How did musicians acquire samples for tracker music (MOD, S3M, XM and the like)?

Question

Many songs in the so called "tracker" format quite popular in the early 90s (think .MOD, .S3M, .XM, .IT and the like) seemingly used sound samples from real synthesizers. This sometimes could also be seen in the sample names in the tracker music files featuring brands such as Korg or Roland.

As many of those tracker songs were written by enthusiasts, how did they manage to grab those samples? Did they really plug a synthesizer's audio output into a line input of a sound card and digitize the analog sound? But were audio cards of the early 90s at all capable of capturing analog audio at reasonable quality?

Or did they find a way to somehow dump the keyboard firmware and/or reverse engineer sample banks provided by the keyboard vendor and convert the samples into a format that could be understood by Scream Tracker / Fast Tracker (or whatever tracker music editor they used)?

Answer 1

I composed a small number of Amiga tracker modules at around the turn of the 1990s, one of which even enjoyed some popularity. These songs were made, first and foremost, for my personal amusement — for exploring music creation and sequencing on a personal computer — but they also ended up being used in some demoscene productions.

My tools of choice were, at first, Oktalyzer (see here as well), and later ProTracker (see here as well).

For the very first experiments, I used whatever sounds were available to me. The instrument samples were borrowed from tracker modules made by other people or originated from the famous ST-## instrument sample disks, originally meant to be used with Karsten Obarski’s Soundtracker, the forefather of ProTracker.

I then spotted this ad in a computer magazine for an Amiga-compatible sound digitizer device. It was a black, nondescript plastic box — a bit larger than a pack of cigarettes — which plugged into the printer (parallel) port on the back of the Amiga. It had a single mono RCA input and a trimmer knob for adjusting the input level. There was also a DE-9 cable for a connection to the joystick port which it used for powering itself. That’s about it.

It was quite similar to this device (more information):

The audio editor I mostly used with it was Aegis AudioMaster:

See this video showing the AudioMaster in action. I never utilized this tool’s built-in sequencing capability, though, but only used it for acquisition and for cleaning up the instrument samples. The actual songs were composed in the tracker programs.

I also used the internal samplers and audio editors built into some trackers, but I tended to use AudioMaster (an external tool) the most.

The audio digitizer device was 8-bit, and only supported monophonic sound, but it was a perfect match for the Amiga capabilities since the Amiga sound hardware had four 8-bit sound channels. (Of course, I would later learn that oversampling and better-than-8-bit dynamics during acquisition would yield better results when downsampled to the target format. But at the time, the Amiga hardware was all that I had for working with sound.)

You would not normally have used stereo samples due to the limited disk and memory resources and the limited number of sound channels (polyphony) available in the hardware so the audio digitizer being mono only was not really a hindrance.

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With the hardware and software in order, I then started digitizing instrument samples from commercially-published songs. These tended to be contemporary (late 1980s, early 1990s) pop and rock music published on C cassettes. Many songs had intro sequences or breaks from where you could get great, clean drum or bass samples. I also sourced some nice strings or pads with usable major and minor and other chords.

A great deal of effort went into finding suitable loop points for sustained sound without it clicking or popping, especially for the strings and the pads. The audio editors had some tools which made this easier, such as functions for finding zero points in the waveform. But a good result would only come by experimenting and listening to how it sounds.

I then started borrowing keyboards from my friends for the purpose of methodically growing my instrument sample library. I used everything I could get my hands on — from cheap entry-level Casios to actual synthesizers, samplers, and drum machines. A friend of mine had an Ensoniq sampler and an Alesis drum machine which were treasure troves.

In the end, the instrument samples in my sample library came from three sources — other people’s sound tracker modules (some of the instrument samples other people had made were just too good to dismiss), self-digitized from compact cassettes containing commercial music and popular songs, and self-digitized from synthesizers and consumer keyboards. I also digitized my own voice a couple of times.

I can no longer recall the purchase price of the audio digitizer device but I’d estimate it was maybe something like €20 or €30 in today’s money. Certainly not a professional thing at any level but worked fine for the purpose it was made.

There’s this nice video from “debuglive” on YouTube which describes the very process:

https://www.youtube.com/watch?v=i9MXYZh1jcs

Answer 2

The four main ways were:

• you knew someone with the sampling card or sampler (many of samplers had the capability to sample sound in CD quality and save it to floppy disk).
• you bought some kind of "sample bank"
• you simply grabbed sounds from other MODs
• you generated fully artificial sound by math algorithms and computed sample data (e.g. simple sawtooth or sine wave, AM/FM modulated with LFO, filtered, envelopes, etc.) The 90s computers have no power to do it real-time, but it was possible to pre-computed in lower quality and then re-compute in full quality

Answer 3

Did they really plug a synthesizer's audio output into a line input of a sound card and digitize the analog sound? But were audio cards of the early 90s at all capable of capturing analog audio at reasonable quality?

Samplers existed even for low-end machines. I remember using a sampler on my Amiga 500. It was 8-bit, but so are the .MOD samples, and sample rate on the Amiga is limited to 28 kHz per channel too.

