Excellent article on DCC
Joe, great job on this article. A few comments and experiences I've had at a large club layout.
First, the club layout runs both DC and DCC cabs simultaneously. So that means there's still block selection panels (we have a relay system with a control panel at each end of the block, so no matter which direction you're running in, you can "get your cab" before you enter the block). When someone "runs a block" it's true that there is the equivalent of a short, and it causes some problems in that power district, but has never caused the system to burn out. Each block is protected by a circuit breaker, and this helps prevent layout-wide issues. We run Digitrax, and currently only have 3 power units (command station and a pair of boosters), but have 10 more boosters on the docket for installation. When we started, the DCC environment didn't include sound and only a handfull of members were running DCC. That ratio is reversing, with a number of the old "die hards" who would never give up their DC finding themselves with some newer models that came equipped with DCC... so when they start using it, they just love it. So, if you're careful in wiring and operating, you can run both modes at the same time on one layout, but it does require the operator to stlll spend some time "running the layout" rather than just "running their train." With over 120 members, it's not likely we're going to get rid of "dual mode" operation any time soon.
Dual mode also brings up another situation that I've encountered. Because of our model of running DC and DCC together, I tend to set CV 29 to disallow "analog conversion." That way if I accidentally run into a DC block, my train simply stops. But nother side effect seems to be that with analog conversion turned off in the decoder, the response on the decoders is better. I'm not 100% sure if this is true for all decoders or all environments. I have noticed that the ...ahem... MRC sound decoders in Athearn units (and perhaps some others) are listed as "dual mode" decoders, and even turning off analog conversion, well.. doesn't. At least not on the units I've experienced.
As for BEMF in consists... I have a number of BLI locos that have BEMF turned on, typically with their QSI sound boards. They run in consist just fine with only a tiny bit of bucking at different speeds... and at slow speeds that BEMF seems to help smooth out the operation of the consist. So, I guess it's a YMMV scenario. I found that the Proto 2000 locos with QSI (especially the freight units) would buck and grind as you suggest, even on tangent track, so I looked at the settings in my Broadway locos and adjusted the Proto units to similar values using Decoder Pro (a tool I can't speak highly enough about, especially for complex decoders with all those indexed CVs!) and the bucking and fighting diminished significantly.
LokSound decoders from ESU have shown me some excellent BEMF characteristics... I have a Division Point DT-6-6-2000 that I put a Baldwin LokSound decoder in, and not only does it sound great, but I can get it to crawl smoothly, with or without a train, at 7 seconds per tie... without any kind of hiccough. Users of the new Paragon2 from Brodaway have also reported stellar slow speed operation on their new units. So you're absolutely correct that BEMF is the way to go for smooth slow operations. It's easy to make a train go fast smoothly... but it sure isn't so easy to make one look great running slowly!
Overall, excellent magazine... keep up the great work... and I enjoyed your DVD series too!
...Darryl