It may have been a gassy tube or a bit close to it’s limits, or both.
NOS tubes are a bit of a dice roll.
OK, just looked, this is likely a new issue copy you are speaking of.
Sounds like it is more likely you hit it’s current limits in repeated ’turn on surge’ spiking and it finally took the tube out.
Sometimes (more likely, actually) it is a VOLTAGE over peak, due to how a power supply is built. Ie, cascading draw that has one tube come on after another and the voltages can spike until all tubes are on line and the current draw increases, which brings the voltage down to manageable levels. Always a problem that one has to plan for when designing or building new power supplies in tube gear. The genalex may have been hit with one over voltage too many. And possibly been a weak example, in the first place.
Check voltage limits in the spec sheets of the given rectifier tube before you try again.
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It's more difficult to quantify old tubes than most people think. Simply paying more for supposedly higher quality is often a roll of the dice.
Personally, going against the opinion of most here, I prefer lower cost older tubes on ebay, and skip the price premium. My experience is that I can usually get at least 2, and often a lot more, very good older tubes for the price of one tube that others fight over.
As far as new 5AR4 tubes go, Sovtek and Shuguang show very good reliability. Sovteks typically sound worse than any other tubes, and that hold true in this case. Shuguangs sound a lot better, but still not good enough, in my opinion. JJ sound best today, unfortunately, they're as brittle as fine porcelain. That means, Shuguangs offer the best compromise today, even if it's not very good
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@artemus_5 You didn’t mention where you sourced your Gold Lion from. I have had great success with Gold Lions sourced from Cryoset. I have been using their 12AU7’s for many years with great results and long life. I just recently replaced the 5AR4 rectifier tube in my SACD player power supply with a Gold Lion GZ34 from Cryoset. I also added a Herbie’s Audio Lab HAL-O III-30 Stabilizer to the GL. The sound is a bit warmer than what I was getting with the Sovtek and the soundstage has opened up a bit. All is good. If you haven’t tried Cryoset, you may at least want to give Ron Sheldon a call and discuss your situation with him.
Good luck!
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I believe the OP is talking about a current production Genalex since he mentions the tube being cryoed. As others have stated sometimes a tube is just bad old or new. A rectifier generally should last a fairly long time. I had a NOS Philco 5ar4 go out with a flash and a bang a few years ago and at the suggestion of my dealer got a variac. For around $100 off eBay it has a 2k transformer and ramps the voltage up slowly. I’ve used it ever since haven’t lost a rectifier.Look for good deals on rectifier tubes on here, I picked up some NOS RCA 5ar4 60s era tubes from member aztubes. They sound fantastic and have been perfectly reliable. |
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 Good point about the thermal issues with a hot running rectifier. I leave my system on 24/7 so there is no thermal shock experienced by the tube.
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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 |
@artemus_5 I leave all of my components charged up 24/7. I have tubes in my line stage, SACD player and SACD player power supply.
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@artemus_5, thank you for clarifying.
That's certainly disappointing news. Given Genalex is the premium Russian tube, even more so. Over time, I've gravitated away from the majority of new production European tubes, both for sonic and reliability reasons. There certainly are Euro tubes I still prefer, but all things being equal, Chinese tubes tend to sound better, last longer, and cost less
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@artemus_5 In light of the fact that you only had the GL tube for 5 months, I think Ron at Cryoset would like to know about the tube's failure and may work with you on a replacement. Can't hurt to call and see what he says!
Please update after you check in with him. I would be interested in his reaction to a premature failure.
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I have a GL GZ34 rectifier in a Dennis Had SEP amp and of the 3 rectifiers I have, this one seems to sound the best (with KT88s anyway), and has performed perfectly under daily abuse, or use, or something. Non cryoed, from Tube Depot |
@wolf_garcia Good to hear that Gold Lion GZ34 has been working well for you. I am not, by the way claiming anything mystical about cryogenic treatment. Once I stopped using NOS Mullards that got noisy quickly in my circuit, I happened to try the Cryoset Gold Lions and had consistently good performance from them that I'm not questioning a good thing. I am currently using a pair of NOS Tung Sol 5687 in my SACD player sourced from the Tube Depot. So far so good with them too!
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I bought a Shuguang 274B that is way cool looking and is in second place among the rectifiers I own, although it seems to work nearly as well as the GL (I might be imagining the differences, as audio geeks do imagine things at times). It's hard to beat a 274B for the "I'm serious about tubes" impression. My SEP "Fire Bottle" came with a JJ 5Y3 rectifier but it was recommended by some Dennis Had SEP amp freaks that it might not have enough mojo (technical term) for the 88s I run for power tubes, although the amp seemed to sound fine with those. Something about tube "SAG" (Screen Actor's Guild?). Note my 274B cost something like 20 bucks including shipping from China…and it's perfect. |
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. |
The tube was not the problem.
The original ST-70 design is hard on GZ-34s and they are the most likely tube to fail in the amp. Its fine as long as you don't push the amp hard, but if you are pushing hard, the limits of the rectifier tube can be exceeded.
The solution is dual rectifiers and there isn't the room on the chassis nor the capacity in the power transformer. If there is any big flaw in the ST-70, that's it- the rest of the circuit is really quite competent.
I've not heard the Bob Latino version, but it appears to have only one rectifier tube for both channels, so its going to have the same problem. The solution- if you like that amp, keep a stash of rectifier tubes on hand.
