EQUIPMENT FORUMS >> SE34I.5 >> Rectifier Tubes

Message started by Louis on 05/25/20 at 20:45:10

Title: Rectifier Tubes
Post by Louis on 05/25/20 at 20:45:10


New to the tube world. My SE34I.5 is my first tube amp. It is part of what I call my all American system (Decware amp, Omega speakers, and MOFI turntable). Well my question,

What are the differences between the 5U4G, 5AR4 and 274b rectifier tubes. (Physical differences, pros and cons of each one of them, and sound differences).

The reason I'm asking is because I just bought an Emerson 5U4G NOS and it has five pins; the Decware supplied tube has four pins. I went by the suggested rectifier tubes listed for the amp (5U4G or 5AR4). I also read the 274b is an alternative for any of these referenced tubes.

Thanks in advance,


Title: Re: Rectifier Tubes
Post by Lon on 05/25/20 at 22:04:36

Louis, there are different forms even of the same tube type so going into physical characteristics is a lengthy and somewhat confusing undertaking. I suggest just googling each tube type and reading up on them.

There are four pin and five pin rectifier designs. In general I believe four pin are earlier and five pin are later. But some newly manufactured rectifiers, such as the 274B type that you were likely sent with the amp and others made by Sophia Electric are four pin. Be cautious with the 274B type: there are modern 274B that are electrically compatible with the 5U4 type and these will work well with the Decware preamps and amps. The 274B of the past and those designed to mimic them in the present however are designed to work with different capacitors than are in the Decware components and will have a shortened life and may blow internal fuses in the Decware components.

There are almost as many favored tube types and brands of rectifiers used in these machines as there are owners. Each will influence the sound of other input, power and voltage regulation tubes, so a synergy of all is what many of us look for. Experimentation is really the only sure fire way to determine what is best for your room, system and tastes.

Title: Re: Rectifier Tubes
Post by GroovySauce on 05/25/20 at 22:10:01

Louis welcome to the Decware family.  Sounds like you have a mighty fine system.  What cartridge are you running?

As far as the sonic differences Iíll leave that to others.  

4 or 5 pins both work.  You should be fine using the Emerson 5u4g

With the 274b tubes double check that they can be used with a 47uf cap

Title: Re: Rectifier Tubes
Post by Ronald Wilkinson on 12/05/20 at 23:58:42

Anyone use a RCA JAN CRC 5R4GY rectifier in Rachel? What do you think of this combo?

Title: Re: Rectifier Tubes
Post by RickG on 05/09/21 at 23:38:33

Does anyone have experience with a USAF-596 rectifier in a Rachael?

Title: Re: Rectifier Tubes
Post by drford on 06/29/21 at 15:11:22

I wanted to poke at this thread and ask for input from folks who are much more experienced than me.

I found an old post on the forum from Steve saying that he thoroughly recommends a NOS rectifier for Rachael. For me, though, I have no idea which one - and I do want a spare around so I'm never down.

NOS GE 5U4GB's seem very easy to come by - and come in both a regular and black plate version for a low price. Are these good? Should I be looking for something else? Where is a good place to source from?

Would love to hear from the voices of experience here, and then I'll just go buy something based on your input.

Thanks in advance,


Title: Re: Rectifier Tubes
Post by CAJames on 06/30/21 at 03:51:48

Here is a good discussion about buying NOS rectifiers:

To answer your question directly though, GE isn't bad but IMO you are better off with RCA or Sylvania.

Title: Re: Rectifier Tubes
Post by drford on 07/02/21 at 17:11:37

Thanks - super helpful. I have ended up w. a Svetlana NOS 5u4 and picked up a pair of 807s while I was at it, so we will see how it all plays out!


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