Prototype For Sale

I'm no longer in need of my original prototype, so I'm going to sell it as-is or part out the individual components. I plan to post the sale on eBay, Craigslist and some Facebook groups dedicated to audio. When I get a chance to take some photos, I might update this post. If you are interested, feel free to contact me at gregg dot plummer at gmail dot com.

This first prototype consists of a combination of amp modules and a FireWire audio interface in a utilitarian aluminum chassis. I was pretty concerned with overheating because of the 5 high powered amps so I used a fairly thick aluminum to help dissipate any heat. It's also vented at the top, just above the amps and there's a very quiet 120mm fan to blow air out the back. BTW, I worked with a mechanical engineer who did some thermal analysis on the prototype to make sure we dissipated the heat. It was probably a little overkill. My price for the prototype is $825. My cost, not including the considerable amount of time designing, building and testing were about $2,500.

The components included are:

Aluminum Chassis - this includes the 120mm fan, special mounting plates for the power supplies and mounting brackets for the audio interface. On the back is the A/C receptacle with a switch (A/C line cord included) and a 10A Bussman time delay fuse socket. On the front, there's a momentary pushbutton switch that has 2 operation modes. In one mode, the audio interface is powered on while the amps remain off. The other mode switches on the audio interface and all the amps. Not sure if anyone would be interested in this because the layout is designed specifically for the rest of the components. The price for the chassis is $295 $100.

Power supplies - At the time of this design, the only practical choice for the system were linear power supplies. I really wanted to incorporate SMPS (switch mode power supplies), but ones with the characteristics I wanted for this high-quality audio application were not available. I used different amps for the front and rear channels, so the system utilizes 2 different power supplies.

• The power supply for the rear channels includes a 400 VA (115/33 Vx2) toroidal transformer and a Hypex HG power supply. My prices are $65 for the 400VA toroid and $100 for the Hypex HG PS.
• The power supply for the front channels includes a 1000 VA (115/45 Vx2) toroidal transformer and a Hypex HG power supply. These are $100 for 1000VA toroid and $100 for the Hypex HG PS.

Amplifier modules - I used the highest quality Hypex UcD amp modules that were available at that time. This prototype only needed to provide power to 5 channels because, in a typical 5.1 home theater system, the subwoofer is self-powered (channel .1). To each amp module, I attached an aluminum plate heat sink with fancy Neutrik speaker binding posts.

• The 3 front channels - right, center, left use Hypex UcD400AD amp modules. These are each rated at 400W RMS into 4 ohms. Unfortunately, only 2 of the 3 are currently working. The one I was using for the center channel has a faulty component that causes the amp to output a terrible thumping sound. So, I'm including it for free with either of the other working modules. I think it just might need a new cap but I'm not sure and Hypex no longer services this amp. The price for the working UcD400AD modules is $85 each or $165 for the pair. 
• The 2 rear surround channels use Hypex UcD180AD amp modules. They are rated at 180W RMS into 4 ohms. My price for a UcD180AD module is $65 or $125 for the pair.

Audio interface - this is the device that your PC will use as the audio device or soundcard in your HTPC. It was the AudioFire8 and was sold by Echo Audio for something like $750. This is a high quality 8 channel FireWire audio interface typically used for audio recording and mastering. I took mine apart and reinstalled it inside my chassis. A rectangular port is cut into the front of my chassis to access the front of the AudioFire8. I also paid Echo Audio $5000 to write a custom multichannel driver so my device could output surround audio. Since my center channel amp stopped working, I used the AudioFire8's software console to reroute the center channels to the front left and right channels balanced evenly. It's now a working 4.1 system and still sounds great. I can put the AudioFire8 back in its original chassis and sell it for $175. Echo Audio still has drivers on their website that you can download for Windows 7, 8 and 8.1. They are no longer developing audio interfaces and have discontinued further updates so it may not work on Windows 10.

