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 - besides the arcing problem, are you enjoying your ANK monoblocks? Are these driving your Spatial X5s? Are yours the parallel SET amps? What 300Bs are you using?

I'm also using mine to drive OB speakers - GR Research NX-Oticas - which also have powered woofers. Mine aren't as efficient as the X5s though, at 92.5db. But I'm going to replace the NX-Oticas with GR Line Force speakers (hopefully) in the next few months - just waiting for the cabinets to be completed and I can start assembling them. The Line Forces are 99db/w efficient so the 300B amps should have plenty of power.

btw - it's only the interstage and output transformers that are C-core. The mains transformer and choke are more conventional (EI-core I believe).


I'm surprised Audio Note would market these amps with what seems to be a design flaw. Are others experiencing same issue, and if not, I'd think it could be improper assembly.


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.  


Not going to happen on my end, so your decision is all on you from here on.

You remind me of a recently new "member" who posted that my abbreviation of Audiogon as A’Gon was "pretentious".



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.