[schw06]

A couple questions for those seasoned rectifier tube veterans:
1. Is there a general consensus on quality between these tube types if given the choice? The application is an el34 based tube amp.
2. Does there happen to be a new production tube that matches the quality of NOS or should I just be looking in the NOS market?
3. Any specific tube recommendations?
   Thank you in advance!
David

[JohnR]

Don't know about 274b but be aware that 5u4 may not be a direct sub for a 5ar4.

[Pez]

I have never heard of any "consensus" between 5AR4 or 5U4. There is a slight difference in voltage, I think it's about 20 V, but it probably won't make a difference if you're using an amp with EL34s through KT88. Most of the time they are interchangeable, but make sure to verify that with your particular amp!

My personal preference (having only used 5AR4) is the skinny bottle 5ar4 Mullards. I also have a fat glass 5ar4 GE labeled Mullard and current issue Sovtek 5ar4/gz34. The Sovtek is nice, cheap, and very reliable. I do find the Mullards sounds nicer. DO NOT get the JJ GZ34, they are terrible. Poorly made and tend to crap out. If you spring for some Mullards they last forever! I pulled one out of my Grandfathers blown Heathkit amp that hadn't seen any action in at least 40 years and it worked and measured like it was brand new.

My guess- 5U4 vs 5AR4 is probably very amp dependent.

[JakeJ]

My experience is similar in that I know nothing of the 274b, and it is important to make sure the 5AR4 and 5U4 can be used in the same circuit.  I have no experience in swapping them.

Did a little search and the 274b equivalents are the 5R4-GY & 5V4.  My understanding is they are not interchangeable with the 5AR4 & 5U4G.

Although the the other two are closer in their ratings they are still not exact replacements for each other.  Slight differences in plate voltages an heater current draw.  And it make a difference if the powers supply is capacitor input filtered or choke input filtered.  You just need to do a little more homework.

Hopefully someone more knowledgable will chime in.

[schw06]

Thanks for the input. The amp I am using can use the 5ar4, 5u4g or 274b equivalents. With that being said, I appreciate anyone's experiences between the varieties. Thanks again,
David

[JakeJ]

Keep pokin' around.  You might also pose this question in the Lab or a crosslink.

[Scott F.]

Be careful in using a 274B. Assuming your power supply design is a CLC (pretty traditional but not guaranteed), you can use a 274B (or A) IF the first cap after the 274 is 4uF or less. If it is greater, it will work but you will eventually nuke your amp....well the power supply anyway.

As Jake said, so much depends on your amp design and the current draw required for the driver/splitter/output tubes. Each of the tubes will sound different as they all deliver slightly different current. Generally speaking, the higher the current delivery, the more authoritative the amp will sound. Notice I said authoritative not better. Each manufacturers tubes sound slightly different.

All that said, I've got 2A3 amp that I can safely swap 5UG4, 5AR4, 274B/A and the GZ32 plus a few others. I've got some of the most collectible tubes in each of the variants. The 274B provides (for me, in this amp, in my system, with this PS design...did I qualify that enough?) a very clean and articulate sound. The GZ32 provides nearly the same sound but with far more authority (different ratings). My Mullard 5UG4 (GZ34) sounds considerably better than the run of the mill new and NOS tubes but still doesn't hold a candle to the 274B and GZ32.

Hope that helps a bit.