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Originally Posted by Arkku
 My first DIY amp; the SOHA II and (slightly modified) power supply, and optional crossfeed filter. The four toggles on the right are for controlling the crossfeed (a true bypass, perspective control, treble compensation and bass compensation). The other toggles are for input/output selection and active/passive mode (the box can be used as a passive volume control and optional crossfeed filter when unpowered).
 Rear panel has two selectable inputs, using switched jacks so that the left can be used alone for stereo or together with the right for mono, and also an alternative miniplug input for convenience on the other input. There are also outputs for pre-amp use (selectable with a front-panel toggle, the headphone output is on the front), and a heater voltage toggle. The power supply case also has a ground lift switch for connecting the audio ground to the mains ground (not at all, through a ground lift circuit or directly—note that the power supply case is always connected to mains ground for safety reasons).  Before case perforations:  The large toggle on the power supply is the on/off switch, the first small one toggles power to the tubes (B+ and heaters, for testing and possible future use as a ±15 V supply for something else), and the second small toggle enables operation with higher current tube heaters by eliminating a resistor in the circuit (normally installed to keep the heater regulator from running quite as hot). The text on the case is still handwritten, I don't know if I'll do something about that or just leave it. |
How does it sound? :P
