Valve amp owners, what's your valve replacement strategy?

[Ittaku]

Looking for a discussion from people who've had valve amps for many years as to their valve replacement strategy. I know that many of you won't know exactly how many hours the valves have been unless your amp has a tube hour counter, but just estimate approximately how long it's been - though there's a good chance such an estimation could be wildly off.

Edited February 15, 2019 by Ittaku

[F18]

Assuming you have a proper parametric tester and can test the tubes, there's really no need to replace that frequently until you start to notice a lower gain or tube going south. 

 

Often manufacturers will not advise how often to replace the valve because there are many variables at play. How much listen time, how often is the amplifier used, the type and manufacturer of the tube etc, how much bias is set for the tubes etc. 

Edited February 15, 2019 by F18

[Ittaku]

I'm aware that thermal cycling is just as important as, if not more than, the number of hours the valves have been powered. I'm particularly vigilant with only switching them on/off once per day and prefer to leave them on for a couple of hours if I'm going to not use the system over lunch etc. and plan to go back to it. Here's the ancient reference I've quoted here before:

https://audiophilereview.com/tubes/leave-it-on.html

Nonetheless, I'm still curious what people like to do themselves

[David Free]

I changed tubes many many times purely to see if  I could change the way my system sounded.

[Guest deanB]

I'm curious as to just how long my 211's will last in my Doge 9 monoblocks, so I keep a log of hours used in a notebook on my phone. 1400 hours logged so far and valve bias is very stable.

Bias can be adjusted from the front panel via the onboard microprocessor which also operates the protection circuit. So I'm thinking the unit will let me know when the valves are beyond their best as the bias indicator light/lights will stay red, indicating the valve is puffed out. 

 

[Ittaku]

6 minutes ago, deanB said:

I'm curious as to just how long my 211's will last in my Doge 9 monoblocks, so I keep a log of hours used in a notebook on my phone. 1400 hours logged so far and valve bias is very stable.

Bias can be adjusted from the front panel via the onboard microprocessor which also operates the protection circuit. So I'm thinking the unit will let me know when the valves are beyond their best as the bias indicator light/lights will stay red, indicating the valve is puffed out. 

 

I'm pretty sure valves can underperform long before they're so bad that they can no longer be biased, but yes bias requirements drift as they age.

[acg]

5 minutes ago, Ittaku said:

I'm pretty sure valves can underperform long before they're so bad that they can no longer be biased, but yes bias requirements drift as they age.

 

Try some Russian tubes.  Some of those vary wildly when new and take many hours for the bias to stabilise, like 30+.  Then they only last a year or so, but they are cheap and plentiful, and they sound great.  Some of those valves tend to make the very occasional little 'ping' when they are on their way out so it is just a matter of identifying the valve and swapping in a new one.

[Guest Muon N']

I work out via research on the net what ones will suit my tastes, and after that the only thing I do is check the output tube bias every 4 months if in regular use. I did have a Winged C run away when the circuit was being adjusted, so i replaced with a quad of replacement Winged C's, the original C's were a bit dodgy i think (maybe seconds). The new set is definite good quality NOS, that was several years ago and I have had no issues since, just checking the bias occasionally.

I don't use the system much at all since getting rid of my TT, so no checking is needed, and now the Marantz player is dead I only use the system to test friends bits of gear if I'm helping them :)

[Ittaku]

11 minutes ago, acg said:

 

Try some Russian tubes.  Some of those vary wildly when new and take many hours for the bias to stabilise, like 30+.  Then they only last a year or so, but they are cheap and plentiful, and they sound great.  Some of those valves tend to make the very occasional little 'ping' when they are on their way out so it is just a matter of identifying the valve and swapping in a new one.

Oh I don't get much choice in what valves I can use which in many ways makes my life easier. I'm just curious what others do. I quite like the matched valves that have been burned in for 72 hours and then tested and matched since they don't drift (upscale audio.)

Edited February 15, 2019 by Ittaku

[Guest Muon N']

They must be amazing tubes if they don't drift over time with use, magic even Joking, of course

 

Why not much choice, are they a rarely used tube type?

[Ittaku]

Just now, Muon N' said:

They must be amazing tubes if they don't drift over time with use, magic even Joking, of course

 

Why not much choice, are they a rarely used tube type?

KT150s. Precisely one manufacturer...

[Guest Muon N']

Just now, Ittaku said:

KT150s. Precisely one manufacturer...

