Tube amplifiers sound better because of the euphonic distortions they add to the music, along with lots of other reasons. I will cover below. These are generally subtle effects most audible to musicians and very dedicated music lovers; casual listeners (people who “listen” with their eyes open while doing something different) usually won’t notice, but sometimes the real difference is so obvious that people’s wives will comment that “wow, that sounds significantly better” when individuals use tubes in the home.
Tube amplifiers measure poorly inside the lab specifically due to these added distortions, however these distortions are often an integral part of what make them sound better. Even today having an all-digital infrastructure from recording studio to SMSL DAC for years and decades and decades have used tube pre-preamplifiers within the microphones themselves. Today their outputs are fed to tube preamplifiers before being digitised for recording, mixing and distribution. We use tubes since they have the music we create sound better: smoother, warmer and cleaner.
Ditto for guitar amplifiers found in creating music. The methods that tubes distort when pushed to the edge tend to be more musical than the artificial sounds that can come from transistor amplifiers when overdriven. Some transistor guitar amplifiers try to mimic tube distortion, but that’s a different article.
Obviously these are all very broad generalizations, and this is simply the maximum amount of as a result of circuit designs combined with tubes or transistors because the devices themselves, but do you know the distortions along with other reasons tube amplifiers sound better?
Tube amplifiers have much more distortion than solid-state amplifiers, but most from it is second-order, which is quite musical. That’s why it’s called “harmonic” distortion. Second-harmonic distortion is the same note, an octave above. Ditto for higher-order even harmonics; they are also exactly the same note more octaves above. Even-order harmonic distortion can be so pleasant that during the 1970s the Aphex Aural Exciter was quite popular in recording and broadcast specifically as it was created to create and add these harmonic distortions! It is possible to still buy it today.
Not just is tube amplifier distortion harmonious, it increases as things get louder – just as they are doing in a musical performance. As instruments play louder, or when you hit a percussion instrument or piano key more strongly, they generate more harmonic content. As notes decay, the portion of harmonic content drops again.
Tube amplifiers mimic this. An excellent tube amplifier such as the Woo Audio WA7 Fireflies increases its distortion directly with output level across three decades of voltage, or perhaps a million-to-one power range. By comparison, here’s the way a typical solid-state amplifier, in cases like this a Crown D-75, lowers its distortion with level, and after that suddenly clips in great amounts (the nearly vertical line on the right):
Be aware that the Woo graph is with regards to voltage output, and also the Crown plot is in terms of power. In fact, the Woo plot covers an electric power variety of over 6 million to 1, whilst the Crown plot only covers a power selection of 50,000 to a single. Using this progressive, “dynamic” distortion, tubes add sharp attacks while retaining long, floating sustains for each and every musical note.
Much like our ears, musical instruments and pretty much everything else natural, tube amplifiers possess the least distortion at the cheapest levels. This is the reason a tube amplifier can sound great played softly, while with transistor amplifiers people are usually having to turn it up to have it sound best. Honestly, I don’t bother using my dbx 3BX dynamic expander using a tube power amp, as it adds excessive dynamic impact.
Mingda Tube Amplifier sound their finest at the volumes at which you actually desire to enjoy them. Just like digital systems, solid state amplifiers measure and sound their worst at lower levels, and possess their best knhcnt at close to their maximum output levels where nobody ever actually plays them. For normal use with normal music at normal levels, the majority of us enjoy our music at about 1mW ~ 1W long term RMS, or about .01W ~ 10W peak. For the majority of applications, a 30 WPC amplifier is approximately right.
What’s sad is the fact that few consumer magazines that try to publish lab results usually only plot performance right down to 100mW, if in fact probably the most relevant power range where we enjoy most amplifiers comes from 1mW to 1W. What happens below 100mW is very important; that’s right where the majority of our music lives!
Sadly even when you pay $150,000 for a couple of overpriced frou-frou solid-state amplifiers, you’ll see its reviewer said many nice aspects of it, but he still said “the greater I cranked them, the greater they sounded” on page three. So for $150,000 they don’t sound best at the levels I would like to enjoy them? Adhere to the money; I don’t take ads from manufacturers.
Don’t let me hold you back if you would like Xiangsheng 728A Preamp, but you don’t want it unless you love to crank it, possess a big room or inefficient speakers, or enjoy very wide dynamic range classical music at concert-hall volume.