Problem areas that I came across when building my Dynahi:
DC-offset adjustment: The most frustrating Dynahi-building step for me. This because I didn't understand what that process was supposed to do, and what I was measuring wasn't making sense even though I had followed the parts-list carefully. I realized this process was required after my boards were populated. After lots of questioning, it turns out the parts-list includes some trimpots with values that may not be appropriate depending on your specific matching of components in your boards. So I had to go through the delays of ordering some other trimpots before my DC-offset adjustment was satisfactory, then I could listen to the amp.
Some transistors soldered reversed on the boards. Yes as silly as it sounds, but you have to be careful, depending on the packaging of some of the transistors, you have to put them on the board differently. The holes on the Dynahi boards are tight for some of the transistors, so unsoldering/resoldering them was a bit difficult.
Populating the stepped attenuator: populated the Elma incorrectly, so it raises the volume counter-clockwise
I can perfectly live with that though, just a record of beginners quirck
Grounding: it appears
my Kevin-recommended grounding scheme is not ideal at least with the Elma, since it causes some loud pops when switching volume during playback. Apparently
Drew found a grounding scheme that eliminates that popping.
Chassis work: the most time-consuming steps for me were chasis-work related. In fact, my current chassis is definitely not yet finalized. Using the Condor power supplies, it is imperative to have the amp boards far enough from them, otherwise you get humming. So I have to put those supplies in their own separate chassis.
Also, I have self-made interconnect runs from the audio inputs at the back all the way to the front of the chassis were the Elma attenuator is located. After looking at the internals of the Veda Audio Dynahis, it makes so much more sense to have the attenuator closer to the back of the chassis, and use a shaft connecting it to the volume knob in the front. The shorter the signal path, the better of course. I'll have to change that eventually.
Transistor matching: I didn't do transistor matching basically because by the time I had my long rows of transistors soldered on my boards, the issue of matching them hadn't even been mentioned. I think an easy transistor matching
like this one wouldn't be too time consuming, but of course, better do that before you populate the boards with them.
After having successfully done the mods on my Tosh 3950 I confidently decided to build the Dynahi. Managed to get my Dynahi built and imho it sounds truly great. But it was very time consuming, and as you can see there were problems, some were rather difficult to sort out, and some are still pending actually. In conclusion, not a beginners project indeed, but hey a lot of fun even for a beginner who likes a challenge.
