I decided to try a different direction for a possible upgrade.  This time using a small stepped attenuator, instead of the very large Alps RK27.  This allows the original PCB to remain with only slight modifications.  It still uses a 1/4″ headphone jack and can either keep the existing 3.5mm inputs or be swapped out for RCA inputs.  Since the original PCB remains this modification could be implemented by skilled Amp1 owners on any existing Amp1 or Amp1 Upgrade.  The key to making this work is flipping the PCB upside down within the enclosure which gives enough clearance for both the stepped attenuator and 1/4″ jack to fit in the stock locations.  The existing hole for the 3.5mm headphone jack must be enlarged to mount the 1/4″ jack but that is the only enclosure modification required.  If RCA inputs are desired the existing holes will also require modification, this can be easily done with a drill press or even hand held drill once the amp is disassembled.  The power LED if kept would require glue/epoxy to mount it to the front panel.

Let’s try this again, before even posting this update on the possible change there is another change.  I didn’t like the amount of work required to make these modifications, (drilling/milling) and the requirement to flip the board upside down within the enclosure.  The best solution is to use a new front panel if changing the pot/output jack, and/or change the rear panel if switching from 3.5mm jacks to RCA’s.  So by adjusting the mounting location of the new stepped attenuator and 1/4″ output jack the main PCB remains in the stock location with only small wiring changes.  To allow quick updates and without locking myself into another front/rear panel design to have EDM cut, milled, engraved, anodized, paint filled (with minimum quantities of course), I’ve opted to try a different solution.

front

Above is a rendering of the new front panel showing the new amp dubbed Amp1S with the “S” referencing the “stepped attenuator”.  This will bolt up to the current Amp1 enclosure/PCB but now raises the volume control and output jack high enough to clear the PCB.  The LED now stays in the stock location and doesn’t require modification.  I’ve found the stock pot and headphone output are difficult to desolder from the PCB, for this reason I won’t be selling an upgrade “kit” at the moment, I will just be selling complete Limited Edition Amp1S amplifiers with the stepped attenuator, 1/4″ output jack and RCA inputs.