Have you considered building your own little headphone amplifier? How about a hybrid tube amplifier? Well, if your answer to either or both of those questions was “yes”, then perhaps you’d be interested in the Coaster DIY project (also known as the Vali Mini) from none other than Schiit.

What’s the Coaster All About?

Well, the Coaster is a bit of an odd-ball. Basically, you can buy the printed circuit board directly from Schiit (for $12 excluding shipping and/or taxes), and they’ll also provide you with a complete circuit schematic and BOM (bill of materials) to be used, as well some documentation of the design.
However, it’s important to understand that this is a fully DIY project, and as such you will get absolutely zero technical support from Schiit. This is actually specifically printed on the rear of the actual PCB. They also will not provide any parts needed other than the PCB, so you’ll either have to order the required parts from suppliers such as Mouser (or equivalent).
The other thing to keep in mind that this will not be a high performance amp. It’s intended to be just a fun and affordable little project that actually works, but from a performance perspective you’d still be far better off buy a ready-made product. Some of the performance parameters listed by Schiit include a THD figure of around 0.5%, signal-to-noise ratio of 90-95dB, crosstalk of -75dB, and an output impedance of roughly 8-ohms (not 0.8!). So again, not terrible, but really not as good as other readily-available products.

Still not scared? Good!

If you wanna have a crack at it, start off by doing some reading on the design of the Coaster. There are a couple of lengthy forum posts on Head-Fi by Jason Stoddard about what went into the Coaster and a couple of possible improvements you can make. You can find those posts here, here, here, and the final one here.

To check out the schematic of the circuit, just click on this link, and likewise the BOM can be found here.

This will of course require you to be competent at reading a PCB, understanding the schematic, as well as being able to properly solder thru-hole components onto a PCB. But, if you’ve got those basics under the belt, then heck, give it a whirl!


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