Building the Audio Note Kit 1 SET amp...

It has been pointed out earlier in this thread that the actual sensitivity of the speaker is in reality 86 to 87 db. Jbrrp1 in your case your may have surplus system gain.

Jbrrp1,
Yeah my Manley EL-84 push pulls in triode mode (20 watts) drove the De Capo's plenty loud with no trouble.

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