I've read through what I could find, and the most relevant post in that thread seems to be the last one: if you can't figure the circuit out from the description, you probably don't have any business building it. It seems to me that several salient points about the circuit are implied, and others are matters of taste to be decided by an experienced builder.
A good example of the the latter is that Apheared never says where the buffer goes, exactly. One post in that thread by someone else says it goes inside the opamp's feedback loop, but Apheared doesn't say that, nor does he confirm or deny it later in the thread. Reading between the lines, it sounds more like he had it outside the loop, and from what I can see in the photos I believe I'm right. Apheared is being very humble in this thread, which tells me he thinks it's a very simple circuit. Since putting the buffer outside the feedback loop is simpler, I infer that's how he had it set up.
Another example is the matter of input capacitors: Apheared never mentions them, but in the protoboard pics you can see a pair of box caps that are in the right place to be opamp input capacitors. Yet, he also specs a 308 ohm input resistor. That resistor and the input cap (if it's present) form a high-pass filter, rolling off low frequencies. If you model this in a program like MicroCap, you find that you'd need a 47uF cap or larger to keep the low-frequency rolloff from eating into the bass audio range. (A 0.1 uF cap as spec'd by Chu Moy for his pocket amp rolls off at about 1 kHz with this resistor! That's why the input resistor is so large in the CMoy design.) Yet the box caps I see in the photo are pretty small, and they're probably film caps, which means they probably aren't
47 uF jobbies. I'd say they're more like 1 uF. So, did he stick with the 308 ohm input resistor, or did he manage to find a very small large-value film cap, or am I just misreading the photos? I can't tell you the answer to any of those questions.
More ambiguity: he says the opamp has been biased into Class-A operation, but doesn't say how. Apparently one is expected to understand the causal mechanism from the mere mention of the effect.
All is not dim to me, however:
|Is the 301 ohm +input resistor Apheared mentioned in the original article eqivalent to R2 in the Cmoy design?
|What the heck is the "parallel of the feedback"?
When using bipolar input opamps, you have to balance the input offset currents. See this article
for how this is done, in the context of using the LM6172 opamp. The same principle applies here. The short version is that running the 332 and 4.7K values through the parallel resistor equation equals 308. See that article for why this relationship is helpful.
Since the AD823 he's using is a FET-input opamp, that's why Apheared describes this balancing as overkill. It really isn't needed, but it's clear he was going a little overboard on the accuracy angle when building this amp. (Evidence: See the oscilloscope stuff at the end of his post.)
|Where do I put the stabilizer cap?
Exactly where Apheared said to: ahead of the TLE2426. I expect he's using the rail splitter as normal, with the stabilizer cap between the power input rails. As Apheared said, this may be overkill. But then, I've been putting 470 uF caps in that position in my BUF634-based power supplies, so I'm just a pot calling the kettle black here.
|And which is the output resistor Apheared was trying to get perfect?
The one between each opamp's output and each buffer's input, of course. See ppl's first post in that thread and Apheared's response.
There: I've answered all your questions and raised some you never thought to ask, and do not know how to answer myself. I'd say you are in for an education if you keep at this project.