Originally Posted by Brandon3858
I think I follow you. But if you could go down tube alley with me; are you saying a tube integrated amp would be "better" as a digital preamp sending a signal to a tube amp?
Tube Alley, good grief. Ok, I'll share some of my experience, but you really should listen to the more knowledgeable engineers who post here. I'm just a hobbyist whose curiosity got the better of me, kind of like where you are now, so maybe this will help you avoid the puddles in Tube Alley. There are lots of puddles, filled with stinky woo, down Tube Alley.
Be aware that tube circuits can sound as neutral as solid state, if they are well designed. This is fairly easy with tube line stages, i.e. somewhere in the signal path before amplification, such as within a hybrid tube/ss receiver, where the tubes are employed in the pre-amp stage. They can be as clean or as dirty as the designer intends, but it's easy to keep line level signals nice and clean. I prefer my front end to be squeaky clean, and see no real reason for tubes there. Tube amplifiers, on the other hand, when coupled with electro-mechanical transducers (speakers, or on the other end of the recording chain, microphones, disc cutters, etc) will display much more of the technical misbehavior responsible for the "tube sound".
Lets talk about "tube sound" a bit. This is a vague term that can allude to a whole host of phenomena, but the point is that most folks who use tubes do so for the sake of altering the presentation for pleasant effect. This is a form of non-defeatable signal processing, and as such deviates from the pursuit of high fidelity audio, hence why it is frowned upon here at AVS forums. It also tells me that if you're getting into it for the sake of altering the sound, upstream tubes make less sense than getting fully dirty with tube amps coupled to speakers.
Tube sound as produced by a tube amp coupled to speakers is typically characterized by a few things. First, the higher output impedance of the tube amp will result in non-linear response that reflects the impedance of the speaker across the audible band unique to that particular pairing. The closer the source impedance gets to the load impedance, the worse it gets. Also, the high source (amp) impedance also may result in room feedback, the so-called Carver effect, where the speakers become microphonic and pick up the room response which becomes part of the amplified signal. Think room-specific reverb. Second, tube amps will have much higher amounts of low order harmonic distortion than solid state amps. There is a close correlation between harmonic distortion and musical tone coloration; second order harmonics are an exact octave above the fundamental, thus are almost imperceptible and tend to add body to the sound; third order harmonics are a quint or twelfth to the fundamental, and tend to result in a closed in, covered sound. A strong second combined with a strong third will open up that covered sound. A strong second and third with significant amounts of fourth, fifth and sixth will result in a more brassy, open, choral tonality. Third, as tube amps overload (something you would never want to do with ss amps), their electrical output increases only slightly, but within that envelope the resulting increase in lower order harmonics are perceived as increased loudness (hence the claims of tube watts being somehow "more powerful" than other watts, which is ridiculous).
Are you starting to see the difficulty with advising anyone contemplating a trip down tube alley? Take two different tube amps, pair them with two pairs of speakers, and you will have four completely different results. Have two of those flowery prose writing reviewers in the mix and you get eight different subjective evaluations. It get's convoluted rather quickly, making it almost impossible to make sense of it all without some knowledge of electrical circuits or the history of hi-fi. And we haven't even scratched the surface of different tube amp topologies yet, e.g. PP tubes tend to cancel even order harmonics, where SET amps typically have both even and odd harmonics in copious amounts. SETs make for terrible amps, but they are somewhat compelling processors, I'll give them that much.
So are you sure you want to go down tube alley? I won't say categorically "don't do it", but strongly suggest you learn more before you jump in. Consider building your own tube gear, as it will be far more stimulating and educational, as well as much more cost effective.Edited by Wayne Highwood - 7/16/13 at 8:50am