I have not used this new rectifier tube from Sophia Electric, yet. Looks like a direct replacement for several Decware amps and the CSP3. It's on sale for $99.99 until May 31st.

https://sophiaelectric.com/collections/274b-5u4g/products/sophia-electric-5u4g

HK

Part of me wants to believe that these pretty blue tubes will sound better than an older US made 5U4 or 5Z3 but the other part remains skeptical.

Time will tell.  I should have it in a few days.  Looking forward to something different.

Has anyone tried their 12ax7 ?

Well, I got the new Sophia 5U4G today. Put it in the amp (fit significantly tighter than my RCA 5U4G). Turned the amp on. Rectifier did not come on and the rectifier fuse blew. I wonder, if for some reason, they aren’t compatible???

It does have a pin guide. It can only go in one way, but it is a tight fit.

Sorry to throw up an unneeded red flag. The tube is on now. Like I said, the tube has a guide on it and I’m not sure what happened when I put it in the first time, but I tried it again and it is working fine!  The first time I put it in it was unnaturally tight, but went all the way down. Anyway, no sense speculating about what was wrong earlier, because it is ok now. So sorry!

It is, Lon. Maybe the best rectifier I’ve heard.

Geno, glad to hear it's working out. How would you say it compares to the RCA 5U4G you had in there?

Thanks. I'll check back in a month or so.

Sounds very promising. I've been using 1940s RCA smooth plate VT-244 JAN tubes that sound pretty great. But more detail and deeper soundstage is always welcomed. Especially with these anniversary amps that can deliver. I'll have to try the 5U4G and 274B from Sophia.

I received the Sophia 5U4G and have given it a quick listen. These are my first impressions of the Sophia 5U4G compared to the Aqua.

The sound is cut from the same cloth but they have a different sound in many ways. The most noticeable difference is in the high end. The Aqua has a more extended high end and a much larger sound stage. The 5U4G has a more intimate sound stage and sounds more like a classic tube sound. Both have a very solid bass foundation but the tonality of the bass in the Aqua sounds more real to me. The Aqua is more clear in the midrange while the 5U4G sounds a little more congested in the midrange.

The Sophia 5U4G does sound really nice and I could easily live with it.
There is more complexity in the differences that I would need more time to discern and describe.

My gut reaction was  I could not wait to re-insert the Aqua in my system.

Doug,

I've considered that possibility and will give it more time to burn in but my Aqua sounded magnificent from the very moment I plugged it in. I guess I will found out when I can pry my hands off the Aqua.

Come to think about it, when I installed the 274B Aquas in my CSP3 and Torii Jr a year ago and months ago respectively, the sound quality took an immediate and substantial jump.  I have had no desire whatsoever to do any comparing.  I get it.

When I put my Aqua back in after listening to the 5U4G, I noticed there was a piece of loose glass in the tube. The Aqua still works fine and sounds wonderful but it gives me caution about the build quality.

Thanks Doug and it’s good to hear about you positive experience with the Sophia tubes.  I think it’s just one of these things that happens and it comes with the hobby.  

Nobody likes it when it does happen and probably the supplier is least happy about situations like this as I’m sure that they do their best but not everything is in their control either.  There are far more serious and important issues to worry about than a couple of tubes regardless of cost.

In for a penny, in for a pound!

I’m following up on the situation that I encountered with the Aqua 274B and the subsequent conversations with Sue at Sophia Electric.  Doug was correct, good people to deal with.  Sue was surprised that I had this issue as they have not had such a situation to date, and she was genuine, I feel.

Because of the time that had transpired I was not given a warrantee on the spare tube but was given a very fair solution.  I am not going to take it at this time and I want it to be clear that it has nothing to do with the way this matter was handled or with a change in my view of  the sonic performance of the Aqua 274B.  

Essentially the problem is with me.  This situation has resurrected a confidence issue that I have had with new production tubes in general.  I was going to spring for a EML 5U4G but at 280.00 a pop... do I want to take the risk now (which has become greater in my mind) - NOT A CHANCE!

So until I can get past myself it would not be right to accept the offer that was extended.  I’m going in a different direction when it comes to tubes and perhaps, I’ll spring for another Sophia eventually because I do like it.

In the meantime, I’ll all follow the experience that all of you will have with the Sophia tubes and that might help.

Hi Chris,

The Sophia 5u4 is a very good tube. But, I have gone back to my Russian 5C3S ‘winged C’ for financial reasons. I think that, for the money, this is my favorite tube in my Zen amp. The Sophia is definitely the better tube if you are willing to pay $100 or more. The 5C3S, at 2 for $30, is a damn nice tube, and for the money, my ‘forever’ rectifier.