Wednesday, January 28, 2009

New Ultraefficient Audio Amplifier Technology

Audium Semiconductor Ltd. (Bristol, England) has raised $8.5 million in a first round of funding. The company claims to have proprietary audio power amplifier technology that requires one-twentieth (1/20) of the power of competitive Class D amplifiers at "normal listening volumes."

This is written on Audium's website:


Today’s audio power amplifiers only achieve optimum efficiency at full output power. Because a typical audio signal has a very high peak-to-average power ratio, amplifiers operate at less than optimum efficiency most of the time.

Audium’s amplifier technology changes all of that by dynamically adapting the DC operating conditions of the amplifier to ensure that it’s always working at peak efficiency.

Benefits include a 20X reduction in power consumption at normal listening levels*, smaller form factor and a saving on heat sinks. What’s more, the Audium advantage increases with the amplifier output power.

*Normal listening level is defined at 70dBC SPL at 1m with a speaker sensitivity of 89dBC/W/m.


Their technology appear to be geared mainly for portable audio, but they do have products with 100W/channel peak power output. The applications mentioned include battery powered MP3 docking station speaker systems and totally wireless speakers for home and PC audio. Obviously, both of these applications would benefit from more efficient amplifiers.

Here's my question: How do they sound?

I can't find any performance specs, other than peak power output and frequency response. No noise or distortion stats. I doubt these are really intended for high fidelity audio.

Tuesday, January 27, 2009

Finally, a Couple Things to Get Excited About

With the state of the economy and all, it's been kind of difficult to keep my spirits up. The nearly daily announcements of layoffs, stock market losses, etc., are a constant reminder of my own serious financial issues. In addition to these challenges, back in December I posted an article about the problem playing HD audio from Blu-ray titles because of PAP and the lack of any standards. I'm not really sure how to classify this problem, I guess it's more of a political or policy problem. There are also technical challenges that I haven't fully solved. For example, FireWire is a good solution for multichannel audio, but fewer and fewer systems are coming equipped with a FireWire connection. Anyhow, none of these factors make it easy to get this business off the ground.

Thankfully, there are a few things that give me optimism. There are two recent developments that really excite and/or interest me. One is the new 32 bit DAC from ESS Technology. The other is the soon to be released switch mode power supplies from Hypex Electronics. I don't have a lot of details to share here, but I can provide a basic overview and will try to get more information and write about it in a future post.

I've written a couple of articles comparing DACs and based upon the specs, it looked like the TI/Burr Brown DACs were best, but ESS actually exceeded all of these with their 24 bit DAC, the ES9008 Sabre. ESS officially announced their new 32 bit DAC around January 5th and I believe demonstrated it at CES 2009 in a private suite by appointment only. The press release claims that the new Sabre32 Reference DAC is the world's best 32-bit audio D/A converter. Using an enhanced 32-bit ESS patented Hyperstream architecture, the Sabre32 further extends the original Sabre Reference's from 24-bit to 32-bit music and raises its mindboggling performance even higher to 135dB dynamic range and -120dB THD. There are 2 versions of the Sabre32 Referernce DAC - the ES9018 8-channel DAC, which is the one we are most interested in, and the ES9012 2-channel DAC. The ES9018 8-channel DAC supports mono, stereo, 4- and 8-channel output modes. These DACs also support very good quality volume control, customizable filter characteristics and advanced jitter elimination capability. To be fair, I should also mention that ESS doesn't claim to have come out with the first 32-bit DAC. I think that achievement belongs to AKM Semiconductor. On December 9th, they announced their 32-bit AK4390 DAC, which is a very nice addition to their line of high quality DACs. However, around the same time as ESS's announcement of their new Sabre32 Reference DAC, they also announced their new Sabre32 Reference ADC, which is the first 32-bit audio A/D converter with an amazing THD of -120dB. Very cool stuff...

Another technical challenge we've been dealing with is the size, weight and cost of high quality linear power supplies. To provide power for 8 channels of amplification requires are very large and heavy torroidal transformer along with the fairly large and expensive capacitors in the power supply circuitry. This becomes a really big problem if you are using 400W or greater amp modules. That is why we've been very interested in the development of audiophile grade switch mode power supplies (SMPS). A lot of electronic devices today, like medical instruments and personal computers, use SMPS technology because of the size, weight and cost savings. However, there are very few choices for affordable SMPSs for audio applications. The biggest problem with a conventional SMPS is electromagnet interference (EMI) and the ability to deal with big changes in load current due to the audio signal amplification. It's easy to design a high quality linear supply for audio applications, but it's a lot more complicated with SMPS. Hypex has been working on this for quite a long time. Awhile ago, I think back in June of '08, they announced the availablity of their SMPS180. Just yesterday, I came across the data sheet for their SMPS400, which I think is suppose to be available in 6 weeks. I haven't had the chance to work with any of these, so I don't know how they sound. Hypex is a pretty low-key company. They don't make products to sell directly to consumers, so you don't get all the usual marketing hype. So it's hard to tell if their SMPSs are something they've made just to satisfy the demand from their OEM customers, or if they are really good. Since it's taken them a long time to develop these, I suspect they are pretty good. The engineers working at Hypex are really dedicated to very high quality audio, so I doubt they would put their names on something that doesn't match the high quality of their amp modules. Here's some useful information from their spec sheet:

"The SMPS400 is a high efficiency Safety Class 2 switch mode power supply specifically designed for use with our range of UcDTM amplifier modules. Key features are high efficiency over the entire load range, extremely small form factor, low weight and very low radiated and conducted EMI. The SMPS400 also features an advanced overcurrent protection which in case of temporary overload simply reduces the output voltage, only when the overload condition remains for a longer time the supply will enter hiccup mode until the overload condition disappears. This feature combined with large electrolytic buffer capacitors leads to the capability of delivering high dynamic headroom power to the connected amplifier. The SMPS400 is optimized from the first phase of design to final implementation to realize the low EMI signature required of the most demanding audio applications."

