Strange Tube question

[sonicblue99]

Hi guys, new to this forum and the whole diy seen.  Gotta say I love it.  Already built some preamps out of an old Akai reel to reel which sound great (thanks to the ef86 channels) and two royer modded mics.  Anyways, I was planning on building some more tube mics and came across some Mullard 7433 tubes.  They look just like the 5840 but after looking at the specs on this site http://www.wps.com/archives/tube-datasheets/ I am wondering if I can use these.  There are slight differences that I don't know if they will make a difference on the circuit (the pin out is different also but I already found a diagram for the pins.)  Now, I must admit my tube knowledge is quite limited, so I figured I could ask for your opinions.

 

[gyraf]

I'd say try it to find out - from specs it is nearly impossible to say, as the important-for-microphone-parameters are never explicitly mentioned in data sheets.

Pay attention to the max. 100V Anode voltage though..

Jakob E.