Quote:
Originally Posted by aerius
The fact is the Dynahi is NOT a beginner's project, there's just no way around that. It's not something like a CMOY or PIMETA that one can just slap together and easily understand and troubleshoot if things don't work. While it's entirely possible that one can just slap the parts on the board and have it work, the problem is what if it doesn't work? That's when you need the experience & knowledge to troubleshoot things, and that experience & knowledge, IMO, is going to be very hard to put into a neat easy guide.
I think a lot of people got in over their heads when they bought the boards, figuring that given a PCB it would simply be a matter of sticking in the parts. It's a bit more involved than that.
My advice? Build and understand the Dynalo first. Same basic principle, much cheaper parts, and no heatsinks to worry about.
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Very true. I agree that this is not for beginners and that the dynalo can be a great place to learn without getting into the larger mechanical challenges. The dynahi is already too expensive for many members. But for those who have lost their minds (like me) and don't think $500-$1000 is out-of-whack for a primo headphone amp, there ought to be an easier road with a more rewarding outcome.
My Dynahi DIY Complaint List (so far):
The Good:
1 - Kevin Gilmore gave us something very nice to work with. (Thank you Kevin)
2 - Readily available amp PCBs via group buy. (Thank you MisterX!)
3 - Readily available PSU board via group buy. (Thank you MisterX!)
The Bad: (or should I say, areas for improvement)
1 - PSU transformers were never really spec'ed out and the sources typically had long leadtimes. PSU circuit does not handle oversized secondary voltages very well. Large dropout voltages make the unit on the thermal-hairy-edge in the dynahi application. I had to re-build mine once already.
2 - The whole heatsink bracket concept is so-so, and it's fabrication is out-of-the-question for a lot of users. A really nice and affordable custom engineered component is almost a necessity.
3 - Incomplete (at best) level of documentation about the theory of operation. A few dozen people or more are up to speed, but many are clueless.
4 - Casework options have serious constraints. You have lots of heat. You must vent the box or attempt to get the heatsinks incorporated into one of the outside walls, where the cool are resides. The box cannot be made really small and pretty to look at. It will never ever be portable. The amp boards run hotter than the PSU if you select the tranformer right, but its parts run hot too.
5 - No one willing to make the matched transistors readily available. Yet. (I don't think Borbely stocks all these parts)
The Ugly: (or should I say, the visually uninspiring)
1 - Dynahi amp circuit is a wonderfully symetrical design, but the layout does not have anywhere near the maximum visual impact that could be made.
2 - The PSU board is nothing special to look at, but the circuit is nice, simple, and easily configured for other applications. Lead bending operations required to lay the parts down flat are truly scary, especially on $15-20 power op-amps. Off-the-shelf transformers, possibly PCB mount toroids, might might make this circuit board something more turnkey for DIY'ers.
3 - Let's cut to the chase. This amp and PSU should be a thing of absolute beauty to look at. Right now it is not. We should find a way to change that.