Building the Audio Note Kit 1 SET amp...

FWIW, regarding what can be expected from a SET architecure as opposed to other tube based designs, my understanding about SETs in general, based purely on what I read, which is consistent with what I have heard to-date, is that its their midrange that make them special. They can do well on the extremes as well but it takes a fairly specialized approach to component matching with high efficiency speakers in particular for them to be able to "do it all", especially in the bass. Of course a smaller room helps to enable doing all that is needed practically in many cases.

I hope it works out with the Decapos. I'm still thinking there is a good chance from what I hear once the technical issues with teh newborn amp are sorted out.

So,
After three separate Skype sessions with Brian leading me through test procedures as well as some voltage meter checks on my own, putting a sine wave through the amp and taking a variety of measurements on the 300 B tubes, here's what we know:
We have verified that one suspect – that the volume pot might have been wired incorrectly (it's actually a somewhat complicated procedure involving six separate connections) – is fine. The volume pot wiring is good.
Most of the AC and DC voltages look perfect, even better than usual.
But there is some odd behavior with a few of the AC voltages vis-à-vis how things react when the volume pot is raised or lowered.
We also discovered that I have four ceramic capacitors soldered in the wrong position on the driver board, although these are not in the signal path and would not be causing the symptoms we've been hearing. (Brian is going to send me a set of replacement capacitors.)
At this point, Brian is pretty convinced that there is a problem with the driver board passing along a clipped or distorted signal. So we're going to do another Skype session and he will lead me through a step-by-step series of voltage checks on each stage of the driver board.
We should be getting there soon!

We also discovered that I have four ceramic capacitors soldered in the wrong position on the driver board, although these are not in the signal path and would not be causing the symptoms we've been hearing. (Brian is going to send me a set of replacement capacitors.)

Rebbi, I don't quite understand that. The ceramic capacitors I see on the driver board in this photo from your blog are C1, C2, C3, and C4, and they all appear to be in the correct locations per the markings on the board.

Where is Brian saying they should be located?

Best regards,
-- Al

fwiw i had a defective input board on one of my ref1000m amps not long after i acquired them . The foil or conductive material on the board had separated from the board resulting in substantial distortion at all volumes. Replacing the board resolved the problem. So a defective circuit board is certainly a logical candidate assuming all else checks out properly. Am interested also in whats wrong with how those capacitors are installed. Looks good in the pic.

OK, I just noticed in this photo that there are printed circuit connections visible within the board forming a direct connection between what I (and you) had believed were the two pads/holes for C1, and likewise for C4. Given that, it becomes apparent that the uppermost ends of C1 through C4 should go to the pads at the top of the board that are adjacent to (and connected to) W20 through W23, respectively. And the reason you need replacements for the capacitors, of course, is that the leads on the original ones were trimmed for mounting in the more closely spaced holes, and will no longer reach the correct locations.

Wow! An understandable and easy to make error, if ever there was one.

Best regards,
-- Al