Just wondering after fitting my 6n3 replacements the other day there was an immediate change in the sound, for the better I might add. however yesterday I replaced the EL34's for some new electro harmonix equivalents and the sound has gone slightly worse, it sounds colder/harder than it did before and some of the detail seems to have gone, it's not a massive change just a slight one, so I was wondering will this get better with time ? and if so how long before the new tubes come on song so to speak ? I have had it playing for about 6 hours so far
thanks
thanks
6N3C or 6N3C-S or 6N3P or 6N3P-E
They are all different, just like a 6L6GT is low power handling compared to 6L6GC then KT77 is similar ...
They have different characteristics, which I am sure you already know.
I have never had to burn valves in as soon as they are working and biased correctly, they start their half life.
They are all different, just like a 6L6GT is low power handling compared to 6L6GC then KT77 is similar ...
They have different characteristics, which I am sure you already know.
I have never had to burn valves in as soon as they are working and biased correctly, they start their half life.
I don't think there is any proof that "burn-in" is actually a real thing, rather than an imaginary one. Personally I've never noticed any sort of difference.
Depends on the valve,
I noticed a change on 6C33C's over about two weeks.
I run the tubes using half of the tubes (single triode) and could switch between each half both sounded the same and I then ran on one half for about 2 weeks and switched over to the other side and there was a big difference. after running the other side for two weeks at switch over both sounded the same. There has been no change since. The getter may have an effect..The sound was warmer on the side that had been run compared to the other side that had just been tested for a couple of hours.
Regards
M. Gregg
I noticed a change on 6C33C's over about two weeks.
I run the tubes using half of the tubes (single triode) and could switch between each half both sounded the same and I then ran on one half for about 2 weeks and switched over to the other side and there was a big difference. after running the other side for two weeks at switch over both sounded the same. There has been no change since. The getter may have an effect..The sound was warmer on the side that had been run compared to the other side that had just been tested for a couple of hours.
Regards
M. Gregg
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I'm with Kstagger on this one. As soon as the filiments have lit up i'd consider the tubes thoroughly burnt in and ready for a good pounding 😀
It depends on how good the vacuum is, and how thoroughly degassed the electrodes are. NOS valves were generally good straight from the box. Modern ones might not be. A few hours at normal working temperature may be needed.
As DF96 said.
I am careful to use hearing as a yardstick, it is rather dependant on various circumstances although I respect M. Gregg's experience. I have however measured cathode currents in a variety of applications, and I did find that warming up (not burn-in) causes a small change, as is to be expected. (Things get hot in there and it will be surprising if electrode physical dimensions do not change at all during warm-up.) My experience was mainly with 6L6GC - some 30 of them - and apart from the above I noticed no change in cathode current over the first weeks.
It is however sadly true that one may find a significant difference between new tubes from the East; some burn-in evidence will not surprise me. I found the slightly more expensive TungSol 6L6GC STR very consistent, and the EH 6L6WXT well ... fair enough so.
I am careful to use hearing as a yardstick, it is rather dependant on various circumstances although I respect M. Gregg's experience. I have however measured cathode currents in a variety of applications, and I did find that warming up (not burn-in) causes a small change, as is to be expected. (Things get hot in there and it will be surprising if electrode physical dimensions do not change at all during warm-up.) My experience was mainly with 6L6GC - some 30 of them - and apart from the above I noticed no change in cathode current over the first weeks.
It is however sadly true that one may find a significant difference between new tubes from the East; some burn-in evidence will not surprise me. I found the slightly more expensive TungSol 6L6GC STR very consistent, and the EH 6L6WXT well ... fair enough so.
The valve gets weaker as it gets older.
The cathode discharge becomes weaker as time goes on.
That's the only mechanism I can think of in regards to burn in.
The cathode discharge becomes weaker as time goes on.
That's the only mechanism I can think of in regards to burn in.
All the "burn in" on a new tube is done by the manufacturer as the next step after evacuating the tube envelope. You only have to do this if you make your own tubes.
err thanks guys, maybe the new 6ca7's need the bias adjusting a bit then ? or these valves are not to my liking ?
Grid currents (often due to the factors stated by DF96) can take some hours to stabilize and that can, in theory and in some circuits, affect sound. This is a case where "burn in" can be somewhat meaningful.
The above mentioned possible mechanisms...that and the first few clip events....nudge a system into gentle clipping and then back it off...typically will be changed but stable after that.
Dan.
Dan.
thanks again
the shanling sp80's mono pwr amps are supposed to be self biasing according to the manual just had a quick read ? the EL34/6CA7 Electro harmonix are the brand new valves the 6n3 seem ok and good it's the big tubes in the amp that seem to have changed the sound for the worse even though it's not big, i had shanuang chinese el34's in there before and they sounded slightly better ?
the shanling sp80's mono pwr amps are supposed to be self biasing according to the manual just had a quick read ? the EL34/6CA7 Electro harmonix are the brand new valves the 6n3 seem ok and good it's the big tubes in the amp that seem to have changed the sound for the worse even though it's not big, i had shanuang chinese el34's in there before and they sounded slightly better ?