"Conventional Switch Mode Power Supplies are commonly unsuitable for audio purposes due to poor peak power capabilities and the inability to handle reversed currents generated by Class D amplifiers as a load. The Hypex SMPS400 achieves these things by using an advanced over current protection circuit, a highly efficient 2 quadrant DC/DC converter which is capable of handling reversed currents and has a peak power handling of many times its rated power."

Like I said, I'm excited about this stuff and when I get more info and possible reviews from people who've used these new components, I'll write about it in a future post.

Wednesday, January 14, 2009

Microsoft's Improved Development Process with Windows 7

First, I still haven't installed Windows 7 even though I'm pretty confident the update will take care of the MP3 problem. I'm still holding off on the install because I really don't have time to play around with Windows 7. Just a little too busy.

Anyhow, I came across a comment on an MSDN blog written by Larry Osterman about the changes the Microsoft engineering team has made during the development of Windows 7. They've introduced the "triad," which is a collection of representatives from developers, testing and program managers. All of their work is organized by triads. All three of these disciplines provide input into the process. Larry says, organizationally, the Windows 7 development process is dramatically better. It's a pretty interesting read -- here's a link to Larry's post.

Having worked several years in software development and project management, their new "triad" structure sounds good to me. The triad reminds me of a conversation I had with Dan Costello many years ago. Dan wanted to use a similar organizational structure with his web development company, Acumium.

Friday, January 09, 2009

Windows 7 Beta and MP3 Files

Here's what Microsoft has written in the Windows 7 Beta Release Notes regarding MP3 files:

"When MP3 files are added (either manually or automatically) to either the Windows Media Player or the Windows Media Center library, or if the file metadata is edited, several seconds of content may be permanently removed from the start of the file. This issue occurs when files contain thumbnails or other metadata of significant size before importing or editing them.

To avoid this, ensure that all MP3 files that may be accessed by a computer running Windows 7 (including those on removable media or network shares) are set to read-only. To do this, in Windows Explorer, find the files, right-click them, click the General tab, and then select the Read-only check box. Then back up all of the MP3 files prior to using Windows Media Player or Windows Media Center.

If some of your files have already been affected, you may be able to recover the data by using the Previous Versions feature. To do this, right-click the file name, click Properties, click the Previous Versions tab, and in the File Versions pane select the most recent previous version."

So going through this procedure to select all MP3 files to make them Read-only could be a major hassle for someone with a mix of MP3s, WMAs, FLACs and AAC files. In my case, I have everything organized by artist, albums and tracks. All tracks in an album use the same filetype, but not all albums were encoded with MP3s. Unless you've got your folders organized by filetype it might take a long time to go through a music collection to modify their properties and backup everything.

Since the warning also applies to MP3 files that are stored on network shares, I think I'll hold off for awhile before installing the Windows 7 Beta. While listening to Microsoft's CES keynote, if I recall correctly, it sounded like Steve Ballmer said they were going to open up the beta for the public today (Friday). If you decide to install the Windows 7 Beta, I'd love to hear back from you if you figured out a good way to protect your MP3 files with minimal hassles.

Thursday, January 08, 2009

Windows 7 Beta Available to MSDN and TechNet Subscribers

This is tempting... but, there is one problem that makes me want to hold off just a bit. Here's what's included in the installation instructions for Windows 7 Beta:

To protect your MP3 files:
  1. Before you install this Beta release, back up all MP3 files that might be accessed by the computer, including those on removable media or network shares.
  2. Install the Beta release of Windows 7; download and install the Update to Windows 7 Beta (KB961367) located on this page.
I better check into this a little bit more before jumping into installing the Windows 7 Beta. At this time, it may be more hassle than I need. Many times all compressed audio is referred to as MP3s. I'll need to learn if this also includes WMA Lossless, FLACs or just real MP3s. Since I don't have that many MP3s, it's not as much a hassle, but nevertheless it is something that warrants a little more investigation. I just have never seen this sort of warning for an OS install and I'm really curious why this is needed.

Wednesday, January 07, 2009

Pioneer subsidiary TAD demos HD Audio at CES '09

Sheffield Labs recording legends Bill Schnee and Doug Sax will be demonstrating 24bit/192KHz audio recorded on Blu-ray discs at CES '09 this week. These recordings are suppose to appeal to audiophiles that want better quality audio than CDs or MP3s (duh!!). I'm not sure what they mean by "giving consumers an unprecedented opportunity to experience digital music that rivals 2-channel analog sound," but I'm guessing they are referring to vinyl and/or reel-to-reel tape, which technically, CD already achieves. Yah, yah, I know vinyl has a better frequency response if you can ignore the noise floor, but you need pretty high end turn tables, cartridges, etc. to achieve this.

I'm not sure if this will be an improvement over DVD-A and SACD, but since those disc formats failed, it's worth trying again. It looks like they will be using a music-only format which utilizes Blu-ray disc technology.

Since I don't have any plans to purchase a Blu-ray player, this doesn't really appeal to me. Personally, I prefer just downloading the high res audio from an online music store and storing them on our media server. All my physical discs are stored away in a closet.

Eventually, I plan to purchase a Blu-ray drive for my HTPC and then I'd like to give these a listen. I'd still want to rip the tracks to the server and use my music library software for playing from my PCs.

For more info, click on this article's title and it will take you to the press release.

BTW, I decided not to go to CES this year. Lots of reasons... the economy, tired of big trade shows, better ways to spend the money, etc., etc.