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July 18, 2017

AMB σ11 Sigma 11 Regulated Power Supply

Version 2 of AMB's σ11 (Sigma 11) regulated power supply has been out since June of 2015, but I'm finally getting around to building my own. AMB (Ti Kan) is mostly known for his headphone amp and DAC designs, but his site offers several power supply options as well.  

The σ11 is a top notch DIY single-rail linear regulated power supply known for low-noise, high-current, excellent line/load regulation, wide-bandwidth, and stability. The circuit features all discrete components and high-current MOSFETs for the output. Per AMB, the σ11 is a great choice for DIY headphone amplifiers, pre-amps, DACs, network media players, and other devices needing a single-rail regulated power supply.

AMB o11 Power Supply PCB

This power supply is a pretty quick build with ~40-50 total parts. A typical builder can populate the PCB in an hour or two. AMB offers the PCBs for sale on his site, along with some of the necessary parts. The rest you'll need to get from Mouser / Digikey or your favorite parts supplier. I went with all stock parts aside from an Antek 50VA toroid instead of the Amveco TE62062 25VA as it was much more reasonably priced, albeit a little larger. Because of this, the Hammond 1455N2201 was the best chassis size for the job. 

Antek 50VA toroid

Rather than leave the Hammond case plain, I wanted to give it a little more character. I sourced a piece of wood online which didn't have a species listed, it simply was called Asian burlwood. I cut a front plate with about a 1/2" overhang in each dimension and drilled holes for the screws to line up with the existing screw holes in the Hammond case. Two coats of satin lacquer gave it a nice sheen. 

Asian burlwood front cover

Two holes were cut into the top of the Hammond case and it was sanded down with 180 grit sandpaper to reveal a grain-like anodization pattern. Powercoated aluminum grating was secured with adhesive underneath the holes... then a permanent furniture market was used to give the bare aluminum a bronze-like color. 

In the rear, I've installed a pair of outputs. The board offers up to four outputs if desired, but an appropriately sized toroid should also be used. If you're not sure about the rating needed, the forum on the AMB website can be very helpful as other people have likely already asked the questions you are wondering. 

AMB σ11 Sigma power supply rear

A Fender-style pilot light was installed up front with an Amber jewel and LED. 

AMB σ11 Sigma power supply front with pilot light

All done! Now I have a nice regulated 24v power supply now with a pair of outputs. 

Please remember that building/modifying circuits can be dangerous to you and/or your surroundings and should only be performed by a certified technician. The owner of this blog and all associated parties can not / will not be held responsible if you attempt a build or modification posted above and cause physical harm to yourself or your surroundings. Many electronics contain high voltages that can kill, and mods, if performed improperly, can be a fire hazard. 

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