want to listen to your sound system at the same level as a symphony orchestra (I assume this is during a loud passage), you would want amplifiers with enough power to deliver around 110 dB. For rock concert levels, something between 120-130 dB. Most of the time you're probably not going to listen at these levels, especially for those of us who share their dwellings with other people, like wives, children, pets, plants, etc., etc. Maybe an amplifier that can provide 105 dB without clipping would be good enough, since you are probably listening between 85-90 dB most of the time. The dynamic range (the difference between the loudest and the quietest sound) for a good system should be from about 105dB down to maybe 35dB. This gives us a total dynamic range of about 70dB.
Now let's take this information and apply it to choosing the right size amplifier for your loudspeakers (if you like to do things ass backwards - you can also choose the right loudspeakers for your amplifier).
- You need to find the loudspeaker's efficiency or sensitivity specification. This is the sound pressure level (SPL) at 1 watt from a distance of 1 meter, given in dB. My Precise Monitor 10s have an efficiency spec of 88dB/1 watt/1 meter. My Era D5s use those 5" long excursion drivers that provide good bass for a small driver, but they are not super efficient with a spec of 86dB. There are a lot of speakers out there today with higher efficiency, but that doesn't mean they will sound better.
- Subtract about 10db SPL to account for the drop in sound level from the speaker to the listening position. (When you double the distance from the speaker, the SPL drops 6dB. The speaker's efficiency spec is based on a distance of 1 meter, and if the distance between the listening position and the loudspeaker is 2 meters, then the SPL drops 6dB. If this distance is 4 meters, the SPL will drop another 6dB for a total of 12dB. If the total distance is 10' (just over 3 meters) then the SPL will drop about 9dB.)
- Add 3dB for each additional speaker in the room that will be playing music at the same level (so when you do this calculation for a stereo system you simply add 3 dB).
- Next, I need to calculate how much amplifier power is needed to get peak levels to 105dB without clipping.
So I take the difference between the peak level and the loudspeaker value:
105dB - 79dB = 26dB, which gives me the amount of power needed from the amplifier.
- Using the first chart, you can see that I will need 400W of power to get 26dBW.
For my example with the Era D5s, I would get:
86dB - 10dB + 3dB (for stereo music) = 79dB.
Here's a handy dandy dynamic slide rule that you can also use to perform these calculations.
Update 4/8/08: I discovered that Crown has a good article on their website to help you determine how much amplifier power is needed for your loudspeakers.
Tuesday, August 28, 2007
A study by Forrester Research found that 27% of online adults in the U.S. have a home network. One third of all these home networks are now used to stream music, movies, TV shows, and other media throughout the home.
Some of the numbers used in our business plan to estimate potential market size are based upon a typical user who is tech savvy, etc. If the user has a home network, specifically used for entertainment purposes, they are more likely to be interested in a product like ours, as opposed to someone who doesn't. It is interesting to note that one of the biggest reasons given for using their home networks for entertainment uses was for streaming music.
It's nice to know there is an actual study that shows how many people who fall into this category.
Monday, August 27, 2007
- “We have been looking into this problem and are working on a doc that will go into the technical details of what we have found.”
- “Please note that some of what we are seeing is expected behavior, and some of it is not. In certain circumstances Windows Vista will trade off network performance in order to improve multimedia playback. This is by design.”
- “The connection between media playback and networking is not immediately obvious. But as you know, the drivers involved in both activities run at extremely high priority. As a result, the network driver can cause media playback to degrade. This shows up to the user as things like popping and crackling during audio playback. Users generally hate this, hence the trade off.”
- “In most cases the user does not notice the impact of this as the decrease in network performance is slight. Of course some users, especially ones on Gigabit based networks, are seeing a much greater decrease than is expected and that is clearly a problem that we need to address.”
- “Two other things to note. First, we have not seen any cases where a users internet performance would be degraded, in our tests this issue only shows up with local network operations.”
- “Second, this trade-off scheme only kicks in on the receive side. Transmit is not affected.”
Friday, August 24, 2007
Troy, aka "pcCinema" on the AVS Forums, is offering to help everyone out. Troy started a thread titled, "Suppose I make it easy for all the newbies and budget folks?" back on August 16th to first announce his intentions and gauge interest. Troy is a former MCSE Senior IT Consultant who was responsible for the large scale automated rollout of PCs to corporate clients. He specializes in writing scripts or deployment tools that would make building high performance HTPCs easy for every newbie out there. He plans to maintain a website that would provide a list of high quality software and hardware components that have been fully tested for performance and compatibility with the required HTPC applications. Best bang-for-the-buck components would be included to make sure systems built from the recommended hardware list would also be affordable. Whenever, newer more advanced hardware or software is available and passes the necessary testing, the list will be updated.
After the user purchases his components based on the recommended hardware and software list, Troy's scripts would be used to assist with the process of assembling and installing all the hardware and software to create a trouble free HTPC. No more driver or codec conflicts. Finally, HD DVD and Blu-Ray playback will be stutter-free without all the hassles many people currently deal with today to get the correct combination of hardware and software to work together.
