Jooyoung Kim

Basics of Mixing – 9.2 Saturation of Transistors and Vacuum Tubes

Hello, I’m Jooyoung Kim, an audio engineer and music producer. I’ve been quite busy lately, and my blog posts have been delayed…^^;;

Today, I want to talk about the saturation effects of transistors and vacuum tubes.

Shall we get started?

First of all, why do we use transistors and vacuum tubes? Let’s start with this question. Why exactly are they used?

In the past, they were found in speakers, amplifiers, and even microphone preamps used by musicians—basically everywhere. The primary reason we use them is to “amplify” small electrical signals.

Now, I believe you understand why components like vacuum tubes or transistors are included in speaker power amps, integrated amps, microphone preamps, and why they are called “amps” in the first place.

In my previous post, “[Link – 9.1 Harmonics and Saturation],” I explained from a non-linear signal perspective why harmonics are produced when signals pass through these devices.

Let’s dive into how these harmonics are generated.

W. Bussey and R. Haigler, “Tubes versus transistors in electric guitar amplifiers,” ICASSP ’81. IEEE International Conference on Acoustics, Speech, and Signal Processing, Atlanta, GA, USA, 1981, pp. 800-803, doi: 10.1109/ICASSP.1981.1171205.

The image above is from a 1981 paper titled Tubes versus Transistors in Electric Guitar Amplifiers. It shows the response of electric guitar amps that use vacuum tubes or transistors.

The graph on the left shows the frequency response, while the one on the right displays harmonic distortion. It’s clear how different they are, even without further explanation.

**References**
O., H. R. (1973). *Tubes Versus Transistors – Is There an Audible Difference?* Journal of the Audio Engineering Society, 21, 267–273.

If you search online for Tubes Versus Transistors – Is There an Audible Difference?, you’ll find this paper. It’s originally an AES paid article, so if there’s any issue with the image, I’ll remove it…^^;;

Anyway, the top left graph shows two triodes (vacuum tubes), and the top right shows two pentodes (vacuum tubes). The bottom left graph combines capacitors and transistors, while the bottom right combines transformers and transistors.

So, what is this measuring? It’s measuring harmonic distortion based on input level. Rather than focusing on specific meanings, it’s enough to note that they are all very different.

If each vacuum tube and transistor has different harmonic distortion characteristics, is it really meaningful to define sound solely based on whether it’s a tube or a transistor? In my view, it’s not that significant.

What’s important for music production, in my opinion, is not differentiating between these categories but understanding how each specific device affects sound individually.

This is a microphone preamp with a vacuum tube… Doesn’t it make sense that different brands of tube preamps have their own distinct characteristics?

As an equipment enthusiast, I find myself trying to understand each piece of gear one by one, and my bank account… well… haha… ha… ha…

To make matters worse, I also play instruments, so it’s quite the struggle… I’ve been hunting for a second-hand bass recently because I’ve decided to play bass myself. It looks like I’ll be carrying this gear addiction with me for the rest of my life.

That’s it for today. In the next post, I’ll discuss the saturation effects of tape 🙂

Sonnox Vocal Production Bundle Sale (~10/20, $64.9)

Hello, I’m Jooyoung Kim, an audio engineer and music producer.

Sonnox is currently offering a great deal on a bundle of vocal processing plugins, so I thought I’d share this with you.

Buy Sonnox Vocal Production Bundle at Plugin Boutique

(If you purchase through the link above or any of the other links below, I receive a small commission, which greatly supports the maintenance of this blog!)

This bundle includes three plugins designed specifically for vocal processing:

Claro: EQ and stereo width control
Vox Doubler (Widen, Thicken): Vocal doubler
Voca: A processor combining compression, saturation, and de-essing

Let’s take a closer look at each, starting with Claro.

Claro

Sonnox’s Claro is a clean and highly functional EQ and stereo width enhancer. You can use it in a simple “Produce” UI, as shown above, or in a more detailed “Tweak” UI that includes a spectral analyzer.

Each frequency band features labels below for negative terms and above for positive ones, making it intuitive even for beginners to use.

Additionally, you can view frequencies in a keyboard format, which can be very familiar and useful for composers.

What impressed me the most about Claro is that you can view the EQ settings applied to other tracks simultaneously!

Moreover, you can adjust the EQ for those other tracks directly within this interface. This is an incredibly innovative feature.

For tracks that experience masking issues and don’t cut through the mix, you can quickly locate the interfering frequencies and make adjustments, significantly streamlining your workflow and saving time.

Claro’s competitor is clearly FabFilter’s Pro-Q3, but considering that you get two additional plugins for just $64.9, it’s a fantastic deal.

Although it’s not a dynamic EQ, it’s the first EQ I’ve seen that also allows width adjustment, making it a plugin I’m seriously considering as my main EQ from now on.

Vox Doubler

The Vox Doubler includes two plugins: Thicken and Widen. The difference is that Widen creates two separate mono tracks, one for each side, while Thicken produces a single stereo track.

While the difference is subtle, it’s perfect for background vocal doubling to emphasize the chorus parts.

Voca

Voca is essentially an all-in-one channel strip. In the compression section, the left/right parameters labeled as “Squish” work like a ratio, and the “Stable” parameter functions similarly to a threshold.