Ah! of course

 

Although it likely can use KT120's and KT88's and KT90's? but if you like the KT150's I can see why you are limited. I am stuck with one make of EL34 as I have not liked any others I have heard, maybe NOS Mullards or Tesla's I would like, but they is crazy $$$

[Ittaku]

Love the KT 150s to death. No way am I giving them up

[Ooogh]

I replace them when they start sounding crap, glowing bright red , start making funny noises or otherwise expire.

 

The one thing I know is they always sound their absolute best just before they fail.

[ThirdDrawerDown]

Aha! A maintenance strategy question! With aspects of life cycling, planned, predictive, or breakdown maintenance regimes, efficiency and cost amortisation!

 

We have a combined strategy where we couple a proven IT project management technique ("sprint") with the tried-and-true accounting method of maximising utilisation ("yield").

 

In other words, when the alarming end-of-life crackle and fiery red glow appears, we race across the room to stop everything as quick as we can before the speakers get damaged.

[Paul R]

We gave up the valves and went SS in the power realm. VTL 300 deluxe monoblocks. 8 power tubes each. We had Ei KT90 valves, arguably the best EVER KT90s ever made. 20 years on, light use only, valves still sound great, but a change in speakers, means not enough juice.

 

Going from triode to pentode could have been good. But then what? GE6550WAs? KT88s? VTL told us we could NOT run KT120s or KT150S. But would the new Tungsol KT90s suit? Or something from China?

 

Replacement Ei KT90s at US$1K each from HK? US$16K for power tubes only? Refurbish the other electronics? Caps et al? What else could one buy at this price? For a whole today designed power amplifier?

 

Economics took hold. We found a SS amp closest to a valve sound. Enter Elektra Reference HD.

 

Spend up to $16k plus on a set of 16 tubes then you HATE the sound? No thanks.

 

Valves are good as long as you have a continuous supply of what you like, especially in the power realm, at a price you will pay. And is not obscene. See above.

 

With preamps, at least, one might have a longer life on light duties. And rolling could be fun.

 

Paul

 

 

[Bronal]

I always buy new (new production or NOS NIB) valves and start from scratch.

 

Preamp valves should last many thousands of hours, even the DHTs now commonly used, as the load on them is very light.  Likewise, rectifier and voltage regulators are also long-lived.  I've tended to replace output valves every 1500 hours or so as they bear the brunt of the work in the amp.  That's about every three years for me.

 

Patrick Turner once demonstrated to me that the only way to test a valve is under load.  His opinion is that valve testers do not tell the whole story.

 

Anyone who follows the Blueglow Electronics channel on You Tube (very informative but one of the best cures for insomnia) will have seen Mark Walker test valves from the equipment he is servicing that are still good after decades of use.  Personally I think his criteria are a little on the low side and I would imagine many SNAers would replace valves at values way above the 55-60% he thinks is OK.  But it does go to show that valves can be long-lived.

[Guest Muon N']

Hmm... that reminds me. I should visit Patrick's site and see how he is doing.

[sir sanders zingmore]

7 hours ago, F18 said:

Assuming you have a proper parametric tester and can test the tubes,

Who has one of these?

[Ittaku]

Not that many votes yet, but the valve rollers are way in the lead. I had a feeling that might be the case

[Addicted to music]

19 hours ago, ThirdDrawerDown said:

Aha! A maintenance strategy question! With aspects of life cycling, planned, predictive, or breakdown maintenance regimes, efficiency and cost amortisation!

 

We have a combined strategy where we couple a proven IT project management technique ("sprint") with the tried-and-true accounting method of maximising utilisation ("yield").

 

In other words, when the alarming end-of-life crackle and fiery red glow appears, we race across the room to stop everything as quick as we can before the speakers get damaged.

The bean counter strategy......

 

 

 

[Guest Muon N']

1 hour ago, Ittaku said:

Not that many votes yet, but the valve rollers are way in the lead. I had a feeling that might be the case

I would be careful using that to draw a conclusion, for example I didn't vote at all as nothing really suited me. I was not even going to post in the thread, so lots of variables that make these things questionable.

[Ittaku]

Wasn't drawing any conclusions, but it's true there are lots of valve rollers.

[Guest Muon N']

1 hour ago, Ittaku said:

Wasn't drawing any conclusions, but it's true there are lots of valve rollers.

I agree, this is true.

[Guest Muon N']

@Ittaku  what about the small signal tubes in the PremaLuna?