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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 consider folks who never previously built anything assembled all but a few of the 300,000 ST70s, the fact that most of them that came up on the used market sported their original (5AR4 and all) tubes, and the majority of that number still worked mostly fine even after all those many, many years.
Unless Bob's using too big a capacitor in the first position of the power supply, which WILL blow rectifier tubes with regularity, there's no need to sweat it. Just get another 5AR4. I recommend spending for a vintage tube for best sonics and reliability. After that, sit back, and enjoy.
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Just realized I made a slight error in my initial post to this thread my amp uses a 5U4GB rectifier not a 5AR4. Sorry about that!
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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 |
I think my new Zyx cartridge is the culprit cause I wasn't playing quite as loud before. It sounds so doggone good though. :) that is because there is less distortion, so you naturally turn it up louder. consider folks who never previously built anything assembled
all but a few of the 300,000 ST70s, the fact that most of them that came
up on the used market sported their original (5AR4 and all) tubes, and
the majority of that number still worked mostly fine even after all
those many, many years. Joe, this weakness in the ST-70 design is pretty well-known. The reason many of the originals worked is that they were Mullards, which were built over-rated in their day. Most modern 5AR4s meet spec, but they won't hold up to a ST-70 like a Mullard will. I used to modified ST-70s for a living years ago. You can't get around this problem very well with solid state as the power supply voltages run too high, so you just have to deal with the fact that your ST-70 is going to eat modern rectifier tubes. There is a wonderful thread on audiokarma.org regarding all the various strengths and weaknesses of the design. I tried looking for it this morning but there are a lot of ST-70 threads over there so I apologize in not at this time being able to back up my comments with something you can get your teeth into. BTW that thread is overall pretty positive- in it you find out that the ST-70 challenged a lot of more expensive amps like the Marantz 8 by having excellent distortion figures and bandwidth. |
@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. |
If you want longer rectifier life, look for a Mullard made in the UK. Beware of fakes on ebay.
I would also look at the cost and compare that to the garden variety. If its more than 4 times the cost, I would just buy the cheaper tubes and get a bunch of them.
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@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 - Not to step on Ralph/s toes, but fake tubes are re-labelled modern production. Wipe off the printing on the tube and you can label it anything you want. Put it in a plain white box and voila...NOS goodness. Also pulls sold as NOS. Be VERY careful on eBay. Most of the "NOS" tubes I bought there turned out to be junk.
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+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.
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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
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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, 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
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Great. Now Ralph has me looking for a genuine old Mullard rectifier. That's just great. Thanks man. |
No school like the old school
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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 |
Whenever I'm with your wife she says the same damn thing to me…so I get that. However, MY wife says things like, "When are you going to sell those extra speakers you don't want?," and "what do you need THAT for again?" I also doubt the Mullard will beat the Genalex by much, but at this point if I don't get one I'll feel like I've let Ralph down somehow, and that would be sad. |
If you don't buy one that's just more for me.
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Like trelja I also like the sound of the JJ EZ34 tube. I would find the specs for the amp and see if the voltage to that tube is correct. Other than that I agree with atmasphere on the design having caused some of the issue.
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OK…now I'm devoting my bitcoin windfall fortune to cornering the vintage rectifier market…ah…the power... |
Hi , thanks for sharing . My Had Inspire came with the same tube . I’ve had zero issues with mine . I did have a new production GL KT-77 , with about 100 hours let go . I didn’t blow a fuse , I blew 2 caps and a resistor and the explosion broke a terminal strip too . IMO it’s not the sellers fault , just the field we play on ( bad luck ). I have NOS Tubes Too, RCA 5U4GB, Phillips 5AR4Y, Mullard GZ -37 coke bottle, Mullard GZ-32. I’ve really come to like the RCA. In musician terminology “ I Get More Sag “. The lower plate voltage ( my amp is self bias ), gives me a richer, more mellow sound . But it lowers my output a little . If you like the way your amp sounds now ( seeet amp BTW ). Get the NOS Mullard GZ-32, maybe $100. They usually last forever. I would consider setting your bias lower , but ask the expert that built it . Also the NOS Mullard GZ-37 ( coke bottle ) is more powerful . I bought one from Upscale Audio . Ask the experts , but I think the old Dynaco came with the Mullard fx32, you can’t do much better , and it’s money well spent . They are plentiful and are labeled RCA too. They have a small hole in the centering pin when you turn them over. Also a smoother sound then the GL. Happy Listening , Mike. |
Yeah I have simple needs. I have a fully modded Modwrite Oppo UDP205 with Modwright PS 9.0 I've been using roughly 6 months. The Sovtek 5ar4 rectifier in the PSU has blown twice, the first time it took out its own fuse ans well as my power conditioner's fuse. That was after less that 2 weeks of having in my system. The second just recently blowing the PSU fuse only. What gives? are the Sovteks electical specs so lowsy they don't work with this board design or is the likely a flaw in the PSU board. I have gone on to NOS Mazda/Phillips 5R4GYS. This is a beautiful tube it just oozes quality and sounds great.
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@mars2K
I have the same set up with no rectifier issues. However, I never used any Sovtek tubes, only a Sophia Electric 274B mesh plate and a NOS CV 717 rectifier that is the same as a 5R4GY tube. Since you have not had issues with your NOS Mazda, I would say that the Sovtek tubes are unable to handle the juice that the rectifier needs. I highly recommend Sophia Electric for new production tubes.
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