Questions about Preamp Tubes


I was thinking of buying a preamp (tube and SS). Will the tubes need constant replacement? If yes, then I would rather just use SS preamp to save myself the trouble/cost. My understanding is that it becomes very, very hard to differentiate between tube/SS in high-end products; however, is this the case in lower-end models? Will it still be the case in cheaper/older preamps by Audio Research and Conrad Johnson (those were the ones I was looking at)? Obviously I will try to try any preamp out if possible to test for synergy, but I don't want to consider tube preamps at all if they have the above problem.
What's your definition of "constant replacement"? Also, how much time each week will you be using the pre?
Small signal tubes, like the 12AX7, etc.. do last considerably longer than tubes such as the 6L6 in most cases. I wouldn't worry about how long they last because they can go on for years. Small tubes are replaced more often because of defects rather than normal wear & tear.

Tube preamps, in my opinion do sound considerably better! Try and get one that's point to point wired but not 40+ years old. Look for basic models without tone controls and tonnage of bells & whistles. Old is OK if it's been refurbished.
Tubes in preamps normally last 5000 to 10000 hours of playing time......
Peterb is right, although to clock 10000hours or over, you'll need premium types. The pres you mentioned are very well designed. They are anything but tube killers. In my opinion you need not worry but insist, should you buy, that the tubes are in good working order and not noisy in the critical places. A bit of tube rush is normal, but it should not interfere with your listening pleasure, even in very soft passages of music.
Preamp tubes (as opposed to output tubes in a power amp) are ordinarily long-lived. I can't remember having one go bad in my last three tubed preamps, two of which were by Conrad Johnson.
Audio Research and C/J are always good pieces to find..Tubes aren't usually that big a deal..The biggest question wether tube or s/s is how well the piece has been taken care of and if it has been back to the factory ( or reliable tech. ) for a service check..Keep in mind the peices are old and do need upgrading and upkeep..Also give us more info in the models you seek and maybe we can provide more info................
With tube preamps, tube replacement is not the problem: the above posters are correct about small-signal tubes, and I would add that the studies done in the 1950's all confirmed that longest life and best sound is achieved by keeping gear using small signal tubes turned on 24/7. Why? Most gear uses solid-state rectification, which is very hard on tubes when the unit is powered up. The thermal cycles they experience at power up and power down also beat them up over time. They pass little current in most preamp circuits. For these reasons, they are, generally speaking, best left on.

Tube preamps have other problems, specifically, noise, the inability to drive long interconnects without bass rolloff, and impedance mismatches with power amps, which also causes bass rolloff (I have written at length about these issues in other threads). However, only top-shelf solid-state preamps layer space and have the musicality of tube preamps. Thus, the conundrum.

A couple of suggestions: for solid-state, the Rowland Synergy IIi can be had for roughly $3k used and performs well; for tube, the basic VAC Renaissance preamp comes in around $3.5-$4k used - it uses output transformers that eliminate the problems of driving long cables and impedance mismatches with amps.

Good luck.
I've had my Mapletree Audio 2A/SE for > 2 years and no tube issues yet. It is by far the cheapest piece in my system at only $675, but the sound is glorious IMO. If you rank gear by price I guess it is "lower-end", though certainly not by sound.
The only problem with tubes is you might get the bug and try different types of tubes to play with the sound. I now have 5 sets of 12ax7/cv4004 and 4 sets of 12au7/5814a tubes and having a blast :)
"Tubes in preamps normally last 5000 to 10000 hours of playing time"

It makes sense to me that tubes in a pre-amp would have greater reliability than in power amps.

But is it all or nothing? In other words does the system sound the same for this long and suddenly die?

Or do subtle changes for better or for worse occur in the sound as the tubes age?

My guess would be the latter, but I do not know for certain.

Some high end tube vendors like VAC even offer automated health monitoring systems in their products to address this. IS this a frivolous feature that does not add value or the real thing? I suspect the latter.

The first case would not concern me much. The second would, in particular if many tubes are involved. I want to spend my time listening, not having to constantly check tube health if I think something does not sound right.
After the initial breaking in period (of the preamp), the sound will be fine for 5000 - 10000 hours of playing.
When the tubes are nearing the end of their life, you will hear them fade away (more noise).
Replacing them after a few years won't cost you a fortune.

15 years ago I owned a Audio Research LS-2b preamp (only one tube inside). The tube did survive the upgrade to a LS22, 3 years later.....
"My understanding is that it becomes very, very hard to differentiate between tube/SS in high-end products; however, is this the case in lower-end models?"

This is a very good question. I think you are on to something here.

I've noticed that the better tube systems I've heard that cost upwards of $10000 do not sound all that much different from some SS products that may cost 1/4 as much. SS products from Musical Fidelity, Classe, and Krell I've heard come to mind.

Even the late 80's vintage Carver SS pre in my system that provides a tube emulation voiced output is not too far off from what I've heard.

Any thoughts on this?
Mapman, Whether it sounds different to you depends, IMHO, more on the developement of your listening skills than anything else. When the differences are very subtle they can be missed by most anyone except the most attentive and especially by those who are looking for the wrong things.

