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Rectifier Tube Concerns

Lavane said:
I've been happy with the TAD GZ-34's with the brown base. They had them made to there own specs. The factory thst was making them isn't in business anymore, so they're having them made elsewhere now with a red base. I don't know it they are as good though. I haven't had one fail yet.
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there seems to be a lot of this with new production tubes, especially chinese. theyre here, then theyre not. a dealer carries em, then they carry something else and what ud been lookin formia gone like it never existed. ive tried to get clear information, but damn the obfuscation is VERY strange to me, unless these tubes are made by child labor or forced uygr labor, whats with the secrecy? its freakin weird dude.

some of these stop-starts can be explained by 2 big events: the shugang (hey im illiterate) factory burning down and the tj full music factory (i believe there are two, but im uncertain) shutting down.

but, man, im still tryin to be make informed
selections, and its difficult with some of this stuff.
 
ceylon said:
there seems to be a lot of this with new production tubes, especially chinese. theyre here, then theyre not. a dealer carries em, then they carry something else and what ud been lookin formia gone like it never existed. ive tried to get clear information, but damn the obfuscation is VERY strange to me, unless these tubes are made by child labor or forced uygr labor, whats with the secrecy? its freakin weird dude.

some of these stop-starts can be explained by 2 big events: the shugang (hey im illiterate) factory burning down and the tj full music factory (i believe there are two, but im uncertain) shutting down.

but, man, im still tryin to be make informed
selections, and its difficult with some of this stuff.
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The Shuagang, or however you spell it, factory may be back up and running?
 
ceylon said:
doesnt seem that way—all those really cool lookin $100 apiece 6SN7 and 6SL7 are still off the market as far as i can tell.
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I don't spend that much on sitnql tubes myself. The Tung-Sol 6SN7's are just fine for me. I have some old stock and new stock Tung-Sol 5881's and I can't tell the difference in how they sound.
 
Lavane said:
I don't spend that much on sitnql tubes myself. The Tung-Sol 6SN7's are just fine for me. I have some old stock and new stock Tung-Sol 5881's and I can't tell the difference in how they sound.
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some times i can tell a bug difference; sometimes i cant tell at all.
 
I haven't read this whole thing, but the 5V4 was mentioned. The ST-bottle 5V4G looks cool, but they have a rather deserved bad reputation for instability. They were quickly replaced by the straight-bottle 5V4GA, which doesn't have the "cool" factor, but behaves much better. If using 5V4Gs, I'd highly recommend using a pair of diodes like the UF4004 inline as "pre-rectifiers," a notion I picked up from dcgillespie long ago.
 
Sam Cogley said:
I haven't read this whole thing, but the 5V4 was mentioned. The ST-bottle 5V4G looks cool, but they have a rather deserved bad reputation for instability. They were quickly replaced by the straight-bottle 5V4GA, which doesn't have the "cool" factor, but behaves much better. If using 5V4Gs, I'd highly recommend using a pair of diodes like the UF4004 inline as "pre-rectifiers," a notion I picked up from dcgillespie long ago.
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I had a RCA ST bottle 5V4 give a lightning show.
 
Lavane said:
I had a RCA ST bottle 5V4 give a lightning show.
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All of the ST-bottle 5V4s were notorious for things like that. I have a pair of very well-balanced tubes that were NOS when I got them that are in my Fisher 70 monoblocks, but the only reason I'm comfortable using them is the UF4004s installed inline.
 
SwedishChef said:
I'm a tube noob, please go easy on me for my ignorance.

Rather than take my Blue Velvet preamp post way off track, I decided to start a new thread that just pertains to rectifier tubes.

The seller that I purchased my first Sylvania 6SN7 pair from on eBay is sending me a 5V4 rectifier to replace my Chickidy China 5Z4p and he suggested that I only use a 5V4 or 5AR4 rectifier tube in my Blue Velvet Pre.
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Sam Cogley said:
I haven't read this whole thing, but the 5V4 was mentioned. The ST-bottle 5V4G looks cool, but they have a rather deserved bad reputation for instability. They were quickly replaced by the straight-bottle 5V4GA, which doesn't have the "cool" factor, but behaves much better. If using 5V4Gs, I'd highly recommend using a pair of diodes like the UF4004 inline as "pre-rectifiers," a notion I picked up from dcgillespie long ago.
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Lavane said:
I had a RCA ST bottle 5V4 give a lightning show.
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Hi gents, I have quoted an excerpt from the original post, where SweedishChef is talking about his "Blue Velvet" Preamp. Now, if we were talking about any kind of power amp, I could understand the concerns (although if you look into the antique TV world the 5V4 saw extensive use as a "Damper" tube in the Horizontal output section, enduring very high voltage and considerable current with no widespread reports of chronic meltdowwn).

If a preamp is operating at values of voltage & current such that any variant of 5V4 would be stressed to the point of failure, I'd say it's got other issues far beyond exceeding the tube's maximum design ratings, yes?
 
init4fun said:
Hi gents, I have quoted an excerpt from the original post, where SweedishChef is talking about his "Blue Velvet" Preamp. Now, if we were talking about any kind of power amp, I could understand the concerns (although if you look into the antique TV world the 5V4 saw extensive use as a "Damper" tube in the Horizontal output section, enduring very high voltage and considerable current with no widespread reports of chronic meltdowwn).

