Lesson 70

Tube vs Solid State

So this comes up in audio quite a bit, and I think there’s a lot of confusion regarding the difference between tube and solid state sound. I think a lot of people who are confused about this don’t even know that they’re confused. Why do I think this... because there seems to be this idea that tubes add “analog warmth” to the “harsh sounding digitalness” and that tubes sound better, 100% of the time. 
So I’d like to dispel this myth, explain a little not about how each works, and talk about the sound differences. 

First off... what is this digital sound that nobody likes? Digital audio is very clean and precise. It’s it’s lack of noise that gives it a a reputation for being, uh, digital... whatever that is. Take tapes for example, the tape itself added hiss and a saturation type distortion, and people love the sound of tape. Some people love the sound of records, which are notoriously noisy, have low dynamic range, and limited high frequency response. And here’s the thing... digital can sound like that too... if you want it to. If you like the sound of tape, you can record your song to tape, and then record the song off the tape into digital. The digital version will sound identical to the tape version. A lot of studios actually do this. Same goes with the sound of an lp, you could directly record the stereo output into a computer, and it will sound identical to the record. So it’s not the sound of digital that people do t like, it’s the fact that digital sound is so clean that it is less “warm”sounding. Anyways, I’m getting off on a bit of a tangent... but it’s relevant. 

Because some people like the sound of noise in the signal. that’s the “analog warmth” that they are talking about. Low quality tube gear has a higher noise floor, and is not very high fidelity. Some people like this, and this is what gets attributed to “tube” sound. And it is tube sound, but here’s the thing, it’s not what tubes should sound like. 

As I mentioned in lesson 1.1 where I explain my philosophy is to put priority on fidelity, and purity. Once that is achieved, if you like the sound of noise and distortion added to the sound, then go ahead and add it, but do so with intention and control.

Tubes and their solid state counterparts, called transistors, are used in audio amplification. They are the primary component that causes the amplification. It is important to note, that they are but one component within a circuit which has many other components that also effect the sound. The other components in the circuit, all together, actually effect the sound more than the tube, or transistor. These other components are the power supply, which plays a huge role in the sound, the resistors and capacitors, which play a minor role in the sound quality, and the output transformer, which plays a moderate role in sound quality. Apart from the quality of individual parts, the circuit design is also a major factor. While there are only really 2 different circuit designs that are commonly used in amplification, there are infinite variations of these designs which give different sounds. Like a gas motor, they all have the same basic design using pistons to turn a crank shaft, but there’s a million different variations of that design. 

Within tube amps, there’s 2 different designs that have a very different sound. One sounds beautiful, the other sounds, well, not so good. The main thing that separates these 2 designs is the power supply. The good ones operate on over 150 volts, usually even over 200 volts. The cheap ones are called a starved plate design, which operate on around 50 volts. The starved plate design is a cheap way of implementing a tube into an audio circuit, and if does very little amplification while adding lots of noise to the signal. These preamps actually use solid state components to perform the amplification, and they stick a tube in there that is actually detrimental to the sound quality, but great for marketing. They call it a tube amp, and amateurs buy it and associate that crappy noisy sound to tube sound, and call it analog warmth. 
The other tube amp design is the good one, that uses a couple hundred volts or more going to the tube. Because of the higher voltage, an expensive power supply is required. Once they’ve dished out for a good power supply, at that point it’s worth it for the rest of the components to be high quality. These are the tube amps that have true tube sound, and that sound is clear and transparent. 

So to get a really nice sounding tube amp, you need several expensive components, such as the power supply, the tubes themselves, and the output transformer. A solid state amp operates at much lower voltages, and can sound really good while using parts that cost much less. 

I don’t want to say that one type of amp sounds better than the other, but at a given price point, a solid state amp will sound better than a tube amp. I think if we are talking cost no object, the best tube amp vs the best solid state amps, I prefer the tube, but it’s not a night and day difference. As a matter of fact, it’s a very tiny difference. 

There’s 2 things that cause this difference. Noise floor and distortion. This can’t be avoided, all amplifiers in existence have them both. The solid state amps have a lower noise floor, and less distortion. The tube amps have more noise, more distortion, but it’s a pleasant distortion that blends with the sound in a way that enhances it. Solid state is technically cleaner, and more precise amplification, but the distortion is more random, and therefore jarring, it’s unpleasant. 

Take this as an example. If I play a note on the piano, I can play 6 notes on top of it that sound nice, that’s like the tube distortion, it sounds nice. And solid state would be if I played less notes, let’s say just 3, but they are random. It does t sound as good.

And before I wrap up this lesson, I just want to mention another marketing tactic. Microphone preamps consist usually of 2 stages of amplification, an input stage, and an output stage. There are some “tube” preamps that are actually hybrids, and use a solid state for one stage, and tube for the other. If you really want a tube preamp, it should state “all tube design”. And with microphones, a proper tube design will have a dedicated power supply box. If it’s a tube that runs on phantom power, then it’s just marketing hype. The iSK 2b Beauty is a true tube microphone, it has an upgraded power supply that sends 220 volts to a high grade tube. It has that clear, transparent and simply beautiful sound that tubes are known for.