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Rectifier tube goes south in VRD Stereo


USNRET
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I just experienced my first tube (5AR4 if I am not mistaken) 'failure'. I powered up today and let the Peach do it's thing and then turned on the VRD stereo amp. I heard a noise from the amp and observed a strange light show from the right channel rectifier. I powered down immediately. I assume a failure of that tube and will have to see where/when I can get one. My questions are; just replace that tube and be done or is there more I should check out. I THINK bias is not affected and therefore no need to dial down and bring back up. Advice please....

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I've only lost two rectifier tubes in about 40 years. Both were in the last two years and both were "Groove Tube"s.

I just replaced them and everything was fine.

What brand rectifier tubes are they?

NOS has a good piece of gear and I'll bet the rectifier tubes are the only issue. Disclaimer is.... Just guessing without seeing it in person.

Stick a new one in and be done with it.

I'll recommend the old faithful Mullard.

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The offending glass was a Sovtek 5AR4. I have ordered a pair of Groove Tubes off Amazon as they were the ones that were immediately available with 2 day delivery.

So, do I plug both in? Can I swap left tube into the right socket and power up with left empty to check rest of electronics first?

What is best way to proceed?

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The offending glass was a Sovtek 5AR4. I have ordered a pair of Groove Tubes off Amazon as they were the ones that were immediately available with 2 day delivery.

So, do I plug both in? Can I swap left tube into the right socket and power up with left empty to check rest of electronics first?

What is best way to proceed?

You can power up just the one channel. However, depending on the power supply design, the decreased current draw from running only one channel can cause the voltages to be elevated. So, while it shouldn't hurt anything to try it briefly, I'd not run it for too long without knowing if the tubes are being subjected to an overvoltage situation.

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Received the pair of Groove Tubes (of course the shipping method was honked up, so much for paying for expedited service). I installed the one old good tube in the 'blown' right channel and new one in the left. Powered up and checked bias because I don't know any better and wanted to be sure. I then installed both of the new pair and re-checked bias after 30 minutes. The bias had drifted no more than .003 vdc since I last checked about 2 months ago. Bottom line is I am back up and grooving.

This pair have a little brighter top glow then the old ones. Thanks for the assist!

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How many hours on the Stereo VRD?

Craig recommends keeping a Spare or two 5AR4s, less than $ 20 per if buying the Grove Tube Variety.

I have heard they last around 5,000 hours or more.

Doing the math that works out to less than 1 penny per hour for both 5AR4s.

You could spend a lot more on tubes, listen couple thousand hours a year and still spend less per year than 1 round of golf at a good course, one month's Electric Bill etc.

Tubes are the cheapest part of my system and per hour this one of the cheapest Hobbies I have ever had.

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How many hours on the Stereo VRD?

I do not know. I got it a few years ago and may have put ohhhhh a couple of hundred hours on it since. I have a couple of spare small and large tubes but did not have any rectifiers. I have 1 extra now, need to get another set.

Actually, the timing could have been a lot worse. I was going to loan the amp to a forum member for the week while I was on vacation so he could check it out. Work interfered and the trip had to be cancelled, if not for that the failure could have occurred at his first power up. I know what I would feel like if I had borrowed the amp and it puked!

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Couple hundred hours in a couple of years, sounds like you are one tube away from having a life time supply of tubes plus backups.



The 5AR4 tube will blow on a Mono VRD if you do not let it cool down for about 5 minutes after turning it off.




Not sure why -- something to do with output tubes being hot and drawing more current than the 5AR4 can handle on startup.




I know they blow up with a Flash and Pop if hot from leading by example.


I did it a couple of months ago and my wife almost did this weekend.




She did ask permission first knowing this issue, I said yes, then screamed NO just in time.




I like the Mullards, last longer, some think they sound better, I think they do sound better but it is not a huge improvement and they are about 5 times the cost of Groove Tubes though.



Since it was only few hundred bucks for a Life time supply I went with the Mullards.

If the budget is an issue this probably a good place to save some coin and stick with the Grove Tubes.


The small tubes are the best place to get a big improvement for the same or less coin than good Mullard 5AR4s.

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Still learning the tube world ropes but this amp had been off for a week when I had the episode. I am the only one I can blame as the wife and kids do not go near this setup. At the age of 3 my son tried to watch a sandwich in a VCR and to this day he and his little sister take a WIDE berth around Daddy's toys. On the other hand , my son now age 8 calls me at work to troubleshoot AV issues because Mom is somewhat technically challenged.

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Couple hundred hours in a couple of years, sounds like you are one tube away from having a life time supply of tubes plus backups.

The 5AR4 tube will blow on a Mono VRD if you do not let it cool down for about 5 minutes after turning it off.

Not sure why -- something to do with output tubes being hot and drawing more current than the 5AR4 can handle on startup.

I know they blow up with a Flash and Pop if hot from leading by example. I did it a couple of months ago and my wife almost did this weekend.

She did ask permission first knowing this issue, I said yes, then screamed NO just in time.

I like the Mullards, last longer, some think they sound better, I think they do sound better but it is not a huge improvement and they are about 5 times the cost of Groove Tubes though.

Since it was only few hundred bucks for a Life time supply I went with the Mullards.

If the budget is an issue this probably a good place to save some coin and stick with the Grove Tubes.

The small tubes are the best place to get a big improvement for the same or less coin than good Mullard 5AR4s.

Agree with this. Groove Tubes are good Sovtek 5AR4's (pre-screened under load by GT). They seem a very good and consistent 5AR4 on the cheap. I've sent many to Guitar Center in a pinch when they want them NOW.

But I do use Mullards, have a good stash on hand so I use 'em. VERY reliable and long lasting.....THE "standard" in 5AR4.

The Sovtek 5AR4 will "blow" in a stereo VRD also after "fast off and on". That tube just can't take re-energizing in that situation, a Mullard is more likely to tolerate it but still not recommended (especially since those Mullards aren't cheap).

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