It's unfortunate you don't have access to someone with an FFT based measurement set up, you might very well find that the amplifier's distortion spectra has changed and not for the better.
A number of my friends have commented on differing distortion performance from brand to brand specifically with the EL34. Curve traces and FFT measurements in the past have indicated IMLE that there is merit to this idea.
Those old Mullards people rave about often sound and measure better than modern production.. Something about attention to QC as evidenced by good alignment of the grids, and excellent plate symmetry..
Put the old tubes back in and listen carefully, and decide.
It ain't likely that they (the new ones) are going to get that much better.
(i.e. It is probably not your imagination)
A number of my friends have commented on differing distortion performance from brand to brand specifically with the EL34. Curve traces and FFT measurements in the past have indicated IMLE that there is merit to this idea.
Those old Mullards people rave about often sound and measure better than modern production.. Something about attention to QC as evidenced by good alignment of the grids, and excellent plate symmetry..
Put the old tubes back in and listen carefully, and decide.
It ain't likely that they (the new ones) are going to get that much better.
(i.e. It is probably not your imagination)
Gm decays from its initial value and tends to stabilise after about 100 hours use. I'm not if the manufacturer does this for you?
I think these days manufacturing test is limited to a quick light up and some very cursory testing if any. I test all of the small signal tubes I buy from current production and a significant % of them are bad right out of the box.
With power tubes I almost always purchase them burned in and matched - this gets the outliers and most of the infant mortality. This approach along with not running them too close to ratings seems to result in relatively good life.
With power tubes I almost always purchase them burned in and matched - this gets the outliers and most of the infant mortality. This approach along with not running them too close to ratings seems to result in relatively good life.
Thanks again guys
I wouldn't know who to ask or where to start over getting the bias checked, the Electro harmonix tubes where recomended as a good tube to replace the old ones, so far my mods have been, change the 6n3 tubes on the cd player = definate improvement
change op amps to LM4562 = definate improvement
now it loks like the last owner changed the single driver tube to 6l7gt i think then lastley i changed the EL34 from standard to the electro harmonix 6ca7 ,everything was slowy getting better untill the EL34's. I dont have the money to get the amps profesionaly modded but i know there is a fair bit can be done to take the shanling sp80 mono blocs into another league.
thanks to everyone for your help so far as i am a noob with valves even though iv'e had valve amps many years ago. I did find some sort of instruction in biasing my amps but I don't have the gear or the knowledge and would rather not damage them, it's a shame someone of here can't help if they even lived close enough ? in the past iv'e had people of forums help me do things and i have done the same for others inc showing them how to make cables, modding marantz cd players etc, I know this kit has the makings of a really good system, with a few tweaks here n there
thanks
I wouldn't know who to ask or where to start over getting the bias checked, the Electro harmonix tubes where recomended as a good tube to replace the old ones, so far my mods have been, change the 6n3 tubes on the cd player = definate improvement
change op amps to LM4562 = definate improvement
now it loks like the last owner changed the single driver tube to 6l7gt i think then lastley i changed the EL34 from standard to the electro harmonix 6ca7 ,everything was slowy getting better untill the EL34's. I dont have the money to get the amps profesionaly modded but i know there is a fair bit can be done to take the shanling sp80 mono blocs into another league.
thanks to everyone for your help so far as i am a noob with valves even though iv'e had valve amps many years ago. I did find some sort of instruction in biasing my amps but I don't have the gear or the knowledge and would rather not damage them, it's a shame someone of here can't help if they even lived close enough ? in the past iv'e had people of forums help me do things and i have done the same for others inc showing them how to make cables, modding marantz cd players etc, I know this kit has the makings of a really good system, with a few tweaks here n there
thanks
Are the shanling monoblocks fixed bias or cathode bias? If fixed there would be a set of bias pots, hopefully one per tube - an inexpensive DMM, a few small tools and the proper procedure are all that would be required to set the bias. If fixed bias the bias should be adjusted when the tubes are replaced.
Should the amps be cathode biased no adjustment is possible and components would need to be replaced to adjust the operating point - this should not be necessary in such a design.
I would strongly recommend reinstalling the old tubes and seeing whether or not the changes you report remain the case or not.
Consider purchasing some other EL34 to try.. If you bought the big bottle 6CA7EH these are actually beam power tetrodes and while great for guitar amps I have avoided these in hifi applications as I think the pentode based EL34 sound better.
Should the amps be cathode biased no adjustment is possible and components would need to be replaced to adjust the operating point - this should not be necessary in such a design.
I would strongly recommend reinstalling the old tubes and seeing whether or not the changes you report remain the case or not.
Consider purchasing some other EL34 to try.. If you bought the big bottle 6CA7EH these are actually beam power tetrodes and while great for guitar amps I have avoided these in hifi applications as I think the pentode based EL34 sound better.
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