swapping out 12ax7 with 5879 in 5e3?

[timmyjoe]

I've got an old 5879 RCA tube. I've heard they are a bit smoother sounding than 12Ax7.

Is it OK to try it in my 5e3? No idea if it is good or not.

Sorry I'm so new to this.

[jordan86]

Don’t try it. It is not a straight substitute for a 12ax7. It is a pentode, more similar to a EF86 but with a different pin out still. Tonally, it is definitely smoother. Pretty extensive reconstructing though to retrofit it into a 12ax7 scenario.

[tubeswell]

^What jordan86 said^


Start with the relevant tube data sheets and start with checking the pin-out. Same pin-outs* are a starting point for tube substitutions, then its heater voltage and current, then its transconductance, plate resistance, and amplification factor.


*the data sheet will tell you the tube base type, whether its a different type of tube (e.g. triode vs pentode etc), and the pin out will tell you what pins are allocated to which electrodes inside the tube

[kagliostro]

OK, that isn't a tube you can swap but with some mod It can be used

if you like more the 5879 or the original is all one other affair

For starting values if you want to give a try look to the Gibson Les Paul schematic (in Doug's archive you can find It)

Franco