Genalex GL GZ-34 Rectifier...Did I just get a bad one? Five months seems

+1 on that.

New Sensor bought the Mullard trademark so their stuff isn't 'fake' but it does not hold up like the original Mullard rectifier did in the ST-70.

Thank you, Ralph.

I’ve seen excellent reliability out of current production Shuguang 5AR4. I think the one I use logged 7 years of steady rotation. My issue with them is that they barely reach a sonic level of adequacy. No idea on how my Sovtek holds up, as I find it unlistenable, and it has little more than break-in hours on it. JJ definitely sound the best of today's tubes that I've tried, though still not as good as vintage Mullard.  But after blowing a half dozen between my various amplifiers inside a year, I’ve grown tired of buying more.

You’re right about the ST70. I consider it a fantastic amplifier, and my Jadis (one of their best) Orchestra Reference and Quicksilver (considered their finest) 8417 both employ the same design even if Leo Fender implemented it prior to Dynaco. I’ve run the gamut on Dynaco "improvements", most of which swap the circuit for a Mullard long-tail pair. None of which improve upon the original. In my experience, presuming a person doesn’t demand more power, there’s just one sonic flaw, which takes less than $20 to address

@swampwalker @atmasphere @trelja 

Thanks for the clarification guys. Though I not a complete newbie to tubes, I don't spend much time rolling unless it sounds bad. FWIW, i ordered (& received) another Genalex Gold Lion GZ34. This is  from Jim McShane. The GL made the amp sing while it lived though it was a short life. I'm going to guess that I just got a bad one or that the Cryo treatment was a culprit or both. My previous rectifier lasted 3 yrs or so. Maybe I'll get that from this one. I'll let you know if I don't.

Trelja, did I understand you to indicate that other amps on the market  use the same circuit with a double rectifier tube?

@artemus_5, yes, the Quicksilver 8417 monoblocks each have dual 5AR4 rectifiers, and use the same circuit as the Dyanco.  Most have converted to EL34 or KT88 operation, as the 8417 became difficult and expensive to source.  This amplifier was the first Quicksilver, and considered by most their best sounding.

However, we need to look at things in totality.  I've actually blown more rectifiers in the Quicksilvers than the Dynaco ST70, as the amps use an initial power supply capacitor too large by a factor of about 4.

The Jadis Orchestra / Orchestra Reference integrateds also use this circuit, though with solid state rectification.  And in this application, with the right tubes, the results sound exceptional.  Still, I'm a fan of tube rectification, and the sonic beauty it lends

Great. Now Ralph has me looking for a genuine old Mullard rectifier. That's just great. Thanks man.