Red MacKay

...But maybe they have the pick of the litter from the supplier and pay more, so simply pass it on. If you need to pay $100ea for 4 tubes instead of $120 for 4, for me that is not an issue when I compare what I spend/waste in other areas of my audio hobby/obsession. Pre tubes will last the normal person around 5 years. Pretty good value in my books. This is a very good read and explains why you pay (a lot) more for premium tubes. Yes, noise is a big issue with small signal tubes and most normal testers that I know can, can't do that. You need to get the output of the tube onto a scope to see noise. And Ruski tubes can have up to 50% difference in output in the same tube type from new. I do believe that channel to channel tube output matching is important for this reason. (unless if you don't mind listening to mismatched output from your speakers.) And yes, it is smart to mix and match/combine (valve) values to get the closest total output match for the channels.

I don't agree here at all. If we are outlaying the likes of $12k for a pre, then I want my $35 tubes to be matched. Yes, it does make a difference. (imho) And ideally you want both halves of each tube to be reasonably close too - or what is the point of spending all that dosh in the first place! It is very easy for differences in tube output to mount into a substantial channel to channel imbalance. ie 5%here, 8% on the next stage, then another 5% and a futher 4%. =22% difference in that channelto the other! But no, not a matched quartet - matched pairs for each channel I believe is fine. Life is too short for unmatched tubes!

I know Elson sells Ruski tubes as a friend purchased some 6c33c tubes from him just last week. Sorry, I have no contact details for Elson, but someone here will for sure.

Oops - Just noticed you are in Sydney. That makes it a bit more difficult. Elson Silva in Sydney might be the man to contact. He is easy to get on with, has lots of tubes in stock and tests and guarantees everything he sells.

I personally would go with the Sovtek over an EH.

Yep - you are all over it Duckman! Why would you need four matched ones? I would have thought two matched pairs would be fine. Maybe it is to do with being balanced. Maybe the OP can take his tubes and get Neil to test them onsite to see what they measure and get just one matched pair the same as htree he already has. It only takes 2 minutes to set up a tester and test a valve. A service you would offer to get return patronage I would have thought.

Paolo - are you after 6H30 ruski tubes or a 6550? I don't know of anyone who sells ruski tubes in OZ. I am not sure what the 6550 is used for, but if it's just as a regulator tube, then the best measuring 6550 should be used in that position. ie, Sovtek, Svetlana etc. New manufacture 6550s are easy to come by. But, if the 6550 is in the signal path and being a REF5SE, I would be hunting around for a NOS oringinal US manufacture coke shaped TUNGSOLs. Here in Melb we have Ray at the HIFI EXCHANGE and there are a crowd in Mt Waverley that sell tubes too. Sorry, I have no idea of their name, but a bit of fosicking and I am sure it can be found. Just my 2cents...

Now this is beautiful gear!

I am not familiar with this product at all. But thanks for the info Chris, I will check it out.

From another one of these I have seen recently, this is how they are.

My thinking here is that you always have losses. Losses when they are in series like here, result is less current capability. The 40A pads have less chance of losing current than a 25A one and less chance to get hot as there is more area of contact to transfer the current and also disapate any resultant heat in the contacts.

@tcliffo1

See Marty - I told you your tubes were rubbish last week! You need to get a pair of these new babies. And because I'm feeling sorry for you, I'll give you $100ea for your old ones towards your trading up. Cos that's what mates do. 🤣

24 slots in a 13sq home is not insignificant. And yes, it is actually a sub board, fed from the main 3 phase board 5 mtrs away. Totally agree. OK, I see your point. But what dill would do that without tracing it first? And the RCD is between the MCB and the GPO, so if they hooked anything with a large current draw, it would trip the MCB immediately anyway. Yep, but I don't want a throttle on current capacity, when I have just spent good money on everything else for a dedicated line to my music room! The contact area on a 20A contactor on a Clipsal 56 Series switch is miniscule compared to the same 56 Series 32A. That is the exception here for my extreme justification. YMMV and that is fine. That poor OP must be wondering why he ever asked the question... I say to him, "hang in there."

It's not a sub circuit, it's the same circuit! Again, I disagree. The AUS/NZ Standards are open for many interpretations. Very little in it is black or white. And that is what this is, your interpretation is different to mine. My sparky is and industrial sparky and not just a house wirejerker. He was happy that it complied within the rules, but struggled that we wasted 2 DIN spots when he felt it was unneccessary. We had a 24 DIN spot board - it was not a problem.