It's also interesting to note that Troy doesn't plan to charge a penny for any of his services. Troy doesn't sell any of the hardware or software, the user will have to shop for everything on his/her own. This is something he plans to do out of the goodness of his heart. Actually, it sounds very altruistic (it is), but he's also doing this out of self preservation. Troy explains that he is disabled and unemployed, waiting for Social Security benefits. He says he has nothing better to do with his time and since this is something he is very good at, he might as well do something he enjoys and allows him to be productive.
"It has been good for me to have a purpose again. I actually feel better physically and mentally now that I have this to focus on," Troy writes. "I've said it before that I've been going out of my mind with boredom, etc. I also want to make it good for the volunteers, and the community at large, and not just those that benefit from the plans directly. What's that they say about how people live longer if they have work to do? And the number one killer of retired people... "
Troy is hoping enough people will donate to his non-profit organization to help pay for the latest hardware and software that will be used to test for performance and compatibility with a high quality HTPC.
Interest in his proposal has been pretty positive. Of the 149 responses so far, it looks like more than 95% have been very encouraging. People are even willing to volunteer their time to help build a website (this one was thrown together pretty quickly by someone with the user name "pc1984" to demonstrate what he can do with a content management system (CMS) based website), help with the legal issues regarding setting up a non-profit organization, writing more advanced automation scripts, writing how-to guides and testing systems.
Well, I hope it works out. Personally, I'm pretty annoyed by all the hassles we have to deal with to get an HTPC to play all the high definition formats today. The latest dual/quad core CPUs from Intel or AMD and video cards from ATI or NVIDIA show promise, but sorting out the right combination of drivers, codecs and applications is enough to piss off an experienced HTPC builder. It will be interesting to see where this leads. I'll be paying close attention.
Good luck Troy!!
Wednesday, August 22, 2007
People have reported on the 2CPU forums that network performance is throttled whenever they play audio in Vista. It looks like more of an annoyance that a critical problem. Hopefully Microsoft will respond with a bug fix in the near future.
UPDATE 8/24: more information about this issues discussed in this AVS Forum thread.
Tuesday, August 21, 2007
He explains that the music industry has 2 major problems with high definition audio:
- most fans, retailers and music publishers don't care about HD audio
- those that are interested in HD audio are a small niche scattered across many competing format choices
He's right. If only people knew what they were missing, maybe there would be more interest in HD audio. Some may argue that DVD quality video is also good enough, but the fact that more people are purchasing HD televisions, obviously they must believe there are added benefits to the higher resolution video images. Otherwise, why bother spending a few thousand dollars on a new screen when the standard definition screens are only a few hundred bucks and they work fine for watching DVDs. Now that they own a nice HD monitor, maybe they'll want to match it with a sound system capable of reproducing the audio tracks in all their higher resolution surround sound glory. If they appreciate the improved quality from the movie's sound tracks, maybe they will demand higher quality audio from the artists that provide rock, jazz, classical, etc., recordings.
Constantin says the second problem is really a mess and it is really about how the companies in the music business are competing to control the next popular format(s). The combination of competing media like SACD, DVD-Audio and now HD DVD and Blu-Ray, along with competing encoding methods like DSD or 24bit PCM with compression schemes from either Dolby, DTS, Meridian, etc., etc., AND the DRM methods employed to restrict copying resulting in a variety of hardware incompatibilities have just made the transition to HD audio very difficult.
All of this has created so much confusion with the average consumer that they are more inclined to just wait it out until a clear winner emerges so they don't mistakenly invest a lot of money in a bunch of discs or equipment that aren't supported in the future. Besides, the latest technology is always pretty expensive. Look at the historical prices of any consumer A/V products. Early VCRs were over $1,000, as were the earliest DVD players. Now look at how much they cost. Nobody wants to repeat the mistake of purchasing a $1,200 Beta VCR, like I did.
So, combining these problems we have the old chicken and the egg dilemma. Most people don't care about HD audio, but why should they? There's really not enough HD content out there to make it worth while on any single format. Maybe the big record labels are unwilling to produce albums on HD media until they are confident a secure HD format is popular enough to make it worth the necessary investment. Since most of the current HD audio content is offered through many small niches on either SACD or DVD-Audio and possibly HD DVD or Blu-Ray in the near future, there obviously is no clear winner. From a business perspective, compared to regular CDs and DVDs all of these higher quality formats are huge losers.
Oh, and to add to the confusion... Interactive MVI discs are the CD's newest rivals.
I guess this is one of the reasons why I think PC audio is the way to go. With a PC, you can play almost every media type and encoding method out there. You might not even have to deal with multiple media types if you choose to download from online music stores that offer HD audio albums.
