SVT-VR tube rotation?

[DannyZ]

I have an American SVT-VR that was re-tubed a year ago when I bought it. I only use channel one. Instead of replacing the whole 6 tube set, can the tube set be rotated to lengthen tube life and possibly get a better tone? I guess it wouldn't hurt none to do so. Based on the picture which tubes service channel one and which serve channel two? Can the preamp tubes be rotated or do they run both channels? Any help would be appreciated.

 

[Phil508]

I believe the 6550s run the power amp. The preamp tubes are for channel 1 or 2 (12ax7?)

So rotating the 6550s should not do anything (except give you a chance to break the tube)

I changed out my preamp section and saw some improvement, did not retube the power yet.

 

[oinkbanana]

the tubes pictured are the power amp tubes, which both channels use ALL of them

the tubes for each channel are in the pre-amp section (right behind the knobs)
there's 5 of them.

http://www.talkbass.com/forum/f15/svt-vr-preamp-tube-question-664585/

V1=12AX7
V2=12AU7
V3=12AX7
V4=12AU7
V5=12AX7

And my based on some research and help from others here at TB in regards to my SVT-HD, this is how it goes (not 100% for the VR though, so if anyone knows better, please correct)

V1+V3+V4: Channel 1
V1: Channel 1 preamp + the bass and treble switched boost and cuts
V3: Channel 1 EQ (bass + treble pots)
V4: semiparametric mids

V2: Channel 2 preamp and EQ

V5: Cathode follower, drives power amp + external amp

The two input channels get combined at V5.

 

[JimmyM]

Tubes are not tires. You don't get extra life out of them by rotating them. They work until they stop working. Use them until they stop working, then replace the tube or tubes that aren't working and nothing else. Retubing is a big scam that tube amp owners pull on themselves. One tube goes out and they think every tube needs to be replaced because the whole thing's going to blow any minute. Not true. Some tubes will blow later today, some will last decades.