The Trouble with Tubes

[fiddlefye]

I love tube gear, truly I do. They provide the sound that "floats my boat". There is a rub, though. I will sort out a combination of gear and tube complements that really nails the sound I am seeking, have a lovely period of sonic bliss and then a tube goes out and throws everything into chaos.

I've pretty much worked out the power amp side of things as the output tubes get changed much more often and I've found what I like there. Keep a spare set on hand and change as needed. Where I get in trouble is in dealing with the small tubes. To make matter more confusing for many years I was getting tubes from my tech who was working from an local estate stash. He would give me a few sets to try for whatever application and I would pick what suited me. Half the time I couldn't even tell who the manufacturer was. Those days are gone and I've been out in the big, scary tube-buying world for awhile now.

So I'm attempting to deal with the 12AU7 situation with the PV-12 and have a few coming in. I recognize that I need to look ahead for 12AX7s for the phono pre. Working on that....

On the topic of tubes. Some wonderful person on the forum sent me these quite awhile ago. Life got busy, my memory got hazy and here are these Raytheon tubes I am sure I owe that wonderful someone money for, but I'm not even 100% sure what they are now. 5751s perhaps?
DSC_3471 by fiddlefye, on Flickr

 

[fiddlefye]

More to come...

 

[paul_b]

They look a lot like 12AT7s.

 

[TubeHiFiNut]

This is why I choose to avoid "unobtainium". There are plenty of tubes out there that are in current production and that, with proper testing and matching, sound quite good.

Just my opinion.

 

[fiddlefye]

They look a lot like 12AT7s.

Could be! I'm hoping that the gent who sent them to me sees the thread, lets me know and I can send some money as well.

This is why I choose to avoid "unobtainium". There are plenty of tubes out there that are in current production and that, with proper testing and matching, sound quite good.

Just my opinion.

I'd agree and I've got that going nicely in terms out output tubes. I don't have any exotic tubes in anything, but the current production stuff just doesn't cut it for my ears in the pieces I've got. 12AT/AU/AX7 and 6922s aren't rare birds.

Maybe I'm just absurdly picky? I get a tube matched chain going between the phono pre, pre-amp and power amp that just brings everything really to life. Mess up one point in the chain and it all goes a bit south. As I've said - part of the problem is that due to the source I've not always in past known exactly what the tubes were in use as many came without indication or illegible.

 

[MikeT.]

I certainly don’t have a depth of experience with tubes as a relative newcomer to tubes but always willing to share.

My Primaluna came with five 12AU7 on the front end, Primaluna brand. Since rolling all five was not a bank-breaker, I dove in and just the one time so far. I replaced all five with Gold Lion 12AU7. It wasn’t an “oh wow” moment but several “that sounds really good” moments strung together.

 

[TubeHiFiNut]

Could be! I'm hoping that the gent who sent them to me sees the thread, lets me know and I can send some money as well.

I'd agree and I've got that going nicely in terms out output tubes. I don't have any exotic tubes in anything, but the current production stuff just doesn't cut it for my ears in the pieces I've got. 12AT/AU/AX7 and 6922s aren't rare birds.

Maybe I'm just absurdly picky? I get a tube matched chain going between the phono pre, pre-amp and power amp that just brings everything really to life. Mess up one point in the chain and it all goes a bit south. As I've said - part of the problem is that due to the source I've not always in past known exactly what the tubes were in use as many came without indication or illegible.

I understand (believe me I do) and have lots of vintage small signal tubes. More than I'll probably ever use.

Your current dilemma is something I've experienced so many times that I finally got tired of going through the hassle.

I've been getting my tubes from Mike Sanders at Quicksilver Audio for 25+ years. He buys huge quantities of the tubes used in his products and meticulously checks (emissions, noise, strength, etc.) and matches them on his curve tracer. Those that don't pass muster get trashed.

They may not be 100% as good as the vintage stuff but they are pretty darn close (at least in the circuits in which I've tried them), are readily available and don't break the bank.

Now I don't worry about the hours I am putting on my tubes. When they go bad, I call Mike and have a new set sent. Problem solved.

If I need a tube that Mike doesn't carry, I can usually find what I need at one of the larger tube sellers.

I am not saying that this is what you should do - each one of us makes those decisions based on our own criteria - but just conveying my experience and thought process regarding how I got to where I am regarding replacement tubes.

As always, just my opinion.

 

[AndyN]

Did you try putting them in the freezer? Sometimes, a bit of warm breath on a frozen tube is enough to reveal the type etching.

 

[fiddlefye]

I certainly don’t have a depth of experience with tubes as a relative newcomer to tubes but always willing to share.

My Primaluna came with five 12AU7 on the front end, Primaluna brand. Since rolling all five was not a bank-breaker, I dove in and just the one time so far. I replaced all five with Gold Lion 12AU7. It wasn’t an “oh wow” moment but several “that sounds really good” moments strung together.

The Gold Lion 12AU7s are actually vastly more expensive than many good NOS tubes, at least in these parts. Some of the Mullards etc. are more money, but there are some great tubes still for a fraction of the cost of the GLs. I use the GL KT-77 and like them a whole lot.

