5U4 Shoulders or not
 

I was wondering if you were restoring a TV that will be run a lot would you stick with 5U4 tubes that have shoulders or the later ones without shoulders ?

whats the difference besides age and size ?

thanks
Mike

I use the 5U4GB types for anything that is going to run a lot. They have the latest improvements for that era.
For applications that let you see the tube the ST is great but I find they don't last as long.

The newer 5U4GB's are a little more stout in design over the G's. However if your set was designed to use the G types then there should be no issue with either.

As for myself, I would use what I would have most of in my stock considering that the GB's are more plentiful to buy. You should get just as good of a service life out of either as well.

The 5U4 family of tubes were so commonly used and a popular choice that they are still abundant today. (however prices seem to be going up!)

The 5U4GB has a higher output current rating (300 mA vs 250 mA for the original 5U4G). The straight-sided bulb allows both ends of the internal structure to be supported, improving vibration/shock tolerance.

The original 5U4G tubes in the ST envelope are getting harder to find and more expensive, because some of the audiophool crowd is convinced that they "sound better". :rolleyes:

There is no question but that the ST tubes sound better. Just ding one on the side and listen closely. Yum!

If a set is really going to run a lot of hours, I'd use a solid-state 5U4 to keep the heat and energy consumption down a bit.

:lmao: I dare you to post that on audio karma next time there is a debate on which rectifier tubes sound better. The responses to that should be priceless.

Jim's idea is a good approach (especially if on a budget or your xformer overheats with a normal 5U4), but if you make your own don't forget to add snubber caps across the diodes to reduce switching noise especially in radio applications.

Also the color of the knobs is more important than most people realize.

I once knew an electric bass guitar player who insisted that the flecks in the paint on the solid wood body gave it a special tone. I should have tried to sell her this bridge I own.

And to stay on topic, yes the solid state replacements are definitely advisable, even if all you consider is the 15 W per 5U4 just for the filament. If you want it to be original, keep the tube handy to plug in when showing off the set. Then of course you can use the ST type for more dramatic effect.

Seems like for audio it would be better to have the one that can handle more current, and is more solidly built..... Then there is the argument that a rectifier tube doesn't actually do any sound amplification....... Anyway as for my 3 cents on audio while posting in the tv section.... I'd like to say nothing sounds like it should sound better than some of Carver's advertising pamphlets..... "Asymmetrically charge coupled, hyper-dine series receiver with sonic holography" They just sounded so cool and advanced even before you turned them on....... ahhhhhhh... oh, yah... I don't think they had 5U4's in em...

Well they look cool.:smoke: As for sounding better, I have a hard time believing what mechanism is involved that could make a difference there. The output tubes and driver and buffer tubes I can understand why (tubes tend to produce some amounts of 2nd harmonic, when down around 45dB it sounds pleasant to the ear).

Good argument. It makes sense that the rectifier tube version wouldn't make a difference in performance or sound unless defective or if the PS was being operated near design limits. If b+ voltage variances occur with different rectifier tubes causing an effect on biasing of signal amplifying tubes I could see that causing an a distinct difference in perceived sound of rectifiers among those unaware of biasing.

I get SS vs. tube rectification having an effect on sound though due to switching noise and reverse leakage found only in solid state diodes....Which makes me wonder how bad selenium rectifiers are compared to tubes and silicon diodes....

Well all things working correctly and within limits, I'm just saying I would imagine you can't tell one good 5U4 from another, as long as it's all operating within limits.

I still feel like there's a "limitless" supply of 5U4s of all types, and honestly I've found that the GBs are more likely to short than the G or GA types. It's only my own opinion though, and I'm sure many will disagree. I know that since they haven't made 5U4Gs for half a century or more, they must be diminishing. But still at every swap meet or garage sale where there is a box of tubes, there is most always a 5U4G or two.

As far as "high usage" restored TVs, I'd still go with the correct style, or why restore a TV in the first place. If you put a wrong-style 5U4 in it, that's along the same theory as putting a new aftermarket digital fuel injection system on a 1938 Cadillac; sure it will run better and get great MPGs, and you can get new sensors and parts for it, but for what purpose???

Charles

Absolutely! The nostalgia is the idea here. On the other hand, if you aren't showing the innards then you can do as you like with what is out of sight. Certainly the quality of performance of old gear can't match modern stuff, so it's not how it works that matters but what it is.

