Rectifier tube replacement...

[fleacr]

I just purchased a Princeton Reverb reissue

and wanted to try out different tubes in it. It calls for a 5ar4

rectifier but I wanted to try a 5r4wgb Bendix I have bought. So the

first question is, can I swap those two without compromising my amp

(do the pins match...). Next, it calls for 3 12AX7 in the preamp

stage. I have bought two 5751 RCA 3mica blackplates and one 12AX7 NOS

mullard. If by putting the 5751's first with the mullard in V3..well

actually I guess the question is, can I mix and match like that as

long as the 12ax7 is nearest to the power tubes? What I'm going for is a nice clean tone from the first two, and then having the mullard come in to both boost the clean as well as add come of the nice mullard warmth to the signal (in my mind, that will work but I dunno about in reality).

Thank you very much!

[tube fanatic]

Well, regarding the rectifier tubes, you need to be careful. If the amp uses a standard CRC or CLC filter, switching to the 5R4 could subject the electrolytic caps to a much higher voltage than was intended. The 5AR4 is a cathode type rectifier which tends to warm up somewhat slowly thereby limiting the voltage to the electrolytics. The 5R4, however, being a filament type rectifier, warms up almost instantaneously; this will allow the electrolytics to "see" a much higher voltage until the remaining tubes in the amp warm up and start drawing current. The 5751 can be swapped for the 12AX7; as to which arrangement will sound better, why not just swap them around and draw your own conclusion? Hope this helps you a bit......