 

[BH]

It is not unusual for small signal tubes to last the lifetime of the equipment. Whenever one experiences premature failure (such as every few years with a few hours/day of use) I suspect filament overvoltage. This is a common occurrence and I often encounter measurements of 7+volts (on tubes designed for 6.3) even in vintage gear at a typical line voltage of 120. If you are handy and have a multimeter, I'd pull one of the tubes in the CJ, turn it on, and measure the filament voltage. If excessive, investing in a variac is worthwhile to drop the line voltage to where the tube filaments are staying within their design parameters. If the filaments receive their specified voltage under the worst case line voltage conditions, the slightly lower voltage they will receive when the line voltage decreases (such as in the summer with A/C use) can only increase the life span.

 

[MikeT.]

@BH , I don’t think I said hello and welcome. Welcome to the Haven!

 

[MikeT.]

The Gold Lion 12AU7s are actually vastly more expensive than many good NOS tubes, at least in these parts. Some of the Mullards etc. are more money, but there are some great tubes still for a fraction of the cost of the GLs. I use the GL KT-77 and like them a whole lot.

I just checked them out and they have gotten MUCH more expensive from when I rolled them in.

 

[BH]

Thanks for the welcome Mike. To clarify the reason for pulling the tube- it allows the measurement to be taken from the top side of the chassis to reduce possible exposure to lethal high voltages.

BH

 

[fiddlefye]

It is not unusual for small signal tubes to last the lifetime of the equipment. Whenever one experiences premature failure (such as every few years with a few hours/day of use) I suspect filament overvoltage. This is a common occurrence and I often encounter measurements of 7+volts (on tubes designed for 6.3) even in vintage gear at a typical line voltage of 120. If you are handy and have a multimeter, I'd pull one of the tubes in the CJ, turn it on, and measure the filament voltage. If excessive, investing in a variac is worthwhile to drop the line voltage to where the tube filaments are staying within their design parameters. If the filaments receive their specified voltage under the worst case line voltage conditions, the slightly lower voltage they will receive when the line voltage decreases (such as in the summer with A/C use) can only increase the life span.

The set that had one tube fail was already used when they went in and that was the better part of two decades ago. They'd probably earned their retirement. No premature death in this case.

 

[Golden Gate ER]

I like a "big bang for your buck" products.

When it comes to tubes I gravitate towards new old stock JAN tubes & new production ValveArt tubes.
ValveArt tubes are very inexpensive with performance & longevity. .

My amps all have bias adjustments for all the PP outputs tubes so I don't worry about perfect matching on that stage. from my experience the largest audio impact of tube matching is the phase splitter/inverter & input stages.
I don't have a fancy plotter, so I graph them out by hand and some arithmetic. This old fashioned way gets them dam close.

 

[fiddlefye]

A wee update - On Saturday I had ordered what I hoped would prove to be a nice pair of Raytheon 12AU7s for the PV-12. Tuesday Ernie came over to the rescue with his tube caddy.

Meanwhile the tunes must go on, so I'd replaced the PV-12 with my Anthem Pre-1. I'd had to re-tube it last year and had gone with the set suggested by the manufacturer, all Russian. Even with a bunch of hours on them it sounded pretty dismal - thin, no life and little interest. Ernie had some lovely suggestions so we put them in and things got much better and even more so with a few hours.

Ernie also brought along a little toy for me to try, a beautifully- built Bottlehead Seduction with very few hours on it. So it got a couple of days audition in conjunction with the Anthem and I find myself liking it very much. SQ is very much in line with my Opera PM-1, but perhaps a bit more mid-range detail and a bit less life at the extremes? It is still playing in as well so we shall see.

The Ratheon 12AU7s had arrived and today I found myself with a bit more free time than anticipated and a great curiosity to compare the nicely-tubed Anthem to a freshly tubed PV-12. This, in spite of my resolution to give the Anthem a few more days before I switched things around. Ah well!

The initial impression was good, if a bit brighter than I'm used to from the pre. Normal stuff, though. Even then the PV-12 ate the Anthem for breakfast right from the start. The Anthem sounded a bit pedestrian by comparison and a titch thin maybe? Six hours in on the tubes in the CJ now and things have settled and focused even more. Listening to a Telefunken recording of Cliquot organs through the Seduction and I can say I've never heard such glorious audio in my house. No, I have to go out on a limb here and say I've seldom heard such beautiful sound in a system anywhere. YMMV in listening to system (and probably would), but such life and vibrancy in the sound. Intense. Oh my....

Yes, I am a happy camper, if possibly guilty of a bit of euphoric hyperbole.

 

[JohnVF]

possibly guilty of a bit of euphoric hyperbole.

There's no guilt needed for such a thing. That's what this is all about, after all. Without euphoria, what would drive this chase?

 

[mhardy6647]

oh, 12AU7s... oops
Gotta go on a spelunking expedition downstairs...

 

[DC]

I had a Bottlehead Seduction (rather modified/upgraded) that I thought was the best phono preamp I had ever had in my system(s). And after I rolled some better tubes in it, it improved on itself. I usually don't "regret" selling items but there are two pieces I would quickly buy back if given the opportunity and that was one of them.

No guilt for a bit of euphoric hyperbole.

Edit: And I like the thread title; very apropos.

 

[fiddlefye]

There's no guilt needed for such a thing. That's what this is all about, after all. Without euphoria, what would drive this chase?

Last evening was the most intensely focused listening session I've ever had. I played a few familiar recordings as one does when evaluating. It wasn't the usual "heard more detail" etc. - more like hearing inside the music in a new way, a rhythmic propulsion driving everything more than usual.

Just listening to the tuner now and the tonal balance has come around nicely. I was a bit worried at first as the lower mid/upper bass was a mite thin and bright. The JAN Phillips set I had initially many years ago was that way and just stayed so. No such issue this time I don't think.