“Bit Crushers” -- introducing a special little effector

I will continue to introduce effectors for which I’ve received requests since the last time. ( Previous article: "Dimension Chorus" -- introducing a special little effector)
This time it's the Bit Crusher, also known as a gaming effector.

I’m kidding, I’ll be serious.

Bit Crushers are often used in home recording rather than for guitar or bass.
A detailed explanation of the function is as difficult as last time, but the simple answer is that they "reduce the resolution of the sound and make it sound like an old gaming console".
They have a squishy retro sound and have been well-received by a small number of players. But as usual, they’re rarely sold in a stomp box format, and I've only seen two available.

Here they are.

MOOER / LoFi Machine

The bit crusher from MOOER.
The logo is printed with dots and I feel that this is the image of the effect.
It has been optimized for guitar, bass, and synthesizer, and the appropriate mode can be selected with a toggle switch.
The center knob controls the bit depth and the right knob controls the sampling frequency (more on these two later).
For some reason, it costs more than 20,000 yen if you buy it from an online shop other than Sound House.

ROWIN / CRUSH BIT

Click here for Rowin's bit crusher.
The MOOER and Rowin have the same housing, knob position, and jack position. The only different function is the operation of the toggle switch.
Rowin’s has HP/BP/LP printed on it. This is an abbreviation for high-pass / bypass / low-pass, and the output range can be switched.
The center knob controls the sampling frequency, and the right knob controls the bit depth.
This also costs more than 10,000 yen anywhere else but Sound House.

■ Theory: What is happening in the effect?

First, let's think about the digital sound itself.
Keywords such as “bit depth” and “sampling frequency” are used.

Bit Depth is also known as sound resolution.
There is a separate sampling frequency that determines the resolution of the sound along with the bit depth.
As anyone who does home recording knows, X bits and Y Hz are set for the digitized audio format.
The general ones are the 16bit/4,4100Hz CD standard and the 24bit-4,8000Hz DVD standard, and these numbers allow you to understand the fine details of the sound.
(Since it may be confusing, you can skip the part in parentheses, but if you multiply the sampling frequency value by the bit depth value, it gives you the bit rate, which is a unit that expresses the quality of audio data.)

These two numbers are written as "1 second is divided by Y times (= Y Hz), and the sound pressure at that time is expressed in 0 steps".
The number of bits is not the number as is, but the stage of 2 to the X power.

In other words, the CD standard "divides 1 second 44,100 times, and the sound pressure at that time is expressed in (2 to the 16th power =) 65,536 steps", and the DVD standard "divides 1 second 48,000 times". The sound pressure at that time is expressed in (2 to the 24th power =) 16,777,216 steps. "

It will be easier to understand if you look at the actual split waves. I am including a simplified graph this time as well.

Suppose this is the waveform of the original analog input. Since the analog waveform has virtually no break in sound pressure or time, it can be regarded as an infinite Hz infinite bit digital signal. By the way, the waveform of this graph is y = (10sinx) / x.

The bit depth is on the vertical axis and the sampling frequency is on the horizontal axis. If this is "divided into half the grid as one unit and the half grid is represented by the depth as one step", it looks like this. Of course, the wave cannot pass through the exact point of this unit, so it is rounded off and treated as the closest point, just like an electronic circuit.

I omitted it because the depth will be 0 from the middle, but when I connect the points, a wave that is smoother than the original graph is created.
This is an (extreme) example of lower bit depths and lower sampling frequencies.
And this is exactly what Bit Crusher is doing.
The main function of the bit crusher is that “the output bits and sampling frequency are lower than the bits and sampling rate of the input sound".
Bit crushers are effectors that produce a unique sound quality by degrading sound in a direction that cannot be produced when modern equipment is used.

By the way, game consoles such as the Famicom and Gameboy have only 8bit = 256 steps of depth and a sampling frequency of about 33000Hz.
The processing power of old processors was low, and there were restrictions on the sound that could be produced per second.
This means that the amount of information is less than 1/256 of that of a CD per same time, and the sound quality is about that level.

I made some sample sound sources this time as well. The bit rates will gradually decrease.
Be careful of the volume when playing, as it is a rustling sound and high-pitched sounds are likely to be produced. Earphones are not recommended.
Since the effect of the bit crusher is hard to work in the low range, the drop rate of the sampling frequency is adjusted only for the bass.

♪Omens of Love / T-Square

Bypass (24-bit, 48000Hz)

24-bit, descent rate: low

12-bit, descent rate: medium

8-bit, descent rate: high

4-bit, descent rate: high

That's it for this time.
Next time is about effectors with built-in vacuum tubes.

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