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

like a terribly short lifespan. I bought it in May and spent the extra money to get a "good" tube. It sounded good while it lived. But it went in a fiery inferno last weekend.  Fortunately it only took out a fuse.

It was running in a Bob Latino VTA ST-70 Dynaco amp. It's a great amp but runs the rectifier a bit hard from my understanding. However the original tube lasted at least 3-4 yrs IIRC. I tried a SS rectifier. YUK!! I put the tube (a spare Sovtek) back in place I've had good luck with the KT-66 Genalex GL's and they have a good reputation (I think). Is this just the luck of the draw. IOW, even a new tube can have a short life span? Or is this odd? Is there any way to avoid it? I'd buy another Gennalex GL if it will last. But I can buy 2 Sovteks for the price of one GL. Sovtek sounds good too.

FWIW, The tube that failed was cryo treated. Could that make a difference in a rectifier tube? As always, Thanks for your help.
artemus_5

Showing 9 responses by artemus_5

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artemus_5 OP
1,992 posts
 
Hifiman
Do you leaveyour amp in standby mode? IOW, How do you keep from running through tubes quickly?

Jond

The Variac is an interesting idea. Thanks
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artemus_5 OP
1,992 posts
 
Trelja
It was not a NOS but a new production Genalex GL.

Hifiman

I bought the GL with a quad of 6p3se/6n3ce from Cryoset. First time I’ve dealt with him but his service was outstanding. And he was very friendly. I didn’t name the vendor because I didn’t believe it to be his fault and didn’t want to give a false impression.
I have some thoughts about it and conclude that cryo treatment is not a good thing for the rectifier tube which is under more stress than the other tubes. There are articles which address this issue of super cooling a fragile tube made of different materials which expand and contract at a different rate. I read this after I posted.
artemus_5's avatar
artemus_5 OP
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Wolf. (I might be imagining the differences, as audio geeks do imagine things at times).

I’ve never done such a thing. That’s my story and I’m stickin’ to it.




Sorry. I just could stop myself from doing that.
artemus_5's avatar
artemus_5 OP
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Ralph. It would make me feel better if you didn't know what you are talking about. But I know you do.. I have thought about keeping a bunch of rectifiers around. I am running through 93.5 db speakers but I am running it somewhat hard. I think my new Zyx cartridge is the culprit cause I wasn't playing quite as loud before. It sounds so doggone good though. But I know it is the bottleneck. I just ordered another Genalex Gold lion. This time not cryoed. Time will tell. Thanks for your response. Try to have some good news next time huh? (-: He said in jest)
artemus_5's avatar
artemus_5 OP
1,992 posts
 
Trelja. Thanks for the encouragement.  I still think the cryo treatment is the main problem. It may be fine for the other tubes. But the different materials expand & contract at different rates,. This may work in tubes which aren't pushed as hard as the rectifier tube in the ST-70. But it isn't a good thing for a rectifier tube IMO. Other articles point this out as well. Jim  McShane is also of your opinion that a good rectifier shouldn't have any problem pushing the ST-70.  And, I got 3-4 yrs on the original tube. So, even though the rectifier is somewhat of a bottleneck its not the be all end all without remedy. I agree with you that hundreds of thousands were built and ran great. Certainly many were pushed as hard as I push mine with less efficient speakers
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artemus_5 OP
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@atmasphere  
 The reason many of the originals worked is that they were Mullards, which were built over-rated in their day.
Does this mean that I need to get a NOS Mullard? If so, which one (if there are differences)?

BTW, I read an article by someone named Campbell who measured the ST-70 for accuracy and concluded that it was among the best measuring amp produced. However, his criticism was the single rectifier tube, noting it should have had 2.
artemus_5's avatar
artemus_5 OP
1,992 posts
 
@atmasphere  Can you show me an example of a fake. I'm not sure how one would fake a tube. How is it done? Thanks
artemus_5's avatar
artemus_5 OP
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@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's avatar
artemus_5 OP
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@wolf_garcia 

Yeah, Me too. But I can't imagine a NOS Mullard is going to  beat the Genalex by very much in sound quality. It is fabulous. This one isn't cryoed. Maybe it will last longer. But I'll probably try a Mullard NOS. Look at it this way Wolf. A professional said we needed it. My wife will still roll her eyes. She told me last night not to change anything because it sounds really good
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