I don't remember any longer, and don't want to throw someone's name out here erroneously. In all fairness, it was over a period of time several years ago but it left a bad taste in my mouth.
Tube brands
- Thread starter Golden Gate ER
- Start date
JJ had QC issues some years ago and that soured some dealers. I had a similar experience with JJ's I bought on the auction site. I'm not a JJ fanboy. I needed a pair of 2A3's and decided on the JJ's because of user comments. Euro Tubes came up on a search and I decided to purchase them there. Per the website, the owner is Czech and has a solid relationship with JJ. So far, all is well and they sound fine in my amp.
I have as well. I bought my JJ’s from EuroTubes as well. Full disclosure, the first pair they sent me were problematic right out of the gate. They sent me out a new pair which I’ve now had for about 4 years without a hiccup. They sound fantastic too!
I have a pair of JJ 2A3-40 from Euro Tubes as well - probably over 2yrs old (but certainly not in daily use) and aside from a little short-term tube rush in one tube on initial power-up, they've been good. I like them for regular use as they seem to have more apparent balls with fuller bass, making them nice all-rounders with many types of music. I view them as a little more disposable than others I have, and they are not in the same league as my favourite old RCAs - I save them for when I really need what they can do. 
Interesting, I tried the EML 45 mesh in the early 2000's in a Korneff 45 amp and had issues with them. I much preferred the solid plate ELM 45.
I've read that the JJ 2A3-40's are 300B's with a 2.5v heater.
The curves are very close to a 2A3 and not all that close to a 300B, so the 2A3-40 will plug into a 2A3 amp and bias up properly without any changes.
Having said that, the 2A3-40 also has the 40W plate of a 300B, so you could certainly stretch the power output well beyond what a typical 2A3 could provide.
Having said that, the 2A3-40 also has the 40W plate of a 300B, so you could certainly stretch the power output well beyond what a typical 2A3 could provide.
Physically the plates of modern 2A3s are shorter than 300Bs (except of course the 2A3-40), and the grid wire spacing and space between filament/grid/plate is going to be slightly different, and the winding of the grid wires is also likely to be a little different.
I would not say that the 2A3-40 is an overall improvement from the single plate RCAs. I would say that they are more robust electrically and physically, but it wouldn't surprise me if the old mono plates still sounded quite a bit better.
When you get to the top level EML/Sophia/KR tubes, I wouldn't bet on the old monoplates necessarily. Those high dollar new tubes also come with a warranty...
When you get to the top level EML/Sophia/KR tubes, I wouldn't bet on the old monoplates necessarily. Those high dollar new tubes also come with a warranty...
Well I wouldn't use a 91B to do much in the way of evaluations. A small change in tube Miller capacitance will dramatically change the performance of that amplifier, which is already rather marginal.
That's good news that the EML and JJ were close in your Sun amp.
That's good news that the EML and JJ were close in your Sun amp.
+ 1 on personal preference. The rest of the system matters too. It's all about synergy.
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