Shannon,
Looks like you have been busy. The board looks great. I can't wait to stuff one and install it in my ST70!!
separks wrote:Folks-
This is just the proto, but a 1/2 unit has been in a Mark III for almost a year performing flawlessly,
When I first met Shannon a couple of years ago, I was just finishing (troubleshooting) a homebrew ST70 driver board project using Kevin Kennedy's schematic.
http://www.kta-hifi.net/ This amp sounds pretty good, but in order to DC couple the 12AX7 to the 12AU7 phase splitter, neither one is operating optimally. So when I was researching driver boards for my MKIII's, Shannon suggested AC coupling to get the 12AX7 operating point better and using the LM334 on the cathode of the phase splitter. He already had some proto boards with a more traditional circuit and I offered to to mod them and install them in the MKIII's. I cut the board traces to add the AC coupling cap and drilled holes to install the LM334. The result in the MKIII's was stunning!!! I thought they were pretty good amps with my upgraded 6AN8 driver (when I rebuilt them the first time, I wanted to keep David Haflers design intact). But with the diytube proto driver board, they have become exceptional amps. In fact, I am enjoying a little REO "157 Riverside Avenue" playing through them right now.
This new ST70 driver board promises to work the same sonic magic with an ST70. Looks like Shannon came up with another winner!!!
JT