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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?
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....
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.
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!!!!!!! :lol:
Even me, who doesn't use valves, knows that, though... :oQuote:
Originally Posted by Mike Reed
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.
Quote:
Originally Posted by DSJR
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.
It's one thing knowing, Dimitri; quite another experiencing it!Quote:
Originally Posted by Themis
I quoted badly, sorry Mike.
My answer was for "other valve owners either didn't know or didn't care".
I apologize. :o
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.
Not a good idea to leave any valve kit on 24/7 IMO.
Those 509's are just so practical - you can expect many years of trouble free music. No worries.
If you ask Tim De P about re-tubing he says ' If it's working and doesn't hum or buzz, leave it alone '.......:lolsign:
I completely agree. All you're doing is wasting electricity and vastly shortening the life of your valves!Quote:
Originally Posted by Ali Tait
Marco.
When I visited Castle Marco, you told me that you kept your valve gear on all the time. Or did I hear you incorrectly?Quote:
Originally Posted by Marco
Regards
Lol - you heard incorrectly!
I only keep the solid-state stuff permanently switched on (CD transport, DAC, tuner and PSU for the Techy). The valve amps are only switched on when they're being used. Both the Croft and copper amp only take 20 mins or so to fully come on song, so there's no major warm-up issues :)
Marco.
When you say "the valve amps are only switched on when they're being used", do you mean switched on from cold or is it just the HT that is switched on?Quote:
Originally Posted by Marco
Regards
Since posting my findings I've come across other references to a burn-in/settling down time for valves (of weeks in some cases, but obviously depends upon usage). One of these was from the States, so it would seem to be a fairly recognisable phenomenon.
Everything else seems to need a 'burn-in' period (odd phrasal verb, that, esp. when used for cables!), so it all seems quite logical to me.
Hi Barry,
Initially switched on from cold. I will knock the HT off though if I leave them for a bit while I'm doing something else :)Quote:
When you say "the valve amps are only switched on when they're being used", do you mean switched on from cold or is it just the HT that is switched on?
However in answer to the thread question, from experience, I would say categorically "yes".
In my experience, most components used in a hi-fi system benefit from 'running-in': from cables to equipment (valves included), to loudspeaker drive units - all sorts!
Marco.
Marco, you're quite wrong you know..................
Running in indeed - never heard such nonsense :rolleyes: ;)
Well I must be cloth-eared also then,cos I'd say stuff definately runs in,including valves.If you are sceptical,go to hifi collective and purchase some ESA Clarity Caps.Stick them in a valve amp and then listen to sound going all over the place for the next fortnight or so.One minute screechy as hell,the next loads of bass and no top end.I thought there was something wrong with them at first,but they did settle down eventually,and now sound very nice indeed.
I was joking.......:lol:
Just like Ashley does when he 'kids on' that 'legacy hi-fi' is crap? ;)
Marco.
Not like that Marco. I NEVER mean anything maliciously as hopefully you know - I've heard too much myself.....
I know - *I* was only joking this time! :lolsign:
Marco.
Quote:
Originally Posted by DSJR
Had me fooled too! Was just about to write a post of incredulity, so I'm awfully glad you quickly exonerated yourself.
Dave was joking ? :eek:
The only thing that needs burn-in is marital relationship... :lolsign:
We have a nine year old Philips 14" TV/Vid and the tube (a valve derivative) has changed in characteristics (in a good way - I doubt it's the driving electronics), the "dynamic range" between dark and light seemingly larger. I'm sure it's not imagined and even at its age (not been used hugely), it's a great little picture..
I'm one of those who can laugh at a joke, yet am totally unable to convey one, even with smilies..............
As for marital relationship needing to burn in - for some of us it takes a bloody long time.... Burn-out is often the result.
:lol: :lolsign:Quote:
Originally Posted by DSJR
Quote:
Originally Posted by Themis
Anything that volatile will stunt your marriage (or is it growth?????)
My bint burns me dinner in all the time....:rolleyes:
"Bint" - lol... Such an endearing term of affection! :eyebrows:
Marco.
