A human's guide to digital storage.

^{(How many songs can I fit on my music player)}

^{You can find a table of Astell & Kern models and their respective song capacities at the end of this article.}

You're buying a portable music player. You want something to escape the hustle and bustle of the bus, the office, uni, or maybe you just want something to help you drift off to sleep.

Astell & Kern offer a wide range of portable music players that do just this. These range in quality, but in general offer a high quality music playing experience, easy to use interface, and are music players only. No email, no messaging, no distractions.

One of the other areas in which they differ is storage. This ranges from 16GB of onboard storage on the CT10, through to a whopping 512GB on the brand new SP2000. But what does this really mean? Is 16GB heaps already, or do you need more? What is on-board storage? Let's take a quick look.

Onboard vs. external storage

Onboard storage is digital storage or memory that is permanent in the device. It can't be removed, and as such is included when you purchase the device.Onboard storage is often referred to as internal storage.

External storage is storage that can be removed from the device. This is often in the form of an SD or Micro SD card (Secure Digital), but technically extends to things like USB thumb drives, flash drives or even external hard (disk) drives.

In this article I will be referring mostly to internal, onboard storage, as well as external storage in the form of micro SD cards.

Bits and Bytes

Digital storage is expressed by its capacity. These days, most storage is listed as either Gigabytes (billions of bytes) or Terabytes (trillions of bytes).
One byte = 8 bits. No, really. Half a byte is a nybble. I'm not making this up.

Okay, but if we go back to 16GB of storage, what does this really mean? How many songs or albums can I put on this? It depends.

Formats

Digital music comes in a range of different formats. You'll likely be familiar with MP3, or at least have heard of it. But there are quite a few others. FLAC, WAV, AAC, ALAC. These are all different types of codecs (code - decode) which operate in different ways. Ultimately, they do the same thing, just at varying qualities and with varying rates of compression.

.WAV

This is a fully uncompressed, lossless file type that is almost always 1411Kbps. That is kilo (thousand) bits per second. And this is because most music is recorded and mastered to be 16bits at 44,100 samples per second, meaning 16 * 44,100 = 705,600. As most of listen to things in stereo, or two channel, we then multiply that by 2 which gives us 1,411,200 bits, or 1411.2Kbps.

No compression, no loss. If we apply this to a 5 minute song, we end up with 423,360 kilobits or (8 bits in a byte) /8 = 52920 kilobytes, /1000 is equal to 52.92 megabytes.

If we take a look at that 16GB again, which is 16,000 megabytes we can fit roughly 300 songs or 25-30 albums, assuming an average 10 songs per album.

.FLAC & ALAC

FLAC, or Free Lossless Audio Codec is a lossless, yet compressed version of wav. As it is lossless, it theoretically should sound identical to .wav. Yet, its compression means it can take up significantly less space.

FLAC is often a variable bit rate, meaning that is can range from ~500Kbps through to ~900Kbps. The compression is more or less effective based on the music's signal.

ALAC is simply Apple Lossless Audio Codec and is very similar to FLAC. ALAC is supported by iTunes and Apple music, whereas FLAC is not.

As it is on average half the data rate of .wav, we can simply double the amount of songs per GB.
16GB stores around 600 songs or between 50 to 60 albums.

MP3

MP3 (Moving Picture Experts Group-3, MPEG-3) is a lossy, compressed codec. As such, MP3 takes up very little space as it uses a lossy compression. The downside is that it reduces the overall dynamic range of your music. Compared to FLAC or WAV, MP3 can sound a bit lifeless, or lacking things like 'soundstage' and 'presense' and other ambiguous, undefined words. MP3 effectively limits the amount of high frequency information making it sound a bit 'closed in'.

MP3 ranges from between 128kbps through to 320Kbps. At this level, the differences can be quite audibly obvious, especially if the gear you are using is of a high quality, such as the Astell & Kern players.

MP3's are often 10-20% the data rate of .wav, meaning only 10-20% its storage requirements. This means roughly 3000 songs for our 16GB of storage, or 250-300 albums.

Astell & Kern offer a massive range of audio players. These all offer some level of onboard storage and the ability to expand using external storage. Based on a 5 minute song average, at a rate of 700Kbps we can expect the following song capacity on Astell & Kern's range: