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Bob Latino

Peter W.

Dogstar

7 posters

When is it time to replace tubes?

Dogstar: Posts : 361
Join date : 2014-06-23

Post n°1

When is it time to replace tubes?

by Dogstar Wed Jul 24, 2019 2:41 pm

OK I actually two questions.

I listen to primarily jazz from the 50’s and 60’s and Rock and Roll from the same era. Back when you could hear true separation in the instruments. Back before the Wall of Sound recording technique became mainstream.

What are the signs of tubes needing to be replaced?
I have Genelex Gold Lion KT-88s and a Weber WZ68 rectifier. I’ve had them for about 3 years and they have maybe a 1000 hours of listening time on them but probably less. To me they sound flat. Or maybe I’ve gotten used to them to the point where I don’t seem to hear the tubular sonic excellence I remember.

I had TungSol KT-120’s and a Tung Sol tube rectifier (can’t remember the model). I remember the music being more 3 dimensional. The speaker setup is the same.

Do tube rectifiers enhance that 3D quality? Or maybe my ears are getting tired.

Thoughts and suggestions please.

Thanks in advance.

Peter W.: Posts : 1351
Join date : 2016-08-07
Location : Melrose Park, PA

Post n°2

Re: When is it time to replace tubes?

by Peter W. Wed Jul 24, 2019 3:18 pm

Mpffffff.... Opinion and Speculation follows at no particular level or relative mix:

I keep a very good, properly calibrated tube tester (Hickok 539B) that with additional tools (VOMs) may be used to match tubes. I also have the various updates and charts to support it, as well as some graded calibration tubes. Having this tool allows me to make some fairly accurate tests, including power tubes.

Were I to purchase new tubes, I would test them and record the results. I would leave them in the tester for a minimum of 30 minutes, each (yes, the tester will sustain that) so a to get accurate results. Whereupon I could re-test in the future against those results and observe any changes shown. Which I could then correlate to what I am hearing, or what I think I am hearing. Put another way, I would have an independently verifiable source of data.

Now, 1,000 hours of use on a tube, even an output tube driven fairly hard *should* be negligible. I have put about 1,200 hours on my office system that started with very well-used tubes in the first place. But, 1,000 hours is a long time between cleaning sockets and re-making connections.

You understand that what you hear is a function in five variables, only three of which are under your control, being: Source/Amplification/Speakers/Health/State-of-Ears. You have control over the first three, and experience, but do not fully control the last two. Your health controls your attitude. The state of your ears will be affected by the weather, what you have been doing the last 12 hours or so, even whether you have ridden in a high-speed elevator in the last 12 hours as a single example. And listener-fatigue is very, very real.

Now, rectifiers make DC current from AC current, which is then filtered and otherwise massaged by your amplifier's power supply. Under the presumption that you are getting the correct B+ levels, and there is no remaining significant AC component in it, that power-supply is rather catholic when it comes to the source of DC current, and will use it 'all the same'. For those who would challenge this contention - let's endeavor to set up a proper double-blind test and see what develops. Short of that, opinions rule, either way.

Source: If you use vinyl, the wear factor is both real and significant. Keep in mind that the typical stylus puts pressure on records at something approaching eight ( 8 ) pounds per square inch, and moving something like nine (9) miles per hour all the while being slammed from side-to-side at up to 20,000 times per second. A lot of energy is being transmitted into the grooves. And, vinyl being an imperfect plastic, it cannot take this sort of abuse more than about once per 24 hours without extensive damage, and will show real (and audible) wear, probably around the 10th playing anyway.

Similarly with various forms of tape, but with an absolute life, but more playback resilience.

So, if nothing has changed in your system and your sources are not suspect in any way, then it would not hurt for you to purchase replacement tubes to the proper configuration you desire. But before doing any of that, clean your tube sockets and pins (carefully, of course), re-make all your connections (speakers and sources), and clean everything along the signal path. No Joy? Try some tubes. But!! Replace them in categories - better yet, have someone else change them (or not) and see if you perceive a difference.

Tubes do certainly wear. And post-blight tubes much more so. But they are not cheap, and you need to be as sure as practical that you are not mis-identifying your perceptions or their sources.

Good luck with it!

Dogstar: Posts : 361
Join date : 2014-06-23

Post n°3

Re: When is it time to replace tubes?

by Dogstar Wed Jul 24, 2019 3:26 pm

Thanks for detailed explanation and your opinions. I do not have a tube tester. But I have removed cleaned and retensioned the socket contacts.

