How long can I expect tubes to last on a preamp or MW CD player?

you don't want to leave tube gear on 24-7

yes i think some of your tubes, based on your description, can stand replacement - when you get new ones, see if the sound improves, then you will know

Yeah, no need to leave on 24/7. 
Replace after 5000 hours.

Thanks for the replies jjss49 and noromance.  Sounds like I'm well over.  The PPT stuff made such a difference in performance, I didn't notice the drop-off in SQ until this past week.

dorkwad is a good name for anyone who leaves their tubes on 24/7.

typically, in use, 10,000 hours.

I have one of these simple testers, love it, lightweight, portable, take it to my friends houses ...

https://www.ebay.com/itm/Accurate-Instrument-Tube-Tester-Model-157/154119691696?hash=item23e23fddb0:...

I check em all periodically, and if I suspect something, one side weaker ... more often than not it ain’t the tube, a loose cable .... I collect old tubes, people gave me many years ago, mostly used, flea markets, their dad dies, out of the basement comes boxes and bags ... ...

check em out later when I or someone needs one, they are nearly all good, the most common problem I find is shorts which that little tester shows easily.

Also use it to check my new tubes and to check matched pairs or quads,

it always agrees with my big bulky hickock tester,

this one, a later model has the instruction book.

https://www.ebay.com/itm/Accurate-Instrument-Company-New-York-NY-Tube-Tester-Model-257-Vintage-WORKS...

elliottbnewcombjr,

Thanks for the compliment--I resemble that remark.  It will change my life.  The rest of the comments were interesting reading and maybe helpful.

i think i will change my handle to numbnuts

I apologies for falling prey to too easy a trap for sarcasm.

let's get back to tubes life 24/7. really? what/where/who/how could you think they need to be left on? or did you just mean you listen a lot every day?

new tubes, break in: leave them on, no signal needed, go to bed, 60 hours. off. on, warm up 10 minutes, now that is how they are gonna sound. off when not listening.

as they age, still equal l/r? have favorite music that helps your awareness of strong center imaging, equal l/r. cd version best for this, just in case cartridge is not perfectly setup. actually, have both lp and cd versions, play cd, all good, play lp, still good? great!

this is my favorite test for balance/imaging

side 2, tracks 2,3 all 3 guitars, and equal audience sounds l/r

https://en.wikipedia.org/wiki/Friday_Night_in_San_Francisco

I just re-read your OP.

You can switch l/r, any volume balance change?

You can put the original tubes back in, different volume? if obvious, get some new ones.

Thanks for the advice e.  I will try that out.  I have that record, not CD, however.  I will say that the system has been leaning slightly towards the left with most all voices.  Didn't used to do that.  I have the TRL DUDE preamp so it will takes a couple days to make sure it's totally without any saved up power in the caps--I like to live, before I switch any tubes.  I can't really remember what tubes are inside other than a pair of SNL7's.  I'm not sure I have changed the other 2.

dork

the tubes you are referring to is the 6SL7 gain tubes in your dude

try swapping them side to side see if the channel imbalance switches

call or email brent jessee or jim mcshane tell them you need replacement tubes for your dude - they will know what to send you (google search will give you their contacts, they are stalwarts in audio tube supply...)

good luck

Thanks jjss49,

I will look into them.

I had a volume balance problem, perhaps it is your tubes.

Turned out to be one of my Cayin A88T's 6sl7's (it also has 6sn7's).

had several used GE 6sl7 downstairs, that proved it was just the tube, not the amp or anything else in the chain. 

bought new 6sl7's from Brent Jesse.

Picked a Sylvania model because the chrome tops would look different from the 6sn7's (I had mixed them up once).

Sylvania did not sound as good as the unidentifiable Cayin tubes, or the used pair of GE's.

Brent had me break in the Sylvanias for 60 hours (no signal needed, just leave then on). Still not as good.

I picked alternate GE, I paid postage only, Brent gave me full credit, and, the GE's I ordered and love were half the price.

Just spoke with Brent today about the 6SN7 tubes and 5AR4GZ34 rectifier tubes. He seems to be hot on the RCA 6SN7 GT tubes and the Mullard GZ34 tube. I looked up my records in my emails sent and figured out I bought the DUDE in late 2016-early 2017.   I bought the MW 5400 about the same time. So the tubes were left on probably 160 days 24/7 and shut off when not in use much of the rest of the time. No matter what, Brent figured by the sound of my system and this amount of use that it is time to change the tubes and it should make a very significant difference. I won’t leave them on anymore when not in use like I did before.   I will talk to Andy at Vintage Tubes in Michigan on Thursday about the 5 tubes I will need. Tomorrow I will be able to safely open the DUDE without fear of curling my hair or worse. 

Thank you e & j for your personal experiences on what happens when tubes begin to deteriorate in sound due to age. I’ve been able fortunate to assemble a really good sounding system because of good ears and a fair idea of what real music sounds like in my head. But I still have a long way to go on understanding the technical aspects of the various components.

Bob