Tube preamplifier lifespan

I would say no,I see absolutely no reason they should...

the owner of psaudio told me that they do, lifespan of only 20 years

Parts quality likely biggest variable, amount of heat generated also important, heat enemy of parts reliability/longevity. My pre uses DHT so relatively low heat, has two chassis, one for power supply, other signal path. 

the thing that confuses me is that i've heard that Mcintosh preamps, using full vacuum tubes last forever. where the BHK preamp only uses two small tubes on the input and mosfets on the output

Perhaps the generalization depends on the brands or the initial quality. 

i'm concerned, since i traded in my 20 year old Bryston preamp (still under warranty) for my 'retirement' system

the owner of psaudio told me that they do, lifespan of only 20 years"

With the exception of the amplifying and rectifier section(if fully tube) components -tubes vs discrete transistors/OP amps, they essentially have the same caps &resistors etc.

Perhaps the SS devices(transistors/OPamps  and diodes) are what will qualify lasting longer comparing the 2?

dunno, but it makes me worry since i have the matching BHK 300 monoblocks each with 2 input tubes

Rectifier tubes get very hot and don't last as long. One reason I purchased the BAT VK-80. The downside is some tubes are very expensive and some tubes just don't last as long as they should. If you have more of a minimalist type tube preamp that uses just a couple of tubes it may be more reliable especially if it uses cheaper and more common preamp tubes.  

it's not the tube life that i'm worried about, the 12au7 tubes are relatively cheap , and there are only 2 of them. it's the comment that the design of a tube preamp won't last nearly as long as a solid state preamp

Onehoursepony,

Utter nonsense.  The only thing that does not last as long is the tubes.   There are Mcintosh, ARC etc... tube preamps still in the field.   

exactly , Mcintosh amps last for a very long time, why would PSaudo preamps and amps not last for as long?

It looks like you are looking for a particular answer or opinion that matches your already made- conclusion 

@tablejockey, Paul McGowan told you that a tubed component only lasts 20 years?

With most tube gear, you can expect a MUCH longer serviceable life than solid state gear.  Most parts can be replaced on tube equipment while many solid state gear becomes unrepairable because a chip or transistor is no longer available.  Also, tube gear has far less parts because the circuit is simple.  One of the technicians at a local shop restored a solid state receiver as a labor of love.  It took, among other things, replacing more than 200 capacitors; this would never be done as a commercial repair.  
 

My tube preamp is about 15 years old and has required no repairs nor replacement of any tubes.  Moreover, most of the parts were very old when it was built by a custom builder.  The power supply is new, but the audio circuit parts are up to 80 years old.

I'm listening to a 25 year old preamp it sounds great and works great haven't had a problem with it besides an occasionally dirty pot and changing tubes. It's a custom job so kind of a one off but tube preamps can last very long and plenty have. 

I have a Sonic Frontiers preamp built in '94 that still sounds great.   Many small signal tubes can last 10,000 hours , that's a lot of listening time.   

I've had it about 5 years and it still works flawlessly.  

This issue just came up with me this month.  I was interested in “daisy chaining” the balanced output from my McIntosh preamp output to my SVS subwoofer input, then balanced output from the SVS to a PS Audio BHK 300 balanced input.  That arrangement would save me significant new in-wall and attic install of a balanced cable run.  The SVS tech was concerned about combining the two components, and specifically the potential additional circuitry strain on the output of my tube preamp output.  The exact point being, it was because I was using a tube preamp.  He said many tube preamps might not be able to handle it (he looked up specs of both pieces of gear and started crunching ohms).  There wasn’t published the necessary spec for the McIntosh preamp, so to be safe, he encouraged me to contact McIntosh.  The McIntosh tech was a bit put off by my question, discussing potential parts wear, saying “we build McIntosh preamps to last 30 years.”

My Lazarus Cascade Basic preamp was bought new ~ 1987 and is still going strong.  I've replaced the power supply caps and resistors, along with some audio caps.  The metal film resistors are all good.  I suppose it depends on a particular preamp, but no issues with this one.

https://photos.app.goo.gl/xNJNjZzSi8vAq67V9

^^^^^ THIS^^^^^

BTW Lazarus was raised from the dead by Jesus.

Go SS!

Yeah I think that what PS Audio said to you is a little misleading. 

It would depend on the quality of the product. But I even have a couple Dynaco preamps that I can personally date back to the 70's that I can plug in & they work. I'm sure some parts are out of spec though. 

I have an Assemblage preamp which is on offshoot from Sonic Frontiers built in like '98. It was modded to the gills with top of the line resistors & overkill pricey Hexfred diodes..the power supply electrolytics were replaced with Films in the original  build. I still use it occasionally & it sounds nice. I do get an audible scratch from the  Nobles volume pot when I pass the 12 o'clock position. 

So I think it depends on the product. 20 years is probably time for some electrolytic replacements but many old tube products are still alive & kicking. Well I did have a tube preamp manufactured in 2012 with a very small chassis that I had to replace the electrolytics after 11 years. Couple bulging caps but just replaced them all. 

gmcleod-

I'm quoting the OP's remark.

I still use a McIntosh C20 stereo vacuum tube preamp from the late ‘50s in my office.  First Mac pre with a glass faceplate and the last with a vacuum tube rectifier.  It’s still 100% original:  tubes, caps, incandescent bulbs.  Never needed to clean the potentiometers.  Those original Telefunken 12AX7s and 12AU7s are approaching 70 years old!  As is the vacuum tube rectifier with its soft start which probably contributes to the continued life of the capacitors.  That, and everything in there is run at a very sane B+ rail.  It still sounds great though admittedly highly colored in a very tubular way 😆. 

I wouldn't trust the opinion of someone who sells new gear about how long it lasts. 

I currently use a 20+ year old Conrad Johnson LS17 tube preamp. I actually spoke to a tech at CJ and asked them this exact question thinking I might need to have it looked over and possibly change some aging parts like caps in the power supply.

His answer, was, other than tubes that obviously need replacement as needed, my preamp, if I perceive it to be functioning well, is just fine.

The CJ LS17 runs 4 6dj8 (6922) type tubes which are likely not as heat generating as other tubes. Also I always have tube savers between my tubes and the tube sockets on the circuit board to keep the pins in the sockets pristine and keep the heat from the tubes a bit removed from the circuit board. I do this with all my tubes in my power amps as well.

To the OP- I am using a Preamp by Linear Tube audio, which claims that they run the tubes in such a way that it can last 10 to 20K hours. I had the amp for about 2 years now, its pretty much turned on 18 hours a day. 7 days a week. 

i had a spare set of NOS 12au7 and 6sn7 and tried to switch it and I have NOT heard a difference between the old tubes the spares. 

so i am just going to speculate that it may last 10K hours or more

I  beleive its the Preamps design that determines the tube life

YMMV...

What??? Paul McGowan said tube preamps only last 20 years?  Where?  When?  He surely knows better than that.  ANY component--tube or solid state--will need refreshing after 20+ years.  But there's nothing special about tube preamps that would cause them to be obsolete after 20 years. Tubes are transconductance devices just like transistors.  Properly employed they work just as well if not better.