So, my R800i stopped biasing properly a few months back AND blew a Gold Lion 300B (so annoyed it's not easy to match single tubes). Skunkie didn't want to deal with this 100 pound beast (not that I blame Skunkie lol), so I shipped this thing out to Scott Frankland in California. Scott was the "F" in MFA (their preamps have kind of a cult following), and he's been an audio designer for decades.So, after Scott took her apart, he discovered a few design issues (the kind of insights we love Skunkie for on the R8). The biggest was that both channels share plate voltage nodes, but that there are no bypass caps for this. He added 18 "critical" resistors and 4 bypass caps to address this issue. A smaller issue was that there wasn’t enough filtration to account for all the hum, so we’ve added more. He also mentioned this was a curious design for audio, but that it wasn’t unheard of. A quote from Scott: "The Willsenton R800i operates the 805 as a power grid tube, which is allowed for RF transmitting tubes but not often seen in audio amps. This means that the operating point is below the diode line on the plate curves, in the area of positive grid bias. This causes the grid to draw a certain amount of current continuously. It’s a technique in RF that allows the tube to be pushed to deliver more power. Of course, that grid current has to be supplied by the driver stage, which in this case is the 300B. The R800i operates the 300B as a cathode follower direct coupled to the 805 grid. This is certainly unusual in audio, but not unheard of. I recall that the early Wavac amps used this (or a similar technique)." I also had Scott modify/upgrade the amp. The mods Scott performed were (in addition to the design issues): • Upgraded caps (VCap ODAM) • Upgraded resistors to 1% values (from ~3% with stock) The amp was burned in and then I got a follow-up email from Scott: "Clearly the Willsenton 300B’s and 805’s were designed to work together, and clearly other brands don’t. I set the bias range to be just below 100mA so that the full range of bias would be available as the tubes age, but I’m concerned that the Gold Lion’s may not bias down with the current adjustment. I recommend that you send me the Gold Lion 300B’s (or have them shipped here) in case a further adjustment is needed." So, I have had a set of PSVane 300B’s and 805’s shipped to Scott so he can swap those in and see how the bias needs to be adjusted. Right now the amp has the stock Willsenton 300B’s and a set of LinLai 805 DG’s in it (the original Willsenton 805’s were not included with the amp when I bought it from the previous owner).Perhaps some of this info will help other R800i owners. I like the sound of the R800i enough that I’ve sold my R8 (even though I like the R8). I am hoping these mods deliver the performance and reliability I’m looking for. I have supplied pics or an unmolested R800i and then the work Scott did. Picture of the guts of an unmolested R800i. The next post has pics of Scott's work.