No problem Robert.
I am pretty sure they are connected back-to-back in parallel across pins 1 and 2 of the op-amp. In other words, they are in the feedback loop of the op-amp. The other two more familiar-looking diodes are also in parallel in the fb loop, but with a series resistor as well.
So the pair with the series resistor conduct first (assuming the measured 0.58V VF is correct, i.e. a Si pair), but they only limit a little due to the series resistance. This begins the gentle limiting of the over all transfer function. Then a package of 3 or 4 series Ge diodes (two packages in anti-parallel) with a VF of about 0.9 V begin to conduct some time after the first pair, but these conduct fully. "Fully" for Ge diodes means they reach a limiting point, but this point forward is a softer limiting function than Si diodes, and hence the difference in sound and intensity of harmonics produced.
Anyway, here is the bottom side of that pcb, if it helps. I haven't compared it to the other pics I posted, but I'm sure it is the same pcb/circuit.
« Last Edit: 2011-10-31, 13:44:37 by poynt99 »