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Tube Rolling

ceylon said:
then i better buy some real good socket savers, cuz i am a very late arrival to audiophilia, and i have a lot of catchin up to do.
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I've actually seen amps ruined from this behavior. Once the grid connection goes intermittent, the tube shorts out and the amp can be badly damaged.

I'd be worried about socket savers affecting stability though.

Lavane said:
I disagree what it comes to old stock Chinese signal tubes. All except a pair of 6N13's sounded thin and sounded like music coming out of a tin can. They were also very microphonic. Tap anywhere around the area around the amp and you can hear it coming through the speakers. Some of those tubes I could yell at and it came through the speakers.
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Those aren't within spec though... those are junk tubes with issues. Could even be rejects that someond is trying to pawn off on unsuspecting customers. Even in the old days companies used selected high quality tubes to allow components to meet spec.

Unfortunately the only tubes which were pretty much guaranteed to meet spec aren't really available anymore.
 
DavidTT said:
Getting back to this thread after a while. I hate to say that, knowing this is ALL subjective, I may be the only listener I know who didn't love the Darlington Labs product. I have come to appreciate them and their approach, their pricing and support, and their participation in the relevant forums. I also am potentially biased by my reaction against 'hype' I see in forums for any particular product, having been through it with the Lounge LCRIII phono amp, which I didn't enjoy at all, among others.

Anyway, I listened for several days, in two separate stints, to an MP-7 I had here to compare with a Hagerman Cornet 3, and I never warmed up to the Darlington. It sounded competent and detailed but it lost out to a certain euphonic sound that I struggle to describe, and which could easily be utterly in my own head when it comes to the Cornet 3. None of this it to denigrate the Darlington product, and I'm aware that I'm the only poster who hasn't raved about these units.

If anything, I suppose I'm lending credence to the idea that @Morgan D might prefer the sound of the Retro Version and enjoy the potential to roll tubes. I was surprised how much I enjoyed the Cornet 3 in comparison to the MP-7, but there it was. There is really something about having tubes somewhere in the chain. FWIW, I have an old Audio Research LS-1 hybrid SS/tube Line State coming my way this week, which will make for some interesting listening. It uses one 6DJ8/ECC88 tube for gain and should be interesting to try out and maybe to tube roll as well.
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We wanted to take this opportunity to let folks know that Older units, even if purchased second-hand, may be eligible for factory updates. Contact the factory for more information.
 
maxhifi said:
What I can't get behind is wearing out tube sockets with obsessive changing of tubes, in exchange for small changes in sound quality.
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ot is not always this. Matter of fact this does not fit the people I personally know that try different tubes. For example my PAS2 and Phone Pre have had the same tubes for a couple years now. I tried about 5 sets in both, probably for at least a month each. Then I did a sit down with the same song and swapped them all, took notes the whole process, decided what I preferred and they haven't been untouched since.
 
Lavane said:
I disagree what it comes to old stock Chinese signal tubes. All except a pair of 6N13's sounded thin and sounded like music coming out of a tin can. They were also very microphonic. Tap anywhere around the area around the amp and you can hear it coming through the speakers. Some of those tubes I could yell at and it came through the speakers.
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I wrote "tube within spec"
 
maxhifi said:
I'd be worried about socket savers affecting stability though.
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In pentodes and in beam power tubes the screen needs a grid stopper as close as possible to the socket pin. Too far away and it introduces instability. Socket savers should never be used in that location.

When I was still building and I would embark on a new projects the first thing I would do when starting to purchase is to obtain proper sockets, modern stuff is the proverbial brown matter. In old tube testers sockets were rated for 10 000 insertions minimum and has pin connectors that were like a little tube around the pin, slotted and had a small spring around them to keep the little tube tight and prevent from widening. Hard, if not impossible, to find these days.
 
peterh said:
I wrote "tube within spec"
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What is within spec?

Often tubes that "test within spec" can be actual rejects because of being microphonic.

Secondly it is not uncommon to have a tube put into service for which it was not designed, especially ex- China or Russian tubes.