Misc components - A handful of components were included to complete this system. To avoid the loud click that normally happens when you turn on the amps, I added Hypex's softstart module. To connect the AudioFire8 to the amps, there are custom cables with 1/4" TRS connectors. Also included is all the hookup wire between toroids, power supplies, and amps.

UPDATE 2/14/2018: Items that have sold are indicated as such by striking the text. I've listed the remaining items on Craigslist here:

https://madison.craigslist.org/ele/d/diy-amplifier-components/6494593237.html

I've reassembled the Echo Audio AudioFire8 and reduced the price to $100:

https://madison.craigslist.org/msg/d/echo-audio-audiofire8-audio/6494579793.html

I'm also selling an M-Audio FireWire 410 for $75:

https://madison.craigslist.org/msg/d/audio-firewire-410-audio/6494554911.html

AND, I'm selling the 5.1 speaker system that I used to demo my prototype. These are awesome speakers:

https://madison.craigslist.org/ele/d/era-design-5-speaker-system/6476114140.html

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 UcD^TM 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.

More Hypex Announcements

Hypex, the Dutch electronics company known for their high quality class D amplifier technology, sent out a newsletter yesterday announcing a couple new products.

First, they announced a new line of switch mode power supplies designed for use with audio amplifiers, especially Hypex's own OEM series of class D amplifier modules. The first one, the SMPS180, will be available some time this summer ('08).

The second announcement was for their new 2500W (yes, this was not a typo, it is 2500W not 250W) class D module, called the UCD2kW. It will also be available coming up this summer ('08).

Open Architecture

In previous posts I've mentioned that we'd really like to design a product that has the modularity and flexibility of the personal computer. Not the closed or proprietary architecture of the Mac, but the open architecture of the PC. Then people could choose the amp modules, power supplies, case, audio interface (soundcard), etc., that would meet their needs for number of channels, sound quality and budget.

From Wikipedia:

"Open architecture is a type of computer architecture that allows users to upgrade their hardware in all of the computer hardware & components (for example the IBM PC had an open architecture). This is the opposite of a closed architecture, where the hardware manufacturer chooses the components, and they are not generally upgradable (for example the Amiga 500 home computer had a closed architecture).

Open architecture allows potential users to see inside all or parts of the architecture without any proprietary constraints. Typically, an open architecture publishes all or parts of its architecture that the developer or integrator wants to share. The open business processes involved with an open architecture may require some license agreements between entities sharing the architecture information."

I'm not sure if we will ever be able to do this, but it is something I am interested in achieving. I think there is great potential here. It may even turn part of the consumer electronics industry upside down or inside out. Of course, this may not appeal to the ultra expensive, high end, "audiophile" producers and consumers, but I think it would really be great for the rest of us.

What do you think? As a consumer, would you like to purchase a system that could be expanded from 2 channels to 8 channels? Or upgrade the DACs or amplifier modules when a new generation is released? Be able to choose from a variety of case manufacturers to have one that best fits your style?

If there are any reps from manufacturers of amplifier modules, power supplies (the best technology for this would be switching power supplies or SMPS), or sound cards reading this, I'd love to hear what you think about this idea? Do you think it would expand your market, or not? Do you think the technical hurdles for designing your components to meet a specific form factor and use of standard connectors would be too limiting? Maybe someone like Creative would offer a version of their X-Fi that would be compatible -- and like the "Intel Inside" promo, they could have "X-Fi" inside. Of course, we could also have "UCD powered", etc.

So, When Will It Ship?

I've been asked several times about the ship date for our product. I don't have an answer for that, but I can tell you about the changes or improvements we need to make to the current prototype before we are ready to ship a commercial product. In this post, I'll give a general overview of improvements needed for each of these subsystems:

1. the chassis
   
2. power supplies
   
3. amplifier modules
   
4. soundcard section
   a. computer interface
   b. drivers/software
   c. digital/analog section - DACs, ADC, etc.
   

I will provide more detailed information about each of these sections in future posts.