I’m considering 6550’s since they are considered to be more musical....along with another tube rectifier.

But can anyone tell me how a tube rectifier affects the sonic quality ?

Dogstar: Posts : 361
Join date : 2014-06-23

Post n°4

Re: When is it time to replace tubes?

by Dogstar Wed Jul 24, 2019 6:08 pm

One other thing. I have a 6SN7 tube in the center socket using an adapter. Perhaps I should consider replacing that tube as well.

Bob Latino: Admin; Posts : 3277
Join date : 2008-11-26
Location : Massachusetts

Post n°5

Re: When is it time to replace tubes?

by Bob Latino Wed Jul 24, 2019 7:33 pm

Dogstar,

Output tubes last maybe 3000 - 4000 hours or roughly 3 hours a day for 3 to 4 years.

Driver tubes last maybe 5000 hours or so.

After the above time, sound quality may suffer slightly and/or you may find that one of your output tubes won't bias properly. If an output tube won't bias properly, it is probably time to replace ALL the output tubes. The tube that won't bias > throw that one away and then save the other 3 output tubes that will still bias as SPARES. Put them back in their boxes and mark the boxes as "spares". Understand that vacuum tubes are "consumables". They have a finite life. They don't last forever.

Understand also that tubes will wear even though there is no music passing through the amp. It is OK to leave the amp ON IF you know you will be going back to listen to the music in maybe 1/2 hour or so. If you know you won't be listening again that day, SHUT THE AMP OFF and save some tube life.

I had someone once leave on a pair of VTA M-125's on for a week when he went on vacation. He came back a week later and the two M-125's were still sitting there glowing. He Emailed me and asked if he had damaged the amps by leaving them on that long? Nope, but he did take 168 hours of life off the tubes.

Bob

deepee99: Posts : 2244
Join date : 2012-05-23
Location : Wallace, Idaho

Post n°6

Re: When is it time to replace tubes?

by deepee99 Sat Aug 03, 2019 11:09 am

Well, at least his caps are well burned-in. Not to mention all his tubes.
Just curious, Bob L., the hours you list for tube life: Do they refer to new-issue tubes only? Because I've been told by several credible people in the tube game that 10k hours can be expected of a properly biased old Tung-Sol 6550.
Your thoughts?

Bob Latino: Admin; Posts : 3277
Join date : 2008-11-26
Location : Massachusetts

Post n°7

Re: When is it time to replace tubes?

by Bob Latino Sat Aug 03, 2019 11:40 am

deepee99 wrote:Well, at least his caps are well burned-in. Not to mention all his tubes.
Just curious, Bob L., the hours you list for tube life: Do they refer to new-issue tubes only? Because I've been told by several credible people in the tube game that 10k hours can be expected of a properly biased old Tung-Sol 6550.
Your thoughts?

Dave > Those figures are for new issue tubes presently made in China, Russia and the Slovak Republic. Older NOS tubes made years ago in the USA, Germany and Great Britain will last somewhat longer. Modern tubes are made with some less expensive metal alloys for the plates, screens and grids inside the tube. I also don't think quality control on the newer tubes is as good as it was years ago.

One of the things that I have learned in dealing with YOUNGER users of tube gear (maybe 40 years old or younger) is that many of them do not realize that vacuum tubes are "consumables" and they don't last forever. Consider them like a light bulb .. Every now and then you have to replace one. Even the newer LED light bulbs will eventually "die".

Bob

deepee99: Posts : 2244
Join date : 2012-05-23
Location : Wallace, Idaho

Post n°8

Re: When is it time to replace tubes?

by deepee99 Sat Aug 03, 2019 12:44 pm

Bob Latino wrote:

deepee99 wrote:Well, at least his caps are well burned-in. Not to mention all his tubes.
Just curious, Bob L., the hours you list for tube life: Do they refer to new-issue tubes only? Because I've been told by several credible people in the tube game that 10k hours can be expected of a properly biased old Tung-Sol 6550.
Your thoughts?

Dave > Those figures are for new issue tubes presently made in China, Russia and the Slovak Republic. Older NOS tubes made years ago in the USA, Germany and Great Britain will last somewhat longer. Modern tubes are made with some less expensive metal alloys for the plates, screens and grids inside the tube. I also don't think quality control on the newer tubes is as good as it was years ago.

