Do valves burn in?

[Mike Reed]

When I replaced the set of valves in my amps recently, I was surprised that there didn't seem to be an immediate improvement. Previously, an output valve had been going down in one amp.

A week or more later, and the sound from all four sources, RADIO, CDP, VINYL and TV has improved.

I'm fully conversant with cable burn-in and s/s amp. burn-in, but valves?

Anybody have any views?

[DSJR]

Nah, Mike, it's your ears getting used to it - as said by people who claim to know......

In reality, I was told that valves used in pairs tend to settle together and an otherwise sceptical electronics engineer called it "electrical annealing," which I think is perfectly acceptable.

It probably doesn't take long for this to happen with valves, but assuming the things haven't been used for some years since manufacture it may be so.

In horology, some insist on stripping clocks down completely and polish every pivot and "re-condition" ever pivot hole and mainspring. Others insist on only taking a good movement apart if absolutely necessary when cleaning and generally servicing when the thing is filthy, as in a long-case that hasn't seen a service bench in many decades and is thick with dust and grime....

[Mike Reed]

Three weeks after replacing all the valves in my E.A.R. 509s, I've answered my own question.

Valves most certainly do burn in! Despite sundry odd changes, there's no getting away from the fact that I've never heard my system sounding so good, and that it must be down to the valves delivering one hundred percent now they've settled in.

Another supporting factor is that I need a much lower setting on my pre. volume control to exact the same loudness. Despite this, dynamic range is phenominal, even a bit frightening on vinyl.

Judging by the paucity of replies to my question (cheers, Dave) valve owners either didn't know or didn't care. As a valve tyro, it's pretty obvious to me already that not only does sound quality in power amps fall off after a year or so but that 'bringing them back to life' brings synergistic advantages.

Some may say that the same happens when s/s amps are serviced (and you do get a slow old burn-in time), but I've not experienced this degree of change beforehand.

[DSJR]

Just check the bias on the new valves now they've had some weeks to settle in...

SS amps like OLD Naim seem to drift all over the place and respond well to a full service, only settling down after six months use or so until the supply caps give out and it all drifts off again. better components when new and perhaps better voltage regulation may have improved this drifting, but it did take place from 110 to 135's until the mid 90's or so, when Naim seemed to get it sorted better......

My Quads have had the input valves changed from Mullards to a matched quad of Telefunkens and one weak KT66 has been replaced with another used but good one. It's probably the amp, but I haven't noticed any change in the tens of hours it's had since.

Those 509's of yours should now have a couple of decades without you needing to worry about replacing the valves.

Now for a proper preamp to use with them......... OUCH!!!!!!!

[Themis]

As a valve tyro, it's pretty obvious to me already that not only does sound quality in power amps fall off after a year...

Even me, who doesn't use valves, knows that, though...

[Ali Tait]

Didn't we answer this question on another thread? I think if you're finding your output valves are only lasting a year,you are leaving your kit on 24/7,or the design is caning the valves.

[Mike Reed]

Just check the bias on the new valves now they've had some weeks to settle in...

My Quads have had the input valves changed from Mullards to a matched quad of Telefunkens and one weak KT66 has been replaced with another used but good one. It's probably the amp, but I haven't noticed any change in the tens of hours it's had since.

Those 509's of yours should now have a couple of decades without you needing to worry about replacing the valves.

Now for a proper preamp to use with them......... OUCH!!!!!!!

Oh ye of little faith (in a 552)! Maybe it's not the valves burning in, but I can't think what else it would be. I check the bias every time I use it, but it seems to have settled fairly well. Ten to twenty years trouble-free listening is a nice thought, but I don't think I'd be too concerned at that juncture!



ALI These amps were on 24/7 for over a year (previous owner), and were 1 1/2 years old when I got them a year ago. Should have been okay then as T de P serviced them, but I'm not really surprised one of the output valves (at least) was going down.

[Mike Reed]

Even me, who doesn't use valves, knows that, though...

It's one thing knowing, Dimitri; quite another experiencing it!

[Themis]

I quoted badly, sorry Mike.
My answer was for "other valve owners either didn't know or didn't care".

I apologize.

[DSJR]

As my mate hifi Dave has suggested, the 509's don't seem to push their valves hard and in my limited experience with them, they DON'T need to be left on 24/7 IMO.

I must admit that the Tube Technology Genesis amps I had ate their output valves after a year or so, the sound getting softer and softer over the last two months. Had they been 50W instead of 100W mono's, they'd possibly have sounded sweeter and lasted a lot longer in my care.