Valves life expectancy

[colinB]

I had the valves in my phono stage changed a year ago after being told the existing ones had gone. Some static discharge problems seemed to go after that but they are back again and i havent played any music for weeks now. Is it possible the valves coud have gone already? They were new stock from a good source.
Theyre signal valves i believe. ecc83 and 81 or something :scratch:

[Barry]

Power valves (i.e. output valves) ought to be changed after 1,000 hours. The small signal valves in your preamp should be OK for 10,000 hours.

Regards

[colinB]

Cheers Barry. My problem is still a mystery then.
I should get somebody to give it a good look over but the Technics isnt very portable! Dont know how i would get it to anybody for a service.

[Reid Malenfant]

Power valves (i.e. output valves) ought to be changed after 1,000 hours.
:eek: Is that recommended Barry or could you safely double the hours?

Even if doubled that still only a year with 5 hours a day listening & a lot power valves are in no way cheap :eek:

I'm staying with solid state kit, nuts to that :mental:

[jantheman]

Quad's advice on my KT88 is around 6,000 hours. The 6HS7 input valves are listed as 15,000 hours.
http://www.quad-hifi.co.uk/downloads/Quad%2024_II_40.pdf

[Barry]

:eek: Is that recommended Barry or could you safely double the hours?

Even if doubled that still only a year with 5 hours a day listening & a lot power valves are in no way cheap :eek:

I'm staying with solid state kit, nuts to that :mental:

Hi Mark,

It's recommended, especially by valve aficionados. No doubt you could get away with 3,000 hours.

Agree about the 'running costs' of valve power amps. But it's a bit like running a performance car: expensive service; expensive insurance; expensive tyres and expensive petrol costs. If you want the performance, you have to pay for it.

Like you, that's why I stick to solid-state gear, but as my friend (who has just renewed the output 'bottles' in his amp) said to me: "You know Barry, the reason why I like my amp so much is because every couple of years I can replace the valves and it sounds like new."

Regards

[colinB]

:lol: That sounds about right.

[Reid Malenfant]

Ah, i think i see what you are saying Barry ;) I'm assuming you'd be refering to something with a class A output stage? With a class B output i'm guessing they'll last considerably longer?

[Marco]

[OPEN public service announcement]

I should point out at this stage that I'm using the same (GEC KT88) output valves in my CLASS A copper amp, as were fitted to it in 1997, and after probably tens of thousands of hours of use, they still measure nearly FULL EMISSION, and above all, sound fantastic! ;)

Never mind the smaller driver and signal valves...... I wouldn't use valves if I had to put up with replacing them so frequently, as was mentioned earlier.

The secret with valves is to buy the BEST genuine NOS ones you can afford, which have been properly matched and tested by a reliable source. Then you can look forward to many YEARS of service from them, unlike the shite current production pish made these days!!

You get what you pay for, people, with valves, valve equipment, or anything else in life.

[/CLOSE public service announcement]

:)

Marco.

[jantheman]

As with any component, tube or SS, stress them or make them work too hard and you will shorten their life. If amp designers can make the valves work optimally without overstressing them then their lifetimes will be increased. I would consider 1000 hours to be very short and would think that at least 3 times that was nearer the norm. Anything less and I would start looking at the reasons for such a short life.
EDIT...just read Marco's post above (posted while I was writing) and couldn't agree more.

[anthonyTD]

hi all,
Marco has made a few valid points which i will comment on. Original old stock valves [on the whole] do tend to last considerably longer than most current production valves, mainly due to them having better materials and more of them [cathode material especialy] output valves tend to have a much harder life than small signal valves, hence they should be changed on average around a 3 to 1 ratio, however, it will depend greatly on how the valves have been used, ie; how hard, and in what position, etc. valves in powerfull class B push-pull output stages tend to have the hardest life due to the high voltages and high current swings needed to produce the power requirements. in class A push-pull, although the valves are being run harder ie; drawing the full current requirements all the time, the valves are being run in a more constant state hence tend to just fade away rather than self detonate as is often found in the B output stage.:eek: Then there are all the parameters inbetween ie; class AB1 AB2, AB etc.
Class A single ended is very similar to class A push-pull as far as usefull life is concerned.
Example, a good military ECC83 [CV4004/M8137] will be guaranteed for at least 10,000 hours, Where as a common version may only last a couple of thousand hours before failing. another example; An original winged C svetlana KT88 output valve being run in a push-pull output stage at around 40 watt per channel should have a usefull life of around 3,000 hours, However, their sonics may have deteriated considerably by the end of that time.
Heat plays a big part on the longevity of valves, [i know its ironic as they need heat to work] hence good ventilation is a major factor.
hope this helps.
Anthony,TD...

[Reid Malenfant]

Cheers for taking the time out Anthony :)


rather than self detonate as is often found in the B output stage.:eek:
Oh i did like that bit :eyebrows:

[anthonyTD]

Cheers for taking the time out Anthony :)



Oh i did like that bit :eyebrows:
:lolsign:
Glad to help.
Anthony,TD...