One of the things that I have learned in dealing with YOUNGER users of tube gear (maybe 40 years old or younger) is that many of them do not realize that vacuum tubes are "consumables" and they don't last forever. Consider them like a light bulb .. Every now and then you have to replace one. Even the newer LED light bulbs will eventually "die".

Bob

Excellent points, Bob. I don't know if they quality as consumables, but capacitors are another "won't last forever" entity, especially among the silicon crew. Their 30-year-old Mac or Dyna or Carver (or whatever) goes chockablock all of a sudden and a $2,000 original price piece of gear ends up listed as a boat anchor on Fleabay for $300 OBO Smile

Smile

when probably $40-$100 worth of caps and a little elbow grease would put things to right. Even transistors wear out over time.
I guess the lesson here is that anything with moving parts wears out over time, even if those moving parts are electrons.

Dogstar: Posts : 361
Join date : 2014-06-23

Post n°9

Re: When is it time to replace tubes?

by Dogstar Sat Aug 03, 2019 1:51 pm

Thanks for associating me with a 40 year old. And mentally I am even younger than that.

About a year after I purchased the amp built by a technician working for Bob Latino one of the TungSol KT120’s I purchased as a matched quad from Tube Depot went bad as well as the TungSol tube rectifier I also installed went bad. I brought it to a service tech highly regarded by AudioKarma to service the amp . Since I don’t claim to be electronics guy. He claimed one of the resistors was never soldered into place and that was the cause of the tube failures. At the time I took his word for it.

When it was all fixed and tested for about a month (20 hours or so) with the Sovtek KT88’s I bought with the amp I installed the Genelex Gold Lions KT88’s and a Webber SS rectifier that I’m still using. It’s now been about 3 years and other than experimenting with a 6SN7 tube in the center preamp socket and checking the bias every 3 months or so I haven’t changed anything and so far everything is working just fine. I’m using TungSol 12AU7’s in the other two sockets. Those are tubes I installed when I originally installed the KT120’s.

I mentioned that the tech made claims but he didn't substantiate his claim and since then I’ve learned that sometimes he fabricates stories to make his repairs so much more grandiose.

Anyway my amp was built in 2012 and other than that one issue has performed perfectly.

My original concern that tubes may need replacing were due to my perception changing. I think my hearing has diminished since it seems that tube sound doesn’t seem as good as it once did...to me anyway.

deepee99: Posts : 2244
Join date : 2012-05-23
Location : Wallace, Idaho

Post n°10

Re: When is it time to replace tubes?

by deepee99 Sat Aug 03, 2019 2:04 pm

Dogstar wrote:Thanks for associating me with a 40 year old. And mentally I am even younger than that.

About a year after I purchased the amp built by a technician working for Bob Latino one of the TungSol KT120’s I purchased as a matched quad from Tube Depot went bad as well as the TungSol tube rectifier I also installed went bad. I brought it to a service tech highly regarded by AudioKarma to service the amp . Since I don’t claim to be electronics guy. He claimed one of the resistors was never soldered into place and that was the cause of the tube failures. At the time I took his word for it.

When it was all fixed and tested for about a month (20 hours or so) with the Sovtek KT88’s I bought with the amp I installed the Genelex Gold Lions KT88’s and a Webber SS rectifier that I’m still using. It’s now been about 3 years and other than experimenting with a 6SN7 tube in the center preamp socket and checking the bias every 3 months or so I haven’t changed anything and so far everything is working just fine. I’m using TungSol 12AU7’s in the other two sockets. Those are tubes I installed when I originally installed the KT120’s.

I mentioned that the tech made claims but he didn't substantiate his claim and since then I’ve learned that sometimes he fabricates stories to make his repairs so much more grandiose.

Anyway my amp was built in 2012 and other than that one issue has performed perfectly.

My original concern that tubes may need replacing were due to my perception changing. I think my hearing has diminished since it seems that tube sound doesn’t seem as good as it once did...to me anyway.

So, Dog, you figure maybe you had a lame tube he replaced and the guy gave you the resistor story to justify his bill although nothing was amiss with it? Shite, I thought only our local automobile mechanic pulled that crap. We've all had our peccadillos with RM, but I've never seen anything come out of Bob's side of VTA but the finest of workmanship.

Dave_in_Va: Posts : 446
Join date : 2013-04-02
Location : Mid. VA

Post n°11

Re: When is it time to replace tubes?

by Dave_in_Va Sat Aug 03, 2019 2:12 pm

I've had my VTA ST 70 (pre-assembled) for about 4-5 years. The only problem I had was exactly yours.