Monday, August 20, 2007
I found this great NRBQ clip on YouTube. I also got a kick out of some of the comments following the clip:
Huzzab: "Before I ever heard these guys, I read two reviews. One was "Good music to get drunk to." The other was "NRBQ doesn't let their exceptional musical ability get in the way of their playing". They certainly didn't let me down! Terry Adams is the devil incarnate."
seantgould: " best American rock and roll band EVER...u can't name any band with keyboard and guitar solos as cool as the Q...sorry, just my opinion"
chalkdavid: "Outstanding. Al and Terry solo their asses off and Joey and Tommy are about the most inventive rhythm section around."
Tuesday, August 07, 2007
In his comments, Mark answers "What is HD Audio?"
Here's the definition the HDSMA prefers - "HD Audio is music or sound that is captured from the acoustic source at or near the fidelity of human hearing."
Mark explains that this means recorded/reproduced sound that has a frequency response of at least 20 kHz and a dynamic range of around 124 dB or more.
He goes on the say that the only consumer formats capable of supporting HD Audio fidelity are SACD and DVD-Audio. However, most of the SACD and DVD-Audio discs released are not true HD Audio because they are performances that were recorded before HD recording equipment was available. The analog tape equipment is only capable of a frequency response of 18 kHz and a signal to noise ratio of 72 dB, which is equivalent to a sample rate less than 44.1 kHz and a bit depth of 12 bits. Mark explains that even though you re-record it at 24 bit/96 kHz, it won't sound any better than the original analog master tape.
Mark also mentions that the HD in HD Radio doesn't stand for high definition, but is instead something like "hybrid digital." I agree that this is only adding to consumer confusion, especially when you consider that the resolution of HD Radio is only 64 kbps, which is half the bitrate of the worst quality MP3 or iTunes downloads available today.
Personally, I think the marketers have really screwed things up. It probably started when the marketing folks at Microsoft referred to the quality of their WMA encoder as "CD quality" when the bitrate was set to 128 kbps. The marketers probably know that if this kind of thing is repeated enough people will just accept it as fact (hmmm, that sounds familiar). Other companies simply play along. Now MusicGiants refers to their losslessly compressed tracks, which are really CD quality, as HD audio to distinguish it from the lossy encoded tracks available from the big music services like iTunes. Their 24 bit/96 kHz tracks are now referred to as "Super HD Audio". According to Mark, MusicGiant's "Super HD Audio" isn't even HD Audio because it was re-purposed from the original analog master tapes instead of recorded with actual HD equipment.
I have listened to 24 bit/96 kHz recordings (both 2 channel and 5.1 surround) from MusicGiants and they do sound better than the same recordings that I already owned on CD. However, I haven't had a chance to listen to the HD Audio offered by AIX Records. I first read about Mark (Dr. AIX) last Winter and am still waiting for them to launch their itrax.com website, which will offer HD Audio downloads. I thought their website was going to go live in June. I wonder what is holding them up... Anyhow, I am looking forward to hearing what Mark calls True HD audio. Hopefully they will have a diverse catalog with a lot of great artists to choose from.
Saturday, August 04, 2007
Wednesday, August 01, 2007
We are still working on the 2nd generation prototype. There are a lot of updates to the original design. The amp modules are higher quality, the audio interface/soundcard section is going to be much improved and we hope to have a new power section. The main things holding us up are:
- The audio interface/soundcard section still uses a FireWire (IEEE1394a) interface. Although, this still seems to be the best solution for multichannel sound, we are searching for a good multichannel USB2 solution. In either case (FireWire or USB2), we have a lot of work to do before completing the drivers and the control panel applet.
- We are still waiting for a couple of key vendors to finish the development of their high quality (audiophile grade) switch-mode power supplies (SMPS). A SMPS will be a much more practical solution for a multichannel system. Linear supplies with adequate power will be very large and heavy and we'd like to design chassis' that weigh a lot less than 40 lbs and are smaller than a 1 drawer filing cabinet.
Saturday, July 28, 2007
Thanks for the flashback, Rocky!
Friday, July 27, 2007
Friday, June 22, 2007
Like a lot of casual fans of reggae, I like music from Bob Marley, Ziggy, Peter Tosh, Third World, Jimmy Cliff, UB40 etc, but I'm not as familiar with some of the lesser known reggae musicians. Thanks to our friends at Sonific, I found a reggae artist that seems to have slipped through the cracks of my reggae music universe. The latest SongSpot (I know, I've neglected this for awhile) is the song "Fight to the Finish" from Lee "Scratch" Perry. His biography sounds interesting: "Some call him a genius, others claim he's certifiably insane, a madman. Truth is, he's both, but more importantly, Lee Perry is a towering figure in reggae -- a producer, mixer, and songwriter who, along with King Tubby, helped shape the sound of dub and made reggae music such a powerful part of the pop music world."
Monday, June 18, 2007
I haven't really been spending much time researching this, because we are focusing on the audio side of things and video is definitely out-of-scope at this time or our project will never get finished.
Anyhow, I came across another Engadget article (I haven't read other blogs for quite a while, so this is maybe a little dated) about MSI's Luxium external graphics solution. The Chinese translation isn't very clear, but most of it makes sense.