The 845 will be a bit simpler with the tools I currently have at hand. The 813 has it all over the 845 in the cool department. The 813 will likely run at lower B+ ( 700 v. 850-900 ), and will require anode caps....

Power from either is comparable. It is hard to tell the diff between 40 and 60 watts.

Either way, it is going to be an entirely Heyboer-Iron affair, and as it develops I plan to share the story.

Just for example, the 845 Iron budget could be:
Power TX
Main L
OPT
PP grid choke
power valve filament TX
driver valve filament TX
rectifier valve TX ( 866's of course!!!)
~$600/channel

and the rest:

Main misc. bits:
bias supply
PS capacitor
pair of coupling caps
4x hum pots
CCS makin's...
tube sockets
~$130

Valves:
2x 866 Hg vapour diodes
2x 10Y/801A
2x 845
if you stay away from NOS metal plate 845, you won't have to sell your first-born
~$400

good glow factor rating for sure!

Damn, that got expensive quick, whatinthehell was I thinking?
regards,
Douglas

Joe

There is another reason to look more closely at the 813: it is easier to drive than the 845.

Also, no sense going to all the trouble of building when the parts or design are not top-shelf. THe assembly/craftsman labour is the same either way, might as well build a really good amp.

Another thing to lean toward the big ones: I already have a medium sized one, a 3-6 dB increase is required to be worthwhile. The medium sized amp is going to gome in at about half the price of the big DH amps with proportionally bigger power Iron.

If it were easy, everybody would be doing it.
regards,
Douglas