As you can see from the prototype photos, the current chassis is not something many people would want in their living or family rooms, unless they're really into the industrial design style. They actually might look kind of cool in an a loft space or something, but that is sooo 90's :). So we need to come up with a more aesthetically pleasing design. We would also like to minimize the size and weight, and allow for optimal heat dissipation. Fortunately, the internal components are relatively small and don't generate too much heat so we should be able to create a chassis that isn't a monster. We'd also really like to design a chassis that would let do-it-yourself (DIY) people build or upgrade their own systems. Much like you can do with PC today. This means the inside of the chassis would include the framing to mount things like power supplies, the printed circuit boards and amp modules. Ideally, the amp modules would simply slide into slots in the back of the chassis.

The main changes we plan to make with the power supplies for our commercial product will be to replace the linear power supplies with switch mode power supplies (SMPS). The latest SMPS technology designed for audio applications is very promising. Compared to general purpose SMPS, the SMPS designed for audio applications usually have much larger capacitors to provide a larger energy reserve for the faster and deeper current demands. General purpose SMPSs are typically designed for fairly constant loads, so they don't usually have large enough capacitance at the outputs for audio applications and adding capacitance to a general purpose SMPS wouldn't work very well because the feedback circuit doesn't take into account this additional capacitance and the added phase shift and oscillation would make it unstable. The main benefit with using the SMPS instead of the linear supplies is since they operate at a much higher frequency, they can be much smaller and lighter than the equivalently powered linear supplies we were using. Since a SMPS recharges its capacitors about 1000 times faster than the rate of a linear power supply, which needs a fairly large transformer and big capacitors to keep up with the current demand, the SMPS can get by with smaller capacitors.

We are pretty pleased with the amplifier modules in the conceptual prototype. The amp modules we've tested are from Hypex Electronics, a Dutch amplifier manufacturer who has developed a very good reputation for high quality products. There are a few things that can be done to optimize these for our application, which will be done if we decide to use their UcD amps in our commercial products. Since we started this business, we have discovered a few other class-D amplifier modules from other manufacturers worth considering. And there is also the possibility of developing our own class-D amp, but unlikely considering the development costs and time. To accommodate our modular chassis design, we would really like to find an amp module that will fit into a small enclosure. This enclosure would be similar to the case of a hard disk drive. It would protect the circuit components, dissipate heat and would allow for an easy method to insert the amp into the back panel of the chassis. If the sizes were standardized, you could upgrade or replace amp modules when newer, better designs were available by simply unplugging the old amp and replacing with the new. We would also be happy to support more than one amplifier manufacturer. Some of the class-D amp modules have a reputation for being very accurate and transparent to the source. These amps sound great, but if the source material isn't very good, like a poor recording, the flaws are pretty noticeable. Other class-D amp modules might be a little more forgiving of these types of recordings. I guess it all depends on your listening preferences. I think it would be nice to have a choice. Now, if only we can find a few manufacturers to work with us on a design for these standard amp cartridges. Wouldn't it be great to have the options of different amp modules just like you currently have with hard drives or video graphics cards?

The soundcard section is where we have the most work ahead of us. The current unit in our conceptual prototype was designed primarily for pro-audio applications - recording and mixing. There are quite a few components that aren't needed in a music playback or home theater system. For example, we don't need 8 balanced inputs if the audio source is the PC. The analog outputs of the pro-audio soundcards are good and usually sound better than your average A/V receiver, but they may not sound quite as good as the high-end dedicated preamp/processors. Their outputs are designed to be good enough for an audio engineer to monitor a mix, but might not meet the needs of someone that is really into critical listening. Our goal is to design a soundcard that sounds as good as some of the high-end dedicated prepros, but at a much lower cost. We've also got a lot of work to do on the software - both the drivers and the control panel applets for controlling things like volume, channel mixing, etc.

Like I said, we'll cover each of these areas in a little more detail in future posts. Please let me know what topics you would like to learn about first.