Status as of Aug. 22, 2012: There are no known quality or reliability issues at this time.
Status as of Sept. 12, 2012: Since the last update, more preamps have gone out, with no reports of problems. I am quite pleased with the improved design, which even looks better on the inside.
Status as of Aug. 19, 2012: A number of preamps have gone out with the corrected design, and I have received nothing but positive reports. I consider this to be a solved problem. However, I will leave this page up for a while, just to document the issue.
This page documents problems encountered with the first batch of HPF-Pre Series 3 preamps that went out during the week of August 6, 2012. I am asking for all of the preamps from the first batch to be returned to me for repair or (more likely) replacement with a new preamp.
It is my policy to be open about the issues that I encounter with this design. At this point, I believe that I have a robust design.
Battery Status LED
The battery status LED doesn't work, or only works sporadically. This is due to a design problem that I solved by switching from metal jacks, to a type of plastic jack that I've been using in Series 1 and 2 preamps, and that is ubiquitous in bass gear.
See below for a picture to help identify bad preamps.
DC Power Jack
A couple of people have noted that DC power plugs seem to be a bit loose when inserted into the DC power jack. However, I've checked out these jacks and they seem OK, plus the electrical connection is definitely good.
The root cause is that there is not a precise standard for this type of DC power jack. The pin has to be a slightly smaller diameter than the hole in the plug, or the two will get stuck together. How much smaller? Makers of both plugs and jacks seem to have adopted differing standards for both the plugs and jacks. In addition, there are very few types of panel-mounted DC power jacks that would fit in the space available in the Series 3 box.
So, I think that this will be a permanent symptom of the preamp.
There are DC power plugs with a two-prong split inner conductor. The Visual Sound 1Spot adapter has such a plug. These plugs mate themselves to a standard power jack quite tightly, and also have a little notch in the outer sleeve that seems to prevent the plug from falling out of the jacks that I've tested, including an old Boss guitar pedal.