I've been tinkering with variations of the original triode Williamson and had thought to use a pair of working Peerless 16309's pulled from Heathkit W5's. But with the traditional Williamson I've run into a lot of strange behavior which I assume comes from oscillation/instability, such as jumps in the output tube bias, extreme driver stage imbalance, wobbly voltages, etc. This leads me to believe that the 16309's really don't have the right specs and were crafted specifically for the Heathkit W5 circuit. I hate to waste them but I'm also leery of going full-steam on the W5 build because they were known to fail in that circuit. Plus, I'd prefer a triode amp.
It occurred to me to duplicate the W5 front end, reduce the B+ on the output stage to about 440vdc, triode-wire the KT66's and adjust the cathode bias values accordingly. The KT66's are running at 60mA, everything else dials in, it seems stable and it sounds lovely. Barring anything I'm not aware of, I thought this was a nice way to employ the 16309's under the assumption that they would behave well and might not be so stressed under these conditions. The standing current is higher than the original, but the B+ is lower and the power demand cut in half. The coupling caps are safely overrated to avoid any problems there. Would it be correct to assume that, under these circumstances, the 16309's might be less prone to problems?
I also assume that changing the outputs to triode mode reduces the feedback, but that doesn't *seem* to be a problem. I haven't found any reference to modifying the W5 to triode operation, so I thought I'd ask if any of the experts here see any problem with this. Appreciate any feedback, thanks!
It occurred to me to duplicate the W5 front end, reduce the B+ on the output stage to about 440vdc, triode-wire the KT66's and adjust the cathode bias values accordingly. The KT66's are running at 60mA, everything else dials in, it seems stable and it sounds lovely. Barring anything I'm not aware of, I thought this was a nice way to employ the 16309's under the assumption that they would behave well and might not be so stressed under these conditions. The standing current is higher than the original, but the B+ is lower and the power demand cut in half. The coupling caps are safely overrated to avoid any problems there. Would it be correct to assume that, under these circumstances, the 16309's might be less prone to problems?
I also assume that changing the outputs to triode mode reduces the feedback, but that doesn't *seem* to be a problem. I haven't found any reference to modifying the W5 to triode operation, so I thought I'd ask if any of the experts here see any problem with this. Appreciate any feedback, thanks!