If you look for the difference in frequency response linearity, often referred to tonallity, there often is little or no difference at all. Either can be warmish, brightish, fast or dull. Although many feel that warmth is automatically obtained by getting tubes, in fact some tube pre-amps might actually brighter than some ss pre-amps.

What I hear when I listen to a tube component, as compared to a ss component, is the tube component lacks what I would call 'grain'.

I suspect that this difference is in the quality of the signal - which I see as one of 'liquidity' which I think has its origins in the treatment of rise time and corresponding decay time which are more reminiscent of live music. Especially the latter (decay). Too short a decay and the sound lacks 'body', too slow and it becomes dullish. Too fast and the signal becomes unnatural, brightish, and ultimately (to me) fatiguing.

Now some folks see this fast decay as additional resolution of detail becauce without the 'tail' you can hear the next signal as being more clean, clear, resolved. I think SS tends to err's on the lack of a more natural decay.

An analogy would be to hear live sound in outdoor open air where the notes might decay naturally but there would be no room effect from a room where we always hear music and think thats where it is most natural. This music wouldn't have much 'body'. I think of this as SS sound. Live music in a great concert hall which has great acoustics and allows a natural decay with some reinforcement. I think of this as tube sound. Live music in a lesser concert hall where its construction emphasizes or guts parts of the sound spectrum - usually to much decay or or in 'modern - show' halls too much glass or other reflecting surfaces. I think of this as either format 'gone bad'. Ever notice the difference between a live recording and a studio recording the principle difference in sound is often only exists because in one you have a audience to absorb sound and the a studio recording the effect of the audience is missing and the sound seems artificial only because we never hear it that way when we go to the hall. Or live music in an echo chamber, YUK

Hope that makes sense. It's not something I think a lot about............

"What I hear when I listen to a tube component, as compared to a ss component, is the tube component lacks what I would call 'grain'."

I think this is the essence of it.

But the question to me is it natural grain or artificially introduced by the recording and/or playback system? Natural grain maybe irrating, but it is what it is. If the equipment introduces grain, then that is not a good thing.

I have heard many good SS systems with just decent digital sources that do not sound "grainy". My system is one example.

Often when there is a problem, it is because the components may not be matched well or the problem may be in the recording itself (natural or introduced during the recording creation process), but I am convinced from listening experience and testing for such things that it is not in the fact that these are SS devices, IMHO.

I would not equate a technical solution like SS or tube to different natural performance venues though. These are two different factors/issues.

Live performances seldom sound perfect either. Many instruments, like violins can have a natural grain to them. Different violin designs sound different, some are considered better than others.

I think SS is inherently better at reproducing the source more correctly, for better or for worse. Tubes I think smooth over some of the rough spots (grain), which as a listener does have its appeal as well. Nothing new here....

Towards the high end of audio, I think these differences do converge and become more alike, but it costs more to achieve it via tubes in general. Even then no two SS or two tube systems will sound exactly alike. The significant differences may be more a result of designer choice regarding how they want their product to sound.
I am currently comparing two highly touted phono-preamps and to my ears it is exactly as Newbee has pointed out. There is the SS, which was raved about in all the mags, incredibly fast, delivering a mass of highly defined and detailed information, so much so, that at first listening I sat there with my mouth open, but soon I found the sound had an unnatural edge, a brightness which made me uncomfortable. On the other hand the tubed unit, where I found rise and decay in its micro timing much closer to what I am used to hear in a live event at my usual row in the hall. Where the SS unit almost explosively assaulted my ears, in perfect timbre yes, every instrument placed clearly on a magnificently delineated stage, the tubed unit did everything almost as well, just a tad less "dramatic", very liquid, but this had the SS unit too, apart from the fact that I heard practically no grain, no veil in its musical rendering, but the tubed unit had something galore, which is rare, it had bloom, it gave an idea of the aura around instruments, which you hear clearly in reality, but rarely in front of your rig. Now what we call bloom, to my mind and knowledge will only be made possible, if as Newbee has mentioned, the rendering of transients, rise and decay times are closer to the real thing, although per se it is a different kettle of fish from what we call a perfect rendering of transients, I believe.

Had not the "gestalt" of music been formed from early age on by live music for me, I would have fallen for the SS- unit. Its totally grainfree, incredibly detailed, dynamically effortless rendering of any kind of instrument, music and voices placed on an impressive sound stage is simply breathtaking. But something is wrong: You cannot say that there is no air. There is, but in a very subtle sense the music does not "breathe", one note is hardly finished and you already have the next thrown at you , perfectly carved out in absolutely perfect timbre everything, but in a very, very subtle, -exaggerated by me, however nonetheless irritating - sense. It is as if each note were somehow alone, does not properly coalesce with the next, as would be the case in the real world of music. The tubed unit does this right. Its musical rendering is much closer to my idea of the gestalt of music. But where bright lights are thrown, as if were, on the music through the SS unit, here the lights are a tad more subdued.

