Applewood

Not from the same store. it's hand made from "Aluminum Square Bar" and just need to cut and drill screw holes.

Yes, 3mm thick transparent acrylic be used and also heat dissipation hole is opened above the driving transistors stage. (those transistors are equipped TO92 heat sink) The temperature of internal and both side heat sink are normal and stable after long time operation, heat insulation gasket with 6 screws between top cover and side heat sink. Heat sinks must have enough volume to be as same designed otherwise the quiescent current must be compromised.

https://www.shun-teh.com.tw/en/category/Aluminum-Extrusion-Heat-Sink-Above-width-200mm/A03.html This company can cut heat sink size and drill screw thread holes according your drawing, even if you only need two piece. It is good choice if you want to design your own case.

Finally completed the dynahi. I really enjoyed this DIY processing. Based on previous experience, this time I spent more time on selecting parts and adjustment, also increased heat sink size, quiescent current increased to 75mA. The gain keeps the original design value (200K/10K) and there is no background noise even using high efficiency earphones. Thank you everyone for your experience and information on this thread.

K701

SS dynalo be considered but not easy to get the circuit board on the web. Although it is an easy-to-drive headphone (K701 & Dharma D1000), it still does not have a good sense of hearing when using several high-power DAP and also headphone amps. This is the second time I built dynahi balanced, and the first one was sold few weeks ago. I really miss its dynamics and timbre…. so I decided to build again with the first successful experience, of course the second one would be more thoughtful components selected.

Thank you very much ! ! One more question. For feedback capacitor value, somewhat confused when I searched for previous discussions on this thread. I am planning to reduce the gain to half of the original design (use 10K/100K ohms) because have a fair driving headphone. Could you please recommend what value the capacitor should use?

Need professional help for Dynahi balanced off-board version v1.43 (That340 / OPA445 version) On the PCB R49 (between R2/R3 to OPA445 pin 6) is printing 5K ohms but on circuit diagram is showing 100R only. Could you please help, which value (5K or 100R) is correct one?