If a preamp is operating at values of voltage & current such that any variant of 5V4 would be stressed to the point of failure, I'd say it's got other issues far beyond exceeding the tube's maximum design ratings, yes?
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The 5V4G was notorious for self-immolation and lighting shows at well under its operating ratings. The 5V4GA is fine, just not pretty. I daresay that none of those TV 5V4s have been 5V4Gs since the first Eisenhower administration. The simple fact is, the 5V4G was yanked off of the market for a reason, and unless you enjoy needlessly imperiling irreplaceable parts around it, using them without pre-rectifier diodes is crazy. IF you can find any with decently matched halves. Even the ones that don't melt down tend to be wildly imbalanced. UF4004s are cheap, and they stabilize the 5V4G's bad behavior. It's a no-brainer. But, feel free to make your own mistakes. I hope you catch them dying before they take anything else out.
 
Sam Cogley said:
The 5V4G was notorious for self-immolation and lighting shows at well under its operating ratings. The 5V4GA is fine, just not pretty. I daresay that none of those TV 5V4s have been 5V4Gs since the first Eisenhower administration. The simple fact is, the 5V4G was yanked off of the market for a reason, and unless you enjoy needlessly imperiling irreplaceable parts around it, using them without pre-rectifier diodes is crazy. IF you can find any with decently matched halves. Even the ones that don't melt down tend to be wildly imbalanced. UF4004s are cheap, and they stabilize the 5V4G's bad behavior. It's a no-brainer. But, feel free to make your own mistakes. I hope you catch them dying before they take anything else out.
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And you really think a preamp, that's gonna likely draw less than 50 MA. from it's B+ supply, is going to flame a tube rated at 175 MA. ? We are still talking preamps here, yes? In a power amp I sure wouldn't use it, but I would have no reservations of using it in the Blue Velvet preamp that is the original subject of this thread......
 
Sam Cogley said:
The 5V4G was notorious for self-immolation and lighting shows at well under its operating ratings. The 5V4GA is fine, just not pretty. I daresay that none of those TV 5V4s have been 5V4Gs since the first Eisenhower administration. The simple fact is, the 5V4G was yanked off of the market for a reason, and unless you enjoy needlessly imperiling irreplaceable parts around it, using them without pre-rectifier diodes is crazy. IF you can find any with decently matched halves. Even the ones that don't melt down tend to be wildly imbalanced. UF4004s are cheap, and they stabilize the 5V4G's bad behavior. It's a no-brainer. But, feel free to make your own mistakes. I hope you catch them dying before they take anything else out.
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Ended up finding an Amazon gift card and purchased an overpriced Genalex u77 / 5AR4. I ended up yanking the 5Z4P that came with the preamplifier after the first power up session with all of the China tubes.

I have no intention of testing the 5V4GA Sylvania that was given to me free. It will likely sit in a drawer just like it sat in a drawer many years before it was given away free. If someone can use it, they can have it, just need to PayPal for shipping. 95/95 is written on the box so I assume the last time it was tested that was what both sides were.
 
SwedishChef said:
Ended up finding an Amazon gift card and purchased an overpriced Genalex u77 / 5AR4. I ended up yanking the 5Z4P that came with the preamplifier after the first power up session with all of the China tubes.

I have no intention of testing the 5V4GA Sylvania that was given to me free. It will likely sit in a drawer just like it sat in a drawer many years before it was given away free. If someone can use it, they can have it, just need to PayPal for shipping. 95/95 is written on the box so I assume the last time it was tested that was what both sides were.
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The 5V4GA would work just fine. It was designed specifically to fix the problems of the 5V4G. I'm sure that 5AR4 will also be a very nice rectifier tube, too.
 
Sam Cogley said:
The 5V4GA would work just fine. It was designed specifically to fix the problems of the 5V4G. I'm sure that 5AR4 will also be a very nice rectifier tube, too.
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Under normal circumstances I would have never purchased the Genalex u77, $75 for a single rectifier is pretty crazy. Maybe the added stability of the 5AR4 will give me a few more hours on NOS 6SN7 pairs? Time will tell.
 
5V4GA.jpg

Here is a Sylvania 5V4GA that will probably hold up well. It was rumored that it is actually a 5AR4, relabeled for the military as a 5V4GA. I have a few and the voltage drop is identical to the 5AR4 as is the construction. "But only its hairdresser knows for sure!"
 
StepheK said:
So I'm curious what people think about a rectifier tube having an impact on sound, especially in an SE amp that has mostly consistent current draw across in. I hear people saying they can now hear angels singing in the background after swapping to XYZ $$$ NOS rectifier, but I have yet to hear any difference in any of my amps swapping these out. Possibly in a PP amp with low value filtering cap where you would see a lot of sag, maybe?
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I believe it's like FlaCharlie stated.. it's different voltage drops thus changing the tube bias and hearing that's what they are hearing? Here's a good youtube video where he shows the the difference with the different rectifier tubes
 
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