Guitar players use tube rolling to obtain a particular sound when the tubes are over driven but if you have a properly designed HiFi amplifier then tube rolling past the first input tube should not have one iota impact due to the negative feedback. Biggest nonsense there is, in other words if there is an audible difference in the subsequent stages then it is either a design without global negative feedback or a heap of brown matter.
 
AmadeusMozart said:
What is within spec?

Often tubes that "test within spec" can be actual rejects because of being microphonic.

Secondly it is not uncommon to have a tube put into service for which it was not designed, especially ex- China or Russian tubes.

Guitar players use tube rolling to obtain a particular sound when the tubes are over driven but if you have a properly designed HiFi amplifier then tube rolling past the first input tube should not have one iota impact due to the negative feedback. Biggest nonsense there is, in other words if there is an audible difference in the subsequent stages then it is either a design without global negative feedback or a heap of brown matter.
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Does this apply to phono preamps?
 
Morgan D said:
Does this apply to phono preamps?
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In Phono preamps there is a lot of feedback to get the correct RIAA correection. However the question will be what is the first stage doing, the initial amplification from the cartridge before it goes to the RIAA correction stage. In that first stage it is crucial to have a tube with the lowest noise and the least microphonic characteristics and unfortunately they are often the most expensive.

The last stage after the RIAA may or may not be included in some form of negative feedback so tube rolling outside of the RIAA correction stage may pay off. But noise in that place is not of primary concern. It totally depends on the overall design.
 
My knowledge is limited but I have one with two gold lion 12ax7s that are very new and I forgot to turn it off all day and when I played a good record it seemed like it really opened everything sonically. Maybe I should leave my phono pre on . I wonder how long the tubes would last. they run less than 100F.
 
AmadeusMozart said:
What is within spec?

Often tubes that "test within spec" can be actual rejects because of being microphonic.

Secondly it is not uncommon to have a tube put into service for which it was not designed, especially ex- China or Russian tubes.

Guitar players use tube rolling to obtain a particular sound when the tubes are over driven but if you have a properly designed HiFi amplifier then tube rolling past the first input tube should not have one iota impact due to the negative feedback. Biggest nonsense there is, in other words if there is an audible difference in the subsequent stages then it is either a design without global negative feedback or a heap of brown matter.
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Specefications is available, these are mostly historic documents but still describes the parameters a tube should adhere to
One example : https://frank.pocnet.net/sheets/030/e/ECC83.pdf

Damaged tubes ( microphonic for instance) are outside spec by definition.
 
Within specification means different things to different manufacturers. And one manufacturers ECC83 is NOT equivalent to another manufacturers ECC83. You ned to check the operating recommendations and then you might notice that on occasion different manufacturers have a different operation points. It was all done to circumvent patents. "It should work but might not be optimal".

Some manufacturers worked qith +/- 20% of specification but there were others that worked with +/- 50%, same as with microphonics - when did they regard it as microphonic?

E.G. I have some Telefunken ECC81 as a driver in my power amplifier. I bought a sleeve, they are all within specification and all matched. But two have a red paint dot on the bottom - those were designed for medical application and are very closely matched and are my favoured tubes.

The 300B tube was rated for 100 000 hours for telephone operation and were never turned off. The damage to tubes is done when the filament runs above rated voltage, they are running at maximum dissipation and are switched on and off. You can run a driver safely at reduced filament voltage - I know Philips used something like 5.4 V for a driver tube that was running at a fraction of its maximum dissipation. I would check filament voltage and would have no hesistation to leave a tube on 24/7 for a pre, especially an ECC83 that is running at 1 mA or less and has a filament volateg perferably around 6 V so it never goes above the 6.3 with mains fluctation. The miltary have noticed longer lifespans (up to double) of tubes when running in a "controlled envrionment" which is temperature, shock and mains voltage within 3%. The other upshot is that when running in a controlled environment you can drive the output tubes closer to their maximum ratings. ( I still stick to the maximum design rating -the output tube I'm using performs best at that level).
 
