Saturday, 5 February 2011

D3a Headphone Amp

Here is the schematic of the D3a amp mentioned in the previous post. Nothing too fancy, but using some nice ideas in the PSU that others have tried before.

Using the CCS to feed the VR Tube ensures that during start up, the in-rush current is limited, and provides a stable operating point for the VR. a further refinement would be use some form of LED or CCS for the tube biasing, to ensure that the operating points remain stable. as suggested on the site, tying the ground of the VR to the top of the cathode, may achieve is, and then the resistor below the cathode, simply sets e same current as the CCS. This will eliminate the cathode bypass resistor, and give the bias point of the tube a stable bias.

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