I have finally published the post about the RH813 amplifier!
This was a very complex and difficult project, both in material and technical terms. The project could not be made without the help of Paul Barker, who has provided tubes and output transformers. Thanks go to Steptoe as well for the pair of 813 tubes he has sent. Somewhere towards the completion of the project Per Lundahl stepped in as well with a pair of LL1688 transformers and LL1638 chokes.
Obviously, this is not the last part of the RH813 story. First of all, the amp needs some sort of box, and I intend to build one during the next couple of weeks: it will not be particularly good looking (at least in details) but it should be stable and solid, providing the amplifier a provisional home until I get a job and am able to source proper material to build a nice box.
I also intend to develop the project through further modification for use with GM70, particularly due to the fact that this tube seems to be bulletproof in terms of performance - and it has no anode cap on top. I might eventually experiment with GK71 as well, but I guess that some already have both GK71 tubes and amps that might be modified to suit the RH813 schematics - thus it is possible that I might not get to use GK71 in this amp, at least until the 813s I have last.
RH813
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Alex Kitic
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Paul Barker
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#2
Nice write up, a lot of time spent polishing the phrasiology much better prose than I could achieve if I spent 4 times as long as you, and it's my birth language.
Makes we want to hook up a GK71 version. Or shall I do sometheing really mental and use the GU-81M. The HF AC heating makes such ideas possible. G2 is limited to 600v.
Makes we want to hook up a GK71 version. Or shall I do sometheing really mental and use the GU-81M. The HF AC heating makes such ideas possible. G2 is limited to 600v.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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Alex Kitic
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#3
The GK71 idea is great, because the two tubes are almost identical at the voltages required for this amplifier. You would end up with a breadboard that begs to be transformed into finalized amplifier.
The GU81M is a monster... it would probably go up to 100W per channel, easily. But I guess you don't need 100W: the GK71 is the road to pursue.
Yes, the HF AC heating makes a lot of projects easily doable.
The GU81M is a monster... it would probably go up to 100W per channel, easily. But I guess you don't need 100W: the GK71 is the road to pursue.
Yes, the HF AC heating makes a lot of projects easily doable.