relationship between rec. and the other tubes?

New to tubes, in my pre I have (1) 5z4p rec tube and (2) 12at7 tubes. What is the relationship between them? When I change diff. Brand 12at7's it affects the low and high and mids. Not sure what the rec. Tube does? Tyring to get a handle on this. Any help is appreated! Thanks.
Tube rectifiers convert AC to DC and is used in the power supply of an amplifier. The 12at7 tubes are signal tubes in your preamp.
Can I assume by that, the rec. Tube is going to have a less "dramatic" impact on the sound of any particular music piece than the signal tubes will?
Because the 12AT7 is directly in the signal path it's obviously going to change the sound. But don't dismiss the rectifier as they can also change the flavor of the sound.

Here is a thread about subs for the 5Z4p. I have never used this tube but I have used a couple of the subs mentioned.
Thanks so much for all your imput.1st tube pre and
Trying to get "tubeucated" LOL
Most tube rolling would be with the 12at7's. You've got to be hard core to start rolling rectifiers. Time to start reading: "A Taste of Tubes" on sonic frontiers/Anthem web site & search for "Joe's Tube Lore". You will learn a lot. Email me if you can't find these.
Rectifiers can definitely alter the sound, but as always, it's system and circuit dependent. I agree that the 12AT7s will have the most effect.

My 6SN7 preamp is also tube rectified, and a good NOS 5AR4 made a noticeable difference over the new production 5AR4s I tried.