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Rectifier 5U4G Getting a Buzz (Read 327 times)
Hearafter
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Rectifier 5U4G Getting a Buzz
05/19/24 at 01:40:11
 
I have a nice hard to find old stock GE Tall 5U4G rectifier that just started making a slight buzz sound coming only from the tube itself. It is a really nice sounding tube but should this be a warning of a failure coming.  Anyone have this come up?  Is it a concern and should the tube be retired. I have never experienced this before.  Thanks
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CAJames
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Re: Rectifier 5U4G Getting a Buzz
Reply #1 - 05/19/24 at 02:12:08
 
What this might be is the cathode is loose and buzzing in response to the 60 Hz voltage being applied. It isn't a good sign, and probably means the tube is going to fail sooner rather than later, but if you like it, and the buzz isn't a problem you might as well ride it out to the end. JMO/YMMV and all that.
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will
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Re: Rectifier 5U4G Getting a Buzz
Reply #2 - 05/19/24 at 17:19:56
 
I have older Decware before the internal fuses on the rectifiers were added, so I have only the fuse at the IEC. Whenever I was trying or using suspect rectifiers, I would replace my more costly IEC fuse with a glass slow blow with heavy internal wire structure, fuses I had taped sound cleaning stickers on, the tape also damping the fuse some. And they sounded pretty good. Then when the rectifier went, I only had to move the taped setup to a new low cost fuse.

I have no experience with interior fuse setups though... So my first question about continuing with a suspect rectifier is, are there costly fuses in the amp, internal or at the IEC. The other question for me... if using a good fuse at the IEC and plain glass on the rectifier... Do the internal fuses fully protect the IEC fuse when a rectifier shorts?

This is one reason I have been trying to dial in Swiss Digital Fuse Boxes in my system, especially for my stuff with rectifiers...Not often for me, but over years, they will fail, sometimes without warning. Not having to worry about losing costly fuses along with a rectifier, though I have not used any tubes that are clearly compromised for quite a few years, I like some 4 Volt, old Euro tubes with different electronic parameters... quite reliable for the most part, but some have blown over years.
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MikeinMontana
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Re: Rectifier 5U4G Getting a Buzz
Reply #3 - 05/19/24 at 17:39:47
 
I dealt with two new rectifiers that blew the internal 6 amp fuse. One after 3 weeks, the other at startup. IEC were fine in both cases. Bad luck, but all good rectfier-wise since. Currently using a cheap, 14 dollar 1951 Zenith 5U4G. Bottom D getter and made by RCA? It was used but read and looks as new. Zenith logo etc perfect. Clean glass top to bottom. I cannot figure out exactly why ..but I love this one a LOT. Been in the amp the longest now. Take care~ Mike  
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will
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Re: Rectifier 5U4G Getting a Buzz
Reply #4 - 05/19/24 at 18:46:39
 
Mike, I had a pretty long affair with older, straight 5U4Gs with my Torii III. As I remember them, they tended to sound like they had more power than 5U4G-STs, generally making everything a little stronger, the nicer ones especially, all parts of the signal strengthened in pretty well balanced ways from bass, through the mids and the highs. The ones I really liked had a full rich sound with spaciousness and fine detail across the spectrum, so textured and good with harmonics, and keeping them from being too warm or thick. Even so, in my system they did tend toward bass in the overall balances ... and other tube choices opening and speeding up the sound some helped the 5U4Gs to be sweet and lively.

A few years ago, I tested some old favs in my tuned up Torii MKIV, and really liked them, full, rich and textured. But finally they were too strong in it, lacking some space and speed I have come to love... The more transparent and easy flow the MKIV became with modifications, the less powerful the rectifier needed to be to pull the deep beauty.

But if a system/room is a little on the lean side, the benefits from a more beefed up sound of a well balanced, and often inexpensive 5U4G can be really nice!
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Hearafter
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“In Tubes We Trust”

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Re: Rectifier 5U4G Getting a Buzz
Reply #5 - 05/19/24 at 21:26:47
 
I have gravitated to old stock Rectifiers with minimal experience with new stock rectifiers. Many OS are available at very reasonable prices so it is low risk to roll.  I have a Hickok tube tester so it’s easy to evaluate their condition.  My preferred ones  that I like in my system are RCA ‘50’s 5R4GY ST brown base, Sylvania 5U4GB USN tall straight bottle with D getter, GE (Ken-Rad)5U4GA tall with D getter.  On my system they just sound better than highly touted Mullard 5U4/GZ34 or the Phillips 5R4GYS Cryo at a fraction of the cost.  Ended up selling those.  I did have one rectifier fail, a nice sounding RCA short straight bottle that just lit up upon starting up my Torii Jr. Fortunately,  I  turned it off quickly with no damage or fuses blown.  Will, I agree with your sound assessment.  I tend to prefer a warmer, full sound, strong lower mid and bass but more  detailed and smooth than dynamic/fast.  I have a Space Tech Lab Super Rectifier on arriving mid week. Will be fun to see how that sounds with dual rectifiers. Great hobby for tube addicts.
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Torii Jr V2
Supratek Cabernet Pre
Lab 12 DAC1 Reference
Bricasti M5 Network Streamer
Ohm Walsh Tall 2000
Too many Tweaks
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