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opc 20th September 2011 01:55 AM

"The Wire AMP" Class A/AB Power Amplifier based on the LME49830 with Lateral Mosfets
4 Attachment(s)
A new run of these boards is now available! Please see the following thread for details:

Hi Guys,

There's a new addition to "The Wire" series of projects I've been working on lately.

It's push-pull amplifier based on the LME49830 front end which drives a pair of ACD101NDD and ACD103PDD lateral mosfets. It's immensely versatile in that you can run essentially any rail voltage from about +/- 10V up to about +/-90V on the mosfets and get anywhere from 1W to 400W of output depending on the load and the rails. This is an amp that can be tailored to any situation.

You can also run the amp in class A, class AB, or class B if that's your thing.

For the input, you can run either fully balance, or with just one 0R jumper it can be configured for SE input. You can run the amplifier AC or DC coupled. There are separate supply options for running the LME49830 on higher rails than the mosfets which improves efficiency and allows for a good regulated supply for the front end. Alternatively, with a pair of 0R jumpers, you can run just a single +/- supply for both the LME and the mosfets.

The board is small enough to fit pretty much anywhere, and all you need to provide is the power supply and the heatsink! I've even got an optional regulated supply board for the LME section.

I've attached the schematic, the Excel worksheet to calculate power outputs and rails, along with the layout and a BOM.

The PCB will be a 3 layer design with a ground plane in the middle and signal routing on either side. The LME has its own heatsink and the two mosfets are mounted on a user supplied sink off the end of the board. The board measures 2.45" by 1.6" and has all the required mounting points.

I will also be running a kit with this that includes all of the parts required to build a complete amplifier. All the user will need to supply is the main heatsink and the power supply.

PCB's are going to be $12 per channel, and a full kit including all 0.1% thin film resistors, and the best caps available for this application will be $78 per channel. I've attached the price list for the amplifier kit which contains all the details.

There will be 50 boards made available, and it will be first come first serve. Please post here if you're interested in a just a board, or a board and a kit, along with how many of each. Any technical question are welcome as well!

Measurements to follow!

EDIT - 27/05/2012

The schematic and layout below are incorrect. For the updated information, along with the assembly guide, please see this post:


opc 20th September 2011 02:30 AM

10 Attachment(s)
Attached below are the measurements for the prototype that this project is based upon.

I ran a worst case test setup with +/- 40V rails on both the LME and the mosfets. The supply was unregulated and sat at a nominal 42VDC under only the load of the bias. The bias was set to 360mA which meant the channel was dissipating about 30 watts at idle. This is considered a class AB setup.

A more ideal setup would be to provide the front end with a regulated supply voltage that is about 10V higher than the rails used for the mosfets. This allows the output stage to be driven fully rail to rail which means more power output with less dissipation, which gives higher efficiency.

The regulated front end would also drastically reduce the 60Hz noise (along with all the harmonics) that can be seen in some of the measurements.

Overall, these numbers are superb and would absolutely destroy any of the class D designs I've seen so many people here get excited about. The noise floor is exceedingly low, and distortion performance is some of the lowest I've ever measured in a power amplifier. At 2.5W with standard class AB bias, you're looking at about 0.000814% THD+N.


qusp 20th September 2011 04:26 AM

count me in, just boards

qusp 2-4 pcb only

geraldfryjr 20th September 2011 04:38 AM

WoW this is a super Design!!
I just love these new generation of parts.

Jer :)

L-Train 20th September 2011 04:58 AM

Hi Owen,

I like it! Just got myself a pair of PSB Alpha B1 bookshelf speakers and was looking to build a nice amp for them. Count me in for 2 full kits (PCB + parts) as well as 2 PCB-only.


qusp 20th September 2011 06:59 AM

gotta love the 8ppm or better distortion from a chip and a couple of fets haha

Ferrari 20th September 2011 07:51 AM

Count me in for 4 PCBs.

holminator 20th September 2011 08:38 AM

count me in for a complete stereo kit, 2 boards and parts.

1543 20th September 2011 11:12 AM

Nice design!

Count me in for 7 PCBs.


qusp 20th September 2011 11:47 AM

yeah definitely 4 not 2 for me, so can we make this a bit more organized guys? i tried to start it just up there but noone followed suit.

qusp 4 x PCB only
L-Train 2 x parts kit and 4 x PCB
Ferrari 4 x PCB only
holminator 2 x pcb and 2 x parts kit
1543 7 x PCB only

21 x pcbs
4 x parts kits

ive counted the pcbs in the kits, easier to keep them separate, so perhaps when you make the post, list the pcb and part separately, so if you want a full kit with parts, list as
1 x pcb
1 x parts kit

does that make sense opc? guys?

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