The Pass B1 in a Hammond Al case. Nice enclosure even better sound. After assembling a vero-brd. ESP P37a for long term customer I was enspired to tackle other simple SS preamps on vero-brd. See the cct. brd. below.
As you can see above the front panel is simple with just a mini on/off switch, 4oz solid brass black chrome kbob on an Alps blue velvet pot and an aqua led. The back holds two sets of gold RCA inputs and one set off outputs. The rear switch switches between the two inputs. The 19V DC power plug is also on the rear.
I power the preamp with a 19V SMPS. Others have done similar with no complaints of noise or switch mode hash. Under test the preamp -3db points are 5hz -> 780khz. 18V p2p into a 10k load and 8V p2p into a 1k load. Impressive!
Though this preamp is more of a driver, being a source follower, than a preamp its ability to drive a reasonable voltage swing into a heavy load is obvious. The sound from this preamp is extremely raw and natural. The B1's ability to dig out absolutely the finest, earthiest detail is striking obvious the second music is passed through it.
I team this blatantly natural sounding preamp with a mid-range rich SET amp for a beautiful combination. Each time a play a different track I am struck by the rawness of the sound and the depth of the detail. The preamp stays on the warm side of clinical without taking any sonic prisoners. Build it if you can take the truth about what you are listening to.
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