I would have something more useful to add probably but it was mostly all down to bad luck! My Herbie (less than a month old) blew a pair of the Rubys the first time I cranked it up. I tried a new pair of Rubys with 4 nearly new Harma Retros
http://www.watfordvalves.com/product_detail.asp?id=846 from watford valves. That seemed to sound slightly nicer at "house" volume, but then when I turned it up loud again it blew the new pair of Rubys and made a big flash and completely shattered the tube fuse!
I was gonna try a pair of Svetlana / Winged-C 6550Cs
http://www.watfordvalves.com/product_detail.asp?id=139 with the 4 Harma EL34s since we thought I might have just been really unlucky with 2 pairs of duff Rubys. My amp won't bias 6550Cs with 4EL34s at the same time though!?! The 6550Cs get a current of 375mA-ish when I put them in, but I can then turn it down to 80mA. The EL34s go down to about 2mA though once the 6550Cs are plugged in, and will only go up as high as 20mA!?! I hope this hasn't damaged my 6550Cs I bought. I think my Herbie is either broken from new as it's less than a month old (and hence blew up my tubes), or the original or replacement tubes were bad and broke it when brand new. It should be able to bias a mixture without a mod shouldn't it or am I confused? It should be going on holiday to see Peter at the end of the month.
Therefore Rubys might be fine but I'm dubious since they blew on me twice and the Harma one's didn't go, but it might be my amp being broken and eating them.
In which case, in a dodgy Herbert at lower volumes, I preferred the tone of Harma EL34 retros over the stock Rubys (but since I only had 4 it had a pair of Rubys too). I think they just seemed to sound a bit richer and smoother to my ears. And they were the only thing I had sitting around at the time! :?
I've never been able to run my Herbie at full volume on more than 4 tubes so I can only comment on "house" volume I'm afraid, but hopefully that might still be useful to you!
When it's sorted out I have some Svetlana / Winged C EL34s to try too (but only a pair)
http://www.watfordvalves.com/product_detail.asp?id=851
and I'll try mixing them with the Svetlana 6550Cs. So I'll let you guys know...
I put one of the RFT ECC83s/12AX7s out my Mesa Triaxis in tube 1 as someone suggested. It sounded nicer again I think. It's back to the TAD one ATM though cuz if it goes to Germany I don't want to find it comes back with all TADs in again accidentally!
In the meantime, since my old '92 Mesa Triaxis is dodgy, it looks like it might be a Digitech 2120 with a pair of Sovtek LPS ECC83 in, with my Marshall EL34 100/100 with that same set of Harma EL34s back in! The 2120 has all the distortion tone of someone cracking walnuts in a paper bag! Nice! :wink: