Thursday, September 21, 2017

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:

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

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

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

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