Modern Made EL34 (or KT77) for Original ST70

BNR_1 wrote:Hello:

So it has been a while since I read a recent update on your personel experience with modern made EL34 tubes for the older (original) Dyanco ST70 amps.  My amp has been restored (removed selenium rectifier, new caps, etc.), and has the original transformers and uses a 5AR4 rectifier.  The driver board is original with RCA 7199 tubes.

I did a search on this topic but most of the recommendations are for the new VTA model ST70 that has a higher rated PT so I see the typical KT88s, etc; or if relevant to the older ST70s the recommendations are dated back to 2010 and 2011.

I saw older postings of using the Russian made 6P3S-E and other variants of 6L6s.  My prefernce is to stick to either a EL34 or KT77 tubes.

The present tubes are SED Winged =C= which are no longer in production so prices are higher.  My experience has not been all that great.  Two tubes went bad after only 300 to 400 hours of use.  In one tube the getter was white as snow and the other tube the getter was flaking off the tube.  But my experenice with this tube is only once, and I have read numerous examples of positive results using this tube.

Any inputs....good or bad?

BTW, I know nothing can beat the older British and American made tubes but present budgets do not permit spending $300 to $400 for a quad.  At this price point Psvane tubes are also out.

Thank you  

BNR_1 wrote:Thank you peterh...now that is a fast response.  Would you mine sharing why the JJ works well?  Have you been using these tubes for a while with low rate of failures?

arledgsc wrote:In a guitar amp I used both JJ and Gold Lion KT-77s.   Liked both but felt the Gold Lions might be better for an audio amp.  Gold Lions are more expensive.

PeterCapo wrote:BNR_1, I have a Ruby 5AR4 in my Cary AE3-MkII preamp, and it has been running well for a few years.  However, when I recently tried it in my Stereo 70, I got popping sounds through the speakers.  Obviously, it could not stand the strain in the Stereo 70, but it does fine in the preamp.

PeterCapo wrote:BNR_1, I have a Ruby 5AR4 in my Cary AE3-MkII preamp, and it has been running well for a few years.  However, when I recently tried it in my Stereo 70, I got popping sounds through the speakers.  Obviously, it could not stand the strain in the Stereo 70, but it does fine in the preamp.

But, this is probably not a reflection on the reliability of the Ruby EL34B-STR.  It is certainly an option.  I believe Doug’s Tubes http://www.dougstubes.com/power-tubes/el34-kt77-6ca7/ruby-el34-bstr.html has these, he checks Ruby’s matching and there is a 6-month warranty, which is pretty good for tubes.

One thing is that Chinese tubes do not come with date codes.  I personally think it is a good idea to have tubes that are electrically matched while also being from the same or close production runs.  I expect that many would disagree as this does make tube buying and selling more inconvenient, but I stand by it.  However, if you do not listen critically, it probably doesn’t matter.

Another issue is that every Chinese octal tube I have owned, and most I have seen pictured online, does not have straight pins.  They are often splayed-out.  This has on occasion wreaked a bit of havoc on my tube socket contacts, so I think it’s worth being prepared to deal with somehow.

In any case, AFAIK, Doug’s Tubes checks Ruby’s matching, which is good because I suspect that a lot of places selling the Rubys just ship them with Ruby’s matching.  I am not sure this purported business of special attention to QA/QC for Ruby Tubes really pans out.  I called Ruby on a couple of occasions to discuss their procedures, and I was told that they pretty much are the same tubes as usual but with Ruby markings - at least that was what I was told, but who knows if the person I spoke with was really in a position to know for sure.