Duff Radio 404 FOUND

The Blog · 404 FOUND

We rebuilt the vinyl and 12-bit modes in 404 FOUND. Here's the research behind them.

Two research papers, the manufacturers' manuals, and a same-loop A/B.

By Ty McDuffey · The Duff Radio Dispatch · September 6, 2026

404 FOUND update: vinyl and lo-fi rebuilt off the SP-404, SP-1200, and MPC60.

TL;DR

  • Vinyl rebuilt: noise ducks under the music, pink instead of white, crackle like real dust
  • SP 12-bit: the top-end brightness we were filtering out is back
  • New MPC 12-bit mode, quieter and rounder
  • Already own it? The web app updated itself. Nothing to reinstall.

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The same loop, clean, then vinyl, SP 12-bit, and MPC 12-bit, with the measurements on screen.

We read 2 research papers and manufacturer's manuals to rebuild the vinyl and lo-fi effects for the new Duff Radio 404FOUND Sampler.

Here's what we studied and what changed since our initial launch.

Vinyl (modeled on the SP-404 and SP-303 vinyl sims)

The vinyl mode is now modeled on the vinyl sim from the SP-404 + the older SP-303. We read Roland's own manuals & a research paper on how record noise behaves... The vinyl noise now ducks under the music and comes back inbetween the gaps, like a real record.

Graph of the loop's loudness over time with the old noise level as a flat line and the new noise level dipping under each hit.
Amber is the music. Red is where the noise used to sit. Green is where it sits now, dipping under every hit.

We're now utilizing pink noise instead of white noise. White noise hisses like a TV, and we found pink sounds more like a record.

Graph comparing a flat white-noise line to a downward-sloping pink-noise line across frequency.
White noise is the same hiss at every pitch. Pink noise fades as it gets higher, like a record.

The vinyl "crackle" used to be simply three identical clicks a second. Now, it arrives randomly like real dust. It's mostly faint, with a few louder moments.

Two rows of spikes: the old row is six identical evenly spaced clicks, the new row is random spikes of varying height.
Old crackle: evenly spaced identical clicks. New crackle: random timing, mostly faint, a few loud.

Best on headphones.

Dry loop (reference)
Old vinyl (last week's build)
New vinyl

Hear it on your own records, free

SP 12-bit (modeled on the E-mu SP-1200)

Now modeled on the E-mu SP-1200. We read a Stanford study that measured the SP-12, the 1200's predecessor, and found the bright top end above 13 kHz the machine never filtered out. Our old lo-fi had a filter that removed exactly that range, so it sounded too much like a generic bitcrusher. Now, that brightness stays.

Bar chart of five frequency bands, old in red and new in green, with the two highest bands boxed to show the new version is louder there.
Measured on the loop in the video: the top two bands come back by about 8 dB. That's the SP sound.
Dry loop
Old lo-fi chain
New SP 12-bit

The difference lives above 12 kHz. Headphones or monitors, not a phone speaker.

MPC 12-bit, new mode (modeled on the Akai MPC60)

Modeled on the Akai MPC60. We pulled from Akai's manual and Roger Linn's own notes, storing samples as non-linear 12-bit at 40 kHz, built for lower noise.

Two ladders of horizontal lines: evenly spaced steps for the SP, and steps that bunch tightly near quiet for the MPC.
Even steps measure quiet sounds coarsely. The MPC's fine steps near quiet are why it sounds rounder.
Dry loop
MPC 12-bit

Already bought it?

Already bought the Duff Radio 404FOUND Sampler software? The web app updated itself. Grab the new standalone from your Gumroad library.

What we read

  1. Yeh, Nolting, Smith. “Physical and Behavioral Circuit Modeling of the SP-12 Sampler.” ICMC 2007, Stanford CCRMA.
  2. Moliner, Välimäki. “Realistic Gramophone Noise Synthesis using a Diffusion Model.” DAFx 2022, Aalto University.
  3. Roland SP-404MK2 Reference Manual, 404 VinylSim.
  4. Roland SP-404MK2 Reference Manual, 303 VinylSim.
  5. Akai MPC60 Operator's Manual, Technical Specifications, and Roger Linn Design's MPC60 FAQ.

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