A question about tubes/valves

[Bill Stevenson]

Last week I replaced all of the tubes in my ARTsa after 18 months of service. This is the second change and both times the improvement in sound just astounds me. Not that there was anything noticeably wrong before the new tubes were installed, but afterwards there was a very big difference. Sweeter, more clarity, more open. I noticed on the cj website that there is a suggestion to replace the small tubes (first stage voltage regulation) twice as often as the power tubes (second stage current regulation). I know that first stage accounts for most of the sound quality. Has anyone tried this idea? It might make sense for me to try new small tubes every 9 months. Thoughts?

[Big Dog RJ]

G'day Bill,
How's it going over there? Trust your ARTsa is working its usual magic with your Sony's.

I may find replacing all tubes (output, input & driver/phase inverter) within 18 months a bit excessive. Then again if you are hearing a significant difference in tonality, plus overall presentation then go with that.

In my experience going back to 1989, there have been cases where people never changed tubes for nearly 8- 10 years, they just kept going. Then there were those who changed according to CJ's advice 2-3 years of normal usage, and this was the safest replacement plan that I stuck with as well.

However, since lately I've found that their newer gear, especially preamps, requires tube changing more often than the vintage models. I would have thought simpler circuitry would yield better performance in the long run but seems like tubes puff out before that long run...

I guess, what CJ is advising its owners is to keep an eye out for that sudden drop in quality, perhaps a dull sound... Therefore, in order to sustain that sparkle, lush mid-range and musical bass, replacing the tubes as often as the owner can afford, would work best.

Many years ago, I remember talking to both Ed and LJ about this, both of them adviced 2-3 years or around 3000-4000 hrs was good enough. Back then it was mainly EL34's and 6550's. Smaller tubes were usually the 12AX7 series, AU, AV and so on... Now it's the 6922 and M8080, 6189, N30P, although tested through time and maybe more reliable, there are definite cases where these tubes have failed within just a matter of few months!

Anyway, I think it's more to do with system configs, and listening levels plus listening sessions more than anything else. Whatever works best for your system stick with that!
Cheers mate, hope all goes well.
RJ

[Bill Stevenson]

Thanks RJ. The CJ website suggests 1500 hours for power tubes on the ARTsa, which implies half that for the small tubes. The ET5 and TEA2MAX get noisy and need new tubes far more often, perhaps every 6 or 8 months on the ET5. I play the system several hours per day so it doesn't take long. On the other hand, the sound to me is worth the price. My Sony speakers just keep me happy and no matter what I hear lately, they have me trained to prefer them.

[Big Dog RJ]

G'day Bill,
1500 hrs only! Well I guess CJ wants the ARTsa to be in tip top condition at any given time, which is a good thing.
Smaller tubes should generally last much longer, I would thought... but I guess times have changed and so have their designs, hence replacing tubes more often makes sense.

The tubes on my PV15 were never replaced, until several years after I acquired it. I also remember with the PV12 and later on with both the PV10L and Classic SE, tubes lasted much longer than these newer designs coming out such as the ETseries. Even my previous ACT2 did not require that much fuss on tubes, other than internal circuit problems, which eventually forced me to sell it off.

I think with the power amps, changing the tubes as often as required is the norm now, plus you'll always get that superb musicality from CJ when their tubes are in top condition.

I wonder what others have experienced...

OK then, enjoy your music and keep those tubes glowing!
Cheers mate, RJ

[Timo62]

Hello Bill ,
The manual for your amp states to replace tubes every two to three years with normal use. If you are hearing a difference after 18 months, then that might be a better time reference for you. You can always experiment with the smaller driver/ buffer tubes with replacing them sooner. I would be curious on how your tubes test after 18 months. How much life are they showing left in them?

[Bill Stevenson]

If I could find a tube tester it would be interesting to test them as you suggest. Finding such a beast these days has proven to be like the quest for the Holy Grail. The sound test using my Mark One, Mod Zero ears tells me that it is time for new tubes perhaps sooner than 18 months. I play my system a lot, several hours per day, which accounts for some of the apparent life span reduction. On the other hand there are no obvious problems, no loud hums or other aberrant behaviors to provide clues that the tubes have reached the end of their useful service life.

