Not just an replacement, but an improvement! 

Emission Labs is the first company to re-introduce the 274A again, in the year 2001. This datasheet is about the 274A and 274B, which only difference is the tube base. These tubes are a full wave rectifiers, and electrically equivalent to  the original  Western Electric historical tubes. Our tubes feature a series connected filament for both diodes together. The series connection  makes the middle of the filaments to be virtually grounded, when  using a filament supply winding with a center tap. This tube is can supply 140mA with a normal C-L-C filter.   It is designed specially for Audio purposes, and is optimized for use with a small size first capacitor. With this tube, you will have only normal rectification current  flowing in the rectifier circuit, and no heavy current spikes.  This will result in less hum radiation into of the preamplifier, an improved sound compared to low impedance rectifier tubes for industry applications,  or solid state rectifiers. 

For ultra low ripple,  it is recommended to use the Lundahl LL1673 dual coil choke, giving higher CMR than a single coil choke. (See  link to circuit diagram, at the bottom of this page). 

• Hard metal filaments (Note1), series connected.
• Two extra large getters 
• Each tube  is numbered, inside the bulb  with a metal Tag
• Hand blown, Globe shaped glass
• Two extra large getters, flashing the complete tube bottom 
• These tubes are shipped in a high quality dual box
• Tube printing with real gold (metal),  red color is burned into the glass 
• 274A has machined, solid tube base pins for highest contact precision. Ideal for the YAMAMOTO tube sockets. 
• 274B uses an octal socket. From Yamamoto, the Octal 8/5p socket  is recommended.  This has only five holes and is specially made for this tube. 
• 274A: Gold plated pins,  black ceramic UX4 socket.  (White bottom)
• 274B: Nickel plated pins,  black phenol Octal socket. 

• See: CIRCUIT DIAGRAM 
• See: Note 2

Note 1)  Hard-metal filaments prevent filament breakage with DHT Tubes.  This material has a higher melting point than the classical nickel wires. 

Note 2)  To prevent large charge current peaks, the first capacitor (C1) should NOT  be larger than  4uF.   If the input capacitor is too large,  this will result in  heavy AC charge current through this capacitor. This is not good for the rectifier tube, and  also the  AC capacitor current peaks may cause hum radiation into the preamplifier.  With the given C-L-C values in  table, the rectifier circuit will work  without any trace of hum.  For ultimate filtering,  with oversized components, you  will have best  results by increasing the choke.  Do not oversize capacitor C1, this  will not give better  results.