[colinB]

Maybe ill change them any way and see what happens. Can anyone recommend a EC81 and a EC83. The caps are cheap chinese ones so i would like to change them while im at it. Theyre 1uf oil in papers . Maybe some Mundorfs.

[Marco]

Cheers for taking the time out Anthony :)


It certainly helped put a more realistic perspective on things! Also, what I wrote stands as being 100% factual :)

I take it you're no longer put off valves for life then, Mark? ;)

Marco.

[Reid Malenfant]

I take it you're no longer put off valves for life then, Mark? ;)

Marco.
No, you & Barry have convinced me not to worry too much about longevity :) However, while i may well have thousands of small signal & power transistors & Mosfets (possibly 5 figures) I only have a case full of valves (which i'll one day have to investigate). Odd thing it is, it was obviously designed to house the valves & it's kind of like a travelling salesmans advertisement, only way i can describe it :scratch:

[Marco]

Hi Colin,

If you want guaranteed, fully tested and reliable great sounding valves, then I'd thoroughly recommend the genuine NOS CV4024 (ECC81 equivalent) and CV4004 (ECC83 equivalent) 'military spec' valves currently being sold by CVC (Chelmer Valve Company). You can order through their website.

They're not cheap, though, at around £60 + VAT each, but having bought some CV4004s recently, I can vouch for how good they are, and unlike the lottery of buying on eBay, being a professional UK company, buying from CVC will be a risk-free purchase :)

Marco.

[WOStantonCS100]

This is an area where I would argue for "clean power": power conditioning/filtering/regulating. Eliminating spikes and voltage drops does wonders for longevity. I've been able to find some quite nice valves and the last thing I want is my electric provider burning them out in a month. :steam: I do not run valve power amps... yet. (Give it a few months. ;) ) However, I've kept the EL34s in my Marshall's running much longer than expected by using "clean" power. And, those valves are driven like there is no tomorrow.

[Barry]

I seemed to have alarmed members unnecessarily concerning how often valves need to be changed. Not being a user of valve amplifiers myself I have no direct experience of this. The figures I quoted were based on the following.


According to the Marshall web site, every two years if used two to three times week.
http://www.marshallamps.com/resources/secret_life_of_valves/valve_life_replacement.asp

as do these websites:
http://www.thedailyguitar.com/6-common-signs-that-amp-tubes-valves-need-replacing

http://fixmyamp.co.uk/2010/09/11/when-should-i-replace-my-valves/

http://www.musicradar.com/forum/archive/index.php?t-31275.html

http://www.roccaforteamps.com/tube_replace.htm


Now it should be noted that these are for guitar amplifiers, which forms part of the ‘sound’ of the guitar, are often driven hard (read played loud) and not treated with kid gloves. However if guitarists can notice a change after 12 to 18 months use than there is some support to my pessimistic estimate. You wouldn’t expect them to only change the strings every five years, would you?

Anthony TD also suggests 3,000 hours here: http://theartofsound.net/forum/archive/index.php/t-1770.html

and mentions that original KT88s could offer up to 40,000 hours of ‘useful’ life. (Though I would like to know how ‘useful’ life is defined.)

One manufacturer http://www.paulsen.co.uk/rod/matissemono.html suggests changing all valves at least every 2 years.

Clearly valves can last for years, even decades, but cannot be expected to sound their best. Often enthusiastic valve users (those who can hear differences between different manufacture of a single design by different companies and in different years), will change valves at least every year.

I would agree with Marco that NOS valves from traditional manufacturers have a longer lifetime than those from newer companies; a lot of expertise and ‘know how’ seems to have been lost.

But at the end of the day it’s all down to what you can hear. But I am reminded that there is a similar situation with the longevity of pick-up styli. It was generally assumed that 1000 – 2000 hours life could be got from a non-grain orientated stylus, with advice to check the stylus every 750 hours. Yet operators working on record pressing quality control, could reliably detect stylus wear after only 50 to 100 hours. This revised the useful life to 400 hours maximum.

[Ali Tait]

I would say it all comes down to the individual valve at the end of the day. After all, you can never predict how long a light bulb will last can you?

[Marco]

Yup - that's undoubtedly true. There's nothing wrong either with what Barry has written.

Ultimately test figures only tell you so much (where have I heard that one before?), therefore when fitting valves, presuming that they don't fail when switched on (or soon after), the only way you'll really know if they are functioning anywhere near optimally or not, when used in audio equipment, is by listening.

It therefore goes without saying that I wouldn't still be using my 14-year old GEC KT88s (despite measuring ok) if they hadn't passed that test with flying colours! ;)

Marco.

[colinB]

Hi Colin,

If you want guaranteed, fully tested and reliable great sounding valves, then I'd thoroughly recommend the genuine NOS CV4024 (ECC81 equivalent) and CV4004 (ECC83 equivalent) 'military spec' valves currently being sold by CVC (Chelmer Valve Company). You can order through their website.

