Hi Doug,
A pleasure reading your books, articles and your insight into this subject matter.
1) How about some Spice simulations showing the benifits of different topologies, provide models and ckts (web site) for us readers to download and run so we can all learn from.
Since LTSPICE is the only free SPICE simulator that I have heard about, then that would have to be the defacto choice for the masses.
2) Always wondered about the performance of protection circuits employing MOSFETs as the pass element. What the hit on distortion is?
3) Possibly Chip Amps, i.e. LME498xx series. That is if you see things that are missing from what is already documented in App Notes etc. I am currently designing an PA based on LME49830/Alfet AL16X16. Wondering about means of S/S protection, advantages vs costs of using a servo vs simple ecaps for input and feedback. Baker Clamps? If LME49810 is any differentt than LME49830 in this particular application
4) Power Supplies? Separate supplies for front-ends, advantages vs additional cost dis-advantages.
5) Maybe Class "D"? I have been using TPA3100D2 in a small portable stereo that I designed of late. I have an issue with AM RFI, I am using a Si4735 chip, need shielding, remote antenna mounting, etc. I am happy with its sound. It is not Class "AB performance" but for what it does, it is great device for many appluications. Some insight hear would help me out. TI has some newer devices that are being offered to address this RFI issue, I guess that I am not the only person with this issue. To be honest I do not even listen to AM radio, but for a prodcut it is probably important to resolve.
2×50-W into a 4-Ω BTL Load at 21 V (TPA3116D2)
2×30-W into a 8-Ω BTL Load at 24 V (TPA3118D2)
2×15-W into a 8-Ω BTL Load at 15 V (TPA3130D2)
Good Luck & Best Wishes
Rick Savas