winged c 6550c is not good for ref 5se??

I had the same experience as the OP. The email response from Upscale was:

"We received your order, but unfortunately we cannot fill it. The SED 6550C used to be the best tube for your application, however the last batch of tubes to come out of the SED factory before it was shut down, have had issues with a soft vacuum. In products like ARC, Rogue, VTL, and several others, this causes the tube to fail prematurely.

We recommend, as does Audio Research, the Sovtek 6550WE..."

I was lucky in that I have a few extras so was able to use one of those.

Hi,if I put in a winged c,in with the sovetek 6h30,would it change the sound of my pre amp for the better. Thanks

For anyone looking to step up from the stock Sovtek whilst keeping their Ref 5SE closer to ARC factory voicing than NOS Tung Sol's I would recommend NOS General Electric 6550.

Thanks,Ill have to try it.Have you tried the 6h30dr.?.The prices seem to be getting very expensive,on ebay.

Hi tsushima1.ive got a winged c and a ge 6550 on the way.It will be interesting to see the difference in sound.