I spent a bit of time over the Jubilee Weekend burning in the Bravo Audio Headphone Amp. The amp runs an 12AU7 valve which is a dual triode tube, which gives an independent stereo path through a single component.
The amp (pictured left) was always designated to live in the office, as I spend a significant portion of my day listening to music on reference quality headphones. The output from the PC was just too low to comfortably drive them. So I knew an amp would be needed.
The initial sound was a little cold, however my years of experience with valves in guitar amps knew that all it needed was a little time to burn in. Also I noticed some crosstalk at this time. A bit of investigation lead to a modification of the heater wiring. Initially the filaments were wired in series , which would account for this. Having them run in parallel solved it nicely.
In day to day performance the amp sounds great, and certainly attracts a lot of attention in the office. Though working in the music and technology sectors does tend to do that. I may make some more mods in due course, probably changing the MOSFETs for lower capacitance ones as this will enhance the high frequencies.
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