Questions about Preamp Tubes

"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.

"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?

Newbee,

"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.

Detlof,

Which two phono pre-amps are you comparing? What is the rest of the system?

Mechans,

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.