Tone Journal

There’s no definitive answer as to why Lou Reed made Metal Machine Music. Landing in 1975 between the pop albums Sally Can’t Dance and Coney Island Baby, the record spawned a mythology all its own: some read it as a deliberate purge of the pop audience his recent fame had won him, others read it as a “f**k you” engineered to break his RCA contract (though he tellingly stayed on the label). Reed himself denied all of it to the end, insisting it was a purely artistic act—born, in his words, out of love for guitar-driven feedback.¹

Experimenting with SynthStamp

Enter the B500. We’d been experimenting with continuous sampling and a melody sequence playing underneath when the results tipped into something uncannily familiar: guitar pitched up and dragged back down, phrases folding over themselves, chaotic breaks ripping across the top. A cacophony, but not an aimless one—the same controlled-noise territory Reed staked out in 1975. The difference is in the making. He assembled his in the studio, guitars leaned into amps, tape sped up and slowed after the fact; ours arrived live, in a single take, direct to video with SynthStamp.

Here’s how we did it:

1. (Stereo) Audio Input

Start by configuring your audio input for mono (L + R) or stereo (L / R). Note that mono is configured by selecting the same source for both left and right channels, the signal is combined and optimized internally.

2. Memory Sequencing

Next, add a melody sequence, Normal mode will suffice. You can just start plunking away on the keyboard and by default quarter notes will populate. For something more interesting try changing the rhythmic pulse by adjusting the duration of groups of notes. In this case, pitch doesn’t matter as much because you’ll be playing back a live buffer of whatever you’re playing on guitar, and unless you plan on sticking to modal scales, dissonance is mostly unavoidable.

3. Continuous Sampling

And that brings us to Continuous Sampling. Though not a formal circuit bend, it falls within the same ideology. On the actual instrument you can set up a continuous trigger on the sampler, ideally corresponding to the full buffer duration of 1.4s, then add a custom input route for line level audio, and voilà. The bonus here is that not only does the keyboard play back realtime audio at different sample rates, you can combine this with a note sequence in memory for hands-free operation of the sampler. This allows focusing on live audio input, which for this purpose is the guitar. Playing along with the sampler as your audio gets drastically modified by a repeating note sequence is like having a conversation with yourself.

Needless to say, we think the results sound pretty close to Metal Machine Music. Or Pachinko.² It’s time to explore your sonic potential.

¹ Doran, John. “Lou Reed Interview: Metal Machine Music Revisited” The Quietus, October 28, 2013, https://thequietus.com/interviews/lou-reed-interview-metal-machine-music/. Accessed July 6th, 2026.

² Pachinko In Your Head: Non-Linear Music. Blue Rahn Studio. Celestial Harmonies, 1998.

We’d like to take a moment to introduce you to the B500. A synth both internally and externally modeled after a popular sampler from the mid-80s. The reason for its popularity was primarily its cost. For $100 in 1985 ($300 in 2026), this sampling keyboard could be yours. That was a fraction of the cost of the nearest competitor, but it also came with a caveat—audio quality was low-fidelity. Over time this sampler was relegated to the toy bin in most stores and minds, eventually experiencing a resurgence, again due to its affordability. This time, hackers, creatives, and engineers ventured to open things up and started tweaking circuits to find new sounds. It wasn’t until Reed Ghazala coined the term Circuit-Bending in 1992 that a movement had been realized.¹

Circuit Bending

Circuit bending is an exploratory art. The premise being that the deeper you go, the more interesting things get. For instance, you could audition every combination of patch capable between analog and digital sections, or try connecting them all in different configurations, or in different combinations of one, two, or three patches, or… you get the picture. And while certain patches will become familiar sounds that you can internalize and reach for with your new sonic vocabulary, there’s always one more sound to be discovered. Whether it’s a new combination of patches, a specific patch that you hadn’t yet tried, or a new sample that happens to sound more interesting when bent with a specific patch, or all of the above, the quest never ends.

Tapping on the orange Circuit Bending button in the B500 will open up the Circuit Bending view. There are three sections that can be patched, representing different features of the synthesizer circuit: analog, digital, and clock. Analog routes can be used to bypass filtering for more gain, connect outputs to inputs for feedback, and route to digital and clock sections to impact address, data, and/or timing functionality with control voltage like behavior. Note that analog-to-digital connections are represented with an orange wire. Digital-to-analog connections are represented with a blue wire. They are treated differently. Also note that bending does not have an effect on synthesized tones, and only the clock section impacts rhythm playback.

Experimental Musical Instruments

For those just beginning their journey, there is a treasure trove of information available on the internet. Take a moment to flip through a few pages of Experimental Musical Instruments.² This is the first page where the term Circuit-Bending is said to have originated. The magazine dates back to 1985, and Ghazala has stated that his interest in manipulating electronics for experimental purposes started as early as the late 60s. It’s important to distinguish the idea of non-standard instrument making for the purposes of sound exploration from bending instruments that already exist to create sounds that the original designer did not intend. While there is sonic overlap and sympathetic interests between the two fields, they are distinct.

And really, this is a new frontier for SynthStamp. The idea that we can model real instruments in a way that permits dynamic connections similar to those made when bending an instrument. Does this inspire you to want to bend other instruments? Are you content with the B500 as a unique one-of-a-kind tool in your plugin kit? Or do you want more?

¹ Ghazala, Reed, Circuit Bending: Build Your Own Instruments, Wiley Publishing, Inc., 2005, p. 12.

² https://archive.org/details/emi_archive/0-START-HERE/