In the saturation section, “Saturate” controls the amount of coloration, while “Focus” adjusts the EQ curve (higher settings boost lows and highs, while lower settings emphasize the midrange).

The “Soften” parameter acts as a de-esser, specifically targeting the area around 5kHz. You can think of this as a versatile all-in-one effect.

Additionally, if you purchase plugins from Plugin Boutique this month, you’ll receive either a “Solina” synthesizer, which focuses on string sounds, or Zynaptiq’s Orange Vocoder Nano.

Exploring This Month’s Free Plugins on Plugin Boutique

Both are incredibly useful plugins, so be sure to claim them if you make a purchase.

That’s it for today’s post. See you next time~!

Basics of Mixing – 9.1 Harmonics and Saturation

Hello, I’m Jooyoung Kim, an audio engineer and music producer.

Today, I’d like to talk about two crucial aspects of sound: harmonics and coloration. As audio engineers, we know from experience—and from measurements—that the audio signal changes when it passes through hardware or plugins.

For example, why do sounds processed through vacuum tubes and tape machines end up so different from each other?

It’s a topic worth considering for anyone involved in sound production: how exactly does the signal change, and why?

Of course, if it sounds good, that’s all that matters. But if we take that approach, we could say the same for EQs and compressors—if it sounds good, it’s good enough, right?

That said, this chapter will focus on explaining the devices that introduce coloration to sound.

When an analog audio signal passes through analog devices, harmonics are generated due to the non-linear behavior of these devices.

For example, when components like transistors (such as OP Amps) or vacuum tubes are part of the circuit, they create non-linear responses in the output, which results in harmonic distortion.

Legendary Marinair Transformer used in Neve Hardware (Photo from AMS Neve)

If you’re a fan of hardware, you’ve probably heard the term “transformer.” When you insert a transformer like the one shown above at the input or output stage of hardware, it creates non-linearities that result in harmonics.

This is why different components alter the character of a device, and why those who modify gear often swap out transformers, tubes, or transistors!

Why do non-linear behaviors generate harmonics? We could explain this through Fourier analysis, but I’ll spare you the math to keep things interesting.

(If you’re curious, look up non-linear systems and functions.)

If you’ve studied music, you might recall learning about harmonics and harmonic series in class. Generally speaking, even-order harmonics sound more harmonious and pleasant, while odd-order harmonics tend to create dissonance and can sound harsher.

So, if a device emphasizes odd-order harmonics, it will sound sharper. On the other hand, if it emphasizes even-order harmonics, it will blend more smoothly into the mix.

Now, are there analog devices that exclusively boost even or odd harmonics? Not really.

UA 1176LN Legacy Plugin that boosts only odd harmonics

As shown above, you’ll find this kind of control in plugins, but not in analog hardware.

Additionally, because of non-linear responses, the levels of second, third, fourth, and other harmonics also vary in non-linear ways.

So how should we understand these devices? Do vacuum tubes and transistors have unique characteristics?

We’ll continue exploring these questions in the next post.

Purchased the Wharfedale D310 4-inch Passive Speakers

Hello, I’m Jooyoung Kim, a mixing engineer and music producer.

A while back, I wrote about connecting passive speakers after I picked some up for free (though I haven’t covered that here on this English blog yet. I’ll make time to write about it soon).

Unfortunately, the ones I found picked up too much external radio interference, so I ended up throwing them away.

But, I still had my old Inkel amp sitting around unused, and I kept thinking it was a shame to waste it. So when I found these Wharfedale D310s for a bargain price, I decided to buy them.

These speakers retail for just $129 overseas, but each one weighs 2 kg, which is pretty hefty for its size.

For audio hobbyists and engineers alike, weight can tell you a lot about a speaker. A heavier build usually means the enclosure is well-designed, and you can expect decent quality woofers and tweeters.

I bought these mainly to refresh my ears when they get fatigued, so sound quality wasn’t my top priority. But the weight alone gave me a good impression.

Interestingly, these speakers have their ports placed underneath. I initially planned to flip them upside down so the tweeters would sit at ear level, but that idea fell apart once I noticed the design.

To my surprise, the sound quality was much better than I expected. At this price point, it made me question why anyone would insist on using active speakers from the pro audio world.

These are also well-shielded, so I didn’t notice any external radio interference. And since these are passive speakers without built-in amps, they have more freedom in the port design, which seems to result in better bass compared to typical 4-inch active speakers.

Even after adding in the cost of my old, cheap Inkel amp, the total was under 200,000 KRW ($150). Compared to similarly sized active speakers, these are a much better deal.

Of course, adding in cables and other extras could push the cost up a little, but you need cables for active speakers too.

I already knew Wharfedale had a reputation for making budget-friendly products, but my personal bias was shattered once again.

The build quality is a bit lacking, but if you look at active speakers in pro audio, it’s often the same. So, I don’t see it as a big issue, especially since this is clearly an entry-level model.

I strongly recommend that musicians challenge their biases and give passive speakers a try. You might be surprised at what you find.

That’s all for today. See you in the next post!

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Claro

Vox Doubler

Voca

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