AmadeusMozart said:
Within specification means different things to different manufacturers. And one manufacturers ECC83 is NOT equivalent to another manufacturers ECC83. You ned to check the operating recommendations and then you might notice that on occasion different manufacturers have a different operation points. It was all done to circumvent patents. "It should work but might not be optimal".
%snip%
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ECC83 / 12AX7 has identical spec and example working points in all the spec sheets i have seen :
One example ( the ECC83 from phillips in previous post ) has an "typical characteristics
at :
Va 100 250
Vg -1.0 -2.0
Ia 0.5 1.2 mA
S 1.25 1.6 mA/V
u 100 100
Ri 80 62.6 khom

Give an example of any ECC83 brand that uses other values of this please
 
Morgan D said:
Hi, I will soon have an all tube system. I just have a general question. Which component in the analog chain effects the system the most? Where should I experiment with tube rolling. My thinking is the phono pre amp has the most influence. I know they all do to some degree . It is a 6L6gc 10 w SET amp.
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If you are doing the SET route, don't forget to look at the coupling caps. They can make as big an improvement as a tube roll.
 
maxhifi said:
Not the functional condition of the caps, but the materials/brand/ratings etc. Lots of SET guys claim improvements in sound quality with one capacitor versus another, similar to tube rolling.
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Well I am gonna have to trust Pat from PJL electronics. I have been happy with his advice and products. I like the fact that I can talk to the builder. I suppose I could ask what he is using. He says he is happy with the sound and he is not the type to boast or push product.
 
peterh said:
ECC83 / 12AX7 has identical spec and example working points in all the spec sheets i have seen :
One example ( the ECC83 from phillips in previous post ) has an "typical characteristics
at :
Va 100 250
Vg -1.0 -2.0
Ia 0.5 1.2 mA
S 1.25 1.6 mA/V
u 100 100
Ri 80 62.6 khom

Give an example of any ECC83 brand that uses other values of this please
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Since you are too lazy to do your home work and interpreting the specifications properly: Check the Mazda-Belvue versus a Philips at e.g. 300 V with an anode resistor of 100K. (Philips was the original developper of the ECC8x.) Different cathode resistor and different max Veff..

Copies of tubes have never the same performance and due to patents since they are never made identical, i.e. they are not a clone but they are a reproduction. (unless licensed by Philips or the factory was (part) owned by Philips). Even a socalled "long plate" and "short plate" behave differently, it can be close but not identical. And then you have some that have a spiral filament versus non-spiral which has an impact on the noise level. Not to forget that one side needs to be used as first stage depending how the filament is fed.

And now you go on my ignore list.
 
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AmadeusMozart said:
Since you are too lazy to do your home work and interpreting the specifications properly: Check the Mazda-Belvue versus a Philips at e.g. 300 V with an anode resistor of 100K. (Philips was the original developper of the ECC8x.) Different cathode resistor and different max Veff..

Copies of tubes have never the same performance and due to patents since they are never made identical, i.e. they are not a clone but they are a reproduction. (unless licensed by Philips or the factory was (part) owned by Philips). Even a socalled "long plate" and "short plate" behave differently, it can be close but not identical. And then you have some that have a spiral filament versus non-spiral which has an impact on the noise level. Not to forget that one side needs to be used as first stage depending how the filament is fed.

And now you go on my ignore list.
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Mazda according to the link :
https://frank.pocnet.net/sheets/020/1/12AX7A.pdf
shows as "caracteristics normales" on p.2 same figures as philips.
Also the plate curves are remarkable similiar.
Any other "clue" ??

BTW 12ax7 was developed by RCA 1946 according to wikipedia.
 
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maxhifi said:
Not the functional condition of the caps, but the materials/brand/ratings etc. Lots of SET guys claim improvements in sound quality with one capacitor versus another, similar to tube rolling.
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Changing caps also improved the sound in my amp.
I always look to see what kind of caps are in my amps/pre.
 
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