:lmao:Actually, they are still being made:

http://www.amazon.com/Sovtek-5U4G-Du.../dp/B0002M71S0

http://www.sweetwater.com/store/detail/MB5U4G

http://www.tubeman.com/item196.htm

Apparently, the audio fetishist market is large enough to justify producing these, even if they are inferior to the straight bulb types. Makes perfect sense, considering that you can also buy 6SN7s with Western Electric style "tennis ball" bulbs on them:

http://www.jacmusic.com/chinatubes/6SN7-Globe-400.JPG

So they take a crappy Chinese 6SN7, and make it even MORE microphonic by removing the structural support and damping provided by the mica supports against the inside of the bulb. And then charge a premium for them! :lmao:

If you want the best of all worlds, remove the 5U4G bulb from the base, install a pair of 1N4007s inside the base, then epoxy the bulb back on. Solid state reliability, reduced heat load, and the correct vintage look.

Hmm. Don't tell that to the two ST 5U4s in my RCA 630TS with 252 date codes.
It runs almost daily.:banana::banana:

i'm thinking of 2 to 4 hours a week if that , i really don't want to go solid state , as far as appearence they wont be seen so thats not as important as them functioning.

i will see what i have on hand and go with one or the other , the later gb would be tougher on the set or no?

mike

STs are just cool lookin tubes they say CLASSIC :D


SR

None of the tubes stress the set more than the other. They all draw the same filament power, and if operating within ratings, perform the same.

ST's have that "shoulder to fry on", so more stuff lands there and gets heated up, producing more of that enchanting tube-set smell!

Oh yes!!!!!!!!!!! :thmbsp:

Charles

The smell of burning dust.

Reminds me of water on concrete in the summer, similar odor.

Burning dust... The popouri of vintage electronics... :D

SR

Don't forget the Russian built 5U3C which is a shoulder envelope with the same basic specs as a 5U4G. Seem to go pretty cheap on ebay.

Give it a shot, might work okay.

C'mon guys, don't all of us use a Western Electric 274B instead of those lackluster 5U4's! Paying less then 700 dollars for a rectfier tube shows your lack of respect for your TV!!
I actually know a few audiophiles with the WE274B's in their headphone amps!!!!!!
Can we adapt the 300B in the TV's also:scratch2:

The term Audiophool comes to mind. Sorry...

or "Audiot" (Contraction of audio and idiot)

Audiophobe.....
They can be fun!
Anyway, Getting back to 5U4's, watch out for some early solid state adapters. They are nothing but silicons in a tube socket filled with epoxy. They can run the voltage a bit too high.
I have used the russian with good results. I have never seen a chinese one but I do stay away from the chinese tubes.

Let's not forget about the "Holy Grail" of rectifier tubes...the Western Electric 274B.

These go for between 1000-1300 usually and are essentially a 5U4G. Somehow, the consensus is that this tube delivers only the 'finest' and 'best sounding' B+ of any rectifier!! From an engineering standpoint, I don't understand it at all. It's just a tube rectifier to me.

Stellar, you just aren't with it. There is a consensus among psychics that good sounding B+ is essential to audio nirvana. Engineers are just heathens anyway.

As a audio customer said years ago....
"You people just make the gear! It takes us to make it sound good!"
My reply was, "Why not design your own gear and you won't need us anymore!"
I got a really dumb look!:D

Just my two cents worth and for the sake of the original topic I greatly prefer all "ST" envelope tubes. There is simply something about the look that attracts me. Maybe it's the feminine curves! LOL! Or maybe in the rectifier case it's that superior sound that is produced. GEEEZ! Oh well, I guess not every one of us really knows what is going on in electronic circuitry. I don't claim to know it all and really wish I knew more, but I do know that rectifiers play ALMOST no role in sound quality. I can say "almost" as if there is no rectification then there is no sound.

Anyway, I am always saddened when one of my old radios or TVs loses an "ST" type of vacuum tube and I must replace it with a plain Jane glass or metal tube. The cream of my radio crop is a working yet unrestored Silvertone model 4663 table top. Most of the tubes are factory Silvertone and the metal shields are form fitted to the "ST" design. To keep the originals I pulled them and use newer tubes so I can always put the probably unobtanium green and white paper labeled Silvertones back in. One actually went bad in all these years since the 30s, but I even hang on to that one for the look if needed as I have seen the radio called the "holy grail of radios" on the Web somewhere. Maybe, maybe not holy grail, but truly a survivor that works as well as the day it rolled off of the assembly line; paper caps and all!! :D