[Timo62]

Bill ,

It can difficult to find someone with a tube tester. It seems like you are putting more hours on your tubes than the average user, which is a good thing!. Nothing wrong with changing the tubes out when you feel they need to be changed.

[Wildcat]

I also feel that different tube types are more rugged than others. The Mullard M8080/CV4058 was actually a military tube. This is electrically equivalent to the common 6C4. My PV14L arrived with a pair of Philips/ECG 6C4s, and I purchased some Tung Sol 6C4s shortly afterwards. Both of them experienced a lot of microphonics at higher volume levels--you could clearly hear the "twang" of the grids inside the tubes! (Twang? I assure you, no country music was involved here!) The M8080s, at any volume, have exhibited no microphonics whatsoever.

This makes me wonder--it appears that the M8080 is a more rugged tube than a 6C4, so perhaps a good-sounding military grade equivalent for 6DJ8/6922/etc., or similar equivalents for the 12AX7, may be worth a look.

I will say that I also use my C-J products on the days I work from home, sometimes six or seven hours at a stretch, and my system isn't lacking at all so far. I am still on the second set of M8080 tubes I received (the first set had one noisy tube after a couple of months, which the company replaced with a new pair for me), and the tubes in the power amp are doing nicely as well. (In fact, Uncle Kevvy at Upscale told me the Brimar 6CG7/6FQ7 are tubes he rarely ever sees go bad.) I get the feeling that the KT120s are not pushed very hard at all, so they should have a good long life.

It could be the newer designs are pushing the tubes harder. In my Premier 11, the original tubes were 6550s, so the KT120s are sort of "over-spec" (under-utilized) as opposed to other amplifier designs that take full advantage of the KT120s' power.

[jeffreybehr]

I also feel that different tube types are more rugged than others. The Mullard M8080/CV4058 was actually a military tube. This is electrically equivalent to the common 6C4. My PV14L arrived with a pair of Philips/ECG 6C4s, and I purchased some Tung Sol 6C4s shortly afterwards. Both of them experienced a lot of microphonics at higher volume levels--you could clearly hear the "twang" of the grids inside the tubes! (Twang? I assure you, no country music was involved here!) The M8080s, at any volume, have exhibited no microphonics whatsoever.

This makes me wonder--it appears that the M8080 is a more rugged tube than a 6C4, so perhaps a good-sounding military grade equivalent for 6DJ8/6922/etc., or similar equivalents for the 12AX7, may be worth a look.

I will say that I also use my C-J products on the days I work from home, sometimes six or seven hours at a stretch, and my system isn't lacking at all so far. I am still on the second set of M8080 tubes I received (the first set had one noisy tube after a couple of months, which the company replaced with a new pair for me), and the tubes in the power amp are doing nicely as well. (In fact, Uncle Kevvy at Upscale told me the Brimar 6CG7/6FQ7 are tubes he rarely ever sees go bad.) I get the feeling that the KT120s are not pushed very hard at all, so they should have a good long life.
...

As I have written many times in years past--perhaps TOO many years past--Mullard M8080s are reliable, excellent-sounding tubes, and the vast majority of American-number 6C4s are highly microfonic. Early with my 6-channel MET1, I bought and tested MANY-dozen 6C4s and tossed the vast majority, keeping maybe a dozen to serve in the surround and '.1' channels. The M8080 designation is the civilian designation, with the CV4058 is indeed a militayr designation.

[Big Dog RJ]

My previous pv15 was fitted with brand new M8080's, just before it was sold for a great trade-in deal to another lucky customer. He has never been happier, and I can see him smiling wide and bright as he's enjoying the pv15 which was looked after me in pristine condition.
Yes, the m8080 is just marvelous no doubt!

Similarly, I came across the Genalex Gold Lion 6922 tube. This is another beauty! And I still can't understand why CJ does not use this tube in all their top preamps, as the majority seems to be EH-electro harmonix, which I think is very inferior compared to the Genalex. The EH tubes are also unreliable in my experience, for that matter I prefer the Sovtek.

Any of you had the same experience? Along with the same reliability issues...
Cheers, RJ