A NOS Mullard EL 34 went out as well as an ANOS Mullard 5AR4.

I'm 100% convinced that the fault was mine for doing a fair amount of tube rolling when I first got the amp without re-tensioning the tube sockets.

Ya gotta do it.

Dogstar: Posts : 361
Join date : 2014-06-23

Post n°12

Re: When is it time to replace tubes?

by Dogstar Sat Aug 03, 2019 3:09 pm

deepee99 wrote:

Dogstar wrote:Thanks for associating me with a 40 year old. And mentally I am even younger than that.

About a year after I purchased the amp built by a technician working for Bob Latino one of the TungSol KT120’s I purchased as a matched quad from Tube Depot went bad as well as the TungSol tube rectifier I also installed went bad. I brought it to a service tech highly regarded by AudioKarma to service the amp . Since I don’t claim to be electronics guy. He claimed one of the resistors was never soldered into place and that was the cause of the tube failures. At the time I took his word for it.

When it was all fixed and tested for about a month (20 hours or so) with the Sovtek KT88’s I bought with the amp I installed the Genelex Gold Lions KT88’s and a Webber SS rectifier that I’m still using. It’s now been about 3 years and other than experimenting with a 6SN7 tube in the center preamp socket and checking the bias every 3 months or so I haven’t changed anything and so far everything is working just fine. I’m using TungSol 12AU7’s in the other two sockets. Those are tubes I installed when I originally installed the KT120’s.

I mentioned that the tech made claims but he didn't substantiate his claim and since then I’ve learned that sometimes he fabricates stories to make his repairs so much more grandiose.

Anyway my amp was built in 2012 and other than that one issue has performed perfectly.

My original concern that tubes may need replacing were due to my perception changing. I think my hearing has diminished since it seems that tube sound doesn’t seem as good as it once did...to me anyway.

So, Dog, you figure maybe you had a lame tube he replaced and the guy gave you the resistor story to justify his bill although nothing was amiss with it? Shite, I thought only our local automobile mechanic pulled that crap. We've all had our peccadillos with RM, but I've never seen anything come out of Bob's side of VTA but the finest of workmanship.

That’s perhaps what I think. The reason is because they really had a minimal amount of time on them. I have a solid state system playing as background music most of the time which is why I have low hours on the amp. Just to reduce my tube gear to critical music sessions...or pretty much sitting back and dedicating my time specifically to listening.

And just now while typing a response I think I realized what is taking the tube sound away.
I did put my amp on the second shelf and because of that I run a computer type fan across the tubes. And I’ll bet the air turbulence from the fan is making it take longer for the electrons to make the circuit. OK so maybe not that really but the sound of the air turbulence itself introduces a noise that wasn’t there before that distracts the olfactory senses from the source sound.

deepee99: Posts : 2244
Join date : 2012-05-23
Location : Wallace, Idaho

Post n°13

Re: When is it time to replace tubes?

by deepee99 Sat Aug 03, 2019 3:44 pm

Dogstar wrote:

deepee99 wrote:

Dogstar wrote:Thanks for associating me with a 40 year old. And mentally I am even younger than that.

About a year after I purchased the amp built by a technician working for Bob Latino one of the TungSol KT120’s I purchased as a matched quad from Tube Depot went bad as well as the TungSol tube rectifier I also installed went bad. I brought it to a service tech highly regarded by AudioKarma to service the amp . Since I don’t claim to be electronics guy. He claimed one of the resistors was never soldered into place and that was the cause of the tube failures. At the time I took his word for it.

When it was all fixed and tested for about a month (20 hours or so) with the Sovtek KT88’s I bought with the amp I installed the Genelex Gold Lions KT88’s and a Webber SS rectifier that I’m still using. It’s now been about 3 years and other than experimenting with a 6SN7 tube in the center preamp socket and checking the bias every 3 months or so I haven’t changed anything and so far everything is working just fine. I’m using TungSol 12AU7’s in the other two sockets. Those are tubes I installed when I originally installed the KT120’s.

I mentioned that the tech made claims but he didn't substantiate his claim and since then I’ve learned that sometimes he fabricates stories to make his repairs so much more grandiose.

Anyway my amp was built in 2012 and other than that one issue has performed perfectly.

My original concern that tubes may need replacing were due to my perception changing. I think my hearing has diminished since it seems that tube sound doesn’t seem as good as it once did...to me anyway.

