[SoundBound]

I see a lot of really good deal on Russian 5C4M rectifier tubes around.  They are military grade tubes and reportedly a substitute for the 5Y3s.

Does anyone have any experience with these?  Any other suggestions for 5Y3 tubes as well?

[poty]

If you are speaking about 5Ц4М - yes, you can use it instead of 5Y3GT, but in many usages here the first capacitor exceeds the max specs value for 5Ц4М. It exceeds the value for 5Y3GT too, but not so dramatically (4uF for 5Ц4М - vs - 20uF for 5Y3GT). I don't think it matters as soon as the DC current is relatively small, but I'd add more serial resistance to the anodes just in case.
You can also try to substitute 6Н2П-ЕВ for 12AX7 positions. In my case I like them in Cornet 2 (with some mods to 3).
With several changes I prefer 6Н1П to 12AU7 too.

[SoundBound]

Thanks Poty for the detailed info.  I have decided to use vintage Sylvania 5Y3WGTA to be on the safe side.  Picked up a couple on eBay that should do the trick.

I have used some Russian military tubes on another project and am pleased with them but on my Clarinet I am planning to use a set of 6350 tubes.  Will have to see how good they are, there is good praise for them out there.  ( I do have to study how to deal with the different pinout and see if the added filament currents cause me any problems, so it's not a given that I go with these).

On my Cornet2 I am currently using new production 12AX7's, but I have a set of Telefunkens that I am strongly thinking of putting in there.