They're not cheap, though, at around £60 + VAT each, but having bought some CV4004s recently, I can vouch for how good they are, and unlike the lottery of buying on eBay, being a professional UK company, buying from CVC will be a risk-free purchase :)

Marco.

Thanks Marco. I was relying on you ;)

[Marco]

No worries, dude - you're welcome :)

Marco.

[WOStantonCS100]

Now it should be noted that these are for guitar amplifiers, which forms part of the ‘sound’ of the guitar, are often driven hard (read played loud) and not treated with kid gloves. However if guitarists can notice a change after 12 to 18 months use than there is some support to my pessimistic estimate. You wouldn’t expect them to only change the strings every five years, would you?

Quite right. Non master volume guitar amps where overdriving the power valves is desired for tone is the equivalent of running your car well into the red line every time you get in it. That gets expensive quick; so, I use run of the mill tooobs :eyebrows: for gigs and save the NOS for recording.

When it comes to hifi applications the average user, I would presume, uses anywhere from 25% on the low side to 50-60% on the high side, from time to time, so the same valves in this application should last a lot longer. It's not quite a "...these go to 11..." scenario. (Long live Nigel !! :lolsign:) Not sure about the low wattage SET guys; but, I would imagine that would be true for the rest. Corrections if I'm wrong, please.

[anthonyTD]

hi all,
there are a lot of interesting points here, However, when we talk about the usefull life of valves i think its important to explain the diffrences.
The term "usefull life" can mean diffrent things to diffrent people, ie,Some people may want to make absolutely sure that they keep their equipment sounding optimum by changing valves way before the recomended time scale, Some will use the recomendation as a guide and will want to get the absolute maximum life span they can before changing them. either is fine as long as the individual accepts the pro's and cons of each scenario. therfore the term "usefull life" is very user dependant, However, there is often a fine line between getting the maximum rated lifespan and the maximum uncompromised sonics.
Anthony,TD...

[Marco]

Indeed.

It'll be very interesting when I replace the current 1960s GEC KT88s in my copper amp, which desipte being 14-years old, test fine and sound great, with some brand new (or much newer ones) of the same type.

This will be done very soon, because as some of you may be aware, I'm currently selling my spare quad on eBay, the auctions for which end today:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=160567530453&ssPageName=STRK:MESELX:IT

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=160567535721&ssPageName=STRK:MESELX:IT

As you can see, things are going rather well! :)

Once done, I'll be reinvesting the money on the best tested and matched quad of 1950s/60s GECs I can find. In my experience, the 1950/60s ones sound best - much better than the later ones.

Naturally, of course, when I do that I'll be expecting a significant sonic improvement, but the fact is, and this is the interesting bit, even though they're ancient and have had more abuse than the bed springs in a whore's boudoir, they still sound WAY better than ANY brand new current production KT88s I've heard, including the superb cryo'd Svetlana 'Winged C' types.

I know, because I used to own some, which I sold to Neil (Dalek DL). I carried out the comparison before I let them go. The Svets are, in my opinion, the best sounding current production KT88s on the market by a country mile, and yet those ancient old GECs still well and truly spanked their arse!!

So, my friends, what does that tell you?? ;)

Anyway, wish me luck in just over 3 hours, when both of the auctions end! :cool:

Marco.

[Tim]

Anyway, wish me luck in just over 3 hours, when both of the auctions end!
I have been watching both these Marco and glad to see that so far all's going well - hopefully you will get a bit more?

Good luck :)

[Marco]

Lol - £331 - ya dancer!! :mex: http://img222.imageshack.us/img222/6861/yayt.gif (http://img222.imageshack.us/i/yayt.gif/) http://img222.imageshack.us/img222/6861/yayt.gif (http://img222.imageshack.us/i/yayt.gif/)

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=160567530453&ssPageName=STRK:MESELX:IT&afsrc=1

Wonder what the next ones will go for? With a win on the Grand National later, this could be a VERY good day!! :eyebrows:

Marco.

[Tim]

I was watching that Marco, sweet...... that was a snipe in action for you, which I think I mentioned to you before and can be a very good way to bid, but you do need nerves of steel at times - good luck with the next one :)

[Marco]

£216 - that'll do me! :cool:

So in total £547 - that's a pretty bloody good result by anyone's standards.... This is when trading on ebay is a real ball!! :eyebrows:

Marco.

[Tim]

Nice one, what you gonna' spend it on?

[Marco]

Another quad of matched GEC KT88s - only better ones!

Or.... Try some of the new Tung Sol KT120s instead, and achieve 50-60 WPC in pure Class A from the Copper amp!!! (And pocket the change) ;)

The latter would involve Anthony having to reconfigure my amp to take them, but either way, the REAL FUN begins now!! :eyebrows:

Marco.

[Marco]

And she's even paid me now, too - wunderbar! :cool:

Marco.

[anthonyTD]

Great result!
Anthony,TD...