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 "the path of least resistance is through a vacuum"

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Vacuum Tube Audio SP9 - 2016 build

these photos document a recent 2016 build of an SP9 preamp

lots of photos loading, this may take a minute . . . .



bare circuit board, ready to stuff with parts

resistors and diodes installed

all parts installed

bare chassis prepped

bottom of circuit board with 6 white jumpers installed
plus 6 tone wires, and output pairs

wires added for B+ and filaments to phono board, and to front panel LED

bare rear panel

installing RCA jacks

alignment of RCA jacks for easier wiring (ground lugs & solder cups)

ground buss wire added

closeup of ground buss wire

rear panel done

inside of rear panel done

adding wires to RCA jacks, grounds slightly longer

red pairs for right channel, white to ground buss

right channel wiring done

adding left channel wires (green pairs), both wires same length for left channel

white wire to ground buss
OK, take a break, we're about half done with this . . . .

rear panel wiring done (except for phono in and preamp out)

bare front panel

bend position tab on selector, and cut off position tab from balance & volume

bend position tab on selector, and cut off position tab from balance & volume

use marker to put an index mark on selector, at fully CCW position (phono)

need to cut length of volume & balance controls with hacksaw

about 40% of length cut off to match length of selector and tone controls

front panel with controls & switches installed

inside of front panel (just missing LED)

top view of chassis so far

wiring of power transformer (tie green & brown together, cut off grey wire)

wiring of IEC power connector on rear, and power switch on front

wiring of SOURCE-TAPE switch and selector switch

volume, balance, SOURCE-TAPE switch and selector switch

close-up of selector switch wiring (need to add phono input later)

rear panel wiring (and outputs bridged by 1K resistors)

front panel wiring

PH12 bare PCB

PH12 PCB stuffed

bottom side of PH12 with input & output wiring added, and B+ jumper

front panel wiring (phono input added)

PH12 phono board installed

top view of finished preamp

rear panel of finished preamp

front panel of finished preamp

full test and burn-in of finished preamp

all done . . . enjoy the music!


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 tubes 4 hifi
 "the path of least resistance is through a vacuum"