Hello.

This blogpost is an appendix to my "Raw Buffers" sound library, where I will detail a few things about working with and recording the setup and some words on the inspiration behind it.

You can buy the library over at ASoundEffect.com

And watch a short introduction video here

Overview

1. The Discman's anti-skip buffer
2. Recording the setup
3. If you want to try it out for yourself
4. Inspiration and listening suggestions

1. The Discman's anti-skip buffer

The library consists of an approach I've worked with for a number of years by now, which involves short-circuiting the anti-skip buffer chip on a Discman to harvest the resulting glitches.

A slew of Discman units from a particular period includes a chip that will continiously record the disc playback output to a buffer, which will be used to avoid gaps in playback when you take your discman out and about, leave it shaking in a bag or accidentally hit it, which would, without the buffer chip, most likely make it stop audio playback for a moment until it picks up again. With the anti-skip buffer chip implementation, it will play back from the buffer once audio playback from the disc will stop, leaving the Discman ample time to catch up and resume regular playback.

Why is this exciting? Because that means you, given the Discman model, can probably mess with this buffer chip to create some wonderfully abrasive and unpredictable glitch sounds.

Simply short-circuting the legs on this chip will result in a whole manor of various digital glitches when the contents of the buffer is scrambled, overloaded and probably receiving unexpected data.

Read more about the technology on Wikipedia.

The technology and implementation goes by different names depending on the CD player manufacturer. Electronic skip protection, anti-skip, anti-shock and so forth.

Let's have a look at how the library was recorded.

2. Recording the setup

This Discman unit has been partly disassembled to allow me to comfortably reach the anti-skip buffer with a wire. This particular Discman model is a Technics SL-XP490 from 1995, where the buffer chip is located to the right from the display when the top shell has been removed, which is a particularly useful location, since I can reach it even when a disc has been mounted and is playing. More on this in the next sections.

I simply record the stereo output straight from the discman into a Sound Devices MixPre-D, then to audio interface at 192kHz/24 bit.

The buffer glitches can get dangeroulsy loud and abrasive, so it can be hard to gain stage it correctly, which is why I have the MixPre-D sitting inbetween the source and my audio interface; it has analogue limiters built in.

Previously I've recorded takes with my own audio material burned on a CD-R and then scrambled with the buffer chip, but for this library release I wanted the harvest the glitches themselves and not the mangling of other material in the buffer - mostly just pure self-sustained glitches.

But I will need a disc to be read by the Discman for the system the engage and play back, so I had to render out a portion of 44.1 kHz/16 bit recording of digtial silence and burn it to disc, which in itself is an activity that makes you ponder your life for a few minutes. I also burned a disc with some pure synthesis waveforms on it, to get some material to mangle without it imparting too much of a sonic footprint to the glitches.

As the disc is playing on the discman, I actively short-circuit (circuit bend if you will) the legs of the buffer chip to listen to what happens.

Pops, crackles, loud beeps, distortions.

These are recorded and edited into longer sections in Reaper based in the type of glitch it is; intensity, crackle, beep, scramble and so on and rendered out. These are marked with metadata wavmarkers for better overview during the future design process.

Given the small footprint of the chip, it is very difficult to just physically touch one leg and short circuit it with another. Most of the time I am most likely actually connecting 4 or more legs at once, which makes this very unpredictable, even if you spend quite a lot of time with it.

You do get a sense of control after a while, knowing that certain connections usually result in a specific sound, but it's not always the case. Sometimes nothing happens, sometimes everything happens all at once. Sometimes you seemingly have to fill the buffer up before it will start to glitch out. Through a lot of experimentation, I think I've learned how to somewhat reliably flush the buffer. Skipping to a new track or starting the current one over mostly seems to flush the buffer and reset it into a stable, non-glitching state.

Depending on the Discman model, you might be able to find the full manual online and see the schematics for it, which will allow you to see the I/O for the chip, but it might not matter a whole lot if you are exploring glitches, but it's nice for educating yourself.

3. If you want to try it out for yourself

A few notes and pointers if you want to try this approach out for yourself:

Stay safe

I am not an electronics expert and I am not sure if there are any possible dangers connected with this. I don't think there should be, but I almost always run the Discman off batteries instead of power supply when doing these recordings. Better safe than sorry.