I won't mention names, the tubed unit his highly renowned but has never been properly reviewed, the SS unit is famous amongst reviewers. They describe it in the most glowing terms. Possibly they are less familiar with live music as the music lovers amongst us audiophiles. But then (grin) perhaps my set up is faulty, a fault most certainly kindly glossed over by the gentle and euphonic distortion of tubes......(;

Which two phono pre-amps are you comparing? What is the rest of the system?
Thanks for all the responses guys - you've answered all of my current primary concerns. However, I encourage you guys to continue your discussions at the tail end of this thread as I'm somewhat new to this audio hobby and am learning all the time. I'm enjoying reading what you guys have to say.

As far as specific equipment I am considering Thorman, I'm not entirely sure if I plan to buy a preamp in the very, very near future and am in a more factfinding type of stage, so I will leave that for a more pertinent time.
The issue of greatest concern with regard to the small signal tubes is not replacement but noise.
I also want to warn you that tube "rolling" is a very addictive hobby that could end up with you begging money from relatives for more NOS tubes.
I don't know in truth about longevity, I have had no new tube failures with the exception of power tubes. Some of the tubes I have were used for 7-8 years and are still fine. Others I run for a few months and they have become irritatingly noisy and a real bummer. If you shell outbig bucks for a special old stock tube and find it useless after a few months you are Sh** out of luck.
I wouldn't forgo a tubed preamp for a SS in a line stage simply because I like tubes. However I don't think of any tube being perfectly noise free when amplified in a phonostage. The order of amplification is so great it is nearly impossible to maintain a truly silent tube phono stage. Others will argue, you will see.
In any event Tube power amps or integrateds produce a bigger, more obvious, holographic three D sound stage, than any SS gear at any price, that I have encountered. Since I go to audio shows and am a member of a large audio group I have heard top flight SS gear. It sounds great but nothing like a tube amp.
In the end I think my AE-3 tube pre is a miricle for 300 bucks.
I happen to own a legendary preamp, which is one of those you mention, an ARC. An SP6B specifically, which is a generally admired and sought after pre given that it is 25 years old.
I prefer my little 2 tube AE-3 which uses 6SN7s. I happen to really like them but I haven't the resources to buy a SLP-05 for 7-8 thousand.
My two cents in summary worry about your power amplification!
If you use power tubes you will hear the tube magic. Don't fall for the tube pre is all you need bit. It is not true period.
If you want to use an SS preamp you will still hear the magic. The other way round is widely believed to be the case, ingnore the insane, hopeless, clones.
A tube in a preamp or preamp section of an integrated accomplishes nothing without using power tubes.
Good luck and believe me or just find out yourself it took me only 6 years of experimenting with tube preamps to hear Nirvana when I finally bought tube power amps.

Your points ring true. I'd agree you can get more inherent "tubiness" from a power amp than a pre amp since the signal transformation that occurs in the power amp is of much greater magnitude than that which occurs in the pre-amp.

But I think I would assert based on my experience that a pre-amp can provide a significantly more tube like sound if designed to do so as well. I've confirmed this on many occasions with my Carver c-6 pre-amp.

The c-6 is actually a solid state pre-amp that provides two sets of pre-amp outputs, one voiced like solid state and one voiced like tubes.

And yes, the tube output voicing does work quite well. It sounds very much like the better tube gear I've heard. The ss outputs do not. I'd wager that any set of ears familiar with the general difference in sound between ss and tubes could easily identify which is which.

The tube voicing provides a sound very much like what Newbee describes above. The solid state voicing in comparison sounds very much like what Newbee describes there as well in comparison.

So if a ss pre-amp is able to provide a more "tubey" sound, I have no doubt the real thing can as well.

The more I compare Carver's "mid-fi" stuff with other more blue blood designs that tend to garner more respect in the audiophile world over time, the more respect I have for what he was able to accomplish in terms of delivering good sound at modest cost.

How did he make a ss pre-amp sound like tubes? I suspect it has to do with the manner in which the gain is applied to the signal. With the ss voicing, dynamic range is clearly greater at the expense of microdynamics. With the tube voicing, the reverse is the case. In many a/b tests I've done with these two alternately voiced ss outputs over the years, the difference is clear as night and day.

This also leads me to believe that other ss designs can achieve a more "tubey" sound in a similar manner when designed to do so, without the the extra maintenance issues associated with real tubes.

I've heard a more tube like sound I think in ss systems from Musical Fidelity, Krell, and Classe, for example.

So in my case, I do like the tube sound and looks as well, but I'm not quite sure that the extra cost and headaches associated with real tubes are absolutely required to achieve the desired sonic results.

I also believe that while ss can be voiced for modest cost to sound like tubes, I'm not sure the reverse is true. The tube gear I've heard capable of resolving (this is different than microdynamics) competitively with good ss without losing the inherent "tubiness" of the sound have all been quite expensive.
I agree with the comments that tubey sound could be obtained by only tube power amps.
SS preamps give cleaner (less thd )sound but tube pres give more opennes and palpability (basic tube characteristic)