Lesson 82

Fidelity of Analog Gear

As part of my philosophy of achieving purest sound, the quality, or fidelity of analog gear plays a large role.
So what am I even talking about when I say fidelity, or sound quality? I suppose it’s a little hard to explain... but this is a video, so let me show you.
Here’s a recording, sounds nice right? So now I’m going to run it through a bunch of analog gear, with the settings fairly neutral, and record it back in. Do you hear the difference? I hope so. It’s not pleasant.
In order to really understand what’s going on here, we need to look under the hood, right at the electronic circuits, to understand where the loss of quality is.
Within most audio circuits, you will have 1 or more amplification stages, and probably an output transformer. You remember lesson 1.4, how Sound flows as electrical fluctuations of voltage? Well, an amplification circuit basically works by replicating the original signal at a higher voltage. Like taking a picture of a picture, but with a bigger and higher resolution camera. Some of the fine details will get lost. Also, there’s generally a tiny amount of static noise created that gets amplified along with the signal. This noise is sometimes not noticeable, but it’s always there to some extent. When you have a song with many parts, all competing to be heard within a limited audio spectrum, having noise embedded within tracks takes away from the ability to give distinction to some of the quieter parts. 
In the context of a song that does not have many parts, like say acoustic guitar and vocals, having noise in the signal does not matter as much. But, when you have many parts all competing to be heard, noise in the signal will use up precious sound space, and it will be more difficult to hear all the parts distinctly. This is a bit difficult to explain, so let’s put it into example.

Here’s a song with just piano and vocals (you were there for me). If I put each part through a couple analog compressors, here’s what they sound like before and after. Not a big difference right? Now using these new tracks to mix a final song, there’s still not a big difference, it still sounds good.

But towards the end of the song, where it’s a more dense mix, what happens if we add just a little bit of noise to each part? As you can hear, the whole mix is muddy, and you can’t hear the subtle parts. Feel free to download the tracks for your own mix practice and experimentation.

So that’s why fidelity is important. Every piece of analog gear will cause noise and signal degradation, but high quality gear will cause less.

So what is it within a circuit that causes this noise and degradation? Well, it’s many things.

Let’s start with the power supply. Audio circuits run on DC voltage. But, usually, they get their power from being plugged into an AC outlet. The power supply will convert the AC to DC. Usually though, the power supplies aren’t perfect, and there’s still traces of ac current. This will cause noise that will go through the amplifier and get louder. 
Another source is the actual amplifier device. This can be a either a tube, or a transistor. This is the component which replicated the signal at a higher voltage. Some tubes are better than others, and some transistors are also better than others. 
Then, there’s the output transformer. This provides 2 functions. It provides the optimal output impedance, and it balances the signal. A transformer is basically a coil of wires right next to another coil of wires. What happens is when the ac signal of audio is passed through the one coil, it jumps over to the other coil. It’s not voodoo.. it’s called induction. Making transformers is an art form by itself. It involves what type of metal the wires strands are made from, their thickness, the number of coils, their distance apart and many more properties. It’s a long and complicated story that I don’t even understand, so to make it short, let’s just say the transformer effects the sound quality.

So what equipment should you be concerned with?
Well, any electronics that touch the audio signal. If you have only a microphone plugged into an interface, then the interface will have an input circuit, and a preamp. Those effect sound quality.
If you are plugging your guitar into an amplifier, the quality of the amplifier will make your guitar sound smooth and pleasant, or muddy. Even if you crank up the distortion, some amps will have a nice distortion, and some will be messy. And keep in mind, every time your guitar signL goes through a pedal.. there’s signal degradation, so keep your pedals to a minimum.

Usually, Anywhere where there is a volume control there is an amplification stage, so if your acoustic guitar is plugged into a reverb pedal with volume control, and a nice Amo that has an input volume and an output volume. That’s 4 gain stages the signal goes through. 
Or, if you are recording vocals with a condenser, or tube microphone through an analog eq and an analog compressor... here’s all the gain stages the signal goes through
1- in the microphone itself is a built in amplifier
2- the preamp will have at least one gain stage, many have 2
3- the eq will have an amplifier for the output.
4- most compressors have an input gain (amplifier)
5- most compressors an output gain, which is an amplifier

So in this example, the signal passes through 5 independent amplifiers. So unless the gear is very high quality, you would likely be better off to use plugins for the ear and compression.