Here is a little update on using the 6080 2.5A tube as a power tube. At this point I am waiting for a second 5A voltage regulator from China, but couldn't resist trying out one channel with a 6080. Picked a 6080 RCA that only earned a so-so rating as driver tube (my notes say 'murky") just in case Something Would Happen.
In order to use it in the LD MKIII it is first plugged into an octal to 9 pin adapter; then into a 9 pin extender to fit inside the ring surrounding the socket. This extender was taken apart and pins #4 and 5 were de-soldered and removed and replaced with two wires going to the external voltage regulator. This necessitated drilling a hole in the side of the extender socket to allow for the two wires to exit neatly.
The tube complement features an all star set up of the 1957 subminiature 6832 as driver (using the built in LD power supply), a 1957 Tung Sol 6SN7GTB as power tube for the left channel (LD powered) and the 1962 RCA 6080 as power tube for the right channel, using the external 5A PS.
A trial run indicated that the amp was getting warm. After an hour it was quite warm, but not too hot to touch. Out of caution I installed a fan to cool off the amp. Here are a couple of pics:
Here is a close up of the extender showing the two wires coming out and teeth #4&5 missing. Used a little piece of white sticker to mark off the right pins and a little piece of blue to line up with the indentation on the top so that it goes together correctly.
Here is the fan assembly. The fan comes from a an old PC power supply and was picked for being fairly quiet. The power supply is a 12V wall wart that once powered a router. The plastic fasteners are used to tie the fan to my equipment rack in such a way that the fan sucks away the hot air instead of blowing directly on the amp. If you touch the 6080 you could burn yourself (ouch, just did), but the fan lowers the temperature of the amp chassis significantly.
Here is the triple dual triode (tongue twister?) line-up. The 6832 is swinging to the music like a buoy on the ocean. (Finally got the nail polish insulation but have yet to decide on fire engine red or turquoise blue.)
The sound is fabulous with a glorious bass and treble (and this is with the worst sounding 6080 I have!). Will have to try to better sounding 6080s and the coke bottle 6AS7 RCA as well. Meanwhile I am just enjoying the sound. Did I mention that this set-up is very quiet as well?
Here I have to quote hypnos 1 on the achievements of the members on this forum:
Unorthodox?...AGREE . But I would also venture to add : resourceful; pioneering; fascinating; educational; rewarding, BRAVE...and not a little MAD! But isn't this precisely what so often results in the greatest quantum leaps in any endeavor? (And, no doubt, been a source of a little amusement for the 'purists', lol!).
Whatever, hopefully what has been achieved is proving to be of great benefit to those LD owners who are now enjoying a level of sound from their lowly machines way beyond what may have ever been thought possible (well, it is for me anyways!). And hopefully also for those yet to come...
Maybe alternating red and blue? LOL......