At your own risk

Once again, I have no real idea whether this could potentially harm your Discman unit. I want to say there is not if you stick to only shorting out the anti-skip buffer chip, but during your explorations you might feel adventurous and brave, so you start connecting to other chips and soldering points - as one does.

I have pretty solidly crashed the Discman unit a few times from doing this (with the display simply saying "Sorry" and shutting off) when connecting to other ICs and soldering points during my explorations. Who knows, maybe you can completely brick the unit from doing this. It's at your own risk.

Watch your ears

The volume spikes from these glitches can get, as mentioned, very, very loud. So please make sure you are monitoring and recording at safe levels and with proper limiters set up.

Researching discman models before purchase

As mentioned in earlier sections, the anti-skip buffer implementation varies - and so does the physical location of the chip.

I have another Discman at my disposal, a Sony ESP 2, which has a limiter built-in, which is very handy for these experiments, but I almost never use it for these experiments as the buffer chip is located underneath the PCB, which means I have to entirely disassamble it, both top and bottom casing, and flip it over to be able to reach the chip during playback, which is cumbersome and fiddly.

The picture is from 2023, where I recorded a video about it. I made a mount for it out of some Meccano pieces, but it wasn't pretty and isn't really ideal.

My advice is to see what units you can buy used, locally or online, and see if the technical schematics are available online, so you can see where the chip is placed and the size of it.

I can only assume the newer the model mean smaller the chipsize, which might make this approach even more difficult if you want to short out specific chip legs - but surely not impossible.

The screenshots above is from the Technics SL-XP490 manual, which shows one side of the unit's PCB. So reading through the manual, identifying the IC name and figuring out where it us can be very useful.

I bought the Technics Discman for these experiments back in 2017-18 and I didn't know all of these things back then, so the fact that the buffer chip was accesible right next to the display was pure luck. But it might be of use to someone reading this who is going in with no experience.

4. Inspiration and listening suggestions

The inspiration behind this approach is primarily glitch music from the late 90s and early 2000s, where artists would manipulate CDs to harvest glitches and arrange these into new material.

For example, Markus Popp/Oval would scratch and write on CDs with felt pens to disturb the CD player's read mechanism, resulting in stutters and glitches. Popp's work is very dear to me, especially those first first few albums, such as Systemisch, 94diskont and ovalcommers.

https://oval.bandcamp.com/album/systemisch-remastered-2013-reissue https://oval.bandcamp.com/album/94diskont-remastered-2013-reissue https://oval.bandcamp.com/album/ovalcommers

On the more abrasive side of the spectrum of inspiration, we have Yasunao Tone's "Solo For Wounded CD", where everything is sourced from scratched CDs. Released on John Zorn's Tzadik label (where he has released some seriously great albums by seriously great artists throughout the years).

https://www.youtube.com/watch?v=CEDi-39o5qw https://www.discogs.com/release/408846-Yasunao-Tone-Solo-For-Wounded-CD

(Note: RIP to Yasunao Tone. He passed away as I was putting this library together)

Another big inspiration when I started exploring this was Nicolas Collins and his approach to manipulating hardware and software.

https://www.nicolascollins.com/texts/cdhacking.pdf

It provides great insight into his thoughts and the history of similar approaches. Worth a read.

The more immediate inspiration came from a Youtube video that I can't seem to find again. I think I found it back in 2016-17. A person had made a break-out banana patchbay for a Discman to connect the buffer chip legs, which was really great. I too tried to make a similar patchbay, but soldering wires for the small buffer chip was a big pain, so I scrapped it and resorted to just doing it with a little wire by hand, which often resulted in me shorting multiple legs and getting more unpredictable results.

5. Goodbye

Gaining access to those sounds was a tiny revelation for me and opened up a world of fun. So after a few years of exploring these sounds on and off, I thought I'd record a proper library of this for myself to use - and for others to enjoy as well.

I hope this provides some insight into my approach to this setup.

I've tried to provide some insight into things that I could have used when I started exploring this. But you'll manage without it. It just requires time and patience.

Get in touch by email if you need some further assistance with this and I'll try to get back to you when I can.

Thanks for reading.