So, Dog, you figure maybe you had a lame tube he replaced and the guy gave you the resistor story to justify his bill although nothing was amiss with it? Shite, I thought only our local automobile mechanic pulled that crap. We've all had our peccadillos with RM, but I've never seen anything come out of Bob's side of VTA but the finest of workmanship.

That’s perhaps what I think. The reason is because they really had a minimal amount of time on them. I have a solid state system playing as background music most of the time which is why I have low hours on the amp. Just to reduce my tube gear to critical music sessions...or pretty much sitting back and dedicating my time specifically to listening.

And just now while typing a response I think I realized what is taking the tube sound away.
I did put my amp on the second shelf and because of that I run a computer type fan across the tubes. And I’ll bet the air turbulence from the fan is making it take longer for the electrons to make the circuit. OK so maybe not that really but the sound of the air turbulence itself introduces a noise that wasn’t there before that distracts the olfactory senses from the source sound.

Dogstar, let me be the first to recommend you as a member of the Facebook chat-room, "Audio Bullshit."
Your analysis is sound. Polarity is everything! Not just in co-ax and speaker wire, but also in air molecules. I would suggest that by reversing the direction of your cooling fan you would immediately discover deeper yet more crisp bass, sound-staging beyond your wildest dreams, and an enhanced midrange fluidity without the annoyance of any redactive inductance of your redunculating turbo-encabulators.
Soldier on, Old Sod, Soldier On!!!! and may the transients be with you, but not decamped in your house demanding a meal.

peterh: Posts : 1869
Join date : 2012-12-25
Location : gothenburg, sweden

Post n°14

Re: When is it time to replace tubes?

by peterh Sat Aug 03, 2019 5:18 pm

Dogstar wrote:OK I actually two questions.

I listen to primarily jazz from the 50’s and 60’s and Rock and Roll from the same era. Back when you could hear true separation in the instruments. Back before the Wall of Sound recording technique became mainstream.

What are the signs of tubes needing to be replaced?
I have Genelex Gold Lion KT-88s and a Weber WZ68 rectifier. I’ve had them for about 3 years and they have maybe a 1000 hours of listening time on them but probably less. To me they sound flat. Or maybe I’ve gotten used to them to the point where I don’t seem to hear the tubular sonic excellence I remember.

I had TungSol KT-120’s and a Tung Sol tube rectifier (can’t remember the model). I remember the music being more 3 dimensional. The speaker setup is the same.

Do tube rectifiers enhance that 3D quality? Or maybe my ears are getting tired.

Thoughts and suggestions please.

Thanks in advance.

If i may tune in ;
i equipped my vta70 after a few hundred hours with :
- a digital hour meter that counts power on time
- a new quad of JJ 6550

After 4300h ( about, i forgot the exact number, i have posted it on another thred here)
i checked the tubes and compared their measurments whith the values as new using
a maximatcher. And yes, the tubes had degraded somewhat. They were still "within spec" and
did function as intended. But i replaced them with a new quad of JJ EL34.

I think the limit for good powertubes is somewhere in this range, 4 - 5000 hours. Abuse
and frequent disturbing may shorten this, but undisturbed with occational check/adjust bias
they should las.

During this time 2 5AR4 was consumed, one chinese and one JJ. ALso a RCA ECC82 started
humming so i replaced them all with JJ ECC82

Why JJ ? Reason is that i buy them from the factory and distribute them in sweden.
Burning them in my own amp is a way to test their quality.

audiobill: Posts : 425
Join date : 2014-03-13
Location : Albany, NY

Post n°15

Re: When is it time to replace tubes?

by audiobill Mon Aug 05, 2019 7:29 am

I will offer a FREE tube "burn in" service to forum members:

Have your new tubes sent directly to me and after two years of "burn in" I will forward them on to you.
Of course, you pay shipping.

Bill

deepee99: Posts : 2244
Join date : 2012-05-23
Location : Wallace, Idaho

Post n°16

Re: When is it time to replace tubes?

by deepee99 Mon Aug 05, 2019 9:17 am

audiobill wrote:I will offer a FREE tube "burn in" service to forum members:

Have your new tubes sent directly to me and after two years of "burn in" I will forward them on to you.
Of course, you pay shipping.

Bill

I will do the same thing Bill's offering, but for one year's burn-in at 10 hours/ day.
In addition, I will cover any shipping costs above $100 each way.
Much better deal.

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Post n°17

Re: When is it time to replace tubes?

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