The Mute Audio GrubDAC
|The Mute Audio GrubDAC is a ground-referenced, USB-input high-fidelity audio DAC. When assembled properly and attached to the computer via a USB 1.1 port, it will be natively detected in Windows, OSX and Linux without the need of any add-on drivers. Once recognized and setup by the operating system, it will be utilized as a high quality audio device. You can then use your choice of media player to play .wav, .mp3, .flac or other audio files. Output can be connected to your choice of 3.5mm, 1/4", or RCA jacks depending upon what you wish to attach to the board.
The GrubDAC represents one of the smallest layouts yet offered to the DIY community for a USB DAC board. The two-sided board is approximately 1" wide by 2" long and the full spectrum of USB-powered recommended components are included. The use of a TPS regulator ensures a quality power source to the on-board ICs while requiring very few supporting parts. The on-board USB connector is of a Mini-USB type, allowing for use of mini-USB cables which are becoming standard in the industry. Despite its small size, the GrubDAC utilizes a ground-referenced design which needs no output capacitors - just a simple RC filter to deal with out-of-audio-band DAC noise. This provides a clean signal without the colouration issues of coupling capacitors.
Due to the small size of the board, it can also be built as a CableDAC. In this configuration, the on-board USB connector is bypassed using a pig-tailed USB cable soldered directly to the board. This configuration provides an amazing combination of convenience and versatility for quality listening.
The GrubDAC can be built for $25-$30, depending on case and connector selections, making it outstandingly economical as well.
(prototype pic of GrubCableDAC)
Basic construction and parts selection is covered in detail within these web pages. Other than the parts in the Bill of Materials, you will need a soldering iron and solder, sufficient for SMD PCB work. This is not as intimidating as it sounds - just be sure you have a low-power soldering iron with a small chisel tip and good solder (eutectic recommended) that is thin and easy to use. A Hakko 936 with a T-0.8D tip or equivalent will go a long way in success of building the Bantam, but is not strictly necessary. Solder should be on the order of 0.025" diameter or smaller, although smaller diameters can be difficult to use (lots of breakage). Eutectic solder is best - a blend of 63/37 tin/lead with a rosin flux core (non-corrosive).
Besides the miscellaneous tools used in PCB work such as needle-nose pliers (smooth jaws), flush cutters, DMM, and wiring tools - strippers, wire cutters, heat shrink, etc., there are a couple of specialized tools that can make the difference between success and failure with building SMD projects:|
Tweezers - These should not be from your mother's, wife's, or girlfriend's makeup kit. Instead, if you invest in only one tool for this project, a quality pair of SMD tweezers is it. There are many to select from and can be found at Mouser, DigiKey, Allied, Newark, and even Fry's. Try to buy one that's specific for SMD and not from a combination kit, unless the kit is specific for SMD work (in which case, it's probably way too expensive for this project). I purchased some #7 stainless-steel, non-magnetic curved tip tweezers:
These were somewhere around $10 for an off-brand copy (GoldTool at Fry's) and have worked fine for me, but be careful that you get good-quality ones with tips that do not flex and are as sharp as a pin, almost. Xcelite makes good ones (shown) and Wiha makes outstanding versions. Others go for the straight tweezers, but I find the curved tip is more natural for me. It is the only tweezer I use.
Flux Pen - These are unbelievably helpful with SMD work, and also unbelievably sticky - so be careful. Used liberally, the flux from a flux pen can almost glue the part down. It can get a bit troublesome if you get it on the tip of your tweezers, though.
Helping Hands - These are more or less obvious. I use ones that are only $1.99 at Harbor Freight, but you shouldn't have to spend more than about $5 almost anywhere that carries them. The board is way too small to hold with your hands while soldering. (Use some electrical tape to protect the PCB surface from the alligator clips.)
DIYforums.org has more than enough information to help you complete the GrubDAC. Besides these web pages, the forum itself provides ample opportunity
to search for answers or for asking direct questions. Most of the GrubDAC designers and prototypers are all very active forum participants and will do their best to get your problem solved.
In addition, there are many other builders that post and answer questions at:
We hope you enjoy building and listening to the Mute Audio GrubDAC!