The differences between tube and solid state amplifiers can be large or small. Many people who prefer tube amps consider them to have great tone and soundstage depth in comparison to solid state but may have a rounded, soft or tubby bass presentation. This actually has more to do with impedance matching between the tube amplifier and the bass speaker driver being used but that is another discussion. Solid state designs are typically said to have more solid or tighter bass than the average tube amp but might fall behind in tone, depth and midrange and treble clarity. They can come across as sounding thin, veiled and grainy to some listeners .There are exceptions both ways as anyone who has listened to Pass Labs or First Watt amplifiers on the solid state side and maybe the higher powered Audio Research and Manley Labs amps on the tube side can attest to. Some who prefer soIid state make a case that tube amps do not actually have a neutral sound but instead are colored and act as tone controls in a way. I for one have heard great examples of both tube and solid state amplification. The arguments either way are valid as far as my listening experience goes and I have concluded it to be a matter of personal choice and component matching. There is also what I believe is a growing number of people who are setting up systems to take advantage of what tubes have to offer from the upper bass through treble and bi-amping by using solid state and separate drivers for the midbass on down and/or solid state driven subwoofers.
There are certainly a few tube amplifiers out there that sound more similar to the better solid state amps than the average tube amplifier and there are definitely some solid state designs that have a sonic signature closer to tube amplifiers than your typical solid state amp. Once one has listened to many systems and components they can start to get a feel for what sonic qualities are important to them and find components that are to their liking. If a person listens mainly to rock, pop and most modern electronic filled music, they might likely prefer the midbass punch and bass control of a quality solid state design compared to these same genre’s played through a tube amplifier. Many of these recording are so heavily processed in the studio that the only people who are ever going to know what the recording is supposed to sound like are the engineers and musicians who were there in the studio. On the other hand if one listens mainly to real acoustic instruments and places a high value on human vocals sounding like the real thing as well as things such as pace, rhythm and timing, the attach and decay of notes and soundstage depth, then most of these listeners migrate toward tube amplifiers or the handful of solid state amps that can render these qualities to a high degree. One approach that is becoming more common is to use a top notch tube preamplifier feeding a solid state amplifier that is transparent enough to hear the difference between the solid state and tube preamplifiers. I have personally heard multiple systems where this approach works very well when using a solid state amplifier such as Pass Labs, Coda, Rowland, Benchmark AHB2 etc.
There are also quite a few high quality digital sources that are capable of putting out a high enough preamp level signal that one can skip using a preamp altogether. Many streamers and DAC’s made today are capable of this and the results can be that the direct input into the amplifier and using the volume control of the source can sound better than using a preamp in between. I personally have not tried this enough times to say whether it is beneficial or not but in some systems I would bet that it does sound better no matter what preamps are available. Following the less is more theory that should be true as long as the gain matching between source and amp are compatible. In my own systems a top notch tube preamp has always won out but I admit this has not been tried too many times.
One thing I have always tried to remember is that how we hear and what qualities are most important to make a given listener happy are always subjective. I have heard hundreds of sytems and every one of them had certain aspects that are great to me and others that I couldn’t live with.
Being honest with yourself about what aspects of sound are critical to you is incredibly important as you will be the one listening to your system the most and others opinions should be considered and weighed accordingly. An example would be when I realized that as much as the pure magic I hear with electrostatic or planar speakers can display, after much listening I just cannot get past the lack of bass dynamics these speaker designs have when compared to standard dynamic drivers. No matter how much I love the purity of sound of these speakers or certain amplifiers for that matter, the lack of dynamics and the speed, attack and decay of notes played on certain instruments turns me away. The opposite is true for me as well when I hear a system that is incredibly revealing with great speed and finesse,(usually from a tipped up treble region) but has no tone or physical presence in the all important upper bass lower midrange area. An example of this would be a system I owned in the 90’s with Wilson speakers and an Audio Research tube amp. The best I had heard to that point but the upper bass and midbass region were so lacking in a large room that it actually became distracting and took away from the performance. I have since convinced myself that there is no replacement for displacement in a large room and have been concentrating on large dynamic drivers and horns with compression drivers. These systems can be very challenging balancing the frequency response out and getting good soundstaging among other things but for this guy lifelike, dynamic presence in the bass through midrange is absolutely critical for me to enjoy my system. One thing I noticed is that even a somewhat quieter instrument like an acoustic guitar played in really any room 10-15 feet away emits an actual physical feeling or sensation from the soundwaves emenating from the body of the guitar itself that nearly all playback systems are incapable of portraying correctly unless the volume is louder than it should be. For those well off enough to have their own sealed up dedicated sound rooms, reproducing sounds with this sort of physicality at normal listening levels is possible with more standard sized speakers. For those of us with large rooms because they need to double as the family living room and are open to the rest of the house, it unfortunately is going to take some significant surface area from dynamic drivers to be convincing. So far in my personal experiments, large dynamic drivers such as Altec, BMS, Faital Pro, EV etc have showed promise as they are very efficient so can be used with the best sounding lower powered amplifiers and are capable of delivering lifelike sound pressures in a large room without sounding strained from being pushed too loud.
The trick is to have enough radiating area to achieve realistic sound pressures without the drivers moving in and out very much at all. I have had good results so far from a 12” Altec 414a run full range on a single ended pentode tube amp in conjunction with a 16” Altec 416b in a separate cabinet driven with a 25 watt First Watt solid state amp from 600hz and down. Another 15” Faital Pro driver driven by a 600 watt class D amp does low bass duty from 150 down to 30hz. All of this in a two piece cabinet 48 inches tall and a 20”wide x 30” deep foot print. A pro audio 18 Sound ND3SN compression driver driving a 10” wide x 8” tall horn will be installed above the 414a and will run from 700hz on up, the 414a will be low passed around the 700hz to relieve it from having to play higher than it should.
This setup has a lot of radiating surface of high efficiency drivers and is capable of moving some air (as real instruments surely do!) at a realistically low volume level. This does take a lot of learning about crossovers, filters and autoformers but at this point in my audio journey it has been a rewarding road to go down. I truly wish that only “hearing” and not feeling my music were enough but we all have to be fussy about something in this life I guess. I am definitely jealous of those that are content with a quality headphone system. Sure would be a lot less work and a lot less expensive!
I apologize for straying from tube versus solid state amps but hoping the above is another prime example of the many reasons that each style of amp are used for different reasons and goals on top of the subjective taste of the listener.
Hoping this area of the site can be a constructive conversation of both amplification styles and we can all learn from each other’s experiences and opinions.