Here's an article from Electronic Design that talks about the advantages of running a Class D amp when compared to other amplifier designs with regard to power efficiency.
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.
Thursday, November 01, 2007
Friday, October 19, 2007
Report Shows More Home Theater Owners Want PC Integration
A recent study by The NPD Group found that 17 percent of consumers are interested in accessing PC content from their home entertainment system (25 percent for consumers with a home network).
“[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.
“[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
Michael Fremer Takes the Million Dollar Challenge
Last Thursday, I wrote a post about James Randi's offer to pay anyone $1 million if they can prove that a $7,250 pair of Pear Anjou speaker cables sound different than their Monster Cable equivalent. It looks like Michael Fremer, a Stereophile Magazine writer, has decided to take up the challenge. To learn more, read this post in Gizmodo. This should be fun.
Tuesday, October 16, 2007
Sony BD-ROM Drive
I read another article today that mentions Sony plans to sell a Blu-ray disc reader for the PC aftermarket in early 2008. They plan to sell the drive, which will not include any writing capability for any disc format, for under $200.
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.
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.
Download & Install The New Vista Service Pack
This post is just a link to the instructions. Not sure if I'm willing to go through this hassle to get the service pack myself, but you are welcome to give it a try. I think I'll wait until the official release.
Sunday, October 14, 2007
How Much Storage Space Will I Need For HD Audio
I've been following several threads (including this AVS Forum thread) that talk about how the audio tracks of an HD DVD or Blu-ray movie when played on your HTPC using PowerDVD Ultra are downrez'd from 24bit/48kHz to 16bit/48kHz because of copy protection issues. I think they say you cannot pass the full resolution digital audio of protected (flagged) sources unless you have a protected path. The protected path is all part of the solution that makes it impossible to copy high resolution audio and video using DRM schemes like AACS for audio and HDCP for video. It seems PowerDVD is trying to comply by just converting every audio track down to 16bit/48kHz even if the tracks are not flagged to be protected. I also thought this rule only applied to digital audio and not analog audio. Nobody seems to have a complete handle on what's really going on here, but I did read that Microsoft and Cyberlink (the developer of PowerDVD) are trying to work together to get this resolved. Hopefully they'll come up with some solution so we can listen to the audio tracks from these discs in all their high resolution glory from our PCs.
'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:
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.
'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
Tchaikovsky SongSpot
It's been awhile since I updated my SongSpot. I don't know if anyone noticed, but they've improved the widget so you can now create a playlist of several songs. I did that with my last SongSpot which included songs from Billy Bragg, Elliot Smith and the Barenaked Ladies. However, I think I might prefer the single song approach unless they'd allow playback of full albums, but I doubt that will happen anytime soom. Anyhow, I decided it's time for an update so I went to Sonific's site to choose something. I noticed the list of "Most Played," so I decided to play a few to see what other people think are the best songs.
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.
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
Teleportation Tweak
Machina Dynamica's Teleportation Tweak
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.
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
BEDINI - QUADRI-BEAM ULTRA CLARIFIER
BEDINI/QUADRI-BEAM ULTRA CLARIFIER
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.
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.
Subscribe to:
Posts (Atom)