On IBM-PCs with a high-end sound card, it was probably possible to get 16-bit/higher sample rate (then convert to 8SVX or whatever).

To create good samples from those keyboards, you had to record the samples with a sampler:

• using different octaves (different octaves often mean different sounds, plus strecting the sample rate will yield mediocre results). Doesn't apply to drum/percussion samples.
• for strings or piano, you had to record chords to avoid wasting module channels (often limited to 4, with a stretch at 7 or 8 but with extra CPU power)
• for strings/leads, you had to make sure the looping point was at the same level as the starting point, else the sample could "click" when looping
• using different note attacks (if you really wanted that the instrument sounded good)

Very rarely, what was possible was to record from real songs, for instance when the drums/instrument is alone on the track.

I also remember buying an audio CD with a lot of sampled sounds from known keyboards and rythm units. Those could be extracted to .wav and converted, or just sampled (wasteful, but converting to .wav wasn't easy before the CD-ROM era).

Or did they find a way to somehow dump the keyboard firmware and/or reverse engineer sample banks provided by the keyboard vendor and convert the samples into a format that could be understood by Scream Tracker / Fast Tracker (or whatever tracker music editor they used)?

That would be difficult and not practical because a sound is often not a sample but a mix of sample + effects. For instance, if you press a key very strongly, the keyboard could issue another sample or a mix of 2 samples because the attack is different (for instance a piano).

Now MT32 emulators exist (for instance munt) and the MT32-like roms have been dumped, but it's still difficult to convert the samples from this data.

Answer 4

But were audio cards of the early 90s at all capable of capturing analog audio at reasonable quality?

Kind of yes, but...

There is relatively little "information" in audio above 10kHz, and you can even go lower than that with many sources. You can certainly recognise presence, absence, or distortion in those higher frequencies, but voice and instruments are perfectly recognisable and clear. The sound will be a little "dull", but in the context of 8-bit audio this was never a problem in principle. As with Dr Johnson's dog, the wonder is not that it does it well, but that it does it at all!

With higher frequencies though, they cause aliasing if they go into the sampler. The effect of aliasing is to give a "reflected" frequency from half the sample rate, so if you sampled at 20kHz and you stuck signals at 11kHz, 12kHz and 13kHz into a sampler then you'd record aliased signals at 9kHz, 8kHz and 7kHz. Basically this gives you all sorts of distorted junk you don't want unless you cut hard at half your sample rate.

8-bit sampling also was not a problem in principle. An interesting feature of sampled sound is that its quality depends as much on dither as it does on bit depth. Appropriate dither adds "hiss", but also recreates the signal properly. The UK audio industry magazine SoundOnSound had a great article about digital sampling where they reduced a piano recording to 3-bit sampling, and with the correct dither it was still perfectly audible.

In practise though, one problem for all sampled audio in the 80s was that anti-aliasing was not well understood - or even when understood, the technology did not exist to filter higher frequencies well enough to prevent aliasing. And the other problem was that dither was also not well enough understood, and at 8-bit or even 16-bit depth the resolution is bad enough that you need it. The result was that sampled recordings suffered for the lack of both these features.

This is why early CDs in the 80s got such a bad reputation for their sound. There was nothing in principle wrong with CDs or with CD players, and the myth of CDs and players having any kind of "sound" is provably mathematically wrong. (The truth is that analogue playback media does have a "sound", and what you hear from a CD is accurate playback without the distortion that vinyl or tape will always add.) Where things went wrong in the early days was with the sampling stage, because the electronics of the day didn't have adequate anti-aliasing and the mastering stage generally didn't include dither. This was mostly solved by the 90s, but the myth persisted.

TL;DR: Audio cards were capable of capturing that audio at reasonable quality; but they often should have had an extra analogue filter on the way in, and the recording needed dithering adding. And awareness of those two features back in the 80s was very low. So sampled audio often did not use those audio cards to the full extend of their abilities.

Answer 5

How did I get samples for the amiga without access to bboards and specialised equipment? Well I played my favourite games/demos and if I liked some music I heard I flicked the amiga off and on again. I then loaded AudioMaster IV as seen above and you could visually hunt through the memory for areas that 'looked like' sounds (i.e. not random noise) as the memory hadn't fully cleared from toggling the power. Then use the Audiomaster IV editing tools to 'cut' the sample, and save it to a floppy

Now how good this was for my amiga, or how ethical it was well hmm... but I amassed hundreds of samples doing this back in the 90s :-)

Answer 6

Mostly I stole them from other people's mods!

For original samples (like all the vocal stuff in Online Pizza), I asked my dad to buy a cheap microphone, then plugged it into the mic port of our PC's soundblaster card, and used the software supplied with the mic to record to WAV.

The trouble is that 8-bit samples in WAV are stored unsigned whereas MOD samples are stored signed. I had no idea how two's complement worked, but after a lot of experimentation I wrote a Turbo Pascal program to strip the header and convert the samples. The quality wasn't ideal, but that was fine for techno!