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Is rectifier tube arcing a problem?

I did some research and couldn’t find a definite answer.  I have an amp that I tried 6 different pairs of 5U4G and 5U4GB. 3 pairs has arcing (RCA 5U4G, TungSol, Svetlana 5C3S) and 3 pairs don’t (RCA 5U4G with hanging filament, EH 5U4GB, Sylvania 5931).  I took the amp to a technician and he checked everything, he can’t find anything wrong.  The problem is, I like the sound of the TungSol and Svetlana which both have arcing.  The technician said it is ok to keep using them, but honestly I am not too comfortable.  But I like their sound.  Is it really ok to keep using the arcing tubes?  Will it damage the amp?

 

 

gte357s
noske
783 posts
 

Check with your manufacturer exactly which type of rectifier you amp is designed for.

Brands don’t matter.

Maybe you have a manual?

The technician said that its OK to continue using rectifiers that are arcing? Is this the wild west?

Throw those tubes out and get new ones of the specified type, and if it keeps arcing what would your own assessment be?

pesky_wabbit's avatar
pesky_wabbit
1,183 posts
 

get new ones of the specified type

5U4‘s are definitely on the upper spectrum of the ruggedness stakes for commercial rectifiers, so I don‘t think they are the problem..

invalid
1,073 posts
 

A dirty tube socket may be your problem.

atmasphere's avatar
atmasphere
11,575 posts
 

@gte357s 

One thing that can cause rectifier tubes to arc is too much capacitance at the input of the power supply. What amp are you using?

I've seen a lot more arcing failure with Russian made rectifier tubes. Depending on the amp you may have to stick with NOS tubes to get reliable service.

In some cases its possible to run solid state rectifiers. A bit of attention has to be paid to the amp circuit since doing so will raise the B+ voltage which may not be a good thing. But if you have good rectifiers (like HEXFREDs) they can be nice and quiet. Amps that use solid state rectifiers usually sound more neutral on account of less power supply sag when more power is required. Tube rectifiers are certainly romantic but other than noise they really don't have a place in a hifi power amp; they are great for blues guitar though.

gte357s OP
281 posts
 

It is a Audio Note Kit Interstage 300B monoblock.   Here is the assembling instructions menu.  I have it built by someone and have another technician to go through it, so, I believe it is not a built issue.  It is design for 5U4G.  However, the company sells the kit, and doesn’t have much detail about the design.  Also, they make their own C-Core transformer.  I read that one possible reason is the transformer is “too good” and has a much lower resistance than others?  Anyway, I think this is more a compatibility issue.  
Any suggestion is appreciated, like adding resistor or capacitor somewhere.

Instruction manual

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