So, just built this up. I'm getting modulation. But I'm not getting any of the lower undulations. The high band works just fine. Detailed voltages forthcoming, but I'm getting 1.26 on pins 1 and 2 of q5 an q6.
Only substitutions are j201s in place of the 2n5457s
I guess if you know and can confirm in another circuit that the XR2206 is legit then reflowing the joints if you haven't done so would be another thing to do.
I don't know how critical the difference between J201 and 5457 in this circuit would be, maybe Chuck would be able to chime in on that.
I have built them with 5485 and 5457 and they worked as heard from youtube demos, pretty full and lush sounding.
I tried 5458s, and a few others I have on hand, but the modulation was even more subtle or non-existent than in the vid. The 2206 works in my my Echo Dream clone just fine. I tried another 2206 from Jameco just to make sure, and it's the same
Close enough I'd say.... hmmm...
I guess double check cap values in signal path, particularly the low side C5 and C8, double check that polarity on C6 and C7 is correct.
I'm wondering, since C6 and C7 are electrolytics, if the could be a bit leaky and cause that. Maybe replace those two with tantalums in 2u2? Bit of a shot in the dark, Chuck would be the better person to make such a call.