I am interested in the useful lifespan of M700 or M1200 amplifiers. For instance, would i have to replace capacitors and/or transistors after 10-15 years of regular use, as is the rule of thumb i’ve been advised for solid state amps?
Between the M1200 and the M700 is either expected to be more long-lived? I ask since i have a feeble understanding of tubes and i understand that there are tubes in the M1200 input stage.
My end goal is trying to figure out the total cost of ownership, including maintenance, refurbishing, etc. for a planned 20 year span.
Welcome to this madhouse, CT_Patriot. I don’t think anyone in this forum can survive a year without an upgrade, let alone 20 years. Yes, amps can have lifespans 20 years or more. Bryston has 20 years warranty on their amps, but I believe it is wise to pick an amp for sound quality instead of longevity. Then you can enjoy the music more everyday you own it.
The only thing predictable regarding tubes is longevity is not a given, and one should not depend on it. Sourcing them can be tricky, and pricey. Should one commit to tubes the cost of a spare set or two is minor. This has been my experience over 45 years and counting. For my preamp(s) I keep 4 sets of spares, as well as my amplifier. I believe the latter has 5 sets (or is it 6) of spare power tubes. When I purchase a tube based item I pick-up a spare set on the spot. As much as I enjoy the sound of tubes life has taught me to keep a spare set of those that I enjoy nearby. No myth.
A should add I have no experience with PS Audio tube equipment.
Small input tubes can last 10,000 hours, but ypu want to monitor how they are doing.
Keep a spare replacement set available and occasionally swap them in and compare the sound with the tubes normally in the preamp. If the sound improves with the new tubes leave them in and buy the next replacement set.
IME this is application dependent. For example my AI Modulus series of preamps the small signal tubes last 1,000 - 2,500 hours depending on the tube. By that I do not mean brand or type. it varies significantly even within a tube family. Other preamps, it may be significantly different. My cj Premier 11 benefits from small signal tube replacement at 2,000 hours. This is with premium vintage GE and RCA tubes from the 1950’s. I’ve had JJ Tesla 6DJ8 and several different Chinese tubes that didn’t last a month. The key is to have a spare set of favored tubes, and when the installed set begins to go order another set.
Not intended to argue, but my experience is different.
The AI Modulus is a well-regarded preamp and has been for many years. It does have a reputation (I’ve never owned one so it’s hearsay on my part) for being tough on tubes. There was a point in time (maybe still) when Kevin Deal would only sell you Russian 6H23 for it because they would last. I thought my 11A was relatively kind on both small signal and output tubes but I ran pretty much exclusively vintage small signal and output as well. But, I never really left them in long enough before I would be onto another set of something else.
I own a BHK250, which is not the same as an M1200 – but I’ll offer my experience for what it may be worth.
A couple of months after purchasing the amp, I upgraded from the factory-installed tubes. This was a long time ago, maybe five or six years. I have not noticed any sonic degradation, but the only way to be sure is to try a new set of tubes since things can gradually go downhill over time. I know I should test this but have been involved with other things. (If you buy a new set and don’t hear any difference, just put it away and try sometime in the future.)
It’s true that you should keep a spare set of tubes on hand. When I do after installing new tubes is put the old ones away, clearly labeled. If a tube does fail — a rare thing in my experience — you won’t be without music while waiting for a replacement.
If you’re considering an M1200, the cost of replacement tubes will be a very small percentage of what you paid for the amp unless you get into uber-expensive NOS tubes.
There’s no reason to expect the M1200 will need more maintenance than the M700 other than replacement of tubes. The added cost of that aspect of ownership is offset by the ability to fine tune the sound of the amp as other aspects of your system changes over time. Depending on speakers and preamp, I change the input tubes on my M1200 amps because what sounds best in one system doesn’t necessarily sound best in another. The M1200 amp modules are a newer design than those in the M700 and if anything, I would expect reliability to be even better with the M1200. IcePower modules have proven to be very reliable in the many amplifiers that use them.
Yes, the M700’s are less maintenance. The M1200’s are more maintenance (replacing one tube in each amp once a year or once every two years), but the M1200’s have more magic.