Is rectifier tube arcing a problem?

BTW, it seems the arcing can developed over time.  Both the Svetlana 5C3S started arcing after several weeks.  Both the RCA arc right the way.  I just got the TungSol.  One of them started arcing after a couple hrs of use.  The other one doesn’t arc (yet).  
 

I also read I should wait 2 or 3 mins before restarting the amp.  I swap cables and restart in less than a min.  Can this be a reason of causing the arcing?  Once the tube starts to arc, it arc every time afterwards.  

Thanks for the reply.  Actually, my question is, do I need to buy another TungSol.  

And if I buy another one, is there a way to prevent it from arcing.  For example, wait a bit longer (5+ mins) before restarting.  Or this arcing is caused by the design of the amp?  Or due to incompatibility?  I read another thread about Elrog 300B failing on Coincident Frankenstein 300B, while EML 300B works just fine.  But since the TungSol are not that expensive, I think I will try one more time.  

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

Short answer is Yes, the arcing happens in both channel.  
 

for the 5C3S, at the beginning, I don’t think they arc.  Then after a month, both tubes arc.  For the RCA, they both arc right the way.  For the TungSol, so far, only one arc.  And when I switch the tube, same behaviour.  
 

maybe as you say I have bad luck, but the percentage seems too high, 50% or 3 out of 6 pairs arc.  That’s why I think could it be a me doing something wrong which cause this.  But there is only one button, I can’t think of anything except I didn’t wait long enough when restarting the amp.  
 

is it very common for 5U4G to arc?  I only have two amps that use 5U4G, and I didn’t roll the tube in my previous amp.  

@atmasphere and others

BTW, is there other rectifier can be used for this amp?  Such as a soft start 5AR4?

@dekay 

I found that thread at the Steve Hoffman Forum.  Honestly, what being explained there is beyond my technical knowledge.  I like the idea about adding a soft start, but I need to take it to my tech to do that.  But do you think adding a soft start will eliminate the arcing?

@imhififan thank you. This seems something small and won’t change the sound.

min the diagram, I need to add two diodes per tube, am I correct?

@atmasphere @imhififan 

Yes, mine also has 220uF capacitor, and yes, the arcing only happens when the amp is turn on. After than, and if the fuse doesn’t blow, the amps sound fine.

here is the wiring diagram of the capacitor and resistors.

Wiring Diagram

Besides adding diodes, is there other recommended options about changing capacitors or resistors?  But I guess changing capacitors and resistors will have a bigger impact to the sound, right?

@atmasphere

thank you very much. A couple more questions:

1) is it able to tell from the diagram if there other rectifier that can be used and handle the current drawn by the 220uF capacitor?

2) is it necessary or recommended to change the other two capacitors? If yes, what values should I use?

3) comparing to adding diodes, in your opinion, which way will yield better sound?

@imhififan 

also to make sure, the diodes should be added at pin 4 and 6 as shown in the second diagram above, with the line on the diode closer to the pin, am I correct?

@imhififan good point.  I also have considered those points, especially I am not that technically inclined.  

@imhififan i am in the the-lesser-the-better camp.  So, I think I will try adding the diodes first.  Thanks for the info though.

@imhififan 

wow, thank you very much, that’s a very clear diagram, now I won’t be worried of making a mistake.

yes, I always want to learn more.  Does the soft start and diode compliment to each other, or I only need to pick one to do?

@atmasphere Thanks for the info.  I think so will experiment the diodes approach first, because it is cheap and easy enough to do it myself.  It is also a good learning experience for me.  At the same time, investigate on changing the capacitors.  It seems it is not too difficult to do as well, if the size are the same.

@sns 

it is a Audio Note Kit, not the Audio Note UK.  However, there is a bit of a history.  What I learn is that the circuit of this monoblocks is initially designed by Andy Grove who is a prime engineer at Audio Note UK.  

@jaytor 

i would say I like them.  I sold my X5 before I bought this amp.  I am using them to drive a pair of JBL 4341 now.  I only have 3 power amps to compare: a custom built 300B by Otomon Lab from Japan using Luxman mq-300 schematics, the ANK, and Coincident 211 Dragon.  I then sold the Otomon Lab.  The ANK sound as good as the Coincident yet different.  The ANK are faster, a bit lighter, better mid range, and a bit more holographic.  The Coincident also sound very good.  It is a 211 push-pull delivering 75W per channel.  It produce a lot more power but also sound very lively and holographic.  I had a McIntosh MC 275 IV before.  It is a KT-77 push-pull, and it sounds boring and flat, which leave me an impression that is the characteristic of a push-pull amp.  It is not the case for the Coincident.  On my Harbeth 40.1, it will be clear it needs the Coincident 211.  But for my JBL, both sounds great.  

Just want to provide an update. I tried adding the diodes but then one of the Sylvania 5931 (which is a rugged 5U4G) dies. I had one of these died died before adding the diodes. And they didn’t arch, but just died with no sound. I think it is not conclusive if the diodes works or not because the tube and symptom are different. But I am concerned and took out the diodes.

then I bought 3 pairs of 5U4GB, 2 pairs of TungSol and 1 pair of Westinghouse. So far so good. I will keep observing. Maybe the amps are just more demanding on the tubes, and some of the old tubes I tried are just bad.