From The Grave
"Burn-in" as applied to anything audio interestingly seems to have it's roots in the final stage of valve production where the Barium getters needed to be flashed and the valve required heating to activate the Cathode coating with a final oven-bake as part of the sealant curing process. There were several stages as I understand it. Coatings are first activated, a vacuum applied to remove the gas (whilst an RF induction coil was placed over the valve to help liberate stray gases and flash the barium getter). The valve base is then sealed with a cement and the valve "burned in" in an oven to harden the sealant and left to cool (anneal) to de-stress the internals. That's the "burn-in" prior to electrical testing under load to help eliminate duds.
When the consumer finally receives the valve, there will be in initial bedding in period where the valves may be biased (in the case of power valves) and the sound will change over time as basically the valve wears out (thousands of hours typically) so the only burn-in that makes sense to me is the first 30 minutes or so after valves are settled, properly biased etc, whilst they come up to optimum operating temperature.
Being boring I am reading the Radiotron Designers Handbook at the moment; I find plenty of reference to valves changing over thier first hundred hours or so (and thereafter for life), complete with specs that demonstrate this and causes too. If the 'Bible' is to be believed it isn't foo, its old fashioned science. In their case they are of course referring to valve function rather than sound of course, but the variance is certainly enough that it would affect sound.
Yes, some valves can change over that timeframe (I have the same book!) and technically a valve's spec alters slowly from new to end of life, but given that the life of many preamp driver valves (say) can be 8000 or more hours, you'd need very golden ears to pick out changes I think. I've had some new 12AX7s that haven't altered sound wise at all (not that you'd notice) in the first 100 hours or so. The fact that some valves change over the first 100 hours may not always correlate to audible differences but there are some output valves where it can be noticeable within the first 50 or so hours depending on the circuit they're in.Quote:
Originally Posted by Jazid
Hmm, seems to me that the drift in signal valve grid current and zero bias point is a good case in question. I agree they aren't supposed to change, but they do. Also agreed you would have to be golden eared indeed to hear the change as it progressed, but sure as lies from politicians you'd hear it when you replace the tubes for others 'elsewhere in their journey through life'!
If you can't hear the change then you should not invest in a valve amp. The extra running cost would be wasted on you. A reasonably seasoned valve amp audiophile can tell the difference between valve sound in a blind test. You can't say the same for a blind test with transistors.Quote:
Originally Posted by Jazid
I think you misunderstand me, I am not saying that you need good hearing to tell a valve amp from a s/s one, rather that you would need something that pretty much all blind testing so far has shown people not to posess; A reliable long term aural memory.Quote:
Originally Posted by StanleyB
However we do posess long term reliable sensitivities to stress and fatigue which might explain why valves used for amplification of music continue to sell to people who consider this characteristic significant whereas they are rarely used in any other kinds of equipment.
I would suggest that this sensitivity explains in part why people are prepared to stump up the extra money and ongoing maintenance costs for valve amps. YMMV of course..
I've used valves for year and have just switched my power amps back to SS though it's still SE. Maybe a more telling characteristic is low or no feedback.Quote:
Originally Posted by Jazid
I don't get this penchant for no feedback :scratch:
Admittedly I haven't heard any zero or low feedback amplifiers, but I thought feedback lowered noise and distortion, and increased linearity and bandwidth.
Is that a bad thing :confused:
Sorry if I'm opening a can of worms, Alan
There are plenty more who can comment....but whatever the design it's down to how good it is and how well it's executed. Feedback can work on some amps but it has to be done well.
Without feedback you make the amp less likely cope with some types of loads and it's spec may look poorer but you should gain on harmonic representation, overall feel of air and space without tiring harshness. Horses for courses and a lot depends on your speakers,
Feedback is used in SS amps because it has to be. Triodes on the other hand, are linear enough to be used without feedback. In fact, DHT's are still the most linear amplifying device yet made.
The finest amplifier I have ever heard was a WAD 300B PP valve amplifier which had no feedback but which had a switch to enable it to be switched in or out. With the feedback switched out the space and atmosphere was staggering but with it switched in all of that was lost. I always used it with no feedback. That amplifier was just so pure and open and spacious it was almost unreal. I have never heard the likes of it since.