45 SE Triode Schematic Required

[Digiverse]

Hi All, I am at the beginning stage of having a 45 SE Triode stereo amp built, I already have a power transformer and some other bits and pieces, what I would like help with is a 45 SE Triode Schematic that allows for the amp to be direct coupled, I am considering using a 5V3A/5AU4 Rectifier tube in the build, any thoughts on this approach ? I will not be doing the build myself, I have a technician friend who is very experienced in building valve amps, although he has not built a amp such as this before, so he is very keen to do so, any help would be much appreciated. Thanks.

 

[timgr]

Here's a direct coupled amp for 45s: https://www.electra-print.com/45drd.php

Also look here about the Loftin-White topology https://tubecad.com/2015/12/blog0335.htm

No personal experience with this topology, but it is interesting. I'd think that cap-coupled would be considerably easier for a first iteration. Seems that all the direct-coupled single ended amps elevate the cathode voltage of the 45 significantly to allow the plate voltage of the driver tube to match the needed grid voltage of the 45. This makes your supply voltage quite a lot higher than it would be with a cap or interstage coupled design, and dissipates a lot of applied power as heat.

Here are a few other 45 SE amps if you aren't dead set on direct coupling - https://www.diyaudio.com/forums/tubes-valves/334208-korneff-45-amp-circuit.html - likely there are plenty of similar threads here at AudioKarma, but this one at DIYAudio is recent and active.