Impressions of the Re-issued Genalex Gold Lion U77/GZ34 Rectifier Tube

First some qualifications. I only have ears to judge. I have little knowledge of circuit design etc. But I have spent about 15 yrs putting a very good system together which I would be happy to show to anyone. I have also learned that synergy is the key to success in putting together the magic that we all are looking for. I am not totally new to tubes. But if my system sounds good, I generally leave it alone. Okay, so that's not completely accurate... I leave it alone longer than many others. My point is that I have not all the different  GZ34 tubes. But I have some. I tried SS as recommended. (Weber Copper cap) It sounded  awful to me and my wife.

My system is listed in my profile. The amp is a Bob Latino VTA ST-70 with all upgrades offered. Bob built the amp in "09. I didn't realized the importance of a good rectifier tube until I got the Genalex Gold Lion. I've had this in a little less than a week. First impression.....WOW!!. The attack of the plucked strings on SRV's "Tin Pan Alley" was fantastic. Extremely sharp. Plenty of air. I was spell bound. But I wasn't expecting what came next. the bass kicked in and was at least an octave or more deeper than it was the previous day when I listened to it with a different rectifier tube.(Sovtek) It hit me in the chest more than it has ever done. I have fought hard to get the adequate amount of bass in my room for years. The room is 5000 cu ft which is a lot to fill. So this is welcomed. If you have a bass heavy system it may not be your cup of tea unless you can tame it. AAMOF, I turned back my sub last night. I've never done that before. 

At first I thought my new cartridge (Zyx 4D) may be playing a big part since it digs out more bass than my previous cartridge. Its been in the system about 6-8 weeks. However, putting on a CD showed the same tendencies as what I had heard on vinyl, though maybe not to the same extent.

I am very happy with the Genalex GL GZ34. The price is $40 which puts it at the top price for the re-issued  GZ34's. I had a GL in the amp before which had a very short life span

However I suspect it may have been due to a weak tube being cryoed and used in a demanding amp. This one is not cryoed and was hand picked by Jim McShane.  The sound is good enough that I would be willing to buy  a new tube each year because the sound is that good. Certainly I hope that isn't the case. However, Jim (& I)  believe that a good GZ34 should handle the ST-70, though that has been pointed out as the short coming of this amp. However, I got at least 3 yrs out of the original GZ34 tube. Maybe I'll get a good life from this one. Like the previous one, I will enjoy it while it lasts. Its a winner.
I have a pair of these Genalex GL GZ34 (aka 5AR4) rectifiers in my PrimaLuna Dialogue Premium PreAmp along with some Genalex GL 12AU7s and a pair of Mazda CIFTE 12AU7s... This combination along with a McIntosh MC152 Amp and a pair of Martin Logan ESLs are very sweet...

"In space no one can hear your cryo tubes scream." ;^)

I know that this is an old post but in case someone still reads it (like me) I have to ask this: cyro freezes everything in the tube and then comes back to a normal temperature. So then the tube goes into its circuit and gets heated. So can someone who is better trained than me (which is about 99% of the people out there) tell me just how they can say for sure that the cyro is working? Did anyone hear the tube before the cryo and then the same tube after? If so, how does the cryo rearrange the molecular structure and keep it the same once the tube heats up for the heat will affect the molecular structure the same as the extreme cold, will it not? When NASA does their cyro on the parts they use, are those parts exposed to very high heat over and over again  such as a tube in a circuit or are they a "one and done" application?

Curious as to thoughts / explanations...and thanks...


You guys are so mean.  A little humillity about the subject on both sides might be in order. I'm willing to concede to either side with some relevent data. I never saw a technical explaination for or against cryo treatment.  Everything said was hearsay and anecdotal and none of it convincing either way.   

Give me the physics please.  After all heating steel and quenching quickly  adds strength why is it so hard to believe that something you may not happen to know might happen in the other direction. Approaching absolute zero transforms many materials into super conducting states. Cryo is far colder than -40 F. Cryo is closer to AbZero than -40 F

BTW When I say say heating steel I'm not talking about leaving it in your barn over the summer.

I wish @geoffait would come back I want to